mtmm abstract booklet
TRANSCRIPT
Department of Chemistry, Indian Institute of Technology Bombay
Powai, Mumbai, Maharashtra, India – 400 076 E-mail: [email protected]
Conference Date: 19-21st May 2016 Conference Venue: VMCC Auditorium, IIT Bombay
Convenor Prof. G. Rajaraman
IIT Bombay, India
Co-convenor Prof. S. Maheswaran
IIT Bombay, India
National /International Advisory Committee
Prof. V. Baskar University of Hyderabad, India Prof. H. Bolvin University of Toulouse, France Prof. V. Chandrasekhar NISER, Bhubaneswar, India Prof. P. Comba University of Heidelberg, Germany Prof. S. N. Datta IIT Bombay, Mumbai, India Prof. P. S. Ghalsasi The MS University of Baroda, India Prof. A. Ghosh University of Calcutta, India Prof. N. Gogoi Tezpur University, India Prof. N. Gulhery University of Toulouse, France Prof. R. Lescouezec Pierre & Marie Curie University, France Prof. T. Mallah University of Paris-Sud, France Prof. R. Maurice UMR CNRS, France Prof. S. Mohanta University of Calcutta, India
Confirmed Speakers
Registration Details*
Students and Post Docs
Faculties and Scientists Participants from Industry Foreign Delegates
*Registration fee covers breakfasts, lunches,
dinners, coffee/tea and conference material
Call for Posters
Authors proposing to present posters on their work are invited to submit a one page abstract through web as MS Word (98 or higher version) document. They are encouraged to use the template provided in the website.
Important Dates
Registration opens on Submission of Abstract Acceptance of Abstract Last date for Registration
Prof. A. Misra University of North Bengal, India Prof. K. S. Murray Monash University, Australia Prof. M. Murrie University of Glasgow, UK Prof. A. K. Powell KIT, Germany Prof. S. Ramasesha IISc Bangalore, India Prof. M. Ruben KIT, Germany Prof. E. Ruiz University of Barcelona, Spain Prof. L. Sorace University of Florence, Italy Prof. A. Sundaresan JNCASR, Bangalore, India Prof. M. Sundararajan BARC, Mumbai, India Prof. F. Totti University of Florence, Italy Prof A. K. Tyagi BARC, Mumbai, India Prof. M. Yamashita Tohoku University, Japan Prof. S. M. Yusuf BARC, Mumbai, India
Prof. T. K. Chandrashekar Secretary, SERB, India Prof. V. Chandrasekhar NISER, Bhubaneswar, India Prof. E. Ruiz University of Barcelona, Spain Prof. L. F. Chibotaru University of Leuven, Belgium Prof. S. K. Ghosh BARC Mumbai, India Prof. J. R. Long University of California, Berkeley Prof. T. Mallah University of Paris-Sud, France Prof. G. Mugesh IISc Bangalore, India
The main emphasis on the conference will be to discuss new directions, new approaches and critical assessment of the hot-topics related to the molecular magnetic materials. The topics to be covered include; * Synthetic approach to Molecular Nano Magnets (MNMs) * Magnetic (SQUID) and spectral characterization (EPR, NMR, MCD, INS and Fluorescence) of MNMs * Density functional and ab initio studies on MNMs * Studies on magnetic nanoparticles * Spintronics devices based on MNMs * Development of MRI contrasting agents based on MNMs * Spin crossover and photo magnetic studies of MNMs.
Prof. K. S. Murray Monash University, Australia Prof. R. Murugavel IIT Bombay, Mumbai, India Prof. F. Neese Max Planck Institute, Germany Prof. A. K. Powell KIT, Germany Prof. S. Ramasesha IISc Bangalore, India Prof. R. Sessoli University of Florence, Italy Prof. R. E. P. Winpenny University of Manchester, UK Prof. M. Yamashita Tohoku University, Japan
Conference official website: http://www.chem.iitb.ac.in/mtmm2016/index.html
Rs. 3,000/- Rs. 6,000/- Rs.10,000/- US$ 200/-
January 15, 2016 March 30, 2016 April 07, 2016 March 30, 2016
IIT Bombay MTMM 2016
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Conference on
Modern Trends in Molecular Magnets
(MTMM)
May 19-21st, 2016
Abstract Booklet of MTMM
Organized by
Department of Chemistry Indian Institute of Technology Bombay
Powai, Mumbai, Maharashtra, INDIA – 400 076
IIT Bombay MTMM 2016
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Abstract Booklet of MTMM 2016
Technical Program
Invited Lectures
Student Presentations
Poster Presentations
Printed in India
May 2016
Conference Web: http://www.chem.iitb.ac.in/mtmm2016/
Conference e-mail: [email protected]
IIT Bombay MTMM 2016
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Preface
Dear Participant,
Welcome to Modern Trends in Molecular Magnets (MTMM) conference organized
by Department of Chemistry, IIT Bombay, India. Molecular Magnetism is an emerging and
multi-disciplinary field. It is challenging and yet developing rapidly in response to the
escalating needs of human race. Over the decades of experience, it is evident that its
success depends on building bridges between different disciplines and aspects of science
starting from physics, chemistry and material science. The theme of the MTMM therefore
is to bring the research groups working in different branches of this field together on one
platform. With this theme in mind, it is our humble effort to assemble the most skilled and
knowledgeable experts and educators in this field along with the vibrant opportunities to
meet young researchers, teachers and students, and gain new ideas and insights through
fruitful, formal and informal interactions.
We are fortunate enough to have speakers who are not only pioneers in the field of
molecular magnetism (MM) but speakers who have invented/formulated new concepts in
this field. The lectures are inclined towards the following objectives - introduce the
potential of molecular magnetism to the heterogeneous audience, take a look at the major
milestones that have been achieved in this paradigm and to provide a snapshot of the
current state of research in the field. The second objective is to identify and highlight
promising opportunities in MM and address the critical challenges present in developing
molecular based devices. This booklet brings together about one hundred and fifty
participants, thirty invited lectures, and about sixty poster presentations and fourteen
selected student presentations. We sincerely hope that the collective and humble efforts
of all involved results in useful resource for students and researchers who are intrigued
by different aspects of Molecular Magnetism and it motivates them to start pursuing
research in this potential area of science.
We gratefully acknowledge Prof. V. Chandrasekhar who has initiated the thought of
bringing this MM community together during an informal discussion a few years ago which
sow the seed for MTMM-2016. We thank all the speakers, students, sponsors who made
this event and booklet possible. Our sincere gratitude to all the student volunteers for
event logistics, technical assistance and arrangements. Finally, we thank our colleagues for
their help and support. We hope that your stay at IIT Bombay is enjoyable and
scientifically beneficial. Thank you!
Convener Co-Convener
[Dr. G. Rajaraman] [Dr. S. Maheswaran]
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IIT Bombay MTMM 2016
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MMooddeerrnn TTrreennddss iinn MMoolleeccuullaarr MMaaggnneettss May 19-21st, 2016
Department of Chemistry, IIT Bombay Powai, Mumbai, Maharashtra, INDIA – 400 076
TECHNICAL PROGRAM
19th May, 2016 (Day-1, VMCC Auditorium) 08:00-09:00 Breakfast and Registration at VMCC Ground Floor Foyer
09:00-09:30 Inauguration at VMCC Auditorium
Chair : Prof. Sourav Pal, IIT Bombay
09:30-10:00 Prof. S. Ramasesha
IISc Bangalore, India
Magnetism in Fused Carbon Ring Systems
10:00-10:30 Prof. Vadapalli Chandrasekhar
NISER,Bhubaneswar, India
Lanthanide ion-containing complexes as new
examples of molecular magnets
10:30-11:00 Prof. Keith S. Murray
Monash University, Australia
Wheels and rings and toroidal states in 3d-4f
clusters
11:00 -11:20 High Tea
Chair : Prof. M. S. Balakrishna, IIT Bombay
11:20-11:50 Prof. Rodrigue Lescouezec
Pierre and Marie Curie
University, France
Photomagnetic effects and SMM behaviour in
cyanide-bridged molecules
11:50-12:20 Prof. Lorenzo Sorace
University of Florence, Italy
Mononuclear vanadyl complexes as potential
molecular spin qubits
12:20-12:50 Prof. Sasankasekhar Mohanta
University of Calcutta, India
Some of our observations on Magnetic exchange,
double exchange and Single molecule Magnet
12:50-14:00 Lunch
Chair : Prof. Debabrata Maiti, IIT Bombay
14:00-14:30 Prof. Viswanathan Baskar
Univ. of Hyderabad, India
Unravelling the coordination chemistry of
organostibonic acids
14:30-15:00 Prof. Ashutosh Ghosh
Univ. of Calcutta, India
The making of a new family or trinuclear Ni(II)
Single Molecule Magnets
15:00-15:30 Prof. Eliseo Ruiz
Univ. of Barcelona, Spain
Mononulear metal complexes: From Single
Molecule Magnet to Magnetoresistance single-
molecule devices
15:30-15:50 High Tea
Chair : Prof. Prasenjit Ghosh, IIT Bombay
15:50-16:20 Prof. Mario Ruben
KIT, Germany
Metal complexes as Single Molecule Qubits
16:20-16:50 Prof. S.M.Yusuf
BARC, Mumbai, India
Novel magnetism in Prussian blue, oxalate and
phenanthroline based molecular compounds
19:30-21:30 Dinner at Gulmohar Lawn
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20th May, 2016 (Day-2, VMCC, Lecture Hall - 21) 08:00-09:00 Breakfast at VMCC Ground Floor Foyer
Chair : Prof. P. Venuvanalingam, Bharathidasan University, Tiruchirappalli
09:00-09:30 Prof. Talal Mallah
Univ. of Paris-Sud, France
Magnetic Anisotropy and Single Molecule
Magnet behaviour in trigonal bipyramidal
mononuclear Co(II) complexes
09:30-10:00 Prof. K. Gopal
Central University of Rajasthan
Molecular Manganese Phosphonates Clusters
10:00-10:30 Prof. Athinarayanan
Sundaresan
JNCASR, Bangalore, India
Structure, Magnetism and Magnetodielectric
Effect in A-Site Ordered Chromate Spinel Oxides
LiMCr4O8 (M= Ga, In, Fe)
10:30-11:00 Prof. Mahesh Sundararajan
BARC, India
Molecular Magnetism involving Supramolecules
11:00 -11:20 Group Photo + Tea
Chair : Prof. C. P. Rao, IIT Bombay
11:20-11:50 Prof. Rémi Maurice
French National Centre
for Scientific Research, France
Zero-Field Splitting in Transition Metal
Complexes: Ab initio calculations, effective
Hamiltonians, and model Hamiltonians
11:50-12:20 Prof. Nathalie Guihéry
The Univ. of Toulouse, France
Magnetic anisotropy in mono- and bi-nuclear
complexes: theoretical insights and prospects
12.20-12:50 Prof. Annie K. Powell
KIT, Germany
Chirality and its Role in Coordination Chemistry – the Jekyll and Hyde Behaviour of Metal Ions in
Separating the Left and Right Sides of the World
12:50-13:00 Mr. Ashrut Ambastha
Mellonox Technologies Inc.
Presentation by Sponsors - Road to Exascale
Computing (Technical Presentation)
13:00-14:00 Lunch
Chair : Prof. Harkesh B. Singh, IIT Bombay
14:00-14:30 Dr. Federico Totti
Univ. of Florence, Italy
Molecular magnets and their journey from
isolated clusters to self-assembled-monolayers
: the key role of computational methods
14:30-15:00 Prof. Peter Comba
Univ. of Heidelberg, Germany
Magnetic interaction in oligonuclear 3d-4f
complexes- synthesis, magnetism spectroscopy
and theory
15:00-17:15 Tea + Poster
17:30 - 19:00 Cultural Programme at PC Saxena Auditorium
19:30-21:30 Banquet Dinner at Meluha the Fern
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21st May, 2016 (Day-3, VMCC, Lecture Hall - 21)
08:00-09:00 Breakfast at VMCC Ground Floor Foyer
Chair : Prof. Raghavan B. Sunoj, IIT Bombay
09:00-09:30 Prof. Helene Bolvin
The Univ. of Toulouse, France
Magnetic properties of actinide complexes
probed by pNMR spectroscopy : a theoretical
contribution
09:30-10:00 Prof. Mark Murrie
University of Glasgow, UK
Probing the magnetic anisotropy in trigonal
bipyramidal 3d single-ion magnets
10:00-10:30 Prof. Sambhu N. Datta
IIT Bombay, India
Organic Molecular Magnets - A reality
10:30-11:00 Prof. Anirban Misra
Univ. of North Bengