rsc macrocyclic and supramolecular chemistry meeting 16 - 17palladium(ii) metallosupramolecular...
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RSC Macrocyclic and Supramolecular Chemistry Meeting
16th
- 17th
December 2019
The organisers than the generous support of the following sponsors:
Practical Information
Venue
The lecture and poster programme will take place in the Sibson building (Lecture Theatre 3).
Tea, Coffee and Lunch will be served in the Sibson Foyer on both days.
The meeting dinner will be held in the Darwin Conference Suite.
Poster sessions will be also be held in the seminar rooms on the group floor of the Sibson Building.
Buses
The Unibus service (Uni 1 and Uni 2) runs every 8-15 minutes and bus service 4 runs every 30 minutes, all from Canterbury Bus Station (Bay B1). All services stop at the University campus and both railway stations. Alight at the bus turning circle on University Road.
Parking
Please park cars in the designated Visitor Car Parks – P (see campus map on the next page) to avoid being fined.
Taxis
The main taxi rank on campus is situated on University Road outside the Venue/ Student Media Centre. Local taxi services provide accessible vehicles and offer both male and female drivers.
Local Taxi operators:
Canterbury Taxis: 01227 444 444
Longleys Cab Company: 01227 710 777
Cab Line 6: 01227 666 666
Cabco Taxis: 01227 455 455
Programme: RSC Macrocyclic and Supramolecular Chemistry Meeting
University of Kent: 16th - 17th December 2019
Event harassment officers: Cally Haynes, Anna McConnell and Claudia Caltagirone
Monday 16th December 2019
09.30-10.20 Arrival, registration, poster setup, coffee
10.20-10.30 Welcome and opening remarks
Session 1 Chair: Chris Hawes
10.30-11.20 Plenary 1: Phil Gale (University of Sydney)
New insights into anion transport mechanisms: voltage-gating,
pumps and HCl selectivity
11.20-11.50 Invited 1: Emily Draper (University of Glasgow)
Using Self-Assembly to Tune Chromic Behavior
11.50-12.10 Talk 1: Barry Blight (University of New Brunswick)
Tuning Chromaticity by Second-Sphere Coordination of
Iridium(III) Complexes
12.10-12.15 Flash 1: Tanya Ronson (University of Cambridge)
Self-assembly of a 5-fold interlocked [2]catenane
12.15-12.20 Flash 2: Simon Lewis (University of Bath)
Azulenes – Colorimetric and Fluorogenic Reporter Motifs for
Chemical Sensing of Analytes of Biological Interest
12.20-12.25 Flash 3: Le Fang (Queen Mary University of London)
A modular ‘click-SNAr-click’ approach to develop subcellular
localised fluorescent probes to image mobile Zn2+
12.25-12.30 A brief word from some of our sponsors
12.30-12.45 MASC AGM
12.30-13.30 Lunch and poster session
Session 2 Chair: Ben Pilgrim
13.30-14.00 Invited 2: Helena Shepherd (University of Kent)
Smart Molecular Materials: From Synthesis & Structure to
Properties & Applications
14.00-14.20 Talk 2: Sarah Pike (University of Bradford)
Development of hybrid foldamers: an innovative class of
anticancer therapeutics
14.20-14.40 Talk 3: Sander Wezenberg (University of Nijmegen)
Supramolecularly directed rotary motion in a photoswitchable
anion receptor
14.40-15.30 Plenary 2: Mike Ward (University of Warwick)
Chemical catalytic properties and photophysical properties of a
coordination cage host
15.30-16.10 Tea/Coffee
Session 3 Chair: Alyssa-Jennifer Avestro
16.10-16.15 Flash 4: Gareth Lloyd (University of Lincoln)
Dynamic Covalent Chemistry coupled to Self-Assembly
16.15-16.20 Flash 5: Larissa von Krbek (University of Cambridge)
Allosteric regulation of anion exchange in an Fe4L6
tetrahedron
16.20-16.25 Flash 6: Benjamin Egleston (University of Liverpool)
Controlling the properties of porous liquids
16.25-16.30 Flash 7: Robert Pow (University of Glasgow)
Embedding electron-rich -systems within an Icosahedral
Inorganic Fullerene
16.30-17.00 Invited 3: James Crowley (University of Otago)
Palladium(II) Metallosupramolecular Cages: Self-assembly and
Molecular Recognition
17.00-18.00 Bob Hay Lecture: Kim Jelfs (Imperial College London) Evolutionary Discovery
of Molecular Materials
18.00-19.30 Poster Session Sibson
19.30 Bar Opens Darwin Conference Suite
20.00 Conference Dinner Darwin Conference Suite
Tuesday 17th December 2019
Session 4 Chair: Timothy Barendt
09.00-09.50 Plenary 3: Tanja Weil (Max Planck Institute for Polymer Research)
TBC
09.50-10.10 Talk 4: Anna Slater (University of Liverpool)
Exploiting flow synthesis and self-sorting for molecular materials
10.10-10.25 Industrial 1: Marcus Winter (Rigaku)
10.20-10.45 Tea/Coffee
Session 5 Chair: Anna McConnell
10.50-11.10 Talk 5: David Magri (University of Malta)
A Lab-on-a-Molecule with an Enhanced Fluorescent Readout on
Detection Of Three Chemical Species
11.10-11.30 Talk 6: Nick Evens (University of Lancaster)
Interlocked Molecules for Useful Applications
11.30-12.00 MASC PhD award lecture Steve Fielden (University of Manchester) Weaving,
Rotating and Threading: Novel Self Assembly and Controlled Molecular Motion
12.00-13.00 Lunch and poster session
12.30-13.00 WISC network meeting all invited
Session 6 Chair: Tim Easun
13.00-13.30 Invited 4: Peter Knipe (Queens University)
Foldamers Coming Full-Circle
13.30-14.20 Plenary 4: Tony Davis (University of Bristol)
Synthetic Lectins – The Host-Guest Chemistry of Carbohydrates
14.20-14.40 Tea/Coffee
Session 7 Chair: Steve Goldup
14.40-14.50 Award of Oral and poster prizes
14.50-15.10 Industrial 2: Catherine Wark (BMG Labtech)
15.10-16.00 Plenary 5: Dave Leigh (University of Manchester)
Making the Tiniest Machines
16.00-16.05 Chris How ERC MASC 2020
16.05-16.10 Anna Slater MASC 2020
16.10-16.20 Closing remarks
A Welcoming Environment for all at MASC2019 The MASC2019 organizing committee is dedicated to providing a harassment-free
conference/meeting experience for everyone regardless of gender, gender identity and
expression, sexual orientation, disability, physical appearance, body size, race, age or religion.
The organizing committee will not tolerate harassment of conference participants in any form.
This includes sexual language and imagery which is not appropriate for any conference venue,
including talks. Conference participants violating these rules may be sanctioned or expelled from
the conference without a refund at the discretion of the conference organisers. The full anti-
harassment policy is described below.
Our Anti-Harassment Policy
Event organisers have identified Cally Haynes, Anna McConnell and Claudia Caltagirone as
designated persons to deal with any harassment complaints. Alongside the organizing committee,
these individuals will deal with alleged harassment issues in a private, unbiased and timely
manner, providing appropriate sanctions if required that include:
• Warning the offender and requiring them to desist.
• Expulsion from the conference with no refund.
• Recommend the banning of the offender from future MASC events.
Harassment includes, but is not limited to:
• Verbal comments that reinforce social structures of domination related to gender, gender identity
and expression, sexual orientation, disability, physical appearance, body size, race, age, religion.
• Sexual images in public spaces.
• Deliberate intimidation, stalking, or following.
• Harassing photography or recording.
• Sustained disruption of talks or other events.
• Inappropriate physical contact.
• Unwelcome sexual attention.
• Advocating for, or encouraging, any of the above behaviour.
Programme Abstracts
Session 1 Plenary 1
New insights into anion transport mechanisms: voltage-gating, pumps and HCl selectivity
Philip A. Gale
School of Chemistry (F11), The University of Sydney, NSW 2006, Australia
Email: [email protected] Web: www.supramolecularchemistry.net
Biography:
Phil Gale is Head of the School of Chemistry at the University of Sydney. Phil is a graduate of the University of Oxford (MA DPhil 1995 DSc 2014) and after two years as a Fulbright Scholar at the University of Texas at Austin (1995-1997) took up a Royal Society University Research Fellowship at the University of Oxford and then subsequently the University of Southampton where he served as Head of Chemistry (2010-2016). Phil is a supramolecular chemist who works on the molecular recognition, sensing and transport of anionic species. In recent years, his work has focused on the transmembrane transport of anions across lipid bilayer membranes. Phil has published 280 primary research papers, review articles, book chapters and books and is a Clarivate Analytics Highly Cited Researcher in Chemistry. He has received a number of awards for his work including the 2018 Izatt-Christensen Award in Macrocyclic and Supramolecular Chemistry, the 2014 RSC Supramolecular Chemistry Award, a Royal Society Wolfson Research Merit Award (2013) the RSC Corday Morgan Medal and Prize (2005) and the Bob Hay Lectureship (2004). Phil is the editor-in-chief of Coordination Chemistry Reviews and Supramolecular Chemistry and a member of the advisory boards of Chem. Sci., Chem, Chem. Soc. Rev., Trends in Chemistry and Chinese Chemical Letters.
Abstract:
The development of synthetic anionophores continues to be the focus of a number of groups worldwide due to the potential application of these compounds in the treatment of diseases caused by faulty anion transport (e.g. cystic fibrosis)1 and in disrupting anion concentration gradients and pH gradients leading to apoptosis and disruption of autophagy.2
In this presentation, the development of selective transporters will be described,3 and how this led to the production of a chloride pumping system capable of creating an anion gradient across a lipid bilayer.4 The synthesis and complexation properties of new tetraurea macrocycles will also be discussed.5 A fluorinated version of this macrocycle rivals the natural product prodigiosin in its ability to selectively transport HCl across lipid bilayers but in contrast to the natural product, the macrocycle’s anion transport properties are voltage-gated.6 The mechanism of this process will be discussed.
This work was supported by the EPSRC (EP/J009687/1), the Royal Society and the Wolfson Foundation, the Australian Research Council (DP180100612) and the Universities of Southampton and Sydney.
References:
1. P.A. Gale, J.T. Davis and R. Quesada, Chem. Soc. Rev., 2017, 46, 2497-2519; H. Li, H. Valkenier, A.G.
Thorne, C.M. Dias, J.A. Cooper, M. Kieffer, N. Busschaert, P.A. Gale, D.N. Sheppard and A.P. Davis, Chem. Sci., 2019, DOI: 10.1039/c9sc04242c.
2. N. Busschaert, S.-H. Park, K.-H. Baek, Y.P. Choi, J. Park, E.N.W. Howe, J.R. Hiscock, L.E. Karagiannidis, I. Marques, V. Félix, W. Namkung, J.L. Sessler, P.A. Gale and I. Shin, Nature Chem., 2017, 9, 667-675;S.
Cheung, D. Wu, H.C. Daly, N. Busschaert, M. Morgunova, J.C. Simpson, D. Scholz, P.A. Gale and D.F. O’Shea, Chem, 2018, 4, 879-895;S.-H. Park, S.-H. Park, E.N.W. Howe, J.Y. Hyun, L.-J. Chen, I. Huang, G. Vargas-Zuñiga, N. Busschaert, P.A. Gale, J.L. Sessler, I. Shin, Chem, 2019, 5, 2079-2098.
3. X. Wu, L.W. Judd, E.N.W. Howe, A.M. Withecombe, V. Soto-Cerrato, H. Li, N. Busschaert, H. Valkenier, R. Perez-Tomas, D.N. Sheppard, Y.-B. Jiang, A.P. Davis and P.A. Gale, Chem, 2016, 1, 127-146.
4. E.N.W. Howe and P.A. Gale, J. Am. Chem. Soc., 2019, 141, 10654-10660. 5. X. Wu, P. Wang, P. Turner, W. Lewis, O. Catal, D.S. Thomas and P.A. Gale, Chem, 2019, 5, 1210-1222. 6. X. Wu, J.R. Small, A. Cataldo, A.M. Withecombe, P. Turner and P.A. Gale, Angew. Chem. Int. Ed., 2019, DOI:
10.1002/anie.201907466.
Session 1 Invited 1
Using Self-Assembly to Tune Chromic Behavior
E. R. Draper, L. Gonzalez, R. Randle and J. J. Walsh
School of Chemistry, University of Glasgow, Glasgow, UK.
Email: [email protected] Web: www.drapergroup.wordpress.com
Biography:
Emily Draper is currently a Lecturer in Chemical Robotics and Automated Synthesis at the University of Glasgow, UK. She holds a Leverhulme Trust Early Career Fellowship and a Lord Kelvin Adam Smith Leadership Fellowship working on aligning self-assembled materials for organic electronics. She completed her PhD at the University of Liverpool in 2015 working on functional gels, before continuing on as a PDRA. She moved to Glasgow in 2016 as a PDRA working on organic photovoltaics before starting her Fellowships in August 2017. Emily then started a Lectureship position at Glasgow in November 2018 before taking time off to have her first child in January 2019. She is enjoying the challenge of being a new mother and an early career researcher (most of the time...). Her research interests include organic electronics, chromic materials, self-assembly, and combining computational and experimental based approaches for materials design.
Abstract:
Chromic materials are used in everyday items from cosmetics to diagnostics. They are of appeal as they provide a visual response to a stimulus with no need for interpretation or training. We are looking at using small organic molecules that self-assemble to be used as chromic materials, in particular for photochromism and electrochromism to be used in displays.
Session 1 Talk 1
Tuning Chromaticity by Second-Sphere Coordination of Iridium(III) Complexes
B. Balónová, B. A. Blight*
Department of Chemistry, University of New Brunswick
Email: [email protected] Web: https://blightba.wixsite.com/blightresearchgroup
Biography:
Associate Professor Barry Blight completed his studies in Canada at Mount Allison University (BSc) and Western University (PhD). He held a Marie Curie (IIF) Fellowship in Prof David Leigh’s research group in Edinburgh, followed by an NSERC PDF in Canada at Queen’s University with Prof Suning Wang. Barry’s first academic appointment was a lectureship at the University of Kent (2013) in the School of Physical Sciences. He then moved to the Department of Chemistry at the University of New Brunswick (2017) in Canada.
Abstract:
Iridium complexes (with various N^C ligands) are undergoing intensive investigation, due to their excellent performance when used as emitters in phosphorescent organic light emitting diodes (PhOLEDs). To fulfil the requirements of full-colour OLED displays, the colour regulation (towards blue, green and red emissions) is highly desirable.1 In this study, we are exploring the colour tuning of different iridium emitters by host- guest assembly with DNA base-pair-like interactions in super strong hydrogen bonded arrays.2 The ideal interactions for holding supramolecular systems together are hydrogen bonds, as they combine relatively strong intermolecular attractions with excellent reversibility. Our findings suggest that this methodology for colour tuning can negate the synthetic manipulation of the ligand structure around iridium,3 which is often costly and time consuming. We are analysing the chromaticity of iridium complexes by simply varying the concentration of compliment-guest (Figure 1),4 while examining the strength of binding and change in the emission properties. This approach focuses on supramolecular chemistry combined with synthesis, which can lead to novel materials with dynamic properties.
References:
1. A.F. Henwood, E. Zysman-Colman, Chem. Commun. 2017, 53, 807. 2. B.A. Blight, C.A. Hunter, D.A. Leigh, H. McNab, P.I.T. Thomson, Nature Chemistry, 2011, 3, 246. 3. B. Balónová, D. Rota Martir, E.R. Clark, H.J. Shepherd, E. Zysman-Colman, B.A. Blight, Inorganic
Chemistry, 2018, 57, 8581. 4. B. Balónová, H.J. Shepherd, C.J. Serpell, B.A. Blight, Supramolecular Chemistry, 2019,
DOI: 10.1080/10610278.2019.1649674
Figure1.Left: Solutions of Ir complexes with aliquots of guest component under UV-light (365 nm), right: Structure of studied Ir complexes hydrogen bonded with guest molecule.
Session 1 Poster 1, Flash 1
Self-assembly of a 5-fold interlocked [2]catenane
T. K. Ronson, Y. Wang, K. Baldridge, J. S. Siegel and J. R. Nitschke
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
Email: [email protected] Web: www.ch.cam.ac.uk/person/tr352
Abstract:
We have previously reported the formation of a variety of different three-dimensional metal-organic architectures using subcomponent self-assembly. This approach relies upon metal template effects to generate complex structures from simple molecular precursors through the formation of both dynamic-covalent (C=N) and coordinative (N→M) linkages allowing a large increase in molecular complexity to be achieved in a single reaction step.1,2 Three-fold symmetric subcomponents have been used to self-assemble M4L4 tetrahedra,3 M12L12 icosahedra4 and M6L4 octahedra5 while four-fold symmetric subcomponents have been used to self-assemble M8L6 cubes6 and M12L6 cuboctahedra.7 To date five-fold symmetric ligands have not been employed in subcomponent self-assembly and remain rare in coordination chemistry.8 Here we report the subcomponent self-assembly of a five-fold interlocked [2]catenane comprised of two [Cu5L2]5+ cages. Formation of the catenane is driven by π−π stacking interactions between corannulene-based ligands. The new structure was characterised in the solid state through X-ray crystallography and in solution though NMR spectroscopy and mass spectrometry.
Two views of the X-ray crystal structure of a 5-fold symmetric [2]catenane.
References:
1. T. K. Ronson, S. Zarra, S. P. Black and J. R. Nitschke, Chem. Commun., 2013, 49, 2476.
2. T. K. Ronson, D. Zhang and J. R. Nitschke, Acc. Chem. Res., 2018, 51, 2423.
3. D. Zhang, T. K. Ronson, J. Mosquera, A. Martinez, L. Guy and J. R. Nitschke, J. Am. Chem. Soc.,
2017, 139, 6574.
4. R. A. Bilbeisi, T.K. Ronson and J. R. Nitschke, Angew. Chem. Int. Ed. 2013, 52, 9027.
5. F. J. Rizzuto, W.-Y. Wu, T. K. Ronson, J. R. Nitschke, Angew. Chem. Int. Ed. 2016, 55, 7958.
6. W.J. Ramsay, F.T. Szczypiński, H. Weissman, T.K. Ronson, M.M.J. Smulders, B. Rybtchinski and
J.R. Nitschke, Angew. Chem. Int. Ed., 2015, 54, 5636.
7. F. J. Rizzuto and J. R. Nitschke, Nat. Chem. 2017, 9, 903.
8. S. Pasquale, S. Sattin, E. C. Escudero-Adán, M. Martínez-Belmonte and J. de Mendoza, Nat.
Commun. 2012, 3, 785.
Session 1 Poster 2, Flash 2
Azulenes – Colorimetric and Fluorogenic Reporter Motifs for Chemical Sensing of Analytes of Biological Interest
L. C. Murfin, M. Weber, C. M. Lopez Alled, W. T. Kim, S. J. Park, C. McMullin, C. L. Lyall, G. Kociok-Köhn, S. D. Bull, K. C. X. Lin, G. Williams, J. Wenk, A. T. A. Jenkins, J. Yoon, H. M. Kim, T. D. James* and S. E. Lewis*
Department of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
Abstract:
Azulene is a non-alternant bicyclic hydrocarbon that has a dep blue colour and an unusually high dipole for a hydrocarbon. It is also an example of a fluorophore that violates Kasha’s rule, since its main mode of fluorescence emission is from the S2→S0 transition. The absorption and fluorescence emission spectra of azulenes are very susceptible to the influence of substituents attached to the ring. We have exploited this fact to design and synthesise colorimetric chemosensors that are able to detect the presence of various inorganic contaminants in water, such as fluoride and mercury. Such chemosensors are applicable to drinking water safety monitoring in regions of the developing world where remote communities are affected by such contaminants. A second aspect of our work concerns the development of fluorescent probes for bioimaging, wherein we have synthesised various “AzuFluor” molecules that are applicable to two-photon fluorescent microscopy of reactive oxygen species in cells.1
References:
1. J. Am. Chem. Soc. 2019, ASAP, doi:10.1021/jacs.9b09813
Session 1 Poster 3, Flash 3
A modular ‘click-SNAr-click’ approach to develop subcellular localised fluorescent probes to image mobile Zn2+
Le Fang, Christopher R Jones, and Michael Watkinson
The Joseph Priestley Building, School of Biological and Chemical Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
Email: [email protected]
Abstract:
Zn2+ is involved in a number of biological processes and its wide-ranging roles at the subcellular level, especially in specific organelles, have not yet been fully established due to a lack of tools to image it effectively. We report a new and efficient modular double ‘click’ approach towards a range of sub-cellular localised probes for mobile zinc. Through this methodology, endoplasmic reticulum (ER), mitochondria (Mito) and lysosome (Lyso) localised probes were successfully prepared which show good fluorescence responses to mobile Zn2+ in vitro and in cellulo. The methodology appears to have wide-utility for the generation of sub-cellular localised probes by incorporating specific organelle targeting vectors for mobile Zn2+ imaging.
Scheme 1 a) The synthetic route towards the sub-cellular targeting Zn2+ probes; (b) the structures of probes.
References:
1. Le Fang, Giuseppe Trigiante, Rachel Crespo-Otero, Michael P. Philpott, Christopher R Jones and Michael Watkinson. Org. Biomol. Chem., 2019, DOI: 10.1039/c9ob01855g.
2. Le Fang, Giuseppe Trigiante, Rachel Crespo-Otero, Chris S. Hawes, Michael P. Philpott,
Christopher R Jones and Michael Watkinson. Chem. Sci., 2019, DOI: 10.1039/c9sc04300d.
Session 2 Invited 2
Smart Molecular Materials: From Synthesis & Structure to Properties & Applications
H. J. Shepherd
Supramolecular, Interfacial and Synthetic Chemistry Group, School of Physical Sciences, University of Kent, Canterbury
Email: [email protected]
Biography:
Dr Helena J Shepherd graduated from the University of Bath in 2006 with an MChem, before moving to Durham University to study for a PhD under the supervision of Dr A.E.Goeta and Prof. J.A.K.Howard. In 2010 Helena moved to the Laboratoire de Chimie de Coordination (LCC-CNRS) in Toulouse, France for a three-year post-doctoral appointment. During that time she investigated the physics of the spin crossover phenomenon under pressure, and initiated a project concerned with novel applications for molecular materials as actuator devices. In 2013, Helena returned to the University of Bath for a post-doctoral position, before taking up the position of Lecturer in Chemistry at the University of Kent in 2015. Since 2018 Helena has been a Senior Lecturer and her research interests focus on synthesis and applications of molecules that change colour and shape in response to various environmental stimuli.
Abstract:
Molecules that change their colour, structure and electronic properties in response to an external stimulus represent an emerging class of ‘smart’ material with potential applications in sensing, actuating and responsive technologies. This talk will look at work within our group, from novel synthetic strategies and fundamental structure-property correlations of spin crossover materials to more recent results in the elaboration of organic molecular and polymeric switchable materials with a view towards application.
The Spin Crossover (SCO) phenomenon leads to a redistribution of electrons within the d-orbitals of some transition metal complexes as a result of an external perturbation. The transition between high spin and low spin states involves a significant change in volume and is often cooperative in crystalline materials due to the complex interactions between active centres. It results in dramatic changes in the optical, mechanical and magnetic properties. We have recently shown the application of mechanochemistry in the synthesis of SCO materials, allowing access to novel functional materials that are inaccessible via traditional solution-state synthesis.1 In this talk our latest results in this area will be presented, including the possibilities for post synthetic modification using mechanochemistry. The talk will also provide an overview of our collaborative work in understanding fundamental SCO phenomena using high pressure X-ray diffraction2 and the development of prototype applications of these materials in actuating devices.3,4
References:
1. J. H. Askew and H. J. Shepherd, Chem. Commun., 2018, 54, 180–183. 2. M. Mikolasek, M. D. Manrique-Juarez, H. J. Shepherd, K. Ridier, S. Rat, V. Shalabaeva, A. C. Bas,
I. E. Collings, F. Mathieu, J. Cacheux, T. Leichle, L. Nicu, W. Nicolazzi, L. Salmon, G. Molnár and A. Bousseksou, J. Am. Chem. Soc., 2018, 140, 8970–8979.
3. H. J. Shepherd, I. A. Gural’skiy, C. M. Quintero, S. Tricard, L. Salmon, G. Molnár and A. Bousseksou, Nat. Commun., 2013, 4, 2607.
4. I. A. Gural’skiy, C. M. Quintero, J. S. Costa, P. Demont, G. Molnar, L. Salmon, H. J. Shepherd and A. Bousseksou, J. Mater. Chem. C, 2014, 2, 2949–2955.
Session 2 Talk 2
Development of Hybrid Foldamers: An Innovative Class of Anticancer Therapeutics
S. J. Pike, Colin C. Seaton and R. M. Lord
Department of Chemistry and Biosciences, University of Bradford, Bradford, West Yorkshire, BD7 1DP, UK.
Email: [email protected] Web: https://www.bradford.ac.uk/chemistry-and-biosciences/
Biography:
I was appointed as Lecturer in Organic Chemistry at the University of Bradford in 2018 and earlier this year I was awarded a UKRI Future Leaders Fellowship which I will begin in Feb 2020.
Abstract:
Organic molecules obtained from natural sources are a prominent class of anticancer therapeutics and they have been widely employed to treat the disease but there are several drawbacks linked with their use including problems associated with resistance and lack of selectivity.1 The biological activity of a drug is directly linked to its structure but many natural organic anticancer therapeutics have highly complicated structures and this means that making structural changes in order to optimise their selectivity or overcome resistance is an extremely challenging process. These disadvantages severely limit their effectiveness at treating cancer and so the development of alternative organic drugs that can overcome these issues is an active area of research.
This research addresses these issues through the development of a new class of bioinspired organic anticancer drugs, based on organic helical oligomers (foldamers).2 These novel foldamers can be systematically modified in order to tune their biological activity and thus they can be readily optimised to overcome current problems of drug resistance and selectivity. This research establishes the link between the stable folded structure of this new class of anticancer drugs and their biological activity through systematic modification of principal structural features that govern their folding behaviour. This new generation of anticancer therapeutics are shown to display activity against a range of cancer cell lines and thus their potential to address some of the growing problems associated with drug resistance and selectivity of current therapeutics is demonstrated.
Figure 1. Crystal structure of a novel, hydrid foldamer highlighting the adoption of a helical structure in the solid-state.
References:
1. S. Fahs, Y. Patil-Sen and T. J. Snape, ChemBioChem, 2015, 16, 1840. 2. S. H. Gellman, Acc. Chem. Res., 1998, 31, 173.
Session 2 Talk 3
Supramolecularly Directed Rotary Motion in a Photoswitchable Anion Receptor
S. J. Wezenberg
Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden (The Netherlands)
Email: [email protected] Web: http://www.sanderwezenberg.com/
Biography:
Sander studied chemistry at the University of Nijmegen where he carried out his Master's research in the group of Prof. Roeland Nolte. He then moved to Tarragona for his PhD studies in the field of supramolecular chemistry with Prof. Arjan Kleij at the Institute of Chemical Research of Catalonia (ICIQ). During this period he spent three months as a visiting researcher in the group of Prof. Joseph Hupp at Northwestern University. After receiving his PhD in 2011, he joined the group of Prof. François Diederich at ETH Zurich as a postdoctoral fellow. He came to the University of Groningen in 2013 to work with Prof. Ben Feringa and was later appointed Assistant Professor. In 2019, He moved to Leiden University to establish his independent research group. His main research interests are in the areas of anion binding, molecular switches, and self-assembled materials.
Abstract:
Inspired by the wealth of dynamic and machine-like functions in Nature, chemists have developed different strategies to control motion in synthetic systems. However, unidirectional rotary motion, such as is observed in ATP synthase, is still enormously challenging to achieve.1 Current artificial rotary molecular motors are typically based on intrinsic asymmetry or specific sequences of reaction steps. By using a photoresponsive anion receptor,2,3 we have developed an alternative approach in which unidirectional rotation is induced upon binding of a chiral phosphate guest (Figure).4 As a result, the direction of rotation is governed by the guest chirality and can be selected and inverted at will. This feature offers unique control of rotary motion and will prove highly important in the further development of molecular machinery.
Figure: Rotational progress in the photoswitchable receptor in the presence of a chiral guest.
References:
1. S. Kassem, T. van Leeuwen, A. S. Lubbe, M. R. Wilson, B. L. Feringa, D. A. Leigh, Chem. Soc. Rev., 2017, 46, 2592.
2. M. Vlatković, B. L. Feringa, S. J. Wezenberg, Angew. Chem. Int. Ed., 2016, 55, 1001. 3. S. J. Wezenberg, B. L. Feringa, Org. Lett., 2017, 19, 324.
Session 2 Plenary 2
Chemical catalytic properties and photophysical properties of a coordination cage host
Michael D. Ward, Nicholas H. Williams, Julia A. Weinstein and Kellie Tuck
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
Email: [email protected] Web: https://warwick.ac.uk/fac/sci/chemistry/research/ward
Biography:
Mike Ward did his BA at Cambridge, studying Natural Sciences (1983-86). He remained in Cambridge for his PhD (1986-1989) with Ed Constable, studying some of the first examples of helicate complexes of transition-metal ions with polydentate ligands. After a post-doctoral year with Jean-Pierre Sauvage in Strasbourg playing with catenates, he started his independent academic career as a lecturer at Bristol in 1990. After 13 years there he moved to Sheffield in 2003, and after 14 years there he moved to the University of Warwick in 2017 where he is currently Head of Department. Mike's interests are all based around the coordination chemistry of transition metal and lanthanide ions and their multinuclear assemblies; in particular, current emphases in his research are on (i) self-assembly and host-guest chemistry of hollow metal/ligand cage complexes, and (ii) photophysical properties of polynuclear complexes and supramolecular assemblies, including applications in imaging and sensing.
Abstract:
An octanuclear cubic coordination cage host has been investigated for (i) its ability to catalyse reactions of bound substrates; and (ii) to effect photoinduced energy- or electron-transfer from the array of chromophores in the cage superstructure to bound guests. Chemical catalysis is based on the ability of the cationic (16+) cage to accumulate anions around its surface which brings them into close proximity to hydrophobic guests which bind in the central cavity in water. Several different substrates undergo reactions promoted by hydroxide ions including an E2 elimination reaction (Kemp elimination), phosphotriester hydrolysis, nucleophilic attack on dinitro-fluorobenzene, and an aldol condensation of indane-dione. Whilst some of the catalysed reactions are associated with strong binding of the substrate in the cage cavity, in other cases blocking the cavity with an inert inhibitor makes no difference to catalysis which we believe to be associated with the exterior surface of the cage.
In addition isostructural examples of this cage type can be prepared containing photophysically-active units in the cage: these are either phosphorescent Os(II) complex units at the cage vertices, or fluorescent naphthyl units incorporated into the ligands. Bound guests are therefore surrounded by a large number of chromophores in close proximity, and in several cases we have observed fast photoinduced electron transfer to the guests generating short-lived charge-separated states (host radical cation, guest radical anion) as a precursor to possible photo-redox catalysis in the cage cavity.
References:
1. M. D. Ward, C. A. Hunter and N. H. Williams, Acc. Chem. Res., 2018, 51, 2073. 2. J. S. Train, A. B. Wragg, A. J. Auty, A. J. Metherell, D. Chekulaev, C. G. P. Taylor, S. P. Argent, J.
A. Weinstein and M. D. Ward, Inorg. Chem., 2019, 58, 2386. 3. W. Cullen, M. C. Misuraca, C. A. Hunter, N. H. Williams and M. D. Ward, Nat. Chem., 2016, 8, 231.
4. W. Cullen, A. J. Metherell, A. B. Wragg, C. G. P. Taylor, C. G. P. Taylor, N. H. Williams and M. D. Ward, J. Am. Chem. Soc., 2018, 140, 2821.
Session 3 Poster 4, Flash 4
Dynamic Covalent Chemistry coupled to Self-Assembly
Gareth O. Lloyd, Cathryn O. Shepherd, Jamie S. Foster, Mary C. Jones
School of Chemistry, Joseph Banks Laboratories, University of Lincoln, Lincoln, LN6 7TS
Email: [email protected] Web: https://staff.lincoln.ac.uk/b3ff17db-4080-4f21-91bacf2c0c9ed8d6
Biography:
Senior Lecturer at the new School of Chemistry at the University of Lincoln. Educated in Zimbabwe, South Africa, and the United Kingdom more recently, supramolecular chemistry has become the mainstay of my research having worked with Profs. Len Barbour, Jon Steed, and Bill Jones. The research group is focused on developing supramolecular materials and assemblies through the application of dynamic reaction chemistry (coordination- and covalent-based systems chemistry).
Abstract:
Dynamic covalent chemistry represents a means to utilise equilibrium chemistry to “control” product distributions through thermodynamic distributions rather than kinetic, in part. The research group is utilising dynamic covalent chemistry to build supramolecular materials but also utilising supramolecular assembly to control the dynamic covalent chemistry outcome (equilibrium). To do this we are using well-studied imine and hydrazone chemistry, but also developing novel dynamic covalent chemistry of 1,3,4,2-dioxazaboroles (work by Cathryn Shepherd). This poster will present our latest results on 1,3,4,2-dioxazaboroles and their potential for sensing and self-assembly, and present our work on dynamic covalent chemistry to make monomers that form supramolecular polymers and their resultant gel materials (Figure 1, work by Jamie Foster).1, 2 Our most recent work is combining supramolecular polymerisation with chemical fuels to develop materials that are out-of-equilibrium or metastable (work by Mary Jones).
Figure 1. Dynamic covalent pathway of a simple 3:1 mixture of reactants (triangle represents the trialdehyde and the curves the hydrazide/amine periphery reactant) that can undergo three imine/hydrazide formations and/or tautomerisation. The control of reactions conditions (thermodynamics) and time (kinetics) means that three physically and chemically distinct materials can be made from this one starting mixture (*).
References:
1. J. S. Foster, J. M. Żurek, N. M. S. Almeida, W. E. Hendriksen, V. A. A. le Sage, V. Lakshminarayanan, A. L. Thompson, R. Banerjee, R. Eelkema, H. Mulvana, M. J. Paterson, J. H. van Esch and G. O. Lloyd, J. Am. Chem. Soc., 2015, 137, 14236.
2. J. S. Foster, A. W. Prentice, R. S. Forgan, M. J. Paterson and G. O. Lloyd, ChemNanoMat, 2018, 4, 853.
Session 3 Poster 5, Flash 5
Allosteric regulation of anion exchange in an Fe4L6 tetrahedron
L. K. S. von Krbek,+ D. A. Roberts,+ B. S. Pilgrim, C. A. Schalley, and J. R. Nitschke
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
Email: [email protected] Web: www.nitschkegroup-cambridge.com
Biography:
Larissa von Krbek received Bachelor and Master’s degrees in chemistry from the Freie Universität Berlin, Germany, in 2010 and 2012, respectively. With a fellowship of the German Academic Foundation (Studienstiftung des deutschen Volkes), she continued as a PhD student in the group of Prof. Dr. Christoph A. Schalley working on the thermodynamic analysis of multivalent crown-ether/ammonium systems and received her doctorate in November 2016.
In January 2017, Larissa joined the group of Prof. Jonathan R. Nitschke as a postdoctoral research fellow, where she is now working on stimuli responsive metal-organic cages and combining cages with classical supramolecular crown-ether/ammonium motives. In April 2017, Larissa was awarded a Feodor Lynen Research Fellowship of the Alexander von Humboldt Foundation in July 2017.
Abstract:
Precise control over guest uptake and release in molecular cages is necessary for applications in catalysis and chemical separations. We report a strategy for regulating the rate of internally-bound anion exchange within an FeII
4L6 metal-organic tetrahedron through external coordination of tripodal tris(alkylammonium) cations. The cage features three flexible 18-crown-6 receptors at each of its FeII vertices, facilitating strong tritopic interactions with the tris(ammonium) cations to effectively ‘cap’ the vertices of the tetrahedron. This vertex-capping mechanism restricts the flexibility of the cage framework, which drastically reduces the rate of anion exchange within its central cavity by 20-fold when tris(ammonium) cations are bound externally. We employ this property to demonstrate allosteric control over guest binding using a multivalent effector.
References:
1. L. K. S. von Krbek, D. A. Roberts, B. S. Pilgrim, C. A. Schalley, J. R. Nitschke, Angew. Chem. Int. Ed., 2018, 57(43), 14121–14124.
2. F. J. Rizzuto, L. K. S. von Krbek, J. R. Nitschke, Nat. Rev. Chem., 2019, 3, 204.
Session 3 Poster 6, Flash 6
Controlling the properties of porous liquids
B. D. Egleston, K. V. Luzyanin, M. C Brand, R. Clowes, M. E. Briggs, R. L. Greenaway and A. I. Cooper
Department of Chemistry and Materials Innovation Factory, University of Liverpool, Crown Street, Liverpool, L69 7ZD, Merseyside, England, U.K.
Email: [email protected] Web: www.liverpool.ac.uk/cooper-group
Biography:
Ben is a final year PhD student in the Cooper group at The University of Liverpool. After completing an MChem degree at Liverpool in 2016, he began working with Prof. Andy Cooper and Dr. Becky Greenaway with a specific interest in porous liquids and organic cage materials.
Abstract:
Understanding the relationships between structure and function in porous materials enables the design of new materials for more specific applications. The invention of permanently microporous liquids as a new class of porous material in 2015 showed that permanent, intrinsic porosity can be produced successfully in the liquid state.1 Porous organic cages (POCs) are discrete molecules containing a permanent internal cavity accessible only through the cage windows. Type 2 porous liquids (PLs) can be produced by combining a highly soluble POC with a solvent that cannot pass through the windows and occupy the cage cavity. These PLs exhibit gas uptake up to 8 times greater than that of the neat solvent. Gas absorption in PLs has been correlated with binding energies in the POC they are prepared from.2 By varying the POC’s structure to change the pore in a PL, we can modify gas uptake and selectivity. Through a small change in POC structure, a large change to the pore’s accessibility in the PL can be achieved. We have ‘switched off’ the uptake of Xe gas in this new PL while retaining uptake of CH4.
References:
1. N. Giri, M. G. Del Pópolo, G. Melaugh, R. L. Greenaway, K. Rätzke, T. Koschine, L. Pison, M. F.
C. Gomes, A. I. Cooper and S. L. James, Nature, 2015, 527, 216–220.
2. R. L. Greenaway, D. Holden, E. G. B. Eden, A. Stephenson, C. W. Yong, M. J. Bennison, T. Hasell,
M. E. Briggs, S. L. James and A. I. Cooper, Chem. Sci., 2017, 8, 2640–2651.
3. B. D. Egleston, K. V. Luzyanin, M. C. Brand, R. Clowes, M. E. Briggs, R. L. Greenaway, A. I.
Cooper, ChemRxiv, 2019, Preprint, https://doi.org/10.26434/chemrxiv.10247528.
Session 3 Poster 7, Flash 7
Embedding electron-rich -systems within an Icosahedral Inorganic Fullerene
R. W. Pow, W. Xuan, D-L. Long, N. L. Bell and L. Cronin*
School of Chemistry, University of Glasgow, University Avenue, Glasgow, G12 8QQ, United Kingdom
Email: [email protected]; [email protected]* Web: www.croninlab.com
Biography:
Final year PhD student in the Cronin Group, University of Glasgow. Interested in the investigation of interactions between large polyoxometalate clusters and organic molecules, utilizing NMR as the primary solution-state analysis.
Abstract:
Keplerates are giant, spherical, metal-oxo clusters comprised of 132 metal atoms arranged to form surface pores, which allow access to a hollow internal cavity. The incorporation of various ligand species at the internal surfaces of the molybdenum-based Keplerate structures allows for some control of the character of this internal cavity, providing a designed confined environment, within which reactions may occur2. Host-guest encapsulation processes, which are facilitated by non-covalent interactions, are utilized in drug delivery, sensing, and separation processes. Keplerates have been used as hosts in guest encapsulation studies, giving insights into hydrophobic effects and pH-driven guest uptake3. In contrast to the wide range of hydrophilic ligands utilized in {Mo132} syntheses, only a handful of ligands appended with hydrophobic aliphatic groups have been incorporated into {Mo132}.
Using direct and ligand exchange approaches, we have coordinated alkenyl carboxylate ligands to the Keplerate inner surface, resulting in a confined, electron-rich, hydrophobic cavity. We have used the resulting structures to drive the uptake of short-chain alkyl thiol species from aqueous solution, which was determined to be a hydrophobically-driven process. The resulting guest clustering within the Keplerate cavity stabilized the guest species, as reflected in the prevention of their evaporation beyond their boiling points.
Figure 1. a) {Mo132} structure highlighting the pore diameter and the fundamental structural building blocks, b) the coordinated alkene ligands to derivatize {Mo132} here, and c) table highlighting the extent of alkene ligand uptake in
comparison to archetypal acetate ligands and the resulting effect on thiol encapsulation (1H NMR).
References:
1. R. Pow, W. Xuan, D-L. Long, N. L. Bell and L. Cronin, 2019, Manuscript submitted for publication. 2. S. Kopilevich, A. Gil, M. Garcia-Ratés, J. Bonet-Avalos, C. Bo, A. Müller, and I. A. Weinstock, J.
Am. Chem. Soc., 2012, 134, 31, 13082-13088. 3. S. Chakraborty, A. Grego Shnaiderman, S. Garai, M. Baranov, A. Müller, I. A. Weinstock, J. Am.
Chem. Soc., 2019, 141, 23, 9170-9174.
Session 3 Invited 3
Palladium(II) Metallosupramolecular Cages: Self-assembly and Molecular Recognition
James D. Crowley, Dan Preston, Jamie E. M. Lewis, Tae Y. Kim, Roan. A. S. Vasdev and Lynn S. Lisboa
Department of Chemistry, University of Otago, PO Box 56, Dunedin, 9054, New Zealand.
Email: [email protected] Web: https://blogs.otago.ac.nz/jamescrowley/
Biography:
James obtained his BSc (Hons) (1998) and MSc (2000) from Victoria University of Wellington and completed his PhD (2000–2005) at the University of Chicago under the direction of the incomparable Prof. Brice Bosnich, FRS. In 2005 he moved to Prof. David Leigh’s group at the University of Edinburgh, where he was awarded a British Ramsay Memorial Trust Fellowship (2006–2008), to carry out research on interlocked architectures and molecular machines. James started his independent career at the University of Otago in 2008 where he is now a Professor.
Abstract:
Discrete, soluble, self-assembled metallosupramolecular architectures can be exploited for the molecular recognition of a wide range of guests including reactive molecules and intermediates, pollutants and drugs.1 I will describe our recent efforts to self-assemble a range of palladium(II)-based metallosupramolecular architectures (Figure 1).2 Additionally, the molecular recognition properties with a variety of guests including drugs (cisplatin), pollutants (CO2, PAHs) and anions will be discussed.3-5
Figure 1: Selected metallosupramolecular cages developed in the Crowley group.
References:
1. T. R. Cook, P. J. Stang, Chem. Rev. 2015, 115, 7001. 2. J. E. M. Lewis, E. L. Gavey, S. A. Cameron, J. D. Crowley, Chem. Sci. 2012, 3, 778. 3. D. Preston, J. E. M. Lewis, J. D. Crowley, J. Am. Chem. Soc. 2017, 139, 2379. 4. D. Preston, K. F. White, J. E. M. Lewis, R. A. S. Vasdev, B. F. Abrahams, J. D. Crowley, Chem.
Eur. J. 2017, 23, 10559 5. 5 Preston, D.; Sutton, J. J.; Gordon, K. C.; Crowley, J. D. Angew. Chem. Int. Ed. Engl. 2018, 57,
8659.
Session 3 Bob Hay Lecture
Evolutionary Discovery of Molecular Materials
Kim E. Jelfs
Department of Chemistry, Imperial College London, Wood Lane, W12 0BZ, United Kingdom
Email: [email protected] Web: www.jelfs-group.org
Biography:
Kim Jelfs is a Senior Lecturer and Royal Society University Research Fellow and specialises in the use of computer simulations to assist in the discovery of supramolecular materials. After a PhD modelling the crystal growth of zeolites at UCL, she worked as a post-doc across the experimental groups at the University of Liverpool, before beginning her independent research at Imperial College in 2013. She was awarded a Royal Society of Chemistry Harrison-Meldola Memorial Prize in 2018.
Abstract:
We have developed an evolutionary algorithm targeted upon the discovery of optimal structures and properties for molecular materials.[1] Intrinsically porous organic molecules have shown promise in separations, catalysis, encapsulation, sensing, and as porous liquids. These molecules are typically synthesised from organic precursors through dynamic covalent chemistry (DCC). If we consider cages synthesised from imine condensation reactions alone, there are approximately 800,000 possible aldehyde and amine precursors, combining these in all the different possible topologies results in over 830 million possible porous organic cages. Therefore, either from a computational or synthetic perspective, it is not possible for us to screen all these possible assemblies. Our evolutionary algorithm automates the assembly of hypothetical molecules from a library of precursors. The software belongs to the class of approaches inspired by Darwin's theory of evolution and the premise of "survival of the fittest". Our approach has already suggested promising targets that have been synthetically realised.[2] Further, we are addressing questions such as which topologies or DCC reactions maximise void size or whether specific chemical functionalities promote targeted applications, such as encapsulation of guests.[3,4] We have also examined the application of machine learning for the rapid prediction of whether porous organic molecules will be shape persistent, retaining an internal cavity, or not.[5]
Finally, we will discuss the application of our approach to other materials, including organic electronic systems.
Figure 1. Computational screening of porous organic cages from precursors through an evolutionary algorithm.
References:
1. L. Turcani, E. Berardo, K. E. Jelfs, J .Comp. Chem., 2018, 39 (23), 1931-1942. 2. E. Berardo, R. L. Greenaway, L. Turcani, B. M. Alston, M. J. Bennison, M. Miklitz, R. Clowes, M.
E. Briggs, A. I. Cooper, K. E. Jelfs, Nanoscale, 2018, 10, 22381-22388. 3. E. Berardo, L. Turcani, M. Miklitz, K. E. Jelfs, Chem. Sci., 2018, 9, 8513-8527. 4. M. Miklitz, S. Jiang, R. Clowes, M. E. Briggs, A. I. Cooper, K. E. Jelfs, J. Phys. Chem. C, 2017,
121 (28), 15211–15222. 5. L. Turcani, R. L. Greenaway, K. E. Jelfs, Chem. Mater., 2019, 31, 3, 714-727.
Session 4 Plenary 3
Synthesis of Supramolecular Biomaterials
Tanja Weil
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
Email: [email protected] Web: https://www.mpip-mainz.mpg.de/weil
Biography:
Tanja Weil joined the Max Planck Institute for Polymer Research (MPIP) in 2017 as one of the Directors. She studied chemistry (1993–1998) at the TU Braunschweig (Germany) and the University of Bordeaux I (France) and completed her PhD at the MPIP under the supervision of K. Müllen. In 2003, she received the Otto Hahn Medal of the Max Planck Society. From 2002 to 2008 she managed different leading positions at Merz Pharmaceuticals GmbH (Frankfurt) such as Director of Chemical Research and Development. In 2008, she accepted an Associate Professor position at the National University of Singapore. Tanja Weil joined Ulm University as Director of the Institute of Organic Chemistry III from 2010 - 2016.
She has received e.g. a Synergy Grant of the European Research Council (ERC) and the science award of the city of Ulm and the Otto-Hahn medal of the Max-Planck Society. Tanja Weil is an associate editor for ACS Nano, a member of the editorial advisory board of J. Am. Chem. Soc. and of the Kuratorium of Angewandte Chemie and she also serves in other journal boards.
Abstract:
Living cells present an enormous complexity in the way, how supramolecular structures are assembled and disassembled to control intracellular processes and other functions. To date, it is not possible to control the formation and dynamics of supramolecular structures in a similar fashion.
We combine peptides, proteins and polymers to construct nanomaterials with high degree of structure definition that are able to interact with cells in a controlled fashion. We apply i.e. the dynamic interaction of boronic acids and catechol or salicylhydroxamate groups that responds to environmental stimuli to form or disassemble these nanostructures. In this way, synthetic extracellular matrices comprising peptide fibrils are prepared that stimulate the growth of neuronal cells in vitro and in vivo. Moreover, supramolecular nanostructures are also formed inside cellular environments, which has important implications for cell viability.
References:
1. M. Hebel, A. Riegger, M. M. Zegota, G. Kizilsavas, J. Gačanin, M. Pieszka, T. Lueckerath, J.A.S. Coelho, M. Wagner, P.M.P. Gois, D.Y.W. Ng, T. Weil, J. Am. Chem. Soc. 2019, 141, 36, 14026-14031.
2. C. Schilling, T. Mack, S. Lickfett, S. Sieste, F.S. Ruggeri, T. Sneideris, A. Dutta, T. Bereau, R. Naraghi, D. Sinske, T. P. J. Knowles, C.V. Synatschke, T. Weil, B. Knöll, Adv. Funct. Mater. 2019, 29, 24, 1809112.
3. J. Gačanin, J. Hedrich, S. Sieste, G. Glaßer, I. Lieberwirth, C. Schilling, S. Fischer, H. Barth, B. Knöll, C.V. Synatschke, T. Weil. Adv. Mater. 2019, 31, 2, 1805044.
Session 4 Talk 4
Exploiting flow synthesis and self-sorting for molecular materials
V. Abet, F. T. Szczypinski, C. Jones, M. A. Little, K. E. Jelfs, and A. G. Slater
Department of Chemistry and Materials Innovation Factory, University of Liverpool, Liverpool, L69 7ZD
Email: [email protected] Web: www.agslatergroup.com Twitter: @annagslater
Biography:
Anna obtained her Ph.D. in supramolecular chemistry from the University of Nottingham (2011). From 2010 to 2016, she held PDRA positions at the University of Nottingham and University of Liverpool. Since December 2016, she has held a Royal Society-EPSRC Dorothy Hodgkin Fellowship at the University of Liverpool. Her current research focuses on the use of flow chemistry for materials science, with a focus on dynamic, reversible chemistry; molecular materials and supramolecular systems; and automation and inline analysis in flow processes.
Abstract:
The ability to control pore size and pore connectivity is a crucial tool in the synthesis of functional porous materials. Porous organic cage crystals—which consist of discrete molecules packed into a porous crystal—have advantages over framework materials, such as solution processability. However, molecular crystals do not contain strong, directional coordination bonds, thus their solid-state packing behavior often exhibits strong solvent-dependence and results in polymorphism. Furthermore, most porous organic cage materials have symmetrical pores due to the high-fidelity self-sorting involved in their synthesis; stepwise routes to lower symmetry structures are generally synthetically intensive and hard to scale. All these challenges will need to be solved to enable the use of such materials in future applications, particularly for the binding of low-symmetry guests such as glucose or polyaromatic environmental pollutants.
Here, I will detail three methods of approaching this problem. First, chiral recognition is used to control self-assembly and develop reticular assembly of porous organic cage materials.1 Then, continuous flow chemistry is used to improve the scalability, sustainability, and speed of cage synthesis.2 Finally, we have developed non-linear aldehydes that promote social self-sorting, and used these to access a family of low-symmetry porous organic cages (Fig 1a-c).3 By using chiral recognition, self-sorting, and enabling technology such as flow synthesis, inline analysis, and automation, we are developing a toolkit to a) rapidly screen for function (Fig 1d); b) probe the fundamentals of self-assembly under continuous flow conditions; c) scale up compounds that are otherwise challenging to access in multigram amounts; d) generate and characterize complex dynamic systems.
Figure 1. a) and b) Crystal structures and c) simulated structure of self-sorted cage compounds formed using a non-
linear aldehyde; d) using continuous flow chemistry and inline analysis to screen for and optimize functional materials.
References: 1. A. Slater et al., Nat. Chem., 2017, 9, 17-25. 2. M. E. Briggs† and A. G. Slater† et al., Chem. Commun., 2015, 51, 17390-17393 3. V. Abet et al., manuscript in preparation.
Session 4 Industrial 1
Session 5 Talk 5
A Lab-on-a-Molecule with an Enhanced Fluorescent Readout on Detection of Three Chemical Species
Glenn J. Scerri, Jake C. Spiteri, Carl J. Mallia and David C. Magri
Department of Chemistry, Faculty of Science, University of Malta, Msida, MSD 2080, Malta.
E-mail: [email protected] Web: https://www.um.edu.mt/profile/davidmagri
Biography:
Prof. David C. Magri is a graduate of Western University in London, Ontario, Canada and a former post-doctoral research fellow with Prof. A. P. de Silva at Queens University, Belfast, Northern Ireland. Together they demonstrated the first molecular three-input AND logic gate as a 'lab-on-a-molecule' prototype. David subsequently lectured in Canada at the University of Prince Edward Island, the University of Ontario Institute of Technology and Acadia University before joining the University of Malta. His research interests include molecular-logic based computation with fluorescent molecules and materials, including the concept of 'Pourbaix sensors', fluorescent logic gates for measuring potential and pH.
Abstract:
We have designed and synthesised the first naphthalimide-based lab-on-a-molecule 1 (Figure 1).1 A lab-on-a-molecule is a molecular device that simultaneously detects for a congregation of three (or more) biologically relevant chemical species.2,3 The design concept consists of ferrocene as an electron donor responsive to the oxidant Fe3+, piperazine as a receptor for binding H+, and N-(2- methoxyphenyl)aza-15-crown-5 ether as a receptor for binding Na+. Molecule 1 is unique as it incorporates three different titrimetric methods: H+ by acid-base chemistry, Na+ by complexation and Fe3+ by redox chemistry. In the presence of high threshold concentration levels of all three analytes, a bright green fluorescence is observed with the naked eye; however, in the absence of just one of the analytes no fluorescence is observed. This latest example exhibits the greatest fluorescence switching ratio and fluorescence quantum yield in aqueous methanol to date. Disease screening is a foreseeable application as specifically designed molecules could be used to test for key analyte combinations in a single rapid test and perform a diagnosis autonomously.
References:
1. J. S. Glenn, J. C. Spiteri, C. J. Mallia and D. C. Magri, Chem. Commun., 2019, 55, 4961.
2. D. C. Magri, G. J. Brown, G. D. McClean and A. P. de Silva, J. Am. Chem. Soc., 2006, 128, 4950.
3. D. C. Magri, M. Camilleri Fava and C. J. Mallia, Chem. Commun., 2014, 50, 1009.
Session 5 Talk 6
Interlocked Molecules for Useful Applications
N. H. Evans
Department of Chemistry, Lancaster University, Lancaster, UK, LA1 4YB.
Email: [email protected] Web: www.supramolecularevans.com
Biography:
Nick completed MChem (2006) and DPhil (2011) degrees at Wadham College, University of Oxford. Working in the laboratories of Prof Paul Beer, his doctoral thesis focused on the electrochemical sensing of chloride anions by rotaxanes and catenanes. After undertaking postdoctoral research on luminescent lanthanide complexes with Prof David Parker at Durham University, Nick was appointed a lecturer at the newly re-opened Department of Chemistry at Lancaster University in 2013. His current research interests are in the area of functional supramolecular chemistry, in particular seeking to exploit rapidly prepared interlocked molecules in useful applications.
Abstract:
Catenanes and rotaxanes have been applied to a number of nanotechnological applications,1 some of which rely on the relative motion of their interlocked components.2,3 While the synthesis of interlocked molecules may be achieved by use of various template methodologies, many of the strategies reported to date involve lengthy multi-step procedures.4,5 To be genuinely useful synthetic routes to catenanes and rotaxanes should be rapid, scalable and generate stable and functionalizable molecules.
Here work carried out at Lancaster will be highlighted: (a) development of synthetic methodology to rapidly access interlocked molecules;6-8 (b) examples of interlocked molecules of fundamental interest (shuttles and mechanical chirality)9,10 and (c) interlocked molecules being put to useful application (receptors for ionic guests and the display of biological functionality).11,12
Figure: Schematic representation of a rapidly prepared, functionalizable rotaxane.
References:
1. S. F. M. van Dongen, S. Cantekin, J. A. A. W. Elemans, A. E. Rowan and R. J. M. Nolte, Chem. Soc. Rev., 2014, 43, 99.
2. J.-P. Sauvage, Angew. Chem. Int. Ed., 2017, 56, 11080. 3. J. F. Stoddart, Angew. Chem. Int. Ed., 2017, 56, 11094. 4. G. Gil-Ramírez, D. A. Leigh and A. J. Stephens, Angew. Chem. Int. Ed., 2015, 54, 6110. 5. M. Xue, Y. Yang, X. Chi, X. Yan and F. Huang, Chem. Rev., 2015, 115, 7398. 6. C. N. Marrs and N. H. Evans, Org. Biomol. Chem., 2015, 13, 11021. 7. N. H. Evans, C. E. Gell and M. J. G. Peach, Org. Biomol. Chem., 2016, 14, 7972. 8. B. E. Fletcher, M. J. G. Peach and N. H. Evans, Org. Biomol. Chem., 2017, 15, 2797. 9. N. H. Evans and G. R. Akien, Supramol. Chem., 2018, 30, 758. 10. C. E. Gell, T. A. McArdle-Ismaguilov and N. H. Evans, Chem. Commun., 2019, 55, 1576. 11. P. J. Grimes and N. H. Evans, manuscript in preparation. 12. M. J. Young and N. H. Evans, manuscript in preparation.
Session 5 Thesis Prize
Weaving, Rotating and Threading: Novel Self Assembly and Controlled Molecular Motion
S. D. P. Fielden, D. A. Leigh
School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
Email: [email protected] Twitter: @FieldenStephen
Biography:
Steve undertook his PhD with Prof. David Leigh from 2015-2019. He is currently completing a postdoc in the group of Prof. Leigh, and will become an oLife Marie Curie Fellow in the group of Prof. Sijbren Otto at the University of Groningen (NL) in early 2020.
Abstract:
Nature has mastered self-assembly: living organisms consist of hierarchal structures (organs, cells, organelles) whose formation and persistence rely on programmed self-assembly. Life is also not a static phenomenon; it is a dynamic set of evolving processes. My PhD concerned the development of new methods of self-assembly and controlled molecular motion, which may prove useful in the production of nanotechnology capable of showing life-like properties.
Molecular Motors and Dissipative Systems Combining orthogonal dynamic covalent chemistries with a molecular switch system permitted the operation of rotary and linear molecular motors that control the motion of crown ethers.1 Dissipative operation was possible using Cl3CCO2H, which could also be used in a related system to regulate catalysis.2
Metal-Free Active Template Rotaxane Synthesis Rotaxanes spontaneously form when a primary amine, electrophile and crown ether are combined in toluene.3 A wide range of novel rotaxanes can be accessed in a single synthetic step with this method.4
Molecular Knots Anion- and cation-mediated weaving of a bespoke ligand generates a 3 × 3 grid, which can be closed to give a molecular endless (74) knot. Weaving at the molecular level may prove useful for the construction of new materials.
References:
1. S. Erbas Cakmak, S. D. P. Fielden, U. Karaca, D. A. Leigh, C. T. McTernan, D. J. Tetlow and M. R. Wilson. Science, 2017, 358, 340.
2. C. Biagini, S. D. P. Fielden, D. A. Leigh, F. Schaufelberger, S. Di Stefano and D. Thomas Angew. Chem. Int. Ed., 2019, 58, 9876.
3. S. D. P. Fielden, D. A. Leigh, C. T. McTernan, B. Pérez-Saavedra and I. J. Vitorica-Yrezabal. J. Am. Chem. Soc., 2018, 140, 6049.
4. C. Tian, S. D. P. Fielden, D. A. Leigh, I. J. Vitorica-Yrezabal and G. F. S. Whitehead. Nat. Commun. 2020, manuscript accepted
Session 6 Invited 4
Foldamers Coming Full-Circle
P. C. Knipe, T. M. C. Warnock, R. Sundaram and M. Fitzpatrick
School of Chemistry and Chemical Engineering, Queen’s University, Belfast, BT9 5AG
Email: [email protected] Web: www.knipechem.co.uk
Biography:
Peter C. Knipe obtained an undergraduate degree in Natural Sciences from the University of Cambridge in 2004. In 2008 he moved to Oxford where he undertook a DPhil with Prof. Martin D. Smith developing catalytic enantioselective electrocyclic reactions under counter-ion control. He subsequently joined the laboratory of Prof. Andrew D. Hamilton FRS, where his postdoctoral work explored the use of synthesis to develop functional molecules and design new motifs to mimic peptide structure and disrupt protein-protein interactions. In 2016, Peter took up his current position of Lecturer at Queen’s University, Belfast, where his group has broad interests in synthesis, catalyst development, supramolecular chemistry and molecular recognition.
Abstract:
Foldamers are unnatural oligomers with well-defined conformations analogous to those adopted by Nature’s oligomeric macromolecules.1 In principle these could perform any of the functions currently performed by proteins (catalysis, transport, signaling, structure etc.), yet many of these have not been achieved since the majority of published foldamers adopt simple helical conformations.
Our recent development of a new class of foldamers will be presented,2 where the simple choice of the constituent heterocycles allows us to create extended, helical and mixed conformations reminiscent of protein tertiary structures. Recent unpublished work on the extension of this system to the formation of macrocycles will be presented.
References:
1. (a) S. H. Gellman, Acc. Chem. Res. 1998, 31, 173; (b) D. J. Hill, M. J. Mio, R. B. Prince, T. S. Hughes, J. S. Moore*, Chem. Rev., 2001, 101, 3893; (c) C. Tomasini, I. Huc, D. J. Aitken, F. Fülöp,
Eur. J. Org. Chem. 2013, 3408; (d) Foldamers: Structure, Properties and Applications, S. Hecht, I.
Huc (ed.), Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim, 2007.
2. Z. Lockhart, P. C. Knipe, Angew. Chem. Int Ed., 2018, 57, 8478.
Session 6 Plenary 4
Synthetic Lectins – The Host-Guest Chemistry of Carbohydrates
Anthony P. Davis
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
Email: [email protected] Web: https://davis.chm.bris.ac.uk/
Biography:
Tony Davis moved from Trinity College Dublin in 2000 to become Professor of Supramolecular Chemistry at the University of Bristol. His research focuses principally on supramolecular chemistry with potential medical applications. He has co-founded two companies to exploit discoveries in carbohydrate recognition and sensing; Ziylo, which was sold in 2018 to Novo Nordisk, and Carbometrics, which continues to work in the area.
Abstract:
Binding carbohydrates in water provides an interesting challenge for supramolecular chemists. On the one hand it is difficult, due the hydrophilic and hydromimetic nature of carbohydrates. On the other hand, it is relevant to many areas of biology. Carbohydrates are exploited as fuels and materials in living systems, and also as labels to control the immune response, protein folding and trafficking, cell-cell recognition, fertilisation, etc. It is important to understand how natural carbohydrate recognition works, and potentially useful to mimic these natural recognition processes with synthetic systems. A particular opportunity lies in sensing glucose. There are approximately 400,000,000 diabetics in the world, of which around 10% are Type 1 (insulin-dependent). Management of their conditions requires methods for blood glucose sensing, either for analytical read-out or for direct control of insulin delivery/activity. Selective recognition of glucose in blood is a key step in reaching these goals. We have been researching the design of biomimetic glucose receptors for a number of years.1 This lecture will discuss the latest developments in our work, including a system which seems to have genuine potential for real-world applications.
References:
1. R. A. Tromans et al. Nature Chem., 2019, 11, 52-56. P. Rios, T. J. Mooibroek, et al. Chem. Sci., 2017, 8, 4056-4061. T. J. Mooibroek et al. Nature Chem., 2016, 8, 69-74.
2. P. Rios et al. Angew. Chem., Int. Ed., 2016, 55, 3387-3392. C. Ke et al. Nature Chem., 2012, 4, 718-723.
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Session 7 Industrial 2
Session 7 Plenary 5
Making the Tiniest Machines
D. A. Leigh
Address: Department of Chemistry, University of Manchester, UK
Email: [email protected] Web: www.catenane.net
Biography:
David is the Sir Samuel Hall Chair of Chemistry at the University of Manchester and a Royal Society Research Professor.
Abstract:
“We are at the dawn of a new industrial revolution of the twenty-first century, and the future will show how molecular machinery can become an integral part of our lives. The advances made have also led to the first steps towards creating truly programmable machines, and it can be envisaged that molecular robotics will be one of the next major scientific areas.”
The 2016 Nobel Prize in Chemistry Committee, October 20161
Over the past 25 years some of the first examples of synthetic molecular level machines and motors—all be they primitive by biological standards—have been developed.2-5 Recently the first programmable systems have been introduced,6-8 the forerunners of a new field of ‘molecular robotics’.
Perhaps the best way to appreciate the technological potential of controlled molecular-level motion is to recognise that nanomotors and molecular-level machines lie at the heart of every significant biological process. Over billions of years of evolution Nature has not repeatedly chosen this solution for achieving complex task performance without good reason. In stark contrast to biology, none of mankind’s fantastic myriad of present day technologies exploit controlled molecular-level motion in any way at all: every catalyst, every material, every plastic, every pharmaceutical, every chemical reagent, all function exclusively through their static or equilibrium dynamic properties. When we learn how to build artificial structures that can control and exploit molecular level motion, and interface their effects directly with other molecular-level substructures and the outside world, it will potentially impact on every aspect of functional molecule and materials design. An improved understanding of physics and biology will surely follow.9,10
References:
1. The Nobel Prize in Chemistry 2016–Advanced Information. Nobelprize.org. Nobel Media AB 2014. Web. 6 Oct, 2016, http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2016/advanced.html.
2. J.-P. Sauvage, Angew. Chem. Int. Ed., 2017, 56, 11080. 3. J. F. Stoddart, Angew. Chem. Int. Ed., 2017, 56, 11094. 4. B. L. Feringa, Angew. Chem. Int. Ed., 2017, 56, 11060. 5. E. R. Kay and D. A. Leigh, Angew. Chem. Int. Ed., 2015, 54, 10080. 6. B. Lewandowski, et al., Science, 2013, 339, 189. 7. S. Kassem, A. T. L. Lee, D. A. Leigh, A. Markevicius and J. Solá, Nat. Chem., 2016, 8, 138. 8. S. Kassem, A. T. L. Lee, D. A. Leigh, V. Marcos, L. I. Palmer and S. Pisano, Nature, 2017, 549,
374. 9. S. Erbas-Cakmak, S. D. P. Fielden, U. Karaca, D. A. Leigh, C. T. McTernan, D. J. Tetlow and M.
R. Wilson, Science, 2017, 358, 340. 10. M. R. Wilson, J. Solá, A. Carlone, S. M. Goldup, N. Lebrasseur and D. A. Leigh, Nature, 2016,
534, 235.
Poster Abstracts
(excluding those associated with Flash Presentations 1-7)
Poster 8
AT-CuAAC Mediated Synthesis of Rotaxane-DNA
A.M. Acevedo-Jake, M. P. Fitzpatrick, M. Galli, M. Kukwikila, A. T. Ball, D. G. Singleton, A. Tavassoli and S. M. Goldup*
Department of Chemistry, University of Southampton, University Road, Southampton SO17 1BJ Email: [email protected] Web: http://goldup.soton.ac.uk/
Abstract:
The mechanical bond has been shown to alter the behaviour and physical properties of naturally occurring biomolecules such as microcin J251 and catenanted DNA,2,3 where its incorporation can both stabilise the biopolymer against degradation and inhibit its biological activity. Recently, Tavassoli developed biocompatible ‘click’ DNA in which a phosphate is replaced by a triazole isostere.4,5 This synthetic DNA is both accurately read and processed by the cell, and has been used to synthesise whole genes. Independently, Goldup has shown it is possible to modify Leigh’s AT-CuAAC approach to ‘click’ azide- or alkyne-modified stoppers inside the cavity of small macrocycles to selectively control the positioning of the macrocycle along the axle component.6 Here we combine Goldup’s and Tavassoli’s methodologies to prepare rotaxane-DNA, in which the macrocycle encircles a biocompatible triazole-linked axle analogue of the E. coli T7 promoter sequence. While the non-interlocked axle forms a stable duplex with T7 reverse and is biologically functional as expected, the mechanically interlocked rotaxane-DNA does not, suggesting the mechanical bond can ‘silence’ the activity of oligonucleotides.
References:
1. J. D. Hegemann, M. Zimmermann, X. Xie, M. A. Marahiel, Acc. Chem. Res., 2015, 48, 1909–1919. 2. D. A. Clayton, J. Vinograd, Nature, 1967, 216, 652–657. 3. B. Hudson, J. Vinograd, Nature, 1967, 216, 647–652. 4. A. H. El-Sagheer, A. P. Sanzone, R. Gao, A. Tavassoli, T. Brown, Proc. Natl. Acad. Sci., 2011,
108, 11338–11343. 5. C. N. Birts, A. P. Sanzone, A. H. El-Sagheer, J. P. Blaydes, T. Brown, A. Tavassoli, Angew. Chemie
- Int. Ed., 2014, 53, 2362–2365. 6. V. Aucagne, K. D. Hänni, D. A. Leigh, P. J. Lusby, D. B. Walker, J. Am. Chem. Soc., 2006, 128,
2186–2187.
Poster 9
Novel Antimicrobial Agents for Clinical Applications
Nyasha Allen1,2, Jennifer R. Hiscock1, Daniel P. Mulvihill2 1School of Physical Sciences, 2School of Biosciences University of Kent, Canterbury, Kent, CT2 7NT
Email: [email protected]
Abstract:
Since their discovery, antimicrobial compounds are vital for the treatment and prevention of disease, making many previously fatal diseases treatable or at worst, manageable conditions. The inappropriate use of these compounds has led to the rapid development of resistance mechanisms within bacteria to the majority of compounds currently marketed. A recent UK governmental review predicted that by 2050 global deaths caused by antimicrobial resistant bacteria will outnumber those attributed to cancer [1]. As new resistance mechanisms emerge and resistance within microbial populations increases, so does the need to further understand the molecular basis of resistance, develop new antimicrobial molecules and use better strategies to manage their use [2]. We discovered a novel class of antimicrobials and have created 50 structurally related members of this class [3-6]. We sought to understand the structure-activity relationships which will result in the determination of the mode of action of these molecules. Subsequently, each variant was screened against S. aureus and E. coli and the minimum inhibitory concentration was calculated for effective compounds. This will enable us to identify predictive tools that will aid the synthesis of the next generation of these novel therapeutic molecules. We will present our latest findings in the ongoing analysis of the effective microbial activity for each variant of this new class of antimicrobial compound. In addition, we will discuss the insights provided by the detailed structure-function analysis.
Figure 1: Microscopy images of intrinsically fluorescent SSAs internalizing in E. coli and MRSA (2 µm)
References:
1. J. O’Neill. (2014) A Review on Antimicrobial Resistance: Tackling a crisis for the health and wealth of nations. London: Review on Antimicrobial Resistance.
2. S. B. Zaman, M. A. Hussain, R. Nye, V. Mehta, K. T. Mamun, N. Hossain (2017) A Review on Antibiotic Resistance: Alarm Bells are Ringing. Cureus. 9(6)
3. J. R. Hiscock, G. P. Bustone, B. Wilson, K. E. Belsey, L. R. Blackholly. (2016) In situ modification of nanostructure configuration through the manipulation of hydrogen bonded amphiphile self-association. Soft Matter. 12: 4221-4228
4. L.J. White, N.J. Wells, L. R. Blackholly, H.J. Shepherd, B. Wilson, G.P. Bustone, T. J. Runacres, J.R. Hiscock. (2017).Towards quantifying the role of hydrogen bonding within amphiphile self-association and resultant aggregate formation. Chemical science. 8 (11): 7620 – 7630
5. S. N. Tyuleva, N. Allen, L.J. White, A. Pepes, H. J. Shepherd, P. J. Saines, R. J. Ellaby, D.P. Mulvihill, J.R. Hiscock. (2018) A symbiotic supramolecular approach to the design of novel amphiphiles with antibacterial properties against MSRA. Chemical Communications.
6. This innovation is protected by an International (PCT) Patent Application No. PCT/EP2018/069568
Poster 10
Hydrogen Bonding Organic Framework Using Perylene
Diimide
Asia Almuhana, Neil R. Champness
University of Nottingham, University Park, Nottingham, NG7 2RD
Email: [email protected]
Biography:
Asia Almuhana is a lecturer at King Faisal University in Saudi Arabia. She is studying PhD under the supervision of Prof.Neil Champness at the University of Nottingham.
Abstract:
Hydrogen-bonded organic frameworks (HOFs) are crystalline systems that are formed by self-
assembly through hydrogen bonding. H-bonding connections feature a weak, flexible, directional,
and reversible interaction indicating that HOFs show high crystallinity, solution processability,
easy healing and purification. These unique advantages enable HOFs to be important for a variety
of future applications. This study details the construction of HOFs using perylene diimides (PDIs)
as building blocks. The building blocks are a series of PDI molecules functionalised with different
H-bonding units at the imide-position, as well as the functionalisation of the bay area with a tertiary
amine which leads to interesting optical and electronic properties. It has been observed that
introducing electron donating substituents at the bay region has large effects in terms of the
compounds UV/Vis maxima and consequently their colour. However, they have little impact upon
the E1/2 values of the two reduction processes but large effects in terms of the oxidation behaviour.
-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Potential (V vs Fc+
/Fc)
20 A
Figure. (a) Crystal structure of G-PDI-1, (b) UV-vis absorption spectra showing the inter-conversion from neutral (green) to monoreduced (red) species of G-PDI-1, arrows indicate the progress of the reduction, (c) Cyclic voltammograms recorded for G-PDI-1 (top/green) and B-PDI-1 (bottom/blue).
G-PDI-1: N,N’-di(tert-Butyl (4-aminophenyl) carbamate)-1,7-dimorpholino-3,4:9,10 perylenetetracarboxylic diimide.
a b
c
Poster 11
Drug-based low molecular weight amphiphiles for the formation of supramolecular hydrogels
M. Amaro-Villegas1, J. R. Hiscock2, A. J. Hall1 and A. A. Edwards1 1 Medway School of Pharmacy, Anson Building, Central Avenue, Chatham, Kent, ME4 4TB, UK. 2 School of Physical Sciences, University of Kent, CT2 7NH, UK.
Email: [email protected] Web: https://www.msp.ac.uk/about/staff/chemistry/edwards_alison.html
Biography:
Miguel joined the Medway School of Pharmacy in 2018 to undertake a PhD, studying the formation of supramolecular hydrogels. Prior to this, he completed a B.Sc. in Chemistry and a M.Sc. in Chemical Research at the University of Castilla-La Mancha (Spain). This was followed by a traineeship at KU Leuven (Belgium) in organic synthesis.
Abstract:
Supramolecular hydrogels are a type of soft material formed by the self-assembly of monomeric units via non-covalent intermolecular interactions.1 These materials simulate the extracellular matrix and therefore have the potential to produce novel classes of biomaterials. When compared to conventional covalently linked polymeric materials, supramolecular hydrogels have advantageous properties, such as reversible and/or triggerable gel-sol transitions and homogeneity of components.
Low Molecular Weight (LMW) amphiphiles represent a class of monomeric unit able to form supramolecular hydrogels. We have previously synthesized several LMW carbohydrate-drug amphiphiles2, and shown that non-steroidal anti-inflammatory drugs (NSAIDs) linked to glucosamine or galactosamine act as hydrogelators (Figure 1).
Figure 1. (a) Chemical structure of potential gelators where Drug A and Drug B are members of the NSAID drug class. (b) Inversion test confirming the formation of a hydrogel with 1 (2.5 mg/mL) and 2 (3.0 mg/mL). TEM images of xerogels created from (c) hydrogel 1 (2.5 mg/mL) and (d) hydrogel 2 (3.0 mg/mL).
Work to date has been focused on: (i) the synthetic optimization of the monomeric units; and (ii) the material characterization of the resultant hydrogels. The purity of the gelator was confirmed through the combined use of TLC and 1H/13C NMR. The ability of 1-4 to form hydrogels was examined in different conditions, using water and aqueous buffer solutions as gelation media. Gelator 1 and 2 were found to exhibit the lowest minimum gelation concentration (MGC) in water at 2.5 and 3.0 mg/mL, respectively, with gelation triggered by a combination of heating and sonication. The hydrogels formed from 1 and 2 were subsequently characterized through a combination of XRD, SEM/TEM, and FTIR to better understand the nature of the self-assembly.3
References:
1. X. Du, J. Zhou, J. Shi and B. Xu, Chem. Rev., 2015, 115, 24, 13165.
2. C. C. Piras, PhD thesis, Medway School of Pharmacy, 2016.
3. L. S. Birchall, S. Roy, V. Jayawarna, M. Hughes, E. Irvine, G. T. Okorogheye, N. Saudi, E. De Santis, T. Tuttle, A. A. Edwards and R. V. Ulijn, Chem. Sci., 2011, 2, 1349.
Poster 12
Singlet Fission of Supramolecular Structures
N. J. Andersen, A. Saywell, J. O’Shea and N. R. Champness
School of Chemistry – University of Nottingham, University Park, Nottingham, NG7 2RD, UK
Email: [email protected] Web: https://neilchampnessgroup.com
Abstract:
Singlet fission is a spin-allowed process where a singlet exciton undergoes fission into two, lower energy, triplet states, yielding two excitons from one photon (see Fig. 1). This presents a remarkable opportunity to surpass the Shockley-Quiesser photo-conversion efficiency limit of ca. 33%, and reach a new theoretical limit of ca. 50%. Singlet fission has thus received significant attention in literature, mostly with the search for clean, reliable energies in mind. However, progress in the development of suitable materials to exploit Singlet Fission has been hindered by the elusive mechanism underpinning the process, and the difficulty of modelling these mechanisms in the solid-state, due to complications arising in covalent dimer moieties.[1]
One molecule of particular attention in this field is pentacene, a well-known chromophore which exhibits exoergic SF. Previous work by the Champness group, in the synthesis of rotaxane based molecular handcuffs, has led to the conceptualisation of a pentacene-pentacene handcuff architecture, which would orient two pentacene motifs into a dimer arrangement, without the necessity for any covalent or rigid structures.[2] In principle, this would allow for investigation into solid state pentacene dimers previously inaccessible through other conventional means. The progress towards realising this structure will be discussed, including attempted synthetic routes and current strategies.
Figure 1. Schematic of Singlet Fission in a pentacene dimer. Dimer A+B (top – blue + blue) is irradiated with light, exciting A to A* (middle – red + blue), Singlet Fission occurs effectively sharing the charge of A* (red) with B (blue), resulting in two triplets A*+B* (bottom - green + green) of a lower energy.
References:
1. M. Smith, J. Michl, Chem. Rev., 2010, 110, 6891-6936. 2. L. Yang, P. Langer, S. E. Davies, M. Baldoni, K. Wickham, N. Besley, E. Besley, N. Champness,
Chem. Sci., 2019, 10, 3723-3732.
Poster 13
Electron transfer in fullerene-based supramolecular assemblies
Timothy A. Barendt
School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT
Email: [email protected] Web: tab-lab.org
Biography:
Following a PhD and Junior Research Fellowship at the University of Oxford, Tim has recently become a lecturer at the University of Birmingham.
Abstract:
The renowned photophysical and redox properties of polyaromatic hydrocarbons such as fullerenes has prompted their wide-spread use in artificial photosynthesis and organic electronics.1 The fact that electron transfer can be an intermolecular process has also motivated a consideration of the supramolecular chemistry of these molecules.2 As such, the electronic communication in a donor–acceptor assembly can be tuned via the non-covalent interactions between components.
Fullerenes are archetypal electron acceptors3 and this presentation will describe how their integration into supramolecular assemblies provides an effective strategy for controlling this process. One example is a fullerene-based rotaxane shuttle in which the outcome of photoinduced electron transfer is dependent on the position of a macrocyclic wheel on the axle component (Figure 1a).4 Another shows that the complexation of C60 as a guest within a macrocyclic host enables a rare example of electron transfer without the need for photoexcitation (Figure 1b).5 As demonstrated with related host–fullerene guest complexes, this behaviour has implications for electron mobility in organic semiconducting materials.6
Figure 1. Electron transfer in fullerene-based supramolecular assemblies; a) a rotaxane shuttle and b) a host–guest complex.
References:
1. D. M. Guldi et al., Chem. Soc. Rev. 2009, 38, 1587 2. D. Canevet et al., Angew. Chem. Int. Ed. 2011, 50, 9248
3. L. Echegoyen et al., Acc. Chem. Res. 1998, 31, 593 4. T. A. Barendt et al., J. Am. Chem. Soc., 2017, 139, 9026 5. T. A. Barendt et al., manuscript submitted 6. T. A. Barendt et al., manuscript in preparation
Poster 14
Halogen Bonding Anion Transporters
L. E. Bickerton, A. J. Stirling, P. D. Beer, F. Duarte and M. J. Langton
Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA
Email: [email protected] Web: http://langton.chem.ox.ac.uk/
Biography:
I completed my BSc(Hons) in Biochemistry and Biological Chemistry at the University of Nottingham and I am currently working towards my MSc(Res) in Inorganic Chemistry at the University of Oxford under the joint supervision of Prof. Paul Beer and Dr Matthew Langton. My project concerns the design, synthesis and application of novel abiotic anion transporters, capable of facilitating the transport of biologically relevant anionic species across lipid bilayer membranes as potential therapeutics for life-threatening disorders such as cystic fibrosis and cancer.
Abstract:
There are many cases within nature whereby the transport of anions across lipid bilayer membranes is crucial to maintain homeostasis. Ions have very low membrane permeability and thus require the action of either a membrane channel, pumps or mobile carriers to facilitate their transmembrane transport. There are over 400 genes which encode for ion channels in the human genome1 and mutations within these genes leads to life-altering channelopathies including Bartter syndrome, Best disease, and Cystic Fibrosis. There is therefore a pressing need to develop synthetic carriers to facilitate ion transport across membranes. In comparison to hydrogen bonding (HB), halogen bonding (XB) – the attractive intermolecular interaction between a polarized halogen atom and a Lewis base – has strict linear geometry making them highly directional, and more hydrophobic.2 Despite these favourable properties, their utilisation in synthetic anion transporters is underdeveloped.3 Here we show that novel iodotriazole halogen bonding anion carriers and their C-H hydrogen bonding analogues can be synthesized via high yielding and versatile click chemistry, to afford highly active and readily accessible anion transporters. The ability of the carriers to transport anions across lipid bilayers was determined using fluorescence assays in multiple vesicle-based experiments, to determine the effect of the XB and HB interactions on anion transport selectivity.
References:
1. P. Imbrici, A. Liantonio, G. M. Camerino, A. Mele, A. Giustino, S. Pierno, A. De Luca, D. Tricarico, J. F. Desaphy and D. Conte, Front. Pharmacol., 2016, 7, 121.
2. L. C. Gilday, S. W. Robinson, T. A. Barendt, M. J. Langton, B. R. Mullaney and P. D. Beer, Chem. Rev, 2015, 115, 7118-7195.
3. A. V. Jentzsch, D. Emery, J. Mareda, S. K. Nayak, P. Metrangolo, G. Resnati, N. Sakai and S. Matile, Nat. Commun, 2012, 3, 905.
Poster 15
Synthesis of novel supramolecular structures based on the spin-crossover complex [Fe(3-bpp)2]
2+ using mechanochemistry and co-crystallisation.
L. T. Birchall and H. J. Shepherd
Ingram Building, University of Kent, Canterbury, Kent, CT2 7NH
Email: [email protected] Web: www.twitter.com/LTBIRCH
Abstract:
Spin-crossover (SCO) materials can change their spin state in response to a variety of stimuli such as temperature, light and guest molecules. These transitions are accompanied by a change in magnetic properties and often a colour change, making them attractive as smart materials.1,2
Octahedral metal complexes containing iron(II) are known to be SCO active when certain ligands such as 3-bpp (2,6-bis(pyrazol-3-yl)pyridine) are bound to the metal.1 Complexes of the formula, [Fe(3-bpp)2]2+ have been studied previously where different counter ions such as [BF4]-, [ClO4]- and [Cl]- have been incorporated.3–5
3-bpp is a particularly interesting ligand due to the two free N-H groups which can be involved in hydrogen bonding. This largely dominates the SCO behavior of the complexes by affecting the electron density in the pyrazole rings, as well as supramolecular connectivity between centres.6,7 Most of the known complexes rely heavily on water-based hydrogen bonded networks, however more rigid structures have been found to show better SCO cooperativity.8 We have begun to investigate the structure-property relationships arising from [Fe(3-bpp)2]2+ based materials in the solid-state.
Mechanochemistry involving both neat and liquid-assisted grinding has been used to allow for rapid screening of many reaction conditions.9 We have successfully synthesized a number of novel compounds, including solvates and co-crystals which have been characterized using both single-crystal XRD and PXRD where appropriate. Co-crystallisation has not previously been investigated in this family of compounds and our results show that desirable rigid structures can be formed using this technique.
References:
1. G. Craig, O. Roubeau and G. Aromí, Coord. Chem. Rev., 2014, 269, 13–31. 2. R. Hogue, S. Singh and S. Brooker, Chem. Soc. Rev., 2018, 47, 7303–7338. 3. K. Sugiyarto, D. Craig, A. Rae and H. Goodwin, Aust. J. Chem., 1994, 47, 869. 4. K. Sugiyarto and H. Goodwin, Aust. J. Chem., 1988, 41, 1645–1663. 5. M. Scudder, D. Craig and H. Goodwin, CrystEngComm, 2005, 7, 642–649. 6. V. Jornet-Mollá, C. Giménez-Saiz and F. Romero, Crystals, 2018, 8, 1–13. 7. P. King, J. Henkelis, C. Kilner and M. Halcrow, Polyhedron, 2013, 52, 1449–1456. 8. V. Jornet-Mollá, Y. Duan, C. Giménez-Saiz, J. Waerenborgh and F. Romero, Dalt. Trans., 2016,
45, 17918–17928. 9. J. Askew and H. Shepherd, Chem. Commun., 2017, 54, 180–183.
Poster 16
Overcoming Antimicrobial Resistance
Jessica E. Boles; Lisa J. White; J. Mark Sutton; Charlotte K. Hind; Daniel P. Mulvihill* and Jennifer R. Hiscock*
School of Physical Sciences, University of Kent, Giles Lanes, Canterbury, CT2 7 NZ
Email: [email protected] Web: https://research.kent.ac.uk/sisc
Abstract:
Antimicrobial resistance (AMR) is fast becoming the greatest threat to human health. It has been predicted that by 2050 the direct impact of AMR will have decreased global Gross Domestic Profit (GDP) by £67 trillion. The exponential rise in global antibiotic consumption, combined with the void in antibacterial drug discovery, indicates that within the next 35 years deaths attributed to AMR will exceed those caused by cancer.1 A novel class of supramolecular, self-associating amphiphiles (SSAs)2,3 have previously been shown to demonstrate antimicrobial activity towards methicillin resistant Staphylococcus aureus (MRSA), a clinically relevant Gram-positive bacterium.4
When considering the hypothesised two-phase mode of antimicrobial action proposed for SSAs, we have developed the theory that the membrane disruption properties of SSAs may be used to increase the efficacy of commonly used antimicrobial agents, and overcome common cellular resistance mechanisms. This means that SSAs could be classed not only as antimicrobials but also as antimicrobial adjuvants.
We have now verified the antimicrobial activity of 50 SSAs against clinically relevant Gram-positive (MRSA) and Gram-negative (E. coli) bacteria. My work in this area has also shown that SSAs can act as antimicrobial adjuvants for peptidoglycan disrupters, DNA collators and membrane active antiseptics (Figure 1). Work in this area remains ongoing and now includes synthetic attempts to co-formulate SSAs with known antimicrobial agents to produce synergistic drug delivery systems.
Figure 1 – Graph showing the antimicrobial adjuvant property of SSAs when used in conjunction with three types of antimicrobial agents.
References:
1. S. Davies, J. Farrar, J. Rex, R. Murry and J. O'Neill, Antimicrobial Resistance: Tackling a crisis for
the health and wealth of nations, 2014.
2. L. J. White, N. J. Wells, L. R. Blackholly, H. J. Shepherd, B. Wilson, G. P. Bustone, T. J. Runacres
and J. R. Hiscock, Chemical Science, 2017, 8, 7620-7630.
3. L. J. White, S. N. Tyuleva, B. Wilson, H. J. Shepherd, K. K. L. Ng, S. J. Holder, E. R. Clark and J.
R. Hiscock, Chemistry-a European Journal, 2018, 24, 7761-7773.
4. S. N. Tyuleva, N. Allen, L. J. White, A. Pépés, H. J. Shepherd, P. J. Saines, R. J. Ellaby, D. P.
Mulvihill and J. R. Hiscock, Chemical Communications, 2019, 55, 95-98.
Poster 17
Molecular knots and links from highly active transmembrane ion channels
David P. August, Stefan Borsley, Scott L. Cockroft, Flavio della Sala, David A. Leigh* and Simon J. Webb
School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
Email: [email protected] Web: http://www.catenane.net
Biography:
Postdoctoral researcher working with Prof. David Leigh, having previously worked for Prof. Scott Cockroft and Dr Euan Kay. Research interests include molecular machines and transmembrane devices. I am particularly interested in the problem of how to pump molecules across a membrane.
Abstract:
Topologically complex molecules have found applications in a wide range of fields, with molecular knots and links displaying a range of desirable properties.1 However, the consequences of molecular knotting are generally not well understood within these applications. The exceptionally strong anion binding of circular helicates and their related knots has been demonstrated2 and applied in catalysis. Here, we explore the ion channel forming abilities of a pentafoil knot3 and a Star of David link,4 which form selective ion channels in phospholipid bilayers. We consider the transport mechanisms and the consequences of topological entanglement. Significantly, the unclosed helicate of the Star of David shows no ion channel forming ability, demonstrating the significance of molecular knotting within this system. As well as providing fundamental insights into the properties conveyed by molecular knotting, the high ion transport activities observed suggest that molecular knots and links may find application as antibiotics.
References:
1. S. D. P. Fielden, D. A. Leigh and S. L. Woltering, Angew. Chem. Int. Ed., 2017, 56, 11166. 2. J.-F. Ayme, J. E. Beves, C. J. Campbell, G. Gil-Ramírez, D. A. Leigh and A. J. Stephens, J. Am.
Chem. Soc., 2015, 137, 9812. 3. V. Marcos, A. J. Stephens, J. Jaramillo-Garcia, A. L. Nussbaumer, S. L. Woltering, A. Valero, J.-F.
Lemonnier, I. J. Vitorica-Yrezabal and D. A. Leigh, Science, 2016, 352, 1555. 4. D. A. Leigh, R. G. Pritchard and A. J. Stephens, Nat. Chem. 2014, 6, 978.
Poster 18
Hybrid Metal Oxide Clusters as A Platform for Multifunctional Redox-Active Nanomaterials
J. M. Cameron, E. Hampson, S. Amin and G. N. Newton*
GSK Carbon Neutral Laboratory for Sustainable Chemistry, University of Nottingham Jubilee Campus, Nottingham, NG7 2GA, UK
Email: [email protected] Web: www.newtonchemistry.com
Biography:
Jamie Cameron obtained his B.Sc. from the University of Glasgow in 2010, after which he remained to study for a Ph.D. with Prof. Lee Cronin on the self-assembly of metal-oxide clusters. In 2015, he was awarded a JSPS Postdoctoral Fellowship to study multi-stable metal complexes with Prof. Hiroki Oshio at the University of Tsukuba, Japan. In 2017 he returned to the UK to assume his current position at the University of Nottingham, where his interests lie in the development of new multi-functional materials assembled with the help of bespoke molecular building blocks.
Abstract:
Polyoxometalates (POMs) are a fascinating class of redox- and photo-active molecular metal-oxide clusters and can be employed as well-defined molecular building blocks in the assembly of a range of supramolecular nanostructures. Here, we will discuss our recent studies on a series of organic-inorganic “hybrid-POM” clusters, formed by the controlled addition of organophosphonate ligands to the metal-oxide core.[1,2] In particular, we will show how a simple one-pot approach can be used to generate asymmetrically functionalised hybrid clusters, in which multiple functionalities can be combined within a single molecular ensemble by the introduction of two distinct organic groups.[3] The reversible self-assembly of these multi-functional clusters into supramolecular nanostructures will also be described and, lastly, we will offer some perspective on the development of this approach as a means to obtain new, modular and multifunctional soft nanomaterials.
Scheme 1. An asymmetric hybrid POM (structure shown inset, right) bearing two different functional ligand groups (A
and B) and a schematic (bottom left) showing its tuneable solvent and cation-dependent self-assembly.
References:
1. K. Kastner, A. J. Kibler, E. Karjalainen, J. A. Fernandes, V. Sans, G. N. Newton, J. Mater. Chem. A, 2017, 5, 11577-11581.
2. S. Amin, J. M. Cameron, J. A. Watts, D. A. Walsh, V. Sans, G. N. Newton, Mol. Syst. Des. Eng., 2019, 4, 995-999.
3. E. Hampson, J. M. Cameron, S. Amin, J. Kyo , J. A. Watts, H. Oshio and G. N. Newton, Angew. Chem. Int. Ed., 2019, doi:10.1002/anie.201912046.
Poster 19
Enhanced DASA Photo-switching Properties due to Piperazine Based Donors
S. W. Connolly, H. J. Shepherd and R. Tiwari
School of Physical Sciences, University of Kent, Park Wood Rd, Canterbury, CT2 7NH
Email: [email protected] Web: https://research.kent.ac.uk/sisc/
Abstract:
Donor-Acceptor Stenhouse Adduct (DASA) photo-switches1, 2 have generated a lot of interest since they were first reported; various areas of research have taken advantage of simple synthesis and the desirable photochromic properties in designing novel systems with interesting applications. The work presented here describes the synthesis of DASA molecules and an analysis of the photochromic properties. The use of piperazine based donors results in a unique structure that leads to changes in the conformation of the cyclized DASA form due to the two amino functionalities. In addition, the photo-switching properties do not suffer from the concentration limitations3 exhibited by previously reported DASAs. UV-Vis spectroscopy was used to analyse the photo-switching properties of the DASAs and illustrate impressive switching efficiency. Single crystal X-ray diffraction data and computational modelling also reveal changes in the proton transfer steps of the photo-switching mechanism that could to explain the improved switching properties observed.
References:
1. Helmy, S., Oh, S., Leibfarth, F. A., Hawker, C. J., & Read De Alaniz, J. Journal of Organic Chemistry, 2014, 79, 11316-11329.
2. Helmy, S., Leibfarth, F. A., Oh, S., Poelma, J. E., Hawker, C. J., & De Alaniz, J. R, Journal of the American Chemical Society, 2014, 136, 8169-8172.
3. Lui, B. F., Tierce, N. T., Tong, F., Sroda, M. M., Luo, H., Read de Alaniz, J., & Bardeen, C. J., Photochemical & Photobiological Sciences, 2019, 18, 1587-1595.
Poster 20
Azole-mediated assembly of redox-active rylenes
R. A. Dawooda, G. Browna, F. H. N. Arnolda,b, A. C. Carrickb, G. P. Grossmanb and A.-J. Avestroa,b*
aDepartment of Chemistry, University of York, Heslington, York, YO10 5DD, UK bDepartment of Chemistry, Durham University, Durham, DH1 3LE, UK
Email: [email protected], [email protected], [email protected]; *[email protected]
Abstract:
Naphthalene diimides (NDIs) belong to a class of redox-active rylenes capable of self-organisation due to favourable aromatic interactions and, as a result, have found utility in the design of functional optoelectronic and semi-conducting materials.1 NDIs preferentially assemble into slip-stacked geometries with relatively few π-contacts or low degrees of π-orbital overlap due to their quadrupolar cores. By utilising the H-bonding ability of pyrazoles2 and other azoles as supramolecular directing groups, we aim to control the nature and degree of π-mediated assembly of NDIs in solution and in the solid state. For instance, the self-complementary H-bonding motif of pyrazoles has been successfully employed to create well designed single-crystalline aromatic assemblies using linear, bent and even trigonal building blocks.2 By systematically varying the sterics, regiochemistry and heteroatom density of azole directing groups, we hope to understand the fundamental interplay between aromatic and H-bonding interactions for preparing NDI-based materials with optimal solid-state charge mobilities and stabilities.
Herein, we present the work of undergraduates and first-year PhD students in which a series of bis(azole) NDI compounds (1a-f, Figure 1a) are prepared and their properties analysed by electrochemical, spectroscopic and X-ray diffraction methods. Solid-state analysis of crystal packing data reveal that, indeed, the nature of the H-bonding unit can have a complex and unpredictable influence on NDI π-orbital interactions in the solid state. For example, in comparing the pure crystal packing of two bispyrazole NDI regioisomers (i.e., 1a and 1c), the 180º H-bonding geometry of 1a does not lead to better π-contact, whereas angling the pyrazoles as in 1c (Figure 1b) leads to highly overlapped S2-symmetric NDI surfaces that are stabilised further by interlayer H-bonding. Solid-state electrochemical analysis will elucidate the impact of controlling π-contacts on thin-film conductivity, which will be explored in the context of organic lithium ion batteries.3
Figure 1: (a) General synthesis of bis(azole) NDI. (b) Single crystal packing structures bis(3-pyrazole) NDI 1c.
References:
1. S. V. Bhosale, C. H. Jani and S. J. Langford, Chem. Soc. Rev., 2007, 37, 331. 2. M. I. Hashim, H. T. M. Le, T.-H. Chen, O. Daugulis, C.-W. Hsu, A. J. Jacobson, W. Kaveevivitchai,
X. Liang, T. Makarenko, O. Š. Miljanić, I. Popovs, H. V. Tran, X. Wang, C.-H. Wu, and J. I. Wu, J. Am. Chem. Soc., 2018, 140, 6014.
3. G. Sun, Y. Hu, Y. Sha, C. Shi, G. Yin, H. Zang, H.-J. Liu, Q. Liu, Mater. Chem. Phys., 2019, 236, 121815
Poster 21
The development of perylene bisimides gels using Alkaline metal triggers
J. G. Egan, J. A. Mena and E. R. Draper*
School of Chemistry, University of Glasgow, Glasgow G12 8QQ
Email: [email protected]
Biography:
My BSc (hons) was carried out in Chemistry at Ontario Tech University in 2017. In my undergraduate studies I joined Dr. Olena Zenkina’s group in the winter of 2016, during this time I designed sensors for the detection of iron down to the ppm level. In 2016/2017 I continued in the Zenkina group for my 4th year honours thesis where she developed electrochromic devices as well as organic-metal complexes using gold nanoparticles that were able to form assemblies. In the summer of 2017, I worked for Prof Brad Easton where I synthesized efficient platinum catalyst for fuel cells. In 2018 I returned to the Zenkina group to complete my MSc; my thesis focused on the development on magnetic nanoparticles for the detection and removal of mercury. During my MSc I went on exchange as a QEScholar, at the University of Glasgow for Dr. Emily Draper Group. Whilst in Glasgow my work focused on the development of gels for use as bio-electronics. She received her MSc in Material Science in from Ontario Tech University in 2019. I returned to the Draper group at University of Glasgow for my PhD, which focuses on the synthesis of perylenes with new functional groups for use as gels.
Abstract:
This work looks at perylene bisimides (PBIs) that were able to form gels at physiological pH using a mineral salt, such as magnesium or calcium, as a trigger for gelation. Eight PBIs with different amino acid side chains were scanned to see which had potential to form gels using the metal salts as triggers. It was narrowed down to two PBIs, one containing a histidine side arm (PBI-H) and the other a leucine side arm (PBI-L). They were able to form invertible samples in the pH range of 7 to 8. The rheology showed that PBI-L was able to form stiffer gels with CaCl2 while PBI-H formed stiffer gels with MgCl2. The rheology of these materials was measured to investigate how several variables effected the bulk rheological properties. As the pH was changed between 7-8 it was seen that PBI-L was able to form more consistent gels while the stiffness of PBI-H changed with pH. The amount of salt used as a trigger also changed the rheological properties, at pH = 7.4 the concentration range in which PBI-H could form gels was narrow while the range for PBI-L was large. How the amount salt affected the formation of the radical anion by light was investigated by UV-vis. It showed that the addition of salt improved the ratio of free PBI to radical for both PBI-L and PBI-H. This work will continue to focus on the effect on the stability of the radical in the presence of the metal salt. With the goal to develop gels that can be used for flexible electronic applications.
Poster 22
Improved identification of organophosphorus simulants for the development of next-generation detection and decontamination technologies.
Rebecca J. Ellaby, Nyasha Allen, Faith Taylor, Ewan R. Clark, Antigoni Pépés, Milan Dimitrovski, Daniel P. Mulvihill and Jennifer R. Hiscock*
School of Physical Sciences, Ingram Building, University of Kent, Canterbury, CT2 7NH
Email: [email protected] Web: https://research.kent.ac.uk/sisc
Abstract:
Organophosphorus (OP) chemical warfare agents (CWAs) represent an ever-present global threat. This threat has been demonstrated many times since this class of CWA were first identified in the 1930’s through release of these agents in small scale events within the UK (2018)1 and Malaysia (2017)2, and larger scale events within Syria (2013)3 and Japan (1995).4 The toxicity and legalities associated with OP CWAs often hinders the development of novel technologies required to counter any events of environmental contamination. It is because of this that the identification of appropriate OP CWA simulants is crucial. To aid this process, a combination of accessible computational modelling techniques and live experimental data have been used to produce novel predictive methods for the identification of appropriate OP CWA simulants for sarin, soman and VX. To date these methods have produced models to identify simulants that mimic: (1) the hydrogen bond acceptor properties of the P=O moiety, common to all OP CWAs; and (2) the reactivity of OP CWAs with a nucleophile – specifically hydroxide, a common agent in current OP CWA decontamination mixtures (Fig. 1). It is hoped that the effective use of physical property specific simulants will aid countermeasure development.
Figure 1: Graphical overview of the predictive methodologies developed.
References:
1. M. Peplow, Chem. Eng. News, 2018, 96, 3-3. 2. T. Nakagawa and A. T. Tu, Forensic Toxicol., 2018, 36, 542-544. 3. H. John, M. J. van der Schans, M. Koller, H. E. T. Spruit, F. Worek, H. Thiermann and D. Noort,
Forensic Toxicol., 2018, 36, 61-71. 4. T. Okumura, N. Takasu, S. Ishimatsu, S. Miyanoki, A. Mitsuhashi, K. Kumada, K. Tanaka and S.
Hinohara, Ann. Emerg. Med., 1996, 28, 129-135.
Poster 23
A Proto-Nucleic Acid-Based Semiconducting Supramolecular Duplex
O. El-Zubir, L. L. G. Al-Mahamad, D. Smith, B. R. Horrocks and A. Houlton
Chemical Nanoscience Labs, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
Email: [email protected] Web: www.ncl.ac.uk/nes/staff/profile/osamael-zubir.html
Biography:
Osama El-Zubir did his PhD at the University of Sheffield in 2012. He was a Postdoctoral Research Associate in the group of Prof Graham Leggett at the University of Sheffield from 2011 to 2014, and since July 2014 at Newcastle University in the group of Prof Andrew Houlton.
Abstract:
Nucleic acid-based materials offer extraordinary capabilities for programmable, hierarchical, structure assembly with multi-dimensional and multi-material complexity. DNA’s robust nature and reliable synthesis associated with the ability to integrate with metals address many of the criteria desired of a materials design toolkit. However, the combination of electrical conduction into the basic framework of duplex DNA remains challenging.1-4 Here, we demonstrate this with a prototypical design based on a sulfur-containing natural nucleoside (6-thioguanosine). This reacts with gold(I) ions to spontaneously assemble luminescent 1D helical chains extending many μm in length5 with the resulting coordination polymer being structurally analogous to a natural duplex DNA. This DNA-like polymer can be uniquely transformed, by oxidative doping, into a wire-like conducting form. Furthermore, this chemistry can be exploited for the site-specific integration of semiconducting sequences into the framework of natural DNA, thus transforming the properties in a fundamental and technologically useful manner.5
Figure. AFM height image of Au-thioguanosine xerogel on a silicon wafer (left) and Au-thiolate-DNA concatemers revealing the extended, micron, lengths of strands (right).
References:
1. A. J. Storm, J. van Noort, S. de Vries and C. Dekker, Phys. Lett. 2001, 79, 3881. 2. C. Gomez-Navarro, F. Moreno-Herrero, P. J. de Pablo, J. Colchero, J. Gomez-Herrero and A. M.
Baro, Proc. Natl Aacd. Sci. USA 2002, 99, 8484. 3. M. Bockrath, N. Markovic, A. Shepard, M. Tinkham, L. Gurevich, L. P. Kouwenhoven, M. W. Wu
and L. 4. L. Sohn, Nano. Lett. 2002, 2, 187. 5. S. Sonmezoglu, O. A. Sonmezoglu, G. Cankaya, A. Yildirim and N. Serin, J. Appl. Phys. 2010,
107, 124518.
6. L. L.G. Al-Mahamad, O. El-Zubir, D.G. Smith, B. R. Horrocks and A. Houlton, Nat. Commun. 2017, 8, 720.
Poster 24
A living supramolecular catalyst that produces polymers
A. H. J. Engwerda and S. P. Fletcher
Chemistry Research Laboratory, 12 Mansfield road, Oxford, OX1 3TA
Email: [email protected] Web: http://fletcher.chem.ox.ac.uk/home
Biography:
Ton was born in Tilburg, the Netherlands. He received his M.Sc. from Radboud university Nijmegen and a PhD from the same university, working on the deracemization of chiral (drug) molecules. He is currently a postdoctoral fellow in Stephen Fletcher’s group at the University of Oxford, studying autocatalysis and out-of-equilibrium systems.
Abstract:
Great efforts are made in chemistry to mimic the complex catalytic systems found in nature.1 Here we describe a functional system that catalyses polymer synthesis. Catalytically active aggregates spontaneously form when the products of two phase-separated reactants undergo supramolecular self-assembly.2,3 An initial period of autocatalytic product formation is succeeded by a period of relative homeostasis, where the product concentration is stable and polymers are instead produced. Polymer size is dependent of multiple reaction variables and can be tightly controlled by addition of terminators. Only after all the reactants have been consumed, does autophagy (self-consumption) of the micellar aggregates result in the destruction of the functional system. Several features of living systems that synthetic mimics often aim to emulate, such as autocatalytic growth, homeostasis, responsiveness to its environment, and the generation of advanced products from a simple building block, are observed in the living supramolecular catalyst. This work demonstrates a new design concept for functional, supramolecular complexes, that are able to self-assemble and catalyse their own formation while also being able to produce complex materials in a controlled manner.
References:
1. M. Raynal, P. Ballester, A. Vidal-Ferran, P. van Leeuwen, Chem. Soc. Rev. 2014, 43, 1734-1787. 2. P. A. Bachmann, P. L. Luisi, J. Lang Nature, 1992, 357, 57-59 3. S. M. Morrow, I. Colomer and S. P. Fletcher, Nat. Commun. 2019, 10.
Poster 25
Dissipative catalysis with a molecular machine
C. Biagini, S. D. P. Fielden, D. A. Leigh, F. Schaufelberger, S. Di Stefano and D. Thomas
School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
Email: [email protected] Web: http://www.catenane.net
Abstract:
We report on catalysis by a fuel-induced transient state of a synthetic molecular machine.1 A [2]rotaxane molecular shuttle containing secondary ammonium/amine and thiourea stations is converted between catalytically inactive and active states by pulses of a chemical fuel (trichloroacetic acid), which is itself decomposed by the machine and/or the presence of additional base. The ON-state of the rotaxane catalyzes the reduction of a nitrostyrene by transfer hydrogenation. By varying the amount of fuel added, the lifetime of the rotaxane ON-state can be regulated and temporal control of catalysis achieved. The system can be pulsed with chemical fuel several times in succession, with each pulse activating catalysis for a time period determined by the amount of fuel added. Dissipative catalysis by synthetic molecular machines has implications for the future design of networks that feature communication and signaling between the components.2
References:
1. C. Biagini, S. D. P. Fielden, D. A. Leigh, F. Schaufelberger, S. Di Stefano and D. Thomas, Angew. Chem. Int. Ed., 2019, 58, 9876. [Hot Paper]
2. P. Remón, U. Pischel, ChemPhysChem, 2017, 18, 1667.
Poster 26
Stimuli-Responsive Release from Rotaxanes
M. P. Fitzpatrick, A. M. Acevedo-Jake, S. M. Goldup*
Department of Chemistry, University of Southampton, University Road, Southampton. SO17 1BJ
Email: [email protected]
Abstract:
By combining Goldup’s small macrocycle variation1 of the AT-CuAAC reaction2 with the click-DNA ligation approach,3 it is possible to “click” terminally modified azide and alkyne oligonucleotides together inside the cavity of a macrocycle, facilitating the formation of the biocompatible triazole backbone and the mechanical bond simultaneously. The resulting mechanical bond was found to suppress duplex formation, effectively acting as a cage to silence oligonucleotide activity.
Here we present recent efforts towards the development of artificial stimuli-responsive oligonucleotide-rotaxanes. Controlled release of an oligonucleotide axle can be achieved through the incorporation of a stimuli-responsive macrocycle that, in response to exogenous (light) or endogenous (enzyme) stimuli, initiates a self-opening mechanism to liberate the oligonucleotide in its bioactive form. Such materials represent an excellent opportunity for the production of novel chemical biology tools for the study gene expression and protein function, as well as having potential therapeutic applications as prodrug antisense agents.
Scheme 1. Synthesis of oligonucleotide-rotaxanes via the AT-CuAAC coupling of azide and alkyne modified oligonucleotides inside a stimuli-responsive macrocycle, and subsequent release of the oligonucleotide axle.
References:
1. H. Lahlali, K. Jobe, M. Watkinson and S. M. Goldup, Angew. Chemie - Int. Ed., 2011, 50, 4151-4155.
2. V. Aucagne, K. D. Hänni, D. A. Leigh, P. J. Lusby and D. B. Walker, J. Am. Chem. Soc., 2006, 128, 2186–2187.
3. M. Kukwikila, N. Gale, A. H. El-Sagheer, T. Brown and A. Tavassoli, Nat. Chem., 2017, 9, 1089-1098.
Poster 27
The First Charge-Neutral POM: Lanthanide induced Contraction of Molybdenum Blue Wheels
E. Garrido Ribo, N. L. Bell and L. Cronin*
School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
Email:[email protected]; [email protected] Web: www.croninlab.com
Biography:
I completed my degree in Chemistry at University of Barcelona in Spain in 2016. However, before finishing my undergrad, I joined the Cronin group to do my research project as part of an Erasmus+ program. After completing my studies, I returned to Glasgow to continue my research in the Cronin group as an intern first, before undertaking a PhD from Oct 2017.
Abstract:
Polyoxometalate Molybdenum Blues (MBs) complexes typically exist as discrete multianionic clusters and are composed of repeating Mo building units.1 Pentagon-centered {Mo8} (blue) building blocks joined by an equal number of {Mo1} units (yellow) as loin and {Mo2} dimer units (red) as skirt along the ring edge. The ring sizes of MB wheels are regulated by the {Mo2} units which control the ring curvature and for this reason, only two homo Mo blue wheels, {Mo176} and {Mo154}, have been discovered. However, by partially replacing {Mo2} linkers with lanthanide ions (green), several lanthanide doped Mo blue (LMB) rings have been found in the last two decades.2,3
Herein we report the synthesis new LMB structures that have all, or almost all, {Mo2} units replaced with lanthanide ions on the inner rim of the wheel (Fig. 1). Three of these compounds consist of a decameric {Mo90Ln10} (Ln = La, Ce and Pr) framework, while a similar {Mo92Ln9} (Ln = Nd, Sm) structure conserves one {Mo2} linker unit in their structure as a consequence of the lanthanide contraction. Remarkably, the decameric {Mo90Ln10} LMB compounds are the first examples of charge neutral MBs wheels. To access these novel compounds, extreme hydrothermal conditions are required, as well as, great care in defining the synthetic parameters.
Fig. 1 Hydrothermal synthesis of MBs with Ln(III) ions results in smaller, formally charge-neutral wheels.
References:
1. A. Müller and P. Gouzerh, Chem. Soc. Rev., 2012, 41, 7431. 2. A. Müller, C. Beugholt, H. Bögge, and M. Schmidtmann, Inorg. Chem., 2000, 39, 3112. 3. W. Xuan, A. J. Surman, H. N. Miras, D. Long, and L. Cronin, J. Am. Chem. Soc., 2014, 136, 14114.
Poster 28
An isostructural pair of two-fold interpenetrated redox-active metal-organic frameworks
J. A. Gould and A.-J. Avestro*
Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
Email: [email protected]; *[email protected]
Abstract:
Conductive metal-organic frameworks (MOFs) are an emerging class of materials in which redox-activity can be introduced through either the metal ions/clusters or the organic linkers, enabling the development of multifunctional materials with inherent electronic, magnetic and optical properties.1
In the Avestro group, we are interested in using MOF scaffolds to manipulate the 3D spatial arrangement and through-space of redox-active π-systems for solid-state electronic, photochromic and energy applications. Herein, we present the serendipitous synthesis and materials characterisation of two isostructural MOFs (Figure 1) with the formula [Fe(X)(BPNDI)] (where BPNDI = bis(4-pyrazolyl)naphthalenediimide and X = OH or Cl). These crystalline materials display two-fold interpenetration of redox-active BPNDI units, thereby generating co-facial π-interactions (3.45 Å) within ligand stacks that can support through-space electron delocalisation and 1D charge transfer processes. Cyclic voltammetry data indicate the electrochemical response of the material is dominated by the redox behaviour of the NDI ligand. Ongoing studies aim to confirm the ambient stability of organic radical anions present in reduced MOF samples as well as determine their solid-state conductivity. Indeed, MOFs comprising 1D [Fe(Pz)2(μ2-X)] chains have been shown to contribute to excellent metal-mediated MOF conductivity when reduced to the Fe(II/III) mixed-valence form (as was recently demonstrated by the Long2 and Dinca3 groups.) Such features are anticipated to deliver material properties suitable for development of these MOFs into novel electrochromic or photochromic conductive materials.
Figure 1. The structure of the H2BPNDI ligand and the [Fe(X)(BPNDI)] materials used in this study.
References:
1. J. Calbo, M. J. Golomb and A. Walsh, J. Mater. Chem. A, 2019, 7, 16571. 2. M. L. Aubrey, B. M. Wiers, S. C. Andrews, T. Sakurai, S. E. Reyes-Lillo, S. M. Hamed, C.-J. Yu, L.
E. Darago, J. A. Mason, J.-O. Baeg, F. Grandjean, G. J. Long, S. Seki, J. B. Neaton, P. Yang and J. R. Long, Nat. Mater., 2018, 17, 625.
3. L. S. Xie, L. Sun, R. Wan, S. S. Park, J. A. DeGayner, C. H. Hendon and M. Dinca, J. Am. Chem. Soc., 2018, 140, 7411.
Poster 29
Enantioselective Catalysis with a Mechanically Planar Chiral Rotaxane
A. W. Heard, and S. M. Goldup
Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ
Email: [email protected] Web: www.goldup.soton.ac.uk
Abstract:
Rotaxanes can display interesting chirality, where the two enantiomers of the compound are distinguished by the orientation of a Cnh macrocycle around a Cnv axle, which are achiral by themselves, and not by the stereochemistry of their sub-components.1
This work demonstrates the synthesis of enantiopure mechanically planar chiral rotaxanes,2 and the first application of these towards enantioselective catalysis. Specifically, we investigated the application of mechanically planar chirality in an enantioselective Au(I)-mediated reaction, as it is typically challenging to achieve enantioselectivity in such processes due to the linear coordination geometry of the Au(I) intermediates. Here we report cyclopropanations of up to 80% ee with high diastereoselectivity,3 comparable to the best conventional ligands in the literature.4
References:
1. E. M. G. Jamieson, F. Modicom and S. M. Goldup, Chem. Soc. Rev. 2018, 47, 5266-5311. 2. R. Bordoli and S. M. Goldup, J. Am. Chem. Soc. 2014, 136, 13, 4817-4820. 3. A. W. Heard and S. M.Goldup, ChemRxiv, 2019, 10.26434/chemrxiv.9701789. 4. M. J. Johansson, D. J. Gorin, S. T. Staben and F. D. Toste, J. Am. Chem. Soc. 2005, 127, 51,
18002-18003
Poster 30
Electrochemical Oxoanion Sensing at Ferrocenyl Halogen- and Hydrogen-bonding Interfaces
R. Hein,† X. Li,† P. D. Beer* and J. J. Davis*
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, U.K.
Email: [email protected] Web: www.beer.chem.ox.ac.uk; www.jjdgroup.co.uk
Biography:
Robert Hein obtained his B.Sc. from Jacobs University Bremen, Germany in 2016, where he worked in the field of supramolecular chemistry under the supervision of Prof. Werner M. Nau. During his studies he spent a semester abroad at Cornell University (with Prof. Geoffrey W. Coates) and furthermore completed a summer project in the group of Prof. Oren A. Scherman at the University of Cambridge. He is currently pursuing a Ph.D. at the University of Oxford under the guidance of Prof. Paul D. Beer and Prof. Jason J. Davis working on electrochemical, supramolecular anion sensors. Other research interests include the development of novel antifouling interfaces for electrochemical (bio)sensors, surface functionalization via diazonium chemistry as well as host-guest chemistry.
Abstract:
The sensing of anions is of the utmost importance in a wide variety of environmental and biological environments. In order to construct simple, cheap and hand-held sensory devices capable of selective detection of different anions, scientists increasingly explore electrochemical techniques as useful, sensitive and scalable means of realizing a real-life potential. Advances in supramolecular anion receptor chemistry have stimulated the rapid development of rationally designed, novel electrochemical anion sensors.1 Recently, halogen-bonding (XB) has emerged as a powerful non-covalent interaction that can drive anion recognition with often enhanced performance over analogous hydrogen bonding (HB) receptors. While it has been studied in some detail in solution, XB-mediated sensing at interfaces, where additional cooperative effects and preorganization can often enhance binding, remains rare.2,3 In order to expand the scope of such sensors we synthesised novel ferrocene-tagged anion receptors containing amide and (iodo)triazole anion binding sites. The additional incorporation of two disulfide anchor groups then allowed formation of self-assembled monolayers on gold electrodes whereby the receptors form well-defined macrocyclic host cavities. These interfaces were then studied by a variety of electrochemical and surface analytical techniques including ATR-IR, water contact angle measurements and XPS. Detailed (electrochemical) anion binding studies were carried out in solution and on the surface using the integrated ferrocene transducer, whose well-defined redox couple was perturbed upon anion binding in aqueous/organic solvent systems. The observed cathodic shifts were hereby largest for the oxoanions nitrate and bisulfate with good selectivity over other anions. Significantly, the surface-confined receptors displayed an enhanced response compared to the solution-phase binding. We furthermore show that, through a rational choice of electrolyte conditions, a voltammetrically stable interface can be obtained which displays a remarkable degree of redox reversibility. This enables not only the repeated use of the sensor, but also paves the way towards the unprecedented investigation of derived redox-capacitive readouts for ion sensing applications.4
References:
1. R. Hein, P. D. Beer and J. J. Davis, Chem. Rev. (Under review). 2. R. Hein, A. Borissov, M. D. Smith, P. D. Beer and J. J. Davis, Chem. Commun. 2019, 55, 4849. 3. H. Hijazi, A. Vacher, S. Groni, D. Lorcy, E. Levillain, C. Fave and B. Schöllhorn, Chem. Commun.
2019, 55, 1983. 4. J. Piccoli, R. Hein, A. H. El-Sagheer, T. Brown, E. M. Cilli, P. R. Bueno and J. J. Davis, Anal. Chem.,
2018, 90, 3005.
Poster 31
Nanosized supramolecular hydrogel beads for biomedical applications
Jordan O. Hill, Carmen C. Piras, and David K. Smith*
Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
Email: [email protected]
Abstract:
Hydrogels are colloidal materials in which a sample-spanning ‘solid-like’ network immobilises a liquid-like aqueous phase. The importance of these materials is derived from their biocompatibility, making them viable structures for applications such as next-generation drug delivery and tissue engineering. Hydrogels may either be synthesised from a polymer gelator (PG) or a low-molecularweight-gelator (LMWG). PGs form hydrogels with high mechanical strength due to the presence of high molecular weight polymers with strong crosslinks. LMWGs typically self-assemble into a hydrogel which is responsive to stimuli such as pH or temperature but is mechanically weak. A composite PG/LMWG material can assemble orthogonally and combine the benefits of the two gels.1 It has recently been shown that a rare “core-shell” gel bead may be obtained where the LMWG – in this case 1,3:2,4-di-(4-acylhydrazide)-benzylidenesorbitol (DBS-CONHNH2) – is contained as the filling within a calcium alginate PG shell (see Fig. 1).2 It was demonstrated that the LMWG retains its versatile chemical characteristics, but the overall structure gains mechanical strength and ease-of-handling as a consequence of having a PG shell.
Here, advances in reducing the size of these PG/LMWG gel-in-gel beads to the nanometre scale are reported. These advances in ‘sizing down’ the gel beads will help in targeting real-world applications for these materials, in particular targeted drug delivery and in vivo use. Controllable microscale and nanoscale bead sizes as small as 300 nm have been achieved, and samples analysed by DLS and SEM. A variety of metal nanoparticles have been incorporated into these beads, based on the fact that DBS-CONHNH2 has the ability to reduce metal ions to form nanoparticles in situ for removal from aqueous environments.3 In particular, we will report the use of iron or copper salts to form magnetic or antimicrobial nanoparticles, respectively.
References:
1. D. J. Cornwell and D. K. Smith, Mater. Horiz., 2015, 2, 279-293. 2. C. C. Piras, P. Slavik and D. K. Smith, Angew. Chem. Int. Ed., 2019, doi: 10.1002/anie.201911404 3. P. Slavík, D. W. Kurka and D. K. Smith, Chem. Sci., 2018, 9, 8673-8681.
Poster 32
Solid State Photochromism of Donor-Acceptor Stenhouse Adducts
T. J. Hitchings and H. J. Shepherd
The Ingram Building, University of Kent, Canterbury, Kent, CT2 7NH
Email: [email protected] Web: https://research.kent.ac.uk/sisc/
Biography:
Thomas Hitchings graduated from the University of Kent in 2019 with a (BSc) in Chemistry with a year in Industry. He completed a final year research project working with Dr Paul Saines looking at the synthesis and characterisation of amine functionalised metal-organic hybrids. Currently undertaking a (MRes) as part of the Shepherd group at the University of Kent looking at molecular crystal systems with novel optical properties.
Abstract:
Donor-Acceptor Stenhouse Adducts (DASAs) are strongly coloured pi conjugated molecules that isomerise in solution and in some polymer systems on irradiation with visible light. The isomerization process causes a large change in chemical structure and results in negative photochromism due to disruption of the conjugated system.1,2 The photoswitching properties are initiated through the irradiation of visible light but the reversibility can be achieved through thermal or frictional input as well as absence of visible light (darkness).3–7
As reported here, this highly reversible photoswitching has for the first time been observed in the solid state. It is believed that dynamic processes attributed to the presence of solvent molecules in the lattice enables sufficient molecular freedom to allow switching in the solid state. A full characterization of the solid-state switching behavior of these systems is underway using single crystal and powder X-ray diffraction, thermal analysis, NMR and reflectivity. Materials exhibiting this property have a range of potential applications in materials development such as humidity/ solvent vapour sensors, use as dopants to produce smart molecular material composites, novel pigment applications and molecular motors.8
References:
1 S. Helmy, F. A. Leibfarth, S. Oh, J. E. Poelma, C. J. Hawker and J. R. De Alaniz, J. Am. Chem. Soc., 2014, 136, 8169–8172.
2 S. Helmy, S. Oh, F. A. Leibfarth, C. J. Hawker and J. R. De Alaniz, J. Org. Chem., 2014, 79, 11316–11329.
3 W. Szymański, B. L. Feringa and M. M. Lerch, Chem. Soc. Rev., 2018, 47, 1910–1937. 4 N. Mallo, P. T. Brown, H. Iranmanesh, T. S. C. Macdonald, M. J. Teusner, J. B. Harper, G. E. Ball
and J. E. Beves, Chem. Commun., 2016, 52, 13576–13579. 5 N. Mallo, E. D. Foley, H. Iranmanesh, A. D. W. Kennedy, E. T. Luis, J. Ho, J. B. Harper and J. E.
Beves, Chem. Sci., 2018, 9, 8242–8252. 6 H. Zulfikri, M. A. J. Koenis, M. M. Lerch, M. Di Donato, W. Szymański, C. Filippi, B. L. Feringa and
W. J. Buma, J. Am. Chem. Soc., 2019, 141, 7376–7384. 7 Y.-D. Cai, T.-Y. Chen, X. Q. Chen and X. Bao, Org. Lett., 2019, 21, 7445–7449. 8 L. Pfeifer, M. Scherübl, M. Fellert, W. Danowski, J. Cheng, J. Pol and B. L. Feringa, Chem. Sci.,
2019, 10, 8768–8773.
Poster 33
Multivalent fullerene adducts for functional materials
Philip A. Hopea, David A. Palacios-Gomezb, Krishnamurthy
Munusamya,c, Debasis Semantac, Christopher Grovesb, and Alyssa-Jennifer Avestroa,d* aDepartment of Chemistry, Durham University, South Road, DH1 3LE, UK bDepartment of Engineering, Durham University, South Road, DH1 3LE, UK cPolymer Science & Technology Department, CSIR–CLRI, Adyar, Chennai 600020, India dDepartment of Chemistry, University of York, Heslington, York, YO10 5DD, UK
E-mail: [email protected]; *[email protected]
Abstract:
Three-dimensional carbon-rich nanostructures, such as fullerenes, continue to receive attention as synthons in the development of advanced functional materials owing to their unique globular shape and excellent photo/electrochemical properties as multi-electron acceptors.1 First reported by Nierengarten et al., the dodecaazido fullerene Az12C60 serves as a key intermediate for the straightforward preparation of Th-symmetric C60 hexakis adducts with an octahedral display of pendant functional groups. Indeed, by utilising Cu(I)-assisted azide–alkyne [3+2] cycloaddition (CuAAC) chemistry, we have installed both (a) redox-active electron acceptors and (b) photo-active electron donors to the periphery of Az12C60 to generate novel fullerene materials with bespoke function in charge transport, charge transfer, and even photocatalysis.
Herein, we present a collection of research undertaken by our group to demonstrate the utility of fullerene hexakis adducts in diverse solid-state composite and device contexts. Fundamental electronic, spectroscopic and high-resolution microscopic analyses reveal that an NDI-based fullerene hexakis adduct (NDI12C60, Figure 1) is capable of accepting at least 24 electrons and n-type electron transport within space-charge limited current diodes. Preliminary studies suggest that favourable NDI–NDI aromatic interactions provide efficient 1D pathways for electron delocalisation to afford carrier mobilities comparable to benchmark PC71BM.3 Co-casting with a π-electron rich hexakis adduct leads to alternative assemblies driven by aromatic charge–transfer interactions. Meanwhile, CuAAC functionalisation of Az12C60 with twelve electron-donating tetrabenzofluorene (TBF) moieties renders a new fullerene material (TBF12C60, Figure 1) that we demonstrate is capable of selective photocatalytic degradation of various waste water dyes.
Figure 1. The functional diversity of fullerene hexakis adducts derived from CuAAC with Az12C60 to generate
an effective charge carrier (NDI12C60) for thin-film organic electronics, a complementary assembly
component (Py12C60), and a selective photocatalyst (TBF12C60) for water remediation.
References:
1. Prato, M. J. Mater. Chem., 1997, 7, 1097–1109. 2. Lehl. J, Pereira de Freitas. P, Delavaux-Nicot. B and Nierengarten, JF. Chem. Commun., 2008,
2450–2452. 3. Wienk. M, M. Adv. Funct. Mater., 2003, 13, 43–46.
Poster 34
Glycan functionalized transition metal assemblies for use as biological sensors
Garrett D. Jackson, Matthew I. Gibson and Michael D. Ward
Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
Email: [email protected]
Abstract:
By translating biological information through carbohydrate-protein interactions, many key processes essential for life can be successfully carried out e.g. regeneration of cellular tissue and cancer cell recognition.1,2 Synthetic analogues of these systems typically consist of dispersed and well defined transition metal nanoparticles, featuring a large number of saccharides or glycans on the surface, aimed at maximising these non-covalent interactions with proteins and thereby acting as sensitive analytical sensors or drug delivery systems.3 The use of structurally-well-defined metal complexes as scaffolds for arrays of glycans (in contrast to use of nanoparticles) is a relatively unexplored field
Utilizing the synthetic chemist’s toolbox, a diverse range of saccharides can be securely attached, through conventional ‘click’ chemistry, to chelating ligands, which can be used to prepare metal complexes. Transition metal complexes can be used with a range of luminescent colours in the UV/Vis region, and mixtures of these can create a ‘bar-code’ allows access to a variety of UV-vis colours, creating a bar-code readout specific to a particular protein target. Through subtle functionalization of the well-established Ward group M8L12 and M4L6 cage systems, an additional supramolecular aspect can be probed, to further advance the field and introduce alternative applications.4
Figure. 1 Two galactose functionalized ruthenium (Left) and iridium (Right) complexes.
References:
1. J. Munkley, I. G. Mills and D. J. Elliott, Nature Reviews Urology, 2016, 13, 324-333. 2. C. R. Bertozzi and L. L. Kiessling, Science, 2001, 291, 2357. 3. B. K. Gorityala, Z. Lu, M. L. Leow, J. Ma and X. W. Liu, J. Am. Chem. Soc., 2012, 134, 15229–
15232. 4. S. Tidmarsh, T. B. Faust, H. Adams, L. P. Harding, L. Russo, W. Clegg and M. D. Ward, J. Am.
Chem. Soc., 2008, 130, 15167–15175.
Poster 35
Co-conformational Mechanically Planar Rotaxanes for Chiral Guest Sensing
E. M. G. Jamieson, and S. M. Goldup
University of Southampton, University Road, Southampton. SO17 1BJ
Email: [email protected] Web: www.goldup.soton.ac.uk
Abstract:
Chiral mechanically interlocked molecules1 are attracting increasing interest and have promising applications in a range of areas such as sensors2 and catalysis.3 While chirality is usually considered as a ‘static’ property of a molecule, and thus the chirality is not dependant on environmental influences, here we report a formally ‘achiral’ system that displays dynamic co-conformational mechanical planar chirality.
Fig. 1. a) Cartoon schematic representation of co-conformationally mechanically planar chiral rotaxane and b) structure of dynamic racemic co-conformationally mechanically planar chiral rotaxane.
We have investigated this system and its binding properties to chiral guests, showing that it displays diastereoselective guest binding. We also demonstrate that binding allows the hand of a CD-silent amino-acid guest to be detected using CD spectroscopy, and this can be used to determine enantiopurity of a proline derived salt.
References:
1. E. M. G. Jamieson, F. Modicom, S. M. Goldup, Chem. Soc. Rev. 2018, 47, 5266. 2. J. Y. C. Lim, I. Marques, V. Félix and P. D. Beer, J. Am. Chem. Soc., 2017, 139, 12228–12239.
3. A. Carlone, S. M. Goldup, N. Lebrasseur, D. A. Leigh and A. Wilson, J. Am. Chem. Soc., 2012, 134, 8321.
N
O
2PF6-
NH
NH
O
N N
NN
N N+
t-Bu
t-Bu
t-Bu
t-Bu
N
O
N
O
2PF6-
NH
NH
O
NN
N N
NN+
t-Bu
t-Bu
t-Bu
t-Bu
N
O
a) b)
Poster 36
Are MOFs the Cholesterol-Lowering Wonder Drugs of the Future?
C. S. Jennings and B. A. Blight
Department of Chemistry, 30 Dineen Dr. Fredericton, New Brunswick, Canada, E3B 5A3
Email: [email protected] Web: https://blightba.wixsite.com/blightresearchgroup
Abstract:
Metal-organic frameworks (MOFs) have quickly proven to be promising candidates across a wide range of research areas. This is namely for their phenomenally large internal surface areas - with some of the most impressive MOFs boasting surface areas of over 7,000 m2/g.1 Among the fields of chemistry that MOFs have enriched, and continue to enrich, are: gas storage,2 semiconductors,3 heterogeneous catalysis4 and newly-designed drug delivery systems.5 There are more than 75,000 MOFs on record at the Cambridge Crystallographic Data Centre, and approximately 6,000 new structures are published each year.6 It is therefore an increasingly worthwhile endeavor to repurpose previously reported MOFs.
We have recently developed a MOF composed of potassium ions and beta-cyclodextrin linking units that can efficiently remove cholesterol (and other sterols) from free solution. This promptly sparked our interest in employing pre-existing structures to execute the same sequestration process. This poster presentation outlines the synthesis, characterisation and cholesterol uptake studies of a disparate series of MOFs, and sheds light on their future as blood-cholesterol lowering wonder drugs.
References:
1. O. K. Farha et al., J. Am. Chem. Soc., 2012, 134, 15016.
2. Y. He, F. Chen, B. Li, G. Qian, W. Zhou and B. Chen, Coord. Chem. Rev., 2018, 373, 167.
3. C. G. Silva, A. Corma and H. García, J. Mater. Chem., 2010, 20, 3141.
4. A. Dhakshinamoorthy, Z. Li and H. Garcia, Chem. Soc. Rev., 2018, 47, 8134.
5. C.-Y. Sun, C. Qin, X.-L. Wang and Z.-M. Su, Expert Opin. Drug Deliv., 2013, 10 (1), 89.
6. N. Notman, Chemistry World, Vol 13, Issue 3, (Mar 2017).
7. B. A. Blight, et al., Manuscript submitted (Cryst. Eng. Comm., Manuscript ID: cg-2019-01457j.R1).
Poster 37
No charge for admission: conformationally switchable macrocycles for selective binding of non-ionic guests
C. D. Jones and A. G. Slater
Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD
Email: [email protected] Web: www.agslatergroup.com
Biography:
Christopher Jones began his career at the University of Cambridge, studying the gas-binding properties of metal-organic macrocycles under the supervision of Dr Gareth Lloyd. He completed a PhD with Prof. Jonathan Steed at Durham University, investigating the self-assembly pathways of low-molecular-weight gelators. His current research in the Slater Group at Liverpool focuses on the continuous flow synthesis of supramolecular materials with novel host-guest binding applications.
Abstract:
Macrocycles are emerging as powerful tools for chemical synthesis, acting as catalysts1 and protecting groups2 through reversible binding of reactive functional groups. However, it is difficult to encapsulate uncharged guests in the presence of more strongly interacting ionic species. To address this challenge, we identified a novel macrocycle 1 that engages in hydrogen bonding with neutral acceptors but excludes anions, even fluoride ions, due to steric constraints. A configurational isomer, 2, is incapable of binding any hydrogen bond acceptors. The macrocycles were prepared from inexpensive reagents via an unprecedented high-yielding cyclisation reaction, with no need for templating or high dilution conditions. The synthesis was performed as a one-pot process, optimised to deliver macrocycle 1 exclusively with minimal purification, and made faster and more scalable by means of continuous flow techniques. The macrocycle shows promise for the control of base-catalysed reactions such as aldol condensations. Furthermore, both 1 and 2 display potentially useful conformational switching behaviour, existing as pairs of atropisomers which crystallise separately but interconvert readily in solution. It is anticipated that these structures will serve as valuable scaffolds for more potent supramolecular nanocontainers, mimicking the flexible binding sites responsible for the exquisite selectivities of biological receptors.3
References:
1. B. Breiner, J. K. Clegg and J. R. Nitschke, Chem. Sci., 2011, 2, 51. 2. A. Galan and P. Ballester, Chem. Soc. Rev., 2016, 45, 1720. 3. L. Marchetti and M. Levine, ACS Catal., 2011, 1, 1090.
Poster 38
Multisite recognition of nucleoside monophosphate anions using europium(III)-based receptors
A. F. Kassir, C. A. Breen and S. J. Butler
Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK.
Email: [email protected] Web: https://butler-researchgroup.wixsite.com/welcome
Biography:
Ahmad studied his bachelor’s and Master’s degree in Organic Chemistry at the Lebanese University. He then went on to do a PhD at University Paris Sud at Orsay in Synthetic Organic Chemistry. In July 2019, he moved to the University of Loughborough as a visiting post-doc researcher, undertaking a project to develop new methods for selective tagging of proteins and sensing target nucleoside phosphates with emissive probes.
Abstract:
Monitoring enzyme reactions to determine enzyme kinetics is an important aspect of drug discovery. Many pharmaceutically important enzyme reactions involve nucleoside phosphate anions,1 e.g., phosphodiesterases are attractive drug targets that convert cyclic AMP into AMP. The creation of synthetic receptors that bind reversibly and selectively to a target phosphoanion under physiological conditions could be utilised to monitor enzyme activity in real-time.2 However, it is challenging due to the similarities in anion structure, shape and size. There are very few examples of receptors that can discriminate AMP from more highly charged anions, such as ADP and ATP.
We present the synthesis and anion binding studies of three phenylboronic acid functionalized europium complexes (e.g. Eu.1). Each receptor binds to nucleoside monophosphate anions in water at physiological pH, displacing the bound water and inducing a large luminescence enhancement. Crucially, selected receptors can discriminate AMP from the more highly charged anions, ADP and ATP. A possible anion binding mode is shown in the Figure below, in which the boronic acid of Eu.1 interacts reversibly with the ribose sugar of AMP. The selective emission response to AMP could allow monitoring of enzyme reactions in which AMP is generated, avoiding interference from other anions in the assay, including ADP and ATP. Finally, inspired by previous studies of glucose sensors,3 we are integrating an ortho-aminomethyl phenylboronic moiety into receptor (Eu.2), which may further improve selectivity towards specific nucleoside monophosphate anions.
References:
1. S. Hewitt and S. Butler, Chemical Communications, 2018, 54, 6635. 2. S. Hewitt, R. Ali, R. Mailhot, C. Antonen, C. Dodson and S. Butler, Chemical Science, 2019, 10,
5373. 3. X. Sun, B. Chapin, P. Collins, B. Wang, T. James and E. Anslyn, Nature Chemistry, 2019, 11, 768.
Poster 39
Rotaxanes as Triggerable Caged G-Quadruplex Ligands
Tim Kench, James Lewis and Ramon Vilar
Department of Chemistry, Imperial College London, London, UK
Email: [email protected] Web: http://www.imperial.ac.uk/vilar-research-group
Abstract:
Rotaxane and catenane based architectures are starting to garner significant interest within a biological context due to the potential for specific programmable actions such as drug release.1 Here, we describe the inclusion of a G-quadruplex (G4) ligand into a mechanically interlocked molecule with this aim. G-quadruplexes are non-canonical DNA structures which can form from cation-stabilised guanine-rich single stranded DNA.2 Bioinformatic and sequencing techniques have identified over 700,000 sequences in the human genome with the potential to form G4 structures,3 and are associated with regulation of transcription, translation, replication and telomeric biology.4,5 Additionally, the discovery that oncogene promoter regions are particularly G-rich has generated significant interest in the development of highly selective small molecule G4 DNA binders as potential anti-cancer drugs.6,7
Metal-organic compounds with aromatic ligands such as salphens are excellent G4 ligands and the emissive and redox properties of platinum-based salphens in particular make them highly suitable for theranostic applications.8,9 We report that the inclusion of a platinum salphen into a rotaxane significantly reduces G4 binding by blocking the surface available for 𝜋-𝜋 stacking. By including a triggerable moeity in the axle, we demonstrate that the release of free platinum-salphen can be activated under certain chemical conditions. Furthermore, the chemical properties of the rotaxane can be modulated through reversible Cu(I) binding.
References:
1. N. Pairault, R. Barat, I. Tranoy-Opalinski, B. Renoux, M. Thomas and S. Papot, Cr Chim, 2016, 19, 103–112.
2. J. T. Davis, Angewandte Chemie Int Ed, 2004, 43, 668–698. 3. R. Hänsel-Hertsch, M. Antonio and S. Balasubramanian, Nat Rev Mol Cell Bio, 2017, 18, 279–284. 4. M. L. Bochman, K. Paeschke and V. A. Zakian, Nature Reviews Genetics, 2012, 13, 770. 5. D. Rhodes and H. J. Lipps, Nucleic Acids Res, 2015, 43, 8627–8637. 6. S. Neidle, Nat Rev Chem, 2017, 1, 0041. 7. S. Balasubramanian and S. Neidle, Current Opinion in Chemical Biology, 2009, 13, 345–353. 8. S. Bandeira, J. Gonzalez‐Garcia, E. Pensa, T. Albrecht and R. Vilar, Angewandte Chemie Int Ed,
2018, 57, 310–313. 9. N. H. Karim, O. Mendoza, A. Shivalingam, A. J. Thompson, S. Ghosh, M. K. Kuimova and R. Vilar,
RSC Advances, 2014, 4, 3355–3363.
Poster 40
Redox-Controlled Assembly of Oligoproline Scaffolds
Kasid Khan,a Pavlína Lipovska,a Ismay F. Fox,a and Dr Alyssa-Jennifer Avestroa,b*
aDepartment of Chemistry, Durham University, Science Site, Stockton Road, DH1 3LE
bDepartment of Chemistry, University of York, Heslington, York, YO10 5DD
Email: [email protected]
Abstract:
Redox-responsive moieties can be exploited to introduce new means of guiding 1D assembly and controlling molecular actuation within the well-defined secondary and tertiary structures of bio-inspired materials. Oligoprolines offer attractive biomolecular scaffolds1 in which, even at short lengths, are able to undergo interconversion between a tight, right-handed helical structure in hydrophobic solvents and an expanded left-handed helical structure in aqueous or polar organic solvents. As a consequence of its turn periodicity, functional groups installed at the 4-position of every third proline residue reside on the same face of oligoproline helices, leading to enhanced conformational stability in solution2 and a reliable platform for studying 1D through-space processes, such as photo-induced electron transfer between photo-excitable donors and electron acceptors across defined distances.3
To-date, only solvent-induced changes in oligoproline conformation and assembly have been explored. However, in this research, we seek to introduce new stimuli to control oligoproline structure. By exploiting simple and robust chemistries such as the Zincke reaction and Cu(I)-assisted azide–alkyne cycloaddition, redox-active viologen dications have been installed to the backbone of oligoproline scaffolds. Their conformational stability and reversible assembly (both intramolecularly and intermolecularly) in response to chemical and electrochemical stimuli are studied by solution-state optical spectroscopy, circular dischroism and electrochemistry. For instance, the reversible pimerisation of viologen radical cations4 is anticipated to afford global isomerization and 1D actuation (expansion/contraction) of the rigid oligoproline scaffold (Figure 1). Meanwhile, solid-state analysis of single crystals provide us with deeper insight towards the through-space interactions and stabilizing effects adopted within these materials. The potential formation of hierarchically assembled bionanostructures that exhibit good electrochemical addressability, high energy capacities and long-range electron delocalisation would bear relevance to the future development of advanced (bio)organic electronic devices.
Figure 2. Potential conformations adopted by viologen functionalised oligoprolines.
References:
1. Nagel, Y. A.; Kuemin, M.; Wennemers, H. Chimia, 2011, 65, 264–267. 2. Lewandowska, U. et al. Nat Chem, 2017, 9, 1068. 4. Serron, S. A. et al. J. Am. Chem. Soc. 2004, 126, 14506-14514. 5. Geraskina, M. R. et al. Angew. Chem. Int. Ed. 2017, 56, 9435-9439.
Poster 41
Anion carriers as potential treatments for cystic fibrosis[1]
H. Li, H. Valkenier, A. G. Thorne, C. M. Dias, J. A. Cooper, M. Kieffer, N. Busschaert, P. A. Gale, D. N. Sheppard and A. P. Davis
School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 4LN, UK
Email: [email protected] Web: www.davis.chm.bris.ac.uk
Biography:
Marion obtained her Diplome d’Ingenieur and Master of Advance Science and Technology from the ESPCI ParisTech. She then joined the group of Prof. Jonathan Nitschke at the University of Cambridge where she obtained her MPhil in 2015 and her PhD in 2019. While at Cambridge, her work focused on the design of novel supramolecular metal-organic containers functionalised with biomolecules and their applications for chemical separation and drug-delivery. She joined the group of Prof. Anthony Davis at the University of Bristol in 2019, working on the development of anion carriers active in vesicles and cells.
Abstract:
Defective anion transport is a hallmark of the genetic disease cystic fibrosis (CF). One approach to restore anion transport to CF cells utilises alternative pathways for transmembrane anion transport, including artificial anion carriers (anionophores). Here, we screened a wide range of anionophores for activity in synthetic vesicles as well as biological activity using fluorescence emission from the halide-sensitive yellow fluorescent protein. Three compounds possessed anion transport activity similar to or greater than that of a bis-(p-nitrophenyl)ureidodecalin previously shown to have promising biological activity.[2] Anion transport by these anionophores was concentration-dependent, persistent and non-toxic at low micromolar concentrations. The results highlighted that anionophores, by themselves or together with other treatments that restore anion transport (lumacaftor and ivacaftor), offer a potential therapeutic strategy for CF.
References:
1. H. Li, H. Valkenier, A. G. Thorne, C. M. Dias, J. A. Cooper, M. Kieffer, N. Busschaert, P. A. Gale, D. N. Sheppard, A. P. Davis, Chemical Science 2019, 10, 9663-9672.
2. H. Li, H. Valkenier, L. W. Judd, P. R. Brotherhood, S. Hussain, J. A. Cooper, O. Jurček, H. A. Sparkes, D. N. Sheppard, A. P. Davis, Nature Chemistry 2016, 8, 24-32.
Poster 42
Squaramide – Napthalimide Conjugates as ‘Turn-On’ Fluorescent Sensors for Bromide Through an Aggregation-Disaggregation Approach
L.K. Kumawat, A.A. Abogunrin, R.B.S. Elmes
Department of Chemistry, Maynooth University, National University of Ireland, Maynooth, Co. Kildare, Ireland
Email: [email protected], [email protected] Web: http://orcid.org/0000-0002-2734-1433
Biography:
Dr. L K Kumawat received his PhD degree from the Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee (India) in 2015. He joined Department of Applied chemistry, University of Johannesburg, South Africa in Feb. 2016 - Jan 2017, and SKLNBD Peking University, Beijing, China (July 2017- Dec 2017) as postdoctoral/visiting researcher. Recently, He is working as an IRC postdoctoral researcher in Maynooth University, Ireland. His research interest focuses on the design and synthesis of squaramide based macromolecule and fluorescent materials, and development of their applications as optical anion sensors.
Abstract:
Squaramide based scaffolds have established themselves as a useful molecular recognition motif to investigate anion binding in chemical and biological systems due to their strong hydrogen binding and aggregation behaviour.1-4 Here, we have synthesised two new squaramide-naphthalimide conjugates (SQ1 and SQ2) where both compounds have been shown to act as selective fluorescence ‘turn on’ probes for bromide in aqueous DMSO solution through a disaggregation induced response. SQ1 and SQ2 displayed a large degree of self-aggregation in aqueous solution as studied by 1H NMR and Scanning Electron Microscopy (SEM). Moreover, the disaggregation induced emission (DIE) response was exploited for the selective recognition of certain halides, where the receptors gave rise to distinct responses related to the interaction of the various halide anions with these receptors. Surprisingly, Br- resulted in a dramatic 500-600% fluorescence enhancement thought to be due to a disruption of compound aggregation and allowing the monomeric receptors to dominate in solution. Finally, initial studies in a human cell line were also conducted where it was observed that both compounds are capable of being taken up by HeLa cells, exhibiting intracellular fluorescence as measured by both confocal microscopy and flow cytometry.
Figure 1: Aggregation –Disaggregation approach of optical probes SQs with bromide anions.
References:
1. Qin, L.; Hartley, A.; Turner, P.; Elmes, R. B. P.; Jolliffe, K. A. Chem. Sci. 2016, 7, 4563. 2. Gale, P. A.; Howe, E. N. W.; Wu, X. Chem 2016, 1, 351. 3. Elmes, R. B. P.; Busschaert, N.; Czech, D. D.; Gale, P. A.; Jolliffe, K. A. Chem. Commun. 2015,
51, 10107
Poster 43
Paramagnetic NMR Spectroscopy for the Characterisation of Metal-Organic Cages
M. Lehr, T. Paschelke, E. Trumpf, A.-M. Vogt, C. Näther, F. D. Sönnichsen and A. J. McConnell
Marc Lehr, Otto Diels - Institute of Organic Chemistry, Otto-Hahn-Platz 3, 24118 Kiel, Germany
Email: [email protected] Web: http://www.otto-diels-institut.de/mcconnell/group.html
Abstract:
While the characterisation of diamagnetic metal-organic cages using NMR spectroscopy is well established, analysis of mixtures of different architectures or lower symmetry cages can be complicated by overlapping signals. Dispersion of the signals can be achieved by using paramagnetic rather than diamagnetic metal centres. However, J-coupling information is lost due to the broad linewidths and many pulse programs used for diamagnetic samples are not suitable for paramagnetic cages. We demonstrate the suitability of adapted NMR spectroscopic techniques for the characterisation of paramagnetic metal-organic cages.
References:
1. M. Lehr, T. Paschelke, E. Trumpf, A.-M. Vogt, C. Näther, F. D. Sönnichsen, A. J. McConnell, manuscript in preparation.
Poster 44
Conformational Control of Pd2L4 Metallo-supramolecular Cages
James E. M. Lewis
Imperial College London, Molecular Sciences Research Hub, London W12 0BZ
Email: [email protected] Web: www.lewisgroup.org.uk
Biography:
Jamie obtained his PhD from the University of Otago under the supervision of Prof. James Crowley. This was followed by postdoctoral research in the group of Prof. Steve Goldup at the University of Southampton, first as a PDRA and subsequently as a Marie Sklodowska-Curie Fellow. Since October 2017 he has been an Imperial College Research Fellow, with his research interests encompassing broad aspects of supramolecular chemistry, including self-assembly and mechanically interlocked molecules.
Abstract:
Since their first report by McMorran and Steel,1 Pd2L4 metallo-supramolecular cages have become a popular class of self-assembled architectures.2 However, as with the majority of metallo-supramolecular species,3 these have almost exclusively employed symmetrical ligands. Upon coordination with metal ions, lower symmetry ligands will likely form a mixture of isomeric products when no significant bias is present (Fig. 1). If this self-assembly process could be controlled then this might allow the effective spatial organisation of different functional groups attached to the ligand framework. In this preliminary study we have used both geometric and steric design parameters to selectively induce the formation of single Pd2L4 cage isomers assembled from ditopic ligands lacking bilateral symmetry. DFT calculations were able to show an appreciable difference in relative energies between cage isomers in experimentally successful cases of self-assembly (i.e. only a single isomer was formed) whilst essentially isoenergetic isomers were found when the self-assembly was unsuccessful (i.e. a mixture of two or more isomers was obtained). It is our hope that the observed correlation between experimental and computational results will allow effective forecasting of self-assembly outcomes to aid in the design of future systems.
Fig. 1 Cartoon representation of possible isomeric structures of an M2L4 cage assembled from ditopic ligands lacking bilateral symmetry.
References:
1. D. A. McMorran and P. J. Steel, Angew. Chem. Int. Ed., 1998, 37, 3295. 2. M. Han, D. M. Engelhard and G. H. Clever, Chem. Soc. Rev., 2014, 43, 1848. 3. R. Chakrabarty, P. S. Mukherjee and P. J. Stang, Chem. Rev., 2011, 111, 6810.
Poster 45
Use of a Coordination Cage as the basis for Colourimetric Guest analysis
M. D. Ludden, M. D. Ward
Department of Chemistry, University of Warwick, Coventry CV4 7AL
Email: [email protected]
Abstract:
Coordination cages are an integral part of inorganic supramolecular structures and in many cases can demonstrate interesting chemical behaviour. The cage described in this work possesses a cavity of approximately 400 Å3, allowing reversible uptake of small ‘guest’ molecules.1
Through binding of a fluorescent guest (4-methyl-7-amino-coumarin), changes in the fluorescence emission can be seen due to quenching through energy transfer to the cobalt ions present in the cage’s structure.2 This fluorescence can be restored upon displacement of the fluorophore by a competing analyte, and serves as the basis for a colourimetric sensor.
Having two fluorescent components results in a change of colour upon one component binding, as the ratio of emission changes. The spectra can be converted to a set of coordinates on the CIE colour chart and a binding constant calculated for the analyte.
References:
1. S. Turega, M. Whitehead, B. R. Hall, M. F. Haddow, C. A. Hunter and M. D. Ward, Chem. Commun., 2012, 48, 2752-2754.
2. S. Turega, W. Cullen, M. Whitehead, C. A. Hunter and M. D. Ward, J. Am. Chem. Soc., 2014, 136, 8475–8483.
Poster 46
ATP Selective Luminescent Receptors for Imaging Nerve Cell Activity in Real-Time
G. Macey, R. Mailhot and S. J. Butler
Department of Chemistry, Loughborough University, Loughborough, LE11 3TT
Email: [email protected] Web: https://butler-researchgroup.wixsite.com
Abstract:
In recent years, an area of intense research has been to study how and where energy is expended in nerve cells and how signalling between the different areas of the brain occurs.1 A useful target to study such signalling is ATP, the main energy source for biological functions.2,3 However, there are only a few existing probes capable of monitoring fluctuations of ATP levels within cells; most encounter issues with anion affinity, selectivity and pH sensitivity.4 Another consideration is the toxicity of such probes and their effectiveness within a complex biological environment.
We report progress towards overcoming the issues highlighted above, in a series of designed europium(III) complexes, each of which possess two functionalised quinoline binding arms and other functional groups to aid water-solubility and enhance ATP selectivity (Figure 1).5,6 We present the development of the first generation probe, which provides a long-lived luminescence signal to visualise changes in concentrations of ATP in the mitochondria of living cells. Ultimately, with the second generation probes we aim to monitor key metabolic processes occurring within a well-defined living neural circuit, termed a ‘brain-on-a-chip’.
Figure 3 - Structure of Eu(III)-based receptors for ATP, striking a balance between anion affinity, intensity of luminescence, and water solubility.
References:
1. Q. Ni, S. Mehta and J. Zhang, FEBS J., 2018, 285, 203–219. 2. M. G. Stovell, M. O. Mada, A. Helmy, T. A. Carpenter, E. P. Thelin, J. L. Yan, M. R. Guilfoyle, I.
Jalloh, D. J. Howe, P. Grice, A. Mason, S. Giorgi-Coll, C. N. Gallagher, M. P. Murphy, D. K. Menon, P. J. Hutchinson and K. L. H. Carpenter, Sci. Rep., , DOI:10.1038/s41598-018-29255-3.
3. H. Imamura, K. P. H. Nhat, H. Togawa, K. Saito, R. Iino, Y. Kato-Yamada, T. Nagai and H. Noji, Proc. Natl. Acad. Sci. U. S. A., 2009, 106, 15651–6.
4. M. Tantama, J. R. Martínez-François, R. Mongeon and G. Yellen, Nat. Commun., 2013, 4, 2550. 5. S. H. Hewitt, J. Parris, R. Mailhot and S. J. Butler, Chem. Commun., 2017, 53, 12626–12629. 6. R. Mailhot, T. Traviss-Pollard, R. Pal and S. J. Butler, Chem. – A Eur. J., 2018, 24, 1–12.
Poster 47
Novel electron deficient dyes and their supramolecular chemistry
Ferdinando Malagrecaa, Joshua Humphreysa, Lluïsa Pérez-Garcíab and David B. Amabilinoa a School of Chemistry, GSK Carbon Neutral Laboratories for Sustainable Chemistry, University of Nottingham, Triumph Road, Nottingham, NG7 2TU United Kingdom
bSchool of Pharmacy, University of Nottingham, University Park, NG7 2RD, UK
Email: [email protected]
Abstract:
Diketopyrrolopyrrole (DPP) pigment and dyes are an increasingly investigated family of organic materials with applications ranging from organic optoelectronics1 to sensor materials2 and bio imaging3, amongst others4. The modification of the DPP core can improve their properties in devices and materials. One of the main challenges associated with the field is the synthesis of electron deficient species for organic electronics to replace the commonly incorporated fullerenes as electron accepting materials whilst giving parallel or improved performance along with increased synthetic and optoelectronic versatility.
In order to achieve this goal, DPP functionalized with pyridine and pyridinium aromatic units have been synthesized. This feature means that the materials are extremely electron deficient in nature and are very good electron acceptors. In addition, the lone pair of the pyridine unit also has the ability to accept a proton and hence this would result in a change in the materials properties. This has the potential to use the material as a sensor or in molecular logic systems.
To investigate their properties, electrochemical and supramolecular experiments have been carried out, especially cyclic voltammetry and in order to determine each systems frontier orbital energy levels, and binding experiments have been performed to see how these molecules can interact with electron rich compounds.
Acknowledgements:
We thank the University of Nottingham through the Beacon of Excellence Propulsion Futures and the EPSRC through the LDMI DTP.
References:
1. A. Tang, C. Zhan, J. Yao and E. Zhou, Adv. Mater., 2017, 29, pp: 1600013. 2. M. Kaur and D. H. Choi, Chem. Soc. Rev., 2015, 44, 58–77. 3. H. Ftouni, F. Bolze and J. F. Nicoud, Dye. Pigm., 2013, 97, 77–83.
4. Y. Cai, P. Liang, Q. Tang, X. Yang, W. Si, W. Huang, Q. Zhang and X. Dong, ACS Nano, 2017, 11, 1054–1063.
Poster 48
Macromolecular MRI Contrast Agents
T. Berki, C. J. Marsden, H. Willcock and S. J. Butler
Department of Chemistry, Loughborough University, Loughborough LE11 3TU
Email: [email protected] Web: https://butler-researchgroup.wixsite.com/welcome
Abstract:
Magnetic resonance imaging (MRI) is an invaluable tool for imaging tumours and diagnosing disease. Despite the widespread use of MRI in the clinic, the largest downfall of the technique is its lack of sensitivity. For this reason, contrast agents have been developed to lower the relaxation time of surrounding water molecules, increasing ‘relaxivity’ and brightening the image.1 Gadoliniumbased contrast agents are regularly used, consisting of a gadolinium(III) ion surrounded by a strongly chelating ligand. However, commercial contrast agents are far from optimal, and the relaxivity is nowhere near the theoretical maximum value.2 We have designed macrocyclic Gd(III) complexes bearing two polymerisable arms, which can be readily polymerised in a single step to form copolymers with different architectures (Figure 1). By decreasing the local rotational motion of the Gd(III) complex through crosslinking, we have developed macromolecular contrast agents with significantly increased relaxivity compared with commercial agents. The macromolecules have increased kinetic stability, reducing the chances of demetallation, and higher efficiency, potentially decreasing the dose concentration required.3 Work is currently ongoing to synthesize macromolecular contrast agents that respond to changes in physiological parameters such as pH in different tissues.
Figure 1. Gadolinium(III) complex (left) acts as a crosslinker between polymer chains, aiding formation of a macromolecular structure (right)
References:
1. T. J. Clough, L. Jiang, K. L. Wong and N. J. Long, Nat. Commun., 2019, 1–14. 2. L. M. De Leõn-Rodríguez, A. F. Martins, M. C. Pinho, N. M. Rofsky and A. D. Sherry, J. Magn.
Reson. Imaging, 2015, 42, 545–565. 3. D. V. Bower, J. K. Richter, H. von Tengg-Kobligk, J. T. Heverhagen and V. M. Runge, Invest.
Radiol., 2019, 54, 453–463.
Poster 49
Dynamic covalent chemistry in anion transporters
L. Martínez-Crespo, L. Halgreen and H. Valkenier
Engineering of Molecular NanoSystems, Ecole polytechnique de Bruxelles, Université libre de Bruxelles, 50 avenue F. Roosevelt, 1050 Brussels, Belgium.
Email: [email protected] Web: http://emns.ulb.be/
Biography:
Luis Martínez Crespo graduated with a BSc in Chemistry in June 2009 from the University of Balearic Islands (UIB), and he obtained his Master’s degree in March 2011 and his PhD in December 2015, both from UIB. During his PhD he was studying the conformational properties of squaramide-based foldable modules for the development of peptidomimetics, under the supervision of Prof. A. Costa and Dr. C. Rotger. From February 2017 to January 2019 he worked as a post-doctoral researcher with Prof. P. Ballester in the Institute of Chemical Research of Catalonia (ICIQ), where he studied aryl-extended calix[4]pyrroles as transmembrane transporters in. In February 2019 he started his current position at the Université Libre de Bruxelles (ULB), as a post-doctoral researcher under the supervision of Dr. H. Valkenier (EMNS group). At ULB, he continues his work in transmembrane transport by using dynamic covalent chemistry to develop new artificial transporters.
Abstract:
Dysfunctional membrane transporters can be the cause of different genetic diseases (e.g. cystic fibrosis is caused by deficient chloride transport). Therefore, artificial compounds able to efficiently replace the dysfunctional proteins could be used to treat those diseases. This has encouraged chemists to develop several synthetic anion transporters, which have been prepared mainly by conventional organic synthesis.1 These molecules usually have hydrogen bonding donor groups (e.g., thioureas) that permit the formation of a complex with the anion to be transported, acting as mobile carriers (Figure 1a).
On the other hand, dynamic combinatorial chemistry (DCC) permits the development of structurally complex receptors from simple building blocks able to form dynamic covalent bonds.2,3 In this study we want to explore the combination of thiourea moieties, as the transport units, with different azomethine-based dynamic bonds, which would permit the development of dynamic combinatorial libraries (DCLs). We have prepared a set of monothioureas containing some of these dynamic bonds (Figure 1b) and we have studied their chloride transport properties using the well stablished lucigenin assay, where liposomes are used as cell membrane models (Figure 1c). Our results show that the functional group (R) present can have significant effects on the efficiency of the transport unit.
Figure 1. a) Mobile carrier transport mechanism: The transporter extracts the anion at one side of the membrane and
the resulting complex diffuses to release the anion at the other site of the bilayer. b) General design of the transporters studied. c) Lucigenin assay: Fluorescence spectroscopy is used to monitor the rate of internalization of chloride in liposomes with lucigenin encapsulated. A transporter will allow the influx of chloride, which will quench the fluorescence of the dye.
References:
1. P. A. Gale, J. T. Davis, R. Quesada, Chem. Soc. Rev., 2017, 46, 2497. 2. P. T. Corbett, et al., Chem. Rev., 2006, 106, 3652.
3. S. R. Beeren, J. K. M. Sanders, J. Am. Chem. Soc., 2011, 133, 3804.
a) b) c)
Poster 50
Anion-π catalysis with rotaxanes
J. R. J. Maynard, and S. M. Goldup
Address: Department of Chemistry, Faculty of Natural and Environmental Sciences, University of Southampton, Highfield, Southampton, SO17 1BJ, U.K.
Email: [email protected] Web: http://goldup.soton.ac.uk/
Abstract:
A series of [2] and [3] rotaxanes have been prepared which explore the potential of the hindered cavity provided by interlocked molecules for anion-π catalysis.1 The prepared catalysts were assessed through the ratio of addition and decarboxylation products in the disfavoured Michael addition of a malonic acid half-thioester to a nitrostyrene.2 The results obtained with the [2]rotaxanes indicate a significant dependence on the stoppering unit. Strikingly, a [3]rotaxane-based catalyst exceeds the selectivity obtained previously with far more complex NDI based catalysts.3
References:
1. Y. Zhao, Y. Cotelle, L. Liu, J. López-Andarias, A.-B. Bornhof, M. Akamatsu, N. Sakai and S. Matile, Acc. Chem. Res., 2018, 51, 2255–2263.
2. Y. Zhao, S. Benz, N. Sakai and S. Matile, Chem. Sci., 2015, 6, 6219–6223. 3. A. B. Bornhof, A. Bauzá, A. Aster, M. Pupier, A. Frontera, E. Vauthey, N. Sakai and S. Matile, J.
Am. Chem. Soc., 2018, 140, 4884–4892.
Poster 51
Topological Chirality in a Molecular Knot with Eight Crossings
John P. Carpenter, Charlie T. McTernan, Roy Lavendomme, Tanya K. Ronson, Jake L. Greenfield, Jonathan R. Nitschke*
Address: Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
Email: [email protected] Web: https://www.sid.cam.ac.uk/aboutus/people/ctm37
Biography:
Charlie received his MChem from the University of Oxford in 2013, working in Prof. Donohoe’s group for his fourth year. He then moved to work with Prof. Leigh in Manchester, investigating the synthesis of artificial molecular machines. In 2017 he moved to Cambridge to work with Prof. Nitschke on self-assembled metal-organic cages, since September 2018 a Leverhulme Early Career Research Fellow and Research Fellow at Sidney Sussex College.
Abstract:
Knots are ubiquitous in the macroscopic world, and have been used by humans for thousands of years. At the molecular level, knots are found in biology (1% of proteins contain knots),1 and form spontaneously in sufficiently long polymer chains,2 with chain breakage occurring more readily at the knotted point.3 The restrictions imposed by knotting can have significant effects on the physical and chemical properties of these species. However, until scientists can easily generate a range of knotted structures it will be impossible to probe these effects. This research contributes towards that goal, designing novel routes to knotted architectures, and controlling their topological chirality. The first synthetic molecular trefoil knots were prepared in the late 1980s.4-6 However, it is only recently that more complex, small molecule, knots have been synthesised, using the circular helicate approach pioneered by the Leigh group.7,8 Herein we report the synthesis of a molecular 819 knot formed by subcomponent self-assembly. Further, we investigate the intrinsic chirality of the knotted structure, exploring how we can selectively form one topological enantiomer of knot over the other.
References:
1. Sułkowska, J. I. et al. Proc. Natl. Acad. Sci. USA 2012, 109, E1715. 2. Frank-Kamenetskii, M. D.; Lukashin, A. V.; Vologodskii, A. V. Nature 1975, 258, 398. 3. Saitta, A. M.; Soper, P. D.; Wasserman, E.; Klein, M. L. Nature 1999, 399, 46. 4. Fielden, S. D. P.; Leigh, D. A.; Woltering, S. L. Angew. Chem., Int. Ed. 2017, 56, 11166. 5. Forgan, R. S.; Sauvage, J.-P.; Stoddart, J. F. Chem. Rev. 2011, 111, 5434. 6. Horner, K. E.; Miller, M. A.; Steed, J. W.; Sutcliffe, P. M. Chem. Soc. Rev. 2016, 45, 6432. 7. Ayme, J.-F.; Beves, J. E.; Campbell, C. J.; Leigh, D. A. Chem. Soc. Rev. 2013, 42, 1700.
8. Danon, J. J.; et al. Science 2017, 355, 159.
Poster 52
Silica bound co-pillar[4+1]arene as novel supramolecular chromatographic stationary phase
Subba Reddy Mekapothula, Dinga Wonanke A. D, Gareth W.V Cave, Matthew Addicoat, John D. Wallis, David J. Boocock.
Nottingham Trent University, School of Science and Technology, Clifton Lane, Nottingham, NG11 8NS.
Email: [email protected], [email protected]
Abstract:
A novel co-pillar[4+1]arene incorporating bromo-octyl substituents has been synthesised for the first time using microwave irradiation in high yield (88%). Co-pillar[4+1]arene was functionalised to the surface of chromatographic silica particles. The resulting new stationary phase has been successfully utilised to separate xylene isomers via liquid chromatographic techniques. The interaction energies from in silico studies support the selective separation of the isomers within the cavity.
A B
Figure 4: Graphical representation of supramolecular cavitand (A) functionalized onto chromatographic silica (B)
Figure 2: Chromatographic separation of xylene isomers and toluene sample on co-pillar[4+1]arene bound-silica stationary phase.
Poster 53
From [2]catenane synthesis to topologically chiral [2]catenane
F. Modicom, J. E. M. Lewis, M. Denis, and S. M. Goldup*
Chemistry, Faculty of Natural & Environmental Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ
Email: [email protected] Web: http://goldup.soton.ac.uk/
Abstract:
Although many of the seminal contributions to the synthesis of mechanically interlocked molecules focus on catenanes, over the past four decades reports of rotaxanes have grown to dominate the field.1 This is in part due to the potential for large-amplitude shuttling motions in rotaxanes that make them attractive for the development of molecular machines.2 Furthermore the greater synthetic challenge involved in catenane synthesis also reduces their accessibility. Catenane synthesis requires a macrocyclisation event to capture the interlocked architecture with the attendant competition between the cyclisation and oligmerisation. To overcome this, catenanes are typically formed under high-dilution conditions leading to long reaction times with moderate to low yields.3-5
Here we describe an operationally simple and high yielding active template synthesis of [2]catenanes.6 In addition to mechanical bond formation using a single pre-macrocycle bearing an azide and alkyne moieties, our method is also suitable for the co-macrocyclisation of readily available bis-alkyne and bis-azide co-monomers and even short alkyne/azide components which oligomerise prior to mechanical bond formation.
We recently extended this methodology to a long standing challenge to access topologically chiral [2]catenanes.7 The principle of this approach rely on the formation of separable diastereoisomers, which would allow to access the enantiopure topologically chiral [2]catenane after removal of the covalent stereogenic centre.
Figure1:Schematic of our proposed approach to topologically chiral catenanes.
References:
1. Bruns, C. J.; Stoddart, J. F. The Nature of the Mechanical Bond; John Wiley & Sons, Inc.; Hoboken, NJ, USA, 2016.
2. Erbas-Cakmak, S.; Leigh, D. A.; McTernan, C. T.; Nussbaumer, A. L. Chem. Rev. 2015, 115, 10081.
3. Sato, Y.; Yamasaki, R.; Saito, S. Angew. Chem. Int. Ed. 2009, 48, 504. 4. Goldup, S. M.; Leigh, D. A.; Long, T.; McGonigal, P. R.; Symes, M. D.; Wu, J. J. Am. Chem. Soc.
2009, 131, 15924. 5. Ito, K.; Mutoh, Y.; Saito, S. J. Org. Chem. 2017, 82, 6118. 6. Lewis, J. E. M.; Modicom, F.; Goldup, S. M. J. Am. Chem. Soc. 2018, 140, 4787. 7. Denis, M.; Lewis, J. E. M.; Modicom, F.; Goldup, S. M. Chem 2019, 5, 1357.
Poster 54
Catalytic Investigations of Aldol Condensations Using Cubic Self-assembled Cages
C. Mozaceanu and M. D. Ward
Department of Chemistry, University of Warwick, Coventry CV4 7AL
Email: [email protected]
Abstract:
Water-soluble coordination cages with hydrophobic interior cavities are of considerable interest as potential enzyme-like catalysts for a variety of applications. Such an example is the [Co8(Lw)12](BF4)16 cage (Hw), which has been investigated as a catalyst for the Kemp elimination reaction and for the hydrolytic degradation of organophosphorus insecticides.1-3 Herein, the catalytic properties of Hw have been investigated in the self-condensation of 1,3-indandione (figure 1). The catalytic studies conducted through UV-Vis spectroscopy have led to the clear demonstration that this aldol reaction is catalysed by the cage at pH 4 under conditions where the uncatalysed reaction is extremely slow. Study of the mechanistic details are still in progress, but it is clear that this aldol condensation can be catalysed by the cage which opens up possibilities for a much wider range of reactions to be studied.
Figure 1. Hw-catalysed self-condensation of 1,3-indandione to bindone.
References:
1. W. Cullen, M. C. Misuraca, C. A. Hunter, N. H. Williams and M. D. Ward, Nature Chemistry, 2016, 8, 231.
2. W. Cullen, A. J. Metherell, A. B. Wragg, C. G. P. Taylor, N. H. Williams and M. D. Ward, J. Am. Chem. Soc., 2018, 140, 2821.
3. C. G. P. Taylor, PhD thesis, University of Sheffield, 2016.
Poster 55
Halogen bonding bimetallic rhenium(I) complexes for anion recognition
A.Vihanga K. Munasinghe, Xiaoxiong Li, Paul. D. Beer
Department of Chemistry, University of Oxford, Oxford, OX1 3TA
Email: [email protected] Web: http://beer.chem.ox.ac.uk/
Abstract:
Halogen bonding (XB), the non-covalent interaction between an electrophilic halogen atom and a Lewis base, has gained great interest in the field of anion recognition. This is due to XB hosts exhibiting unique anion selectivity trends and often superior binding affinities over hydrogen bonding (HB) host analogues.1 The complexation of transition metals to XB receptors has been reported to further augment anion recognition by preorganising the binding site and polarizing XB donors.2
Herein we report a series of novel XB hosts which show enhanced binding towards anions upon Re(I) complexation (Figure 1). The effect of spacer group variation between the two XB binding sites towards anion binding has been investigated by a series of 1H NMR titration studies.
References:
1. A. Brown and P. D. Beer, Chem. Commun., 2016, 52, 8645–8658.
2. M. J. Langton, Y. Xiong and P. D. Beer, Chem. - A Eur. J., 2015, 21, 18910–18914.
Poster 56
Liquified Bipyridine Macrocycles Towards the Active Template Synthesis of Mechanically Interlocked Functional Liquid Materials
Edward A. Neal and Takashi Nakanishi
International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute of Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
Email:[email protected] Web:https://www.nims.go.jp/research/group/frontier-molecule/index.html
Biography:
Ed received his Ph.D. in Chemistry from Queen Mary, University of London (QMUL) in 2016, developing methodology towards homocircuit and heterocircuit [3]rotaxanes under Prof Stephen Goldup. After work at the University of Southampton, Kanazawa University, QMUL and the Barts and the Royal London School of Medicine and Dentistry, he was awarded a JSPS Postdoctoral Fellowship to join Dr. Takashi Nakanishi’s Frontier Molecules group at the National Institute of Materials Science in Japan in 2019.
Abstract:
Mechanically Interlocked Molecules (MIMs) contain macrocyclic components, with or without stoppered axles, that can rotate or translate in relation to the other to control function in sensing applications, reaction control, switchable catalysts and highly complex molecular machines.1 Active Template (AT) methods, in which a catalytic metal centre both holds components together and proactively mediates the formation of MIMs, have vastly accelerated their development over nearly 15 years, especially rotaxanes (ring-on-axle) or catenanes (ring-on-ring).2 While a non-Active Template liquid system3 and a few liquid crystal4 rotaxanes have been reported, many functional MIMs are solids that only operate in solution, restricting their materials applications.
The design principles of Functional Molecular Liquids take a functional molecular core and render it a liquid through the addition of disordered alkyl chains, without the loss of function.5 In this work we show the development of a bipyridine-based macrocycle6 for novel liquid AT rotaxanes.
Fig. 1. Design philosophy of liquid bipyridine macrocycles
References:
1. E. A. Neal and S. M. Goldup, Chem. Commun., 2014, 50, 5128. 2. M. Denis and S. M. Goldup, Nature Rev. Chem., 2017, 1, 0061. 3. T. Ogoshi, et al., J. Am. Chem. Soc., 2012, 134, 50. 4. Aprahamian, et al., Angew. Chem. Int. Ed., 2007, 46, 4675. 5. Shinohara, et al., Mol. Syst. Des. Eng., 2019, 4, 78-90; E. A. Neal and T. Nakanishi in System-
Material Nanoarchitectonics, Springer, Tokyo, 2020, accepted. 6. J. E. M. Lewis, et al., Chem. Sci., 2016, 7, 3154.
Poster 57
Combining Hyaluronic Acid with Perylene Bisimides to Yield Thin, Flexible Photoconductive Films
S. O’Nion and E.R, Draper
A5-25, Joseph Black Building, University of Glasgow, University Pl, Glasgow G12 8QQ
Email: [email protected] Web: https://drapergroup.wordpress.com/
Biography:
Upon graduating in 2016 with a BSc (Hons) in Chemistry with Professional Experience from the University of Strathclyde, I worked in industry for six months before returning to academia to undertake a PhD at the University of Glasgow. During my undergraduate studies, I spent a year in industrial placement working as an R&D assistant at Biogelx, focusing on the development process and analysis of peptide-based supramolecular hydrogels. Following this, I undertook my final year research project in the Nanometrology department under the supervision of Professor Karen Faulds where I utilised surface enhanced resonance Raman scattering (SERRS) for the detection of reactive oxygen species in prostate cancer cells. After graduating, I worked a fixed-term position at Hyaltech Ltd. within the R&D team on process improvement projects for the production of viscoelastic polymeric solutions. I joined the group in 2017 under the supervision of Dr Emily Draper and in partnership with Hyaltech Ltd.
Abstract:
Perylene bisimides (PBIs) have been utilised as materials for organic electronics, with applications including organic light emitting diodes and bulk heterojunctions. When functionalised at the terminal imide positions with the amino acid, valine (PBI-V), the material exhibits both solubility in water and n-type semiconducting properties. This is a result of conversion to the radical anion upon irradiation with light of a sufficient wavelength. The use of these materials in their solid state, however, is limited due to their brittle nature and tendency to fracture when subjected to bending or stress.
Previous literature has shown sugar-based additives can be used as a means of prolonging the lifetimes of the radical species for persistent conductivity. Here we present the effects of combining PBI-V with a solution of high molecular weight (HMW) hyaluronic acid (HA), a viscoelastic polysaccharide. Solutions of HA can be dried in air to yield thin, flexible and optically transparent films with high tensile strength. Combining solutions of both PBI-V and HA, it was found that similar films could be generated that maintain the native properties of the PBIs.
In these two-component systems we have shown that HA acts as a scaffolding structure, providing stability of the material without inhibiting the photo and electronic properties of the PBI species. In addition, the surface uniformity and reproducibility of the dried material has also shown to increase when HA is used as an additive.
References:
1. Ilze Lāce, Dr. Stephen Sproules and Dr. Emily R. Draper, ChemNanoMat., 2018, 4(8), 776-80.
Poster 58
Pillar[5]arene based Molecular Shuttles
Arjun Patel, Neil R. Champness
School of Chemistry – University of Nottingham, University Park, Nottingham, NG7 2RD, UK
Email: [email protected] Web: www.neilchampnessgroup.com
Abstract:
Rotaxanes have been widely employed in the construction of molecular machines, utilising the possibility of relative motion between their axle and macrocyclic components.1 Pillarenes are a relatively new class of macrocycle and are a highly symmetrical, tubular macrocycle consisting of [n]1,4-dialkoxybenzene (or hydroquinone) units bridged in the para-position by methylene units in the 2 and 5 positions. The electron rich cavity of a pillar[5]arene makes it a compelling candidate for host-guest interactions with electron deficient rod like molecules such as bis(imidazole) alkanes for use in the construction of rotaxanes.2
In this work, two rotaxanes, a [2]rotaxane and a [3]rotaxane have been synthesised, along with its corresponding dumbbell molecule, using pillar[5]arene macrocycles as hosts for the interaction. Under analysis of 1H NMR, the [2]rotaxane has shown the macrocycle to be barricaded onto one side of the 1,4-dioxybenzene ring along the dumbbell molecule in CDCl3. Proton NMR in DMSO-d6 has shown that the macrocycle can bypass the barricade and shuttle freely between both alkyl chain stations. Additionally, the [3]rotaxane pushes the macrocycles close together in DMSO-d6.
Figure 1: Top, a [2]rotaxane in chloroform, confined to one side of the dumbbell molecule; middle, [2]rotaxane with shuttling ability over the 1,4-dioxybenzene component in DMSO; and bottom, the [3]rotaxane in DMSO where the macrocycle are pushed together.
References:
1. S. Erbas-Cakmak, D. A. Leigh, C. T. McTernan and A. L. Nussbaumer, Chem. Rev., 2015, 115, 10081–10206.
2. T. Ogoshi and T. Yamagishi, Chem. Commun., 2014, 50, 4776–4787.
Poster 59
Synthetic Selection of Enhanced Therapeutic Aptamers
Alexandra R. Paul1, Michelle D. Garrett2, Helen Lavender3, Christopher J. Serpell1
1School of Physical Sciences, Ingram Building, University of Kent, Canterbury, CT2 7NH
2School of Biosciences, Stacey Building, University of Kent, Canterbury, CT2 7NJ
3Centauri Therapeutics, Discovery Park Limited, Innovation House, Ramsgate Road, Sandwich, CT1 9FF
Email: [email protected] Web: https://research.kent.ac.uk/serpell/
Abstract:
Aptamers are single-stranded oligonucleotide sequences that bind with high affinity and specificity to diverse targets1. The recognition capacity of aptamers can be harnessed for therapeutic agents. The chemistry of aptamers is largely limited to that of nucleic acids, which has caused a slow development of clinical aptamers. Non-natural modifications of nucleic acids are known to enhance aptamer affinity however there is not a technology for selecting the right modifications amongst millions of possibilities.
This project will develop the first general method for discovery of nucleoside modifications which increase aptamer binding efficacy. A library will be created of over 1 million different chemical modifications on a known aptamer sequence (minE07). This aptamer binds to the Epidermal Growth Factor Receptor (EGFR) which is a protein that is over-expressed in cancer cells2, the aim is to improve the binding between minE07 and EGFR. Our aim is to improve the affinity of minE07 for EGFR by using flow cytometry to separate out the best bound sequences from the one-bead-one-sequence library. Here we present steps towards the aptamer library synthesis, fluorescent activated flow cytometry sorting and protein binding assays.
References:
1. Dunn, M. R., Jimenez, R. M. & Chaput, J. C. Analysis of aptamer discovery and technology. Nat. Rev. Chem. 1, 0076 (2017).
2. Herbst, R. S. Review of epidermal growth factor receptor biology. Int. J. Radiat. Oncol. Biol. Phys. 59, 21–26 (2004).
Poster 60
Donuts and Holes
N. Pearce, E. S. Davies, K. Reynolds, M. W. George and N. R. Champness
University of Nottingham, University Park, Nottingham, NG7 2RD
Email: [email protected] Web: https://neilchampnessgroup.com/
Biography:
I (Nic) have been part of the Champness group since 2011, when I joined the group as an undergraduate synthesising molecular tiles with five-fold symmetry. My research has since focused on supramolecular systems of redox-active dye molecules, in particular naphthalene and perylene diimides, in search of interesting electrochemical properties.
Abstract:
Pillar[5]arene is an electron rich macrocycle that has been widely used in the construction of inclusion complexes and rotaxanes.1 We have thoroughly examined the electrochemical properties of pillar[5]arene and a simple [2]-rotaxane derivative finding that the macrocycle can be reversibly oxidised to form a stable radical.
Figure left: Time resolved infrared spectra of a PDI-(bis)pillar[5]arene [3]-rotaxane following photoexcitation at 532 nm; top right: Schematic representation of a PDI-(bis)pillar[5]arene [3]-rotaxane; bottom right: Proposed mechanism for charge-transfer from the pillar[5]arene ‘donut’ to the perylene diimide ‘hole’ in a rotaxane structure.
We have expanded the scope of this oxidation by synthesising a [3]-rotaxane from pillar[5]arene and an electron-accepting perylene diimide chromophore, determining through a combination of electrochemistry, time-resolved infrared spectroscopy and transient absorption measurements that electrons can be passed through space from the pillar[5]arene (the donut) to the perylene diimide acceptor (the hole), without the need to have a covalent link between these components.
References:
1. K. Yang, S. Chao, F. Zhang, Y. Pei and Z. Pei, Chem. Commun., 2019, 13198.
Poster 61
Highly efficient squaramide receptors for anion binding and transmembrane transport
G. Picci, C. Caltagirone, R. Quesada
Università degli Studi di Cagliari, Dipartimento di Scienze Chimiche e geologiche, SS 554 Bivio per Sestu, 09042 Monserrato (CA), IT
Email: [email protected]
Biography:
Giacomo Picci graduated in Chemistry in 2015 at University of Cagliari, Italy. Currently he is a Ph.D student at University of Cagliari under the supervision of Prof. Claudia Caltagirone. He works on Supramolecular Chemistry of anion recognition and sensing
Abstract:
This work reports a new family of symmetric squaramide-based receptors functionalised with different fluorophores (L1-L5, Figure 1) for anion recognition and transport. The fluorophores were chosen with the aim to explore the possibility to tune the binding/recognition event depending on the heteroatoms in the squaramide substituents. The anion binding properties of the five receptors towards different anion guests (F-, CN-, AcO-, BzO-, H2PO4
-, and Cl-) were studied by means of 1H-NMR spectroscopy in DMSO-d6 and UV-Vis and fluorescent spectroscopies in DMSO and MeCN.
Moreover, in order to test the capability of L1-L5 to mediate chloride transport across membranes, we investigated their transmembrane anion transport activity.
Figure 1 Receptors described in the presentation
References:
1. G. Picci, M. Kubicki, V. Lippolis, R. Mocci, A. Porcheddu, P. C. Ricci, R. Quesada, C. Caltagirone,
paper in preparation.
Poster 62
Supramolecular Organic Chemistry Research Group
Ben S. Pilgrim
School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD
Email: [email protected] Web: https://www.thepilgrimgroup.co.uk/
Biography:
In October 2019, Dr Ben Pilgrim started his own research group at the University of Nottingham as part of their Green Chemicals Beacon of Excellence. There will be at least one fully funded PhD studentship in the group to start in 2020. Ben is happy to talk to anyone interested at the poster session or at any other time during MASC.
Ben studied for his MChem in Chemistry at St John's College, University of Oxford, where he undertook a final year project on oxidative cyclisation reactions. Ben remained at Oxford for his postgraduate work with Prof. Timothy Donohoe. Ben’s DPhil work on palladium-catalysed routes to aromatic heterocycles was awarded a Commendation by the Division of Physical Sciences. Ben then moved to the University of Cambridge to undertake a Herchel Smith Research Fellowship with Prof. Jonathan Nitschke on the 'Post-assembly Modification of Metallosupramolecular Architectures'. Ben was subsequently awarded a Royal Commission for the Exhibition of 1851 Research Fellowship in order to study 'Stimuli-responsive Molecular Containers'. Ben's research interests span supramolecular chemistry, self-assembly, heterocyclic chemistry and catalysis.
Abstract:
The Pilgrim Group's research will cover multiple projects falling within the overall theme of Supramolecular Organic Chemistry. Some particular project areas include:
Supramolecular catalysis: Innovative approaches that allow multiple catalysts to work in tandem, and permit their isolation and recovery, is vital for securing a sustainable future. My research programme seeks to develop such systems by using combinations of molecular cages as catalyst-containing nanoboxes that work in tandem to produce complex molecules. Cage encapsulation could render toxic catalysts bench-safe, sensitive catalysts stable to atmospheric conditions, and open new strategies for controlling reaction regioselectivity and stereoselectivity.
Click cascade reactions and their applications: Harnessing different cascade reactions that probe a diverse library of functionality combinations would rapidly advance the state-of-the-art in chemical conjugation strategies. Selective arrays could be developed to probe the coexistence of two analytes within a sample, the presence of reactive intermediates within a particular phase, the successful copolymerisation of two different monomers, or the successful incorporation of amino acids within a protein. The group will target novel conjugation partners based on reactive reagents for cycloaddition reactions such as tetrazines and oxanorbornadienes.
For more detail and for discussions, please come and visit the poster!
References:
1. D. A. Roberts, B. S. Pilgrim, G. Sirvinskaite, T. K. Ronson, J. R. Nitschke J. Am. Chem. Soc., 2018, 140, 9616-9623.
2. D. A. Roberts, B. S. Pilgrim, J. R. Nitschke Chem. Soc. Rev., 2018, 47, 626-644.
3. B. S. Pilgrim, D. A. Roberts, T. G. Lohr, T. K. Ronson, J. R. Nitschke Nat. Chem. 2017, 9, 1276-1281.
4. D. A. Roberts, B. S. Pilgrim, J. D. Cooper, T. K. Ronson, S. Zarra, J. R. Nitschke J. Am. Chem. Soc. 2015, 137, 10068-10071.
Poster 63
Transparent-to-Dark Photo- and Electrochromic Windows
Rebecca Randle and Emily R. Draper
School of Chemistry, University of Glasgow, Glasgow, UK, G12 8QQ
Email: [email protected] Web: https://drapergroup.wordpress.com/blog/
Biography:
Rebecca graduated with an 1st class MChem (hons) degree in Chemistry with a Year Abroad in 2018 from Cardiff University. During her undergraduate studies Becky spent a year under the supervision of Professor Brad Easton at UOIT in Oshawa focusing research upon the effect of contaminants upon electronic properties and efficiency of glassy carbon electrodes. Following this, she undertook a final year research project under supervision of Professor Simon Pope in Cardiff, looking at the synthesis and photophysical properties of novel naphthalimide ligands. Becky joined the Draper group at the University of Glasgow in 2018 with a DTP studentship. Her research currently involves the synthesis and self-assembly of electrochromic materials that reversibly change colour upon application of external stimuli such as voltage, light or heat.
Abstract:
Stimuli responsive naphthalene diimide (NDI) derivatives are excellent candidates for application in smart windows1. They have an advantage over costly alternatives such as transition metals, not only in ease of synthesis but in their high colouration, pale native state, fast switching times and tunability. The radical anion or further reduced dianion of an NDI functionalised with a simple amino acid is responsible for the desirable transition from transparent to black; Figure 1 shows images of this colour change. The NDI radical produces absorbance bands in the visible region which can be easily identified using absorbance spectroscopy. Here, we describe how colouration, intensity and switching times can be influenced and perfected by controlling pH and functionalisation of a self-assembling NDI in aqueous solution. The appearance of a transmissive and pale native state in aqueous, benign solvent, as well as a resistance to degradation by temperature, UV or moisture also gives these systems an advantage over other smart window alternatives such as polymers. Controlling transmittance in windows allows significant reduction in energy usage in buildings as well as offering on demand privacy or tinting against bright sunlight glare.
Figure 5: Native and reduced states of NDI functionalised with isoleucine at 10 mg/mL buffered to pH 9.2 using Sodium Carbonate. Colouration was achieved by application of -2.5 V for 120 seconds and is reversed by application of 0.4 V for 180 seconds
References:
1. L. Gonzalez, C. Liu, B. Dietrich, H. Su, S. Sproules, H. Cui, D. Honecker, D. J. Adams and E. R. Draper, Commun. Chem., 2018, 1, 77.
Poster 64
Mechanically interlocked molecules as potential TADF-active emitters
F. Rizzi, M. A. Jinks, P. Rajamalli, E. Zysman-Colman and S. M. Goldup
Department of Chemistry, University of Southampton, Rm 4001, Building 30, 22 Hartley Ave, Southampton,SO17 3QZ
Email: [email protected] Web: http://goldup.soton.ac.uk/
Abstract:
Mechanically interlocked molecules have been recently exploited for various applications, including sensing[1], as molecular machines[2] and as photoactive functional materials[3]. Here we synthesized a novel family of [2]- and [3]-rotaxanes with potential thermally activated delayed fluorescence (TADF) activity. The design is based on a donor–acceptor emitter reported by the Zysman-Colman group, where a carbazole moiety is linked to a benzophenone moiety.[4] We exploited the active template copper azide–alkyne cycloaddition (AT-CuAAC) to thread small macrocycles close to the D–A core. Two of the rotaxanes, 1 and 2, were characterised by UV-Vis and fluorescence spectroscopy, and their binding to guest cations was studied through UV-Vis and fluorescence titrations.
References:
1. Lewis, J. E. M.; Galli, M.; Goldup, S. M., Chem. Commun. 2017, 53, 298-312 2. Baroncini, M.; Casimiro, L.; de Vet, C.; Groppi, J.; Silvi, S.; Credi, A., ChemistryOpen 2018, 7,
169-179 3. Li, J. J.; Zhang, H. Y.; Zhang, Y.; Zhou, W. L.; Liu, Y., Adv. Optical Mater. 2019, 7
4. P. Rajamalli, D. Rota Martir, E. Zysman-Colman, J. Photonics Energy 2018, 8, 1-26
Poster 65
Design of Self-Assembly Heterotopic Ligands for the Synthesis of Biologically Relevant 3-D Architectures
J. A. Robson, L. L. K. Taylor, I. J. Vitorica-Yrezabal and I. A. Riddell
Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL Email: [email protected] Web: www.imogenriddell.wixsite.com/riddellgroup
Biography:
Jonathan completed his undergraduate degree and PhD at Imperial College London working under the supervision of Dr James Wilton-Ely. His PhD focused on using ruthenium (II) vinyl complexes to detect carbon monoxide in biological environments. At Manchester, Jonathan's research is focused on the encapsulation and stabilisation of proteins within supramolecular structures.
Abstract:
Self-assembly is a coordination-driven design strategy used to form three-dimensional metal-organic architectures. Traditionally, symmetric multitopic ligands have been employed to form highly symmetric metal-organic products that can be readily characterised spectroscopically.1 In contrast, the synthesis and self-assembly of heterotopic ligands with metal salts has been sparsely explored. These synthetically more challenging ligands could however lead to the construction of more elaborate architectures with a wider range of applications.2
Pyridyl benzimidazole, pyridyl aldehyde and bipyridyl motifs are commonly incorporated in symmetric homotopic ligands employed in self-assembly reactions. Here we report the design and synthesis of asymmetric heteroditopic ligands incorporating these motifs. In combination with amine based linkers and metal salts this strategy led to the formation of tetrahedral, trigonal bipyramidal and cubic 3-D architectures. Notably, tritopic linker TREN, Fe(BF4)2 and a heterotopic ligand forms the trigonal bipyramidal complex [Fe6L6F6T2](BF4)7. This architecture displays unprecedented site-specific binding of iron in three distinctly different electronic configurations, incorporating a unique [FeIII(μ-F)6(FeII)3]3+ star motif at its core.3
References:
1. D. L. Caulder and K. N. Raymond, Acc. Chem. Res., 1999, 32, 975–982.
2. S. P. Argent, H. Adams, T. Riis-Johannessen, J. C. Jeffery, L. P. Harding and M. D. Ward, J. Am. Chem. Soc., 2006, 128, 72–73.
3. L. L. K. Taylor, I. J.Vitorica-Yrezabal, I. Borilović, F. Tuna, and I. A. Riddell, submitted.
Poster 66
Stereoselective Synthesis of Topologically Chiral Catenanes
Arnau R. Rubio, Florian Modicom and Stephen M. Goldup
Building 30, 22 Hartley Ave, Southampton SO17 3QZ
Email: [email protected] Web: http://goldup.soton.ac.uk/
Abstract:
Topologically chiral catenanes are interlocked structures composed of 2 or more macrocycles of Cnh symmetry.1 This type of chirality is a direct consequence of the mechanical bond, which forces the macrocycle rings into an arrangement that desymmetrises their previously existing symmetry operations. The stereoselective synthesis of these architectures is still a challenge and usually requires the tedious separations of diastereomeric mixtures.2 In this work, we have carried out the highly stereoselective active template-copper (I) azide-alkyne cycloaddition (AT-CuAAC) synthesis3 of topologically chiral catenanes with selectivities of up to 94:6 diastereomeric ratio. This will facilitate to access highly enantioenriched topologically chiral catenanes to further study their properties and applications.
References:
1. Ellen M. G. Jamieson, Florian Modicom, Stephen M. Goldup* Chem. Soc. Rev. 2018, 47, 5266.
2. Mathieu Denis, James E. M. Lewis, Florian Modicom, Stephen M. Goldup* Chem. 2019, 5, 1357.
3. Mathieu Denis and Stephen M. Goldup* Nat. Rev. Chem. 2017, 61.
Poster 67
Aqueous Recognition of Purine and Pyrimidine Bases by Anthracene‒Based Macrocyclic Receptor
S. K. Samanta, D. V. Eker and A. P. Davis
School of Chemistry, University of Bristol, Cantock’s Close, BS81TS, Bristol, UK.
Email: [email protected] Web: https://davis.chm.bris.ac.uk/
Biography:
Soumen Samanta received a PhD degree from University of Siegen, Germany studying molecular nanorotors with Prof. Michael Schmittel. After a postdoctoral stay with Prof. Lyle Isaacs at the University of Maryland, USA, Soumen started working in the group of Prof. Anthony P. Davis at University of Bristol, UK.
Abstract:
Anthracene‒based receptor has been proven to be an excellent host for molecular recognition.1‒
4 We demonstrate the ability of anthracene-based receptor to recognise several purine and pyrimidine bases (hypoxanthine, uric acid, caffeine, adenine, thymine etc) in water. Selective detection and sensing of biologically relevant analyte like hypoxanthine and uric acid will be interesting as uric acid and hypoxanthine are important biomarker for diagnosis of several diseases like hypouricemia, acute cardiac ischemia and prostate cancer. Binding affinities are determined by 1H NMR, fluorecence and ITC titration. Interestingly, highest affinity of hypoxanthine (Ka = 8.7 × 106 M-1) was observed with good selectivity over other bases. Particularly, hypoxanthine binds 50 times stronger than other stronger guest like uric acid (Ka = 1.7 × 105 M-1). We have also determined the affinity of several nucleotide bases. Interestingly we observed that cooperative binding event for thymine and uracil leading to homodimerisation within the hydrophobic cavity of anthracene-based receptor. Among nucletide bases, adenine (Ka = 1.3 × 105 M-1) and thymine (Ka = 5.8 × 105 M-1) bind strongly. This study demonstrates the possibilty of anthracene‒based receptor in selective detection of hypoxanthine in biological media.
References:
1. R. A. Tromans, T. S. Carter, L. Chabanne, M. P. Crump, H. Li, J. V. Matlock, M. G. Orchard and A. P. Davis, Nature Chem, 2019, 11, 52-56.
2. E. M. Peck, W. Liu, G. T. Spence, S. K. Shaw, A. P. Davis, H. Destecroix and B. D. Smith, J. Am. Chem. Soc., 2015, 137, 8668-8671.
3. C. Ke, H. Destecroix, M. P. Crump and A. P. Davis, Nature Chem., 2012, 4, 718-723.
4. H. Destecroix, C. M. Renney, T. J. Mooibroek, T. S. Carter, P. F. N. Stewart, M. P. Crump and A. P. Davis, Angew. Chem. Int. Ed., 2015, 54, 2057-2061.
Poster 68
DNA-Peptide Conjugation Leading to Emergent Properties
A. Sato, E.R. Taylor, C.J. Serpell and M.R. Reithofer
School of Physical Sciences, Ingram Building, University of Kent, Canterbury CT2 7NH, UK
Email: [email protected] Web: https://research.kent.ac.uk/serpell/
Abstract:
Peptide-oligonucleotide conjugates (POCs) are hybrid compounds consisting of peptides covalently linked with nucleic acids such as DNA and RNA. Integrating the unique characteristics of peptides with oligonucleotides in a unified system may lead to the formation of structures with new-sophisticated functions that were absent in the individual biomolecules, known as emergent phenomena.1 The novel and growing field of POCs embeds enormous potential for the development of highly biomimetic nanomaterials applicable in tissue engineering, oncology and drug delivery.2-4
This project aims to create a variety of POCs using different peptides and DNA oligonucleotides in order to investigate how their self-assembly may result in unique emergent properties. The primary objective of the project involved the synthesis of the specific peptides that have been utilised in conjugation reactions with DNA. So far, three beta sheet-forming peptides (KLVFFA, HYFNIF and RVFNIM) and a collagen mimetic peptide (POG)6 have been obtained and the analysis with CD and AFM confirmed their predicted structures. The successful conjugation strategy by which the POCs were confirmed by LC-MS involved the use of thiol-maleimide chemistry. Purification of the conjugates is currently being conducted prior to proceeding analytical steps due to the presence of unreacted DNA.
Figure 1. AFM images of peptide a) HYFNIF and peptide b) (POG)6.
References:
1. T. MacCulloch, A. Buchberger and N. Stephanopoulos, Org. Biomol. Chem., 2019, 17, 1668. 2. C. D. Spicer, E. T. Pashuck and M. M. Stevens, Chem. Rev., 2018, 118, 7702. 3. J. Winkler, Ther Deliv., 2013, 4, 791. 4. N. Stephanopoulos, Bioconjugate Chem., 2019, 30, 1915.
Poster 69
Sequence controlled release of ibuprofen from polymeric nanoparticles
S. Shehataa, C. J. Serpell, S. C. G. Biagini a Supramolecular, Interfacial and Synthetic Chemistry Group, School of Physical Sciences, Ingram Building, University of Kent, Canterbury CT2 7NH, UK
Email: [email protected]
Abstract:
Non-steroidal anti-inflammatory drugs (NSAIDs) possess analgesic, antipyretic and anti-inflammatory properties and are amongst the most widely prescribed drugs worldwide. Pain relief is the primary clinical use for NSAIDs but they also show potential use as therapeutic agents for the treatment of rheumatoid arthritis but also in some types of tumours such as breast, colorectal, or prostate cancers1,2. Although the mechanism of NSAIDs on preventing cancer is still not clear, it is thought that NSAIDs act as tumour suppressors by inhibiting the cyclooxygenase (COX), enzyme that catalyses the formation of prostaglandins which are thought to be responsible for a variety of oncogenic events2.
In this study, the aim is to investigate the delivery and release3 of these drugs for tumour therapy with the use of polymeric prodrugs as polymer drug carriers4. In particular polymers deriving from ring opening metathesis polymerisation (ROMP) have been used. Thanks to the ability of ROMP of forming both homo and co-polymers with a controlled length and composition, it was possible to synthesise amphiphilic block co-polymers in which the lipophilic part contains the NSAID drugs, namely ibuprofen, while the hydrophilic part is made of polyethylene glycol methyl ester (PEGOMe)5. The latter leads to the formation of polymers with good water solubility and controlled self-assembly morphologies. Ibuprofen release has been studied using physiological conditions (water, phosphate buffer saline PBS, foetal bovine serum FBS and pig liver esterase PLE) and base conditions (2M NaOH)1, showing that this system is stable to the physiological ones but in a strong alkaline environment the drug can be released over a period of up to four days6.
Figure 6: Representation of amphiphilic block copolymer based on ROMP polymerisation, its self-assembly and release of ibuprofen.
References:
1. S Akkad, CJ Serpell, Macromol. Rapid Commun. 39 (14), 1800182. 2. Z Zhang, F Chen, L Shang, Cancer Manag. Res., 2018, 10, 4631–4640. 3. Y. Zhou, B. Zhang, Y. Yu, H. Shen, Q. Meng, H. Hu, L. Zhou, Y. Zhang, B. Yu and Y. Shen, Polym.
Chem., 2018, 00, 1-3. 4. D Smith, EB Pentzer, ST Nguyen, Polym. Rev., 2007, 47 (3), 419–459. 5. S. C. G. Biagini and A. L. Parry, J. Polym. Sci. Part A. Polym. Chem., 2007, 45, 3178-3190.
6. S. Shehata, C. J. Serpell, S. C. G. Biagini, ChemRxiv, 2019.
Poster 70
Coordination Chemistry and Crystal Engineering of Picolyl-Substituted Cyclic Amines
Valentyna Slyusarchuk, Barnaby O’Brien and Chris S. Hawes
School of Chemical and Physical Sciences, Keele University, Staffordshire ST5 5BG, U.K.
Email: [email protected] Web: www.hawesgroup.wordpress.com
Abstract:
Weak interactions play a key role in dictating the extended structure of crystalline coordination polymers and metallo-supramolecular assemblies,1 and have been widely employed to this end in a diverse variety of crystalline architectures.2 In our efforts to increase the hydrophobic character of microporous materials, we have recently examined small aliphatic carbocycles and cyclic amines.3 We aim to further develop the crystal engineering aspects of non-aromatic building blocks in these systems, which tend to exhibit more diffuse intermolecular interactions, but which may offer new opportunities where hydrophobicity or constrained flexibility are beneficial.
For this study, we have prepared analogous piperidine and morpholine-substituted pyridine derivatives, in order to compare and analyze the subtle influence of C-H···O hydrogen bonds and restricted conformational freedom of these groups in crystalline coordination compounds. Using Ag(I) as a soft Lewis acid favors coordination of both the tertiary amine group of morpholine or piperidine as well as the ancillary picolyl group, giving coordination polymers, while trichlorocobaltate complexes, coordinated by the picolyl substituent only, reveal the crystal packing influence of the piperidine and morpholine groups when non-coordinating.
Figure 1 (Left) Structure of an Ag(I) coordination polymer of N-(4-picolyl)-morpholine, with hydrogen atoms omitted for clarity; (Right) Hirshfeld surface with dnorm map of external contacts for a discrete trichlorocobaltate complex of the N-(4-picolyl)-morpholinium cation.
References:
1. G. R. Desiraju, Nature, 2001, 412, 397. 2. K. Rissanen, CrystEngComm 2008, 10, 1107; H. T. Chifotides and K. R. Dunbar, Acc. Chem. Res.
2013, 46, 894; T. J. Mooibroek, P. Gamez and J. Reedijk, CrystEngComm 2008, 10, 1501 3. C. S. Hawes, G. P. Knowles, A. L. Chaffee, K. F. White, B. F. Abrahams, S. R. Batten and D. R.
Turner, Inorg. Chem. 2016, 55, 10467
Poster 71
Triple Decker Handcuff Rotaxanes
M. Tarnowska, and N.R. Champness
Chemistry Building at Nottingham University
Email: [email protected] Web: https://neilchampnessgroup.com/
Abstract:
Mechanically interlocked molecules (MIMs) and handcuff rotaxanes in particular, which are systems containing multiple covalently bonded macrocycles, through which a rod is threaded then stoppered, are an example of such species. MIMs have wide ranging applications in nanoscale electronics, systems which mimic biology, and many others.1 Since its recent discovery, DMPillar[5]arene has been used extensively in MIMs due to its interesting host-guest properties,2 and this work deals with triple decker handcuff rotaxanes containing it, as well as perylene diimide (PDI) cores and imidazole groups. The feasibility of the synthesis of such handcuff rotaxanes using a templated, clipping method, utilising interactions between PDI cores and between DMPillar[5]arenes and imidazole groups is investigated. After successful synthesis of the proposed handcuff rotaxane shown on Figure 1, these handcuffs can be probed for interesting communications between the PDI centres using cyclic voltammetry, spectroelectrochemistry and electron paramagnetic resonance spectroscopy. Previous results within the group have discovered a new molecular orbital shared by PDI centres on a double decker handcuff.3
Figure 1: The proposed structure of the triple decker rotaxane handcuff.
References:
1. D. B. Amabilino and J. F. Stoddart, Chem. Rev., 1995, 95, 2725-2828. 2. K. Yang, S. Chao, F. Zhang, Y. Pei and Z. Pei, Chem. Commun., 2019, 55, 13198-13210 3. L. Yang, P. Langer, E.S. Davies, M. Baldoni, K. Wickham, N. A. Besley, E. Besley and N. R.
Champness Chem. Sci., 2019, 10, 3723-3732
Poster 72
Hierarchal and Emergent Assembly through DNA – Peptide Conjugation.
Emerald. R. Taylor,a A. Sato,a Dr M. Reithofer,b Dr C. Serpell*a. a School of Physical Sciences, University of Kent, Ingram Building, University of Kent, Canterbury CT2 7NH, UK
b Department of Inorganic Chemistry, University of Vienna, Währinger Straße 42, 1090 Vienna, Austria
Email: [email protected] Web: http://research.kent.ac.uk/serpell/
Abstract:
This research aims to take two naturally occurring self-assembling models and coerces them to work together to produce self-assembled materials with properties which stem from the interaction of their respective assembly regimes in an orthogonal approach.1 Orthogonal self-assembly generally takes two forms; hierarchal self-assembly where one interaction leads to the formation of a structure and a second interaction leads to the formation of a super structure;2 and emergent assembly, where the indirect interaction between different systems leads to the development of new occurrences,3 similar to those found in biology. DNA is well known for self-assembling into double helix structures. Peptides are well known for producing secondary structures such as beta sheets; alpha helices and 3D structures such as coiled coils.4 These systems have complex and varied uses within nature, however their use in synthetic systems are as yet basic in comparison to natural systems.5 Most biological reactions rely upon small molecule interactions such as catalysis by an enzyme.6 However more complex tasks require cooperation between molecules from different families, an example of this cooperation can be taken from ribosomes which use both RNA and proteins to produce proteins.7,8 This work will discuss the advancements made in this project to date.
Figure 1: Design strategy for DNA-peptide hybrid nanostructures.
References:
1. Wei, P., Yan, X. & Huang, F. Chem. Soc. Rev. 44, 815–832 (2015). 2. Zayed, J. M., Biedermann, F., Rauwald, U. & Scherman, O. A. Polym. Chem. 1, 1434 (2010). 3. Serpell, C. J., Edwardson, T. G. W., Chidchob, P., Carneiro, K. M. M. & Sleiman, H. F. J. Am.
Chem. Soc. 136, 15767–15774 (2014). 4. Thomas, F., Burgess, N. C., Thomson, A. R. & Woolfson, D. N. Angew. Chemie - Int. Ed. 55, 987–
991 (2016). 5. Weaver, J. C. et al. Science. 336, 1275–1280 (2012). 6. Robertson, E. G. & Simons, J. P. Phys. Chem. Chem. Phys. 3, 1–18 (2001). 7. Ashkenasy, G., Chotera, A., Sadihov, H., Cohen-Luria, R. & Monnard, P. A. Chem. - A Eur. J. 1–
30 (2018). 8. Yonath, A. Angew. Chemie - Int. Ed. 49, 4340–4354 (2010).
Poster 73
Creating Transient Gradients in Supramolecular Hydrogels
Lisa Thomson and Dave J. Adams
School of Chemistry, University of Glasgow, Glasgow, G12 8QQ
Email: [email protected]
Abstract:
The self-assembly of small gelator molecules, such as dipeptides, in water produces hydrogels.1 Using a trigger to provoke this self-assembly, homogeneous gels can be reproducibly generated by various methods, for example a pH switch.2 The assembly begins with the formation of fibres which entangle and trap the water, resulting in a gel. The type of trigger used affects the properties, structures and network of the gel. As gels are formed via self-assembly, we possess little control with regards to how their networks form. There is an interest in gradient gels within a single network as these systems have possible applications in tissue engineering and sensors.3
Using a photoacid generator (PAG) and UV light, we have demonstrated the ability to form gradient strength hydrogels and selectively pattern gels using a photomask. These effects are temporary as when left without intervention, the gels become homogeneous over time. We use bulk rheology to examine our gels as a whole, and using the localised technique of cavitation rheology,4 we are able to prove the existence of gradients created by controlling the self-assembly of the gel network.
References:
1. N. M. Sangeetha and U. Maitra, Chemical Society Reviews, 2005, 34, 821-836. 2. D. J. Adams, M. F. Butler, W. J. Frith, M. Kirkland, L. Mullen and P. Sanderson, Soft Matter,
2009, 5, 1856-1862. 3. P. Liu, C. Mai and K. Zhang, Frontiers of Chemical Science and Engineering, 2018, 12, 383-
389. 4. J. A. Zimberlin, N. Sanabria-DeLong, G. N. Tew and A. J. Crosby, Soft Matter, 2007, 3, 763-
767.
Poster 74
Macrocyclic Anionophores
Hennie Valkenier
Engineering of Molecular NanoSystems, Ecole Polytechnique de Bruxelles, Université libre de Bruxelles, 1050 Brussels, Belgium.
Email: [email protected] Web: http://emns.ulb.be/
Biography:
Hennie Valkenier studied Chemistry at the University of Groningen and obtained her PhD from this university in 2011 with a thesis on Molecular Electronics. After a year of teaching in West-Africa, she joined the group of Prof. Tony Davis at the University of Bristol as a postdoc to develop transmembrane transporters for chloride. In 2015, she moved to the Université libre de Bruxelles, where she worked as a postdoc with Profs. Kristin Bartik and Gilles Bruylants. In 2018, she has obtained a permanent position as F.R.S.-FNRS Research Associate at the Université libre de Bruxelles and has been awarded an ERC starting grant. This allows her to work with a team of talented students/postdocs on the development of new ion receptors for transmembrane transport.
Abstract:
Absence or malfunction of membrane proteins forming anion channels is the cause of several channelopathies, such as cystic fibrosis. Synthetic anion carriers have the potential to take over part of the function of these proteins.1-3 Such carriers extract the anion from the aqueous phase, move it across the apolar interior of the lipid bilayer while shielding its charge, to then release it on the other side of the membrane.
Macrocyclic receptors are preorganised in a particular way, often leading to remarkable selectivities in binding and hence unique behaviour in anion transport. A first example are bambus[6]uril macrocycles, which are highly efficient in exchanging Cl− and HCO3
−,4 while related biotin[6]urils do not show any transport of HCO3
−.5 This can be rationalised based on the different affinities and binding modes that these macrocycles have for the different anions.4,5 Another example are calix[6]arene tris(thio)ureas, of which the cavity can be exploited to transport organic ion pairs.6
Figure 1. Liposomes with the dye lucigenin encapsulated (a) were used to study anion exchange by bambus[6]urils (b), biotin[6]urils (not shown), and calix[6]arenes (c).
References:
1. H. Valkenier, A. P. Davis, Acc. Chem. Res. 2013, 46, 2898–2909. 2. P. A. Gale, J. T. Davis, R. Quesada, Chem. Soc. Rev. 2017, 46, 2497–2519. 3. H. Li, H. Valkenier, A. G. Thorne, C. M. Dias, J. A. Cooper, M. Kieffer, N. Busschaert, P. A. Gale,
D. N. Sheppard, A. P. Davis, Chem. Sci. 2019, 10, 9663–9672. 4. H. Valkenier, O. Akrawi, P. Jurček, K. Sleziaková, T. Lízal, K. Bartik, V. Šindelář, Chem 2019, 5,
429–444. 5. M. Lisbjerg, H. Valkenier, B. M. Jessen, H. Al-Kerdi, A. P. Davis, M. Pittelkow, J. Am. Chem. Soc.
2015, 137, 4948–4951. 6. G. Grauwels, H. Valkenier, A. P. Davis, I. Jabin, K. Bartik, Angew. Chem. Int. Ed. 2019, 58,
6921–6925.
Poster 75
Thiolated Pillar[n]arenes, and their applications
A. W. Wahrhaftig-Lewis, N. R. Champness and A. Saywell.
University of Nottingham Chemistry department Vaughan Parry Williams Pavilion, Clifton Blvd,
Nottingham NG7 2RD
Email: [email protected] Web: https://neilchampnessgroup.com/
Abstract:
A series of sulfur containing cyclic compounds are to be synthesised and investigated. The macrocycle being utilised for this research; pillar[n]arene was first reported in 2008 by T. Ogoshi.1 This macrocycle, comprised of repeating hydroquinone units, has been the focus for a plethora of research groups due to its ease of synthesis and functionalisation, and its extended capabilities in host guest chemistry and in the synthesis of molecular machines. Incorporating thiol groups in this macrocycle leads to new and interesting properties, which will be explored.
Firstly, due to sulfur’s affinity for gold surfaces, partially thiolated pillar[5]arenes were synthesised and deposited onto a gold 111 surface for STM analysis. This asymmetric macrocycle was also deposited onto a gold electrode so cyclic voltammetry could be performed, and both the stability on the surface, and comparisons to the unsubstituted pillar[n]arene was assessed.
Figure 1: Left. Proposed model of thiolated copillar[5]arene, first synthesised by R.R.Kothur.2 Right; initial STM images after high vacuum deposition
In conjunction to this, by taking advantage of the reversible sulfur to sulfur bond, a new class of nanotubes are to be synthesised. Pillar[n]arenes with alkoxythiols on the 1 and 4 positions of each hydroquinone are to be synthesised, and then via templating in a carbon nanotube a disulfiude bound pillarene nanotube is to be synthesised. With the assistance of transmission electron microscopy, a timeline of the formation of said nanotubes can be ascertained. To further this, by expanding on the solvent-free synthesis of pillar[6]arene reported by Santral,3 and the research conducted by Ogoshi regarding the conversion from pillar[5]arene to pillar[6-15]arene, manipulation of the nanotubes’ cavity size can be synthetically controlled.4
References:
1. T. Ogoshi, S. Kanai, S. Fujinami, T. A. Yamagishi and Y. Nakamoto, J. Am. Chem. Soc., 2008, 130, 5022–5023.
2. R. R. Kothur , F. Fucassi , G. Dichello , L. Doudet , W. Abdalaziz , B. A. Patel , G. W. V. Cave , I. A. Gass , D. K. Sarker , S. V. Mikhalovsky and P. J. Cragg , Supramol. Chem., 2016, 28, 436.
3. S. Santra, D. S. Kopchuck, I. S. Kovalev, G. V. Zyryanov, A. Majee, V. Charushin and O. N. Chupakhin, Green Chem., 2015,
4. T. Ogoshi, N. Ueshima, F. Sakakibara, T. Yamagishi, and T. Haino Organic Letters 2014, 11, 2896-2899
Poster 76
Using Enthalpy to Unpick Capsule Catalysis
Jianzhu Wang, Patrick Boaler and Paul J. Lusby*
The University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK
Email: [email protected] Web: http://www.lusby.chem.ed.ac.uk/
Biography:
I completed my BSc degree in Medicinal and Biological Chemistry in the University of Edinburgh (2017) with a final year project with the Lusby group. I continued working with the Lusby group for me PhD where my research focuses on the catalytic applications of supramolecular capsules.
Abstract:
Synthetic capsules have the potential to be excellent non-covalent catalysts.1-3 Their hollow interiors provide a confined pocket that can stabilise transition states, reminiscent of how an enzyme functions. However, this bio-inspired approach remains a niche method, in part due to a very narrow reaction scope. This limitation principally stems from the general incompatibility of bimolecular fusion reactions, as they invariably result in poor turnover due to product inhibition.4-
7 We have recently shown how this problem can be avoided,8 using a method that avoids the entropic activation associated with conventional capsule catalysis, instead using enthalpy to underpin activity.
This presentation describes the expansion of this approach to non-pericyclic C-C bond forming processes. We show that a similar Pd2L4 capsule catalyses the reaction of archetypal pro-nucleophiles with complementary electrophiles (Scheme 1), exhibiting unprecedented activity. Mechanistic investigations show that this activity stems from pro-nucleophile activation coupled to a significant acceleration of the subsequent C-C bond forming step. The capsule is so effective that catalysis can be achieved in the absence of any obvious base, while the comparable background process shows no detectable reaction. As with our previous work, the capsule is also able to turnover; this even facilitates preparative scale catalysis with as little as 2 mol% cage. We also demonstrate how the capsule influences stereoselectivity that would be otherwise difficult to achieve using conventional catalysts.
Scheme 1. Pd2L4 capsule catalysed non-pericyclic C-C bond forming reactions.
References:
1. M. D. Pluth, R. G. Bergman and K. N. Raymond, Angew. Chem. Int. Ed., 2007, 46, 8587–8589. 2. J. L. Bolliger, A. M. Belenguer and J. R. Nitschke, Angew. Chem. Int. Ed., 2013, 52, 7958–7962. 3. W. Cullen, M. C. Misuraca, C. A. Hunter, N. H. Williams and M. D. Ward, Nature Chem, 2016, 8,
231–236. 4. J. Kang and J. Rebek, Nature, 1997, 385, 50–52.
5. T. Murase, S. Horiuchi and M. Fujita, J. Am. Chem. Soc., 2010, 132, 2866–2867.
6. A. Parthasarathy, L. S. Kaanumalle and V. Ramamurthy, Org. Lett., 2007, 9, 5059–5062.
7. M. Yoshizawa, M. Tamura and M. Fujita, Science, 2006, 312, 251–255.
8. V. Marti-Centelles, A. L. Lawrence and P. J. Lusby, J. Am. Chem. Soc, 2018, 140, 2862–2868.
Poster 77
Controllable self-association leads to the formation of multifunctional antimicrobial materials
Lisa J. White; Jessica E. Boles and Jennifer R. Hiscock*
School of Physical Sciences, Ingram Building, University of Kent, Canterbury, CT2 7NH
Email: [email protected] Web: https://research.kent.ac.uk/sisc
Abstract:
Supramolecular Self-associating Amphiphiles (SSAs)1-5 are a novel class of amphiphilic salt that contain an uneven number of covalently linked hydrogen bond donating and accepting groups, meaning that they are ‘frustrated’ in nature. The hydrogen-bonded, self-associative properties of members of this class of compounds have been extensively studied in the gas phase, solution state, solid-state and in silico. SSAs from this class of compound has been shown to kill a variety of clinically relevant bacteria, including those with known antibiotic resistance.6 We have also observed these multifunctional antimicrobials undergoing controllable molecular self-association events in an aqueous environment to produce spherical aggregates. The addition of salt to this aqueous environment results in the production of gel fibres to form alcohol-free topical use hydrogels (Fig.1). These hydrogels have been characterised using traditional methods such as; inversion tests, rheometry and scanning electron microscopy. Uniquely due to the intrinsically fluorescent nature of the SSA we have been able to observe the extended fibrous networks of those gels formed in the solution state using confocal microscopy.
Figure 1: SSA in an aqueous environment forming a spherical aggregate. The addition of salt results in the formation of fibrous networks and resultantly a hydrogel. TBA -Tetrabutylammonium
References:
1. L. J. White, S. N. Tyuleva, B. Wilson, H. J. Shepherd, K. K. L. Ng, S. J. Holder, E. R. Clark and J. R..Hiscock, Chem. Eur. J., 2018, 24, 7761.
2. T. L. Gumbs, L. J. White, N. J. Wells, H. J. Shepherd and J. R. Hiscock, Supramol. Chem., 2018, 30, 286.
3. L. J. White, N. J. Wells, L. R. Blackholly, H. J. Shepherd, B. Wilson, G. P. Bustone, T. J. Runacres and J. R. Hiscock, Chem. Sci., 2017, 8, 7620.
4. J. R. Hiscock, G. P. Bustone, B. Wilson, K. E. Belsey and L. R. Blackholly, Soft Matter, 2016, 12, 4221-4228.
5. L. R. Blackholly, H. J. Shepherd and J. R. Hiscock, CrystEngComm, 2016, 18, 7021. 6. S. N. Tyuleva, N. Allen, L. J. White, A. Pépés, H. J. Shepherd, P. J. Saines, R. J. Ellaby, D. P.
Mulvihill and J. R. Hiscock, Chem. Communications, 2019, 55, 95-98.
Poster 78
Through-space electronic tuning of core-heteroannulated isoindolediimides
P. K. Yerramsettia,b, R. A. Ivesa, J. P. Andrea, J. C. Westb
and A.-J. Avestroa,b* aDepartment of Chemistry, University of York, Heslington, York YO10 5DD, UK bDepartment of Chemistry, Durham University, Durham DH1 3LE, UK
Email: [email protected] ; *[email protected]
Abstract:
Core-functionalised naphthalenediimides (cNDIs) are one of the most widely investigated classes of π-conjugated organic molecules, finding broad applicability1 in supramolecular chemistry, catalysis, chemical sensors, synthetic ion channels, biomedical theranostics, organic semiconductors and electronic/energy devices. The diversity of cNDI molecules is traditionally accessed2 via 2,7- and 2,3,6,7-halogenated derivatives that can be substituted further by SNAr chemistry to afford tunable π-electronic properties3 (i.e., absorption, emission, and two-electron redox). Core annulation at the naphthalene core has also been shown as a viable strategy for producing emergent redox- and photoelectronic phenomena that are not necessarily accessible or straightforward to attribute from core substitution methods.4 For instance, it was recently shown in one reported example5 that unsubstituted NDIs can be ‘core-transformed’ into fluorescent isoindolediimides (IDI) via an unusual diketonediimide (DKDI) intermediate (Figure 1). However, despite their potential for wide applicability as organic electronic materials and dyes, the structure–property relationship of IDI molecules has not been explored any further.
We have undertaken the task of investigating the breadth of IDI optical, redox, and self-assembly properties by varying the N-substituent (for solubility) as well as the X-substituent of the isoindole core (for properties tuning). During our studies, we encountered subtle, but definite, fluorescent tuning effects that originate from close through-space interactions of the IDI π-surface with functional groups presented by non-conjugated X-substituents. We are currently focused on determining the extent of through-space tuning using a combination of experimental photospectroscopy, X-ray diffraction and variable temperature analysis that is backed by DFT calculations. The higher optoelectronic functionality offered by functional IDIs presents opportunities to develop new self-assembled molecular, gel and crystalline materials.
Figure 1. Tunable fluorescence of isoindolediimides (IDIs) via π-conjugated and through space effects.
References:
1. M. A. Kobaisi, S. V. Bhosale, K. Latham, A. M. Raynor and S. V. Bhosale. Chem. Rev. 2016, 116, 11685.
2. N. Sakai, J. Mareda, E. Vauthey and S. Matile. Chem. Commun., 2010, 46, 4225. 3. S.-L. Suraru and F. Würthner. Angew. Chem. Int. Ed. 2014, 53, 7428. 4. A. Insuasty, S. Maniam and S. J. Langford. Chem. Eur. J. 2019, 25, 7058. 5. S. Maniam, S. Sandanayake, E. I. Izgoridina and S. J. Langford. Asian. J. Org. Chem. 2016, 5, 490.
Poster 79
Chiral Bipyridine Macrocycles for Synthesis of Mechanically Chiral Rotaxanes and Catenanes
Shu Zhang and Stephen M. Goldup
University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom
Email: [email protected] Web: http://goldup.soton.ac.uk/
Abstract:
Although mechanically chiral interlocked molecules1 have been discussed since the 1960s,2 it has been difficult to synthesize them on scale. Previously, we have reported an active template approach3 to mechanically planar chiral rotaxanes4 and topologically chiral catenanes,5 using an achiral bipyridine macrocycle in combination with chiral half axle components or a chiral macrocycle precursor, respectively. Here, we demonstrate a chiral bipyridine macrocycle that allows us to synthesize either mechanically planar chiral rotaxanes or topologically chiral catenanes in good to excellent diastereoselectivity. This simple general approach opens even more chemical space for exploration in search of applications of mechanically chiral molecules.
Figure 1. Synthesis of mechanically planar chiral rotaxanes
References:
1. E. M. G. Jamieson, F. Modicom and S. M. Goldup, Chem. Soc. Rev., 2018, 47, 5266-5311. 2. G. Schill, Academic Press, 1971. 3. V. Aucagne, K. D. Hanni, D. A. Leigh, P. J. Lusby and D. B. Walker, J. Am. Chem. Soc., 2006, 128,
2186-2187. 4. R. J. Bordoli and S. M. Goldup, J. Am. Chem. Soc., 2014, 136, 4817-4820. 5. M. Denis, J. E. M. Lewis, F. Modicom and S. M. Goldup, Chem, 2019, 5, 1512-1520.
Event sponsor contact details
First name Surname Affiliation Email
Danielle Bradshaw Fluorochem [email protected]
Lorraine Croucher BMG Labtech [email protected]
Robin Driscoll RSC Books [email protected]
Rob Eagling CHEM [email protected]
Lara Johnson Shimadzu [email protected]
Mary Kedward Strem [email protected]
Nilesh Mistry Radleys [email protected]
Brunello Nardone CEM [email protected]
Craig Smith Anton Paar [email protected]
Kaleigh Sunday Supramolecular Chemistry [email protected]
Lee Walsh CAS [email protected]
Joe Webb Dixon Science [email protected]
Marcus Winter Rigaku [email protected]
Delegate contact information
First name Surname Affiliation Email
Amanda Acevedo-Jake University of Southampton [email protected]
Dave Adams University of Glasgow [email protected]
Nyasha Allen University of Kent [email protected]
Asia Almuhana University of Nottingham [email protected]
Shuntaro Amano University of Manchester [email protected]
Miguel Amaro-Villegas
Medway School of Pharmacy [email protected]
Nathan Andersen University of Nottingham [email protected]
Stephen Argent University of Nottingham [email protected]
Fraser Arnold University of York [email protected]
Alyssa-Jennifer
Avestro University of York [email protected]
Olukayode Babarinde University of Nottingham [email protected]
Krzysztof Bak University of Oxford [email protected]
Federica Balduzzi University of Bristol [email protected]
Timothy Barendt University of Birmingham [email protected]
Stefano Biagini University of Kent [email protected]
Laura Bickerton University of Oxford [email protected]
Lee Birchall University of Kent [email protected]
Barry Blight University of New Brunswick [email protected]
Jessica Boles University of Kent [email protected]
Stefan Borsley University of Manchester [email protected]
Grant Brown University of York [email protected]
Claudia Caltagirone University of Cagliari [email protected]
Jamie Cameron University of Nottingham [email protected]
Stuart Cantrill Nature Chemistry [email protected]
Adam Carrick Durham University [email protected]
Alessio Cataldo Universite libre de Bruxelles [email protected]
Bini Claringbold University of Kent [email protected]
Sean Connolly University of Kent [email protected]
James Cooper Northwestern University [email protected]
Peter Cragg University of Brighton [email protected]
Edward Cross King's College London [email protected]
Scott Dalgarno Heriot-Watt University [email protected]
Tony Davis University of Bristol [email protected]
Ruhee Dawood University of York [email protected]
Yuying Ding University of Cambridge [email protected]
Jack Doolan University of Kent [email protected]
Emily Draper University of Glasgow [email protected]
Robert Eagling CHEM [email protected]
Timothy Easun Cardiff University [email protected]
Alison Edwards Medway School of Pharmacy [email protected]
Jacquelyn Egan University of Glasgow [email protected]
Benjamin Egleston University of Liverpool [email protected]
Rebecca Ellaby University of Kent [email protected]
Robert Elmes Maynooth University [email protected]
Osama El-Zubuir Newcastle University [email protected]
Ton Engwerda University of Oxford [email protected]
Nicholas Evans Lancaster University [email protected]
Le Fang Queen Mary University of London
Stephen Fielden University of Manchester [email protected]
Matthew Fitzpatrick University of Southampton [email protected]
Ross Forgan University of Glasgow [email protected]
Jona Foster Sheffield University [email protected]
Emily Friar University of Kent [email protected]
Phil Gale University of Sydney [email protected]
Eduardo Garrido Ribo University of Glasgow [email protected]
Steve Goldup University of Southampton [email protected]
Jamie Gould University of York [email protected]
Becky Greenaway University of Liverpool [email protected]
Barny Greenland University of Sussex [email protected]
Sarah Griffin University of Nottingham [email protected]
Greta Grossman Durham University [email protected]
Prashant Gudeangadi University of Kent [email protected]
Chris Hawes Keele University [email protected]
Cally Haynes UCL [email protected]
Andrew Heard University of Southampton [email protected]
Robert Hein University of Oxford [email protected]
Jordan Hill University of York [email protected]
Kira Hilton University of Kent [email protected]
Jennifer Hiscock University of Kent [email protected]
Thomas Hitchings University of Kent [email protected]
Simon Holder University of Kent [email protected]
Philip Hope Durham University [email protected]
Andy Houlton Newcastle University [email protected]
Claire Housley University of Nottingham [email protected]
Rob Ives University of York [email protected]
Garrett Jackson University of Warwick [email protected]
Ellen Jamieson University of Southampton [email protected]
Kim Jelfs Imperial College London [email protected]
Chris Jennings University of New Brunswick [email protected]
Christopher Jones University of Liverpool [email protected]
Paraskevi Kasapidou University of Cambridge [email protected]
Ahmad Kassir Loughborough University [email protected]
Olivia Keers University of Kent [email protected]
Timothy Kench Imperial College London [email protected]
Aidan Kerckhoffs University of Oxford [email protected]
Kasid Khan Durham University [email protected]
Marion Kieffer University of Bristol [email protected]
Peter Knipe Queens University Belfast [email protected]
Heike Kuhn University of Oxford [email protected]
Lokesh Kumar Kumawat
Maynooth University [email protected]
Marc Lehr Christian-Albrechts-Universität zu Kiel
Dave Leigh University of Manchester [email protected]
Alex Lewis University of Nottingham [email protected]
James Lewis Imperial College London [email protected]
Simon Lewis University of Bath [email protected]
Gareth Lloyd University of Lincoln [email protected]
David Lozano University of Southampton [email protected]
Michael Ludden University of Warwick [email protected]
Paul Lusby University of Edinburgh [email protected]
Georgie Macey Loughborough University [email protected]
David Magri University of Malta [email protected]
Ferdinando Malagreca University of Nottingham [email protected]
Catherine Marsden Loughborough University [email protected]
Luis Martinez Universite libre de Bruxelles [email protected]
Jack Maynard University of Southampton [email protected]
Anna McConnell University of Kiel [email protected]
Liam Finn McGarry Newcastle University [email protected]
Charlie McTernan University of Cambridge [email protected]
Subba Mekapothula Nottingham Trent University [email protected]
Isis Middleton University of Edinburgh [email protected]
Edward Mitchell University of Oxford [email protected]
Florian Modicom University of Southampton [email protected]
Cristina Mozaceanu University of Warwick [email protected]
Vihanga Munasinghe University of Oxford [email protected]
Brunello Nardone CEM [email protected]
Edward Neal National Institute of Materials Science, Japan
Mark Newman University of Nottingham [email protected]
Kendrick Ng University of Kent [email protected]
Lisa North University of Kent [email protected]
Sam O'Nion University of Glasgow [email protected]
Georgia Orton University of Nottingham [email protected]
Aniello Palma University of Kent [email protected]
Jessica Pancholi University of Oxford [email protected]
Arjun Patel University of Nottingham [email protected]
Alexandra Paul University of Kent [email protected]
Lydia Pearce University of Sussex [email protected]
Nic Pearce University of Nottingham [email protected]
Samuel Penty University of Oxford [email protected]
Giacomo Picci University of Cagliari [email protected]
Sarah Pike University of Bradford [email protected]
Ben Pilgrim University of Nottingham [email protected]
Jerico Piper University of Warwick [email protected]
Robert Pow University of Glasgow [email protected]
Callum Pritchard University of Warwick [email protected]
Becky Randle University of Glasgow [email protected]
Imogen Riddell University of Manchester [email protected]
Federica Rizzi University of Southampton [email protected]
Jen Robertson University of Nottingham [email protected]
Jonathan Robson University of Manchester [email protected]
Andrey Romanyuk University of Birmingham [email protected]
Tanya Ronson University of Cambridge [email protected]
Arnau Rubio University of Southampton [email protected]
Soumen Saamanta University of Bristol [email protected]
Akiko Sato University of Kent [email protected]
Andrea Savoini University of Southampton [email protected]
Abbie Scholes University of Liverpool [email protected]
Christopher Serpell University of Kent [email protected]
Sarah Sharp Royal Society of Chemistry [email protected]
Sara Shehata University of Kent [email protected]
Helena Shepherd University of Kent [email protected]
Zoe Sinclair University of Glasgow [email protected]
Anurag Singh Universite libre de Bruxelles [email protected]
Anna Slater University of Liverpool [email protected]
Valentnya Slyusarchuk Keele University [email protected]
Jonathan Steed Durham University [email protected]
Burin Sudittapong University of Warwick [email protected]
Andrew Surman Kings College London [email protected]
Marysia Tarnowska University of Nottingham [email protected]
Chris Taylor University of Warwick [email protected]
Emerald Taylor University of Kent [email protected]
Lisa Thomson University of Glasgow [email protected]
Max Tipping University of Warwick [email protected]
Hennie Valkenier Universite libre de Bruxelles [email protected]
Larissa Von Krbek University of Cambridge [email protected]
Jianzhu Wang University of Edinburgh [email protected]
Michael Ward University of Warwick [email protected]
Mike Watkinson Keele University [email protected]
Tanja Weil Max Planck Institute for Polymer Research
Thomas Welsh University of Glasgow [email protected]
Sander Wezenburg Leiden University [email protected]
Lisa White University of Kent [email protected]
Pavan Yerramsetti University of York [email protected]
Liang Zhang East China Normal University [email protected]
Shu Zhang University of Southampton [email protected]
Finally, have a happy Xmas and a fantastic new year!!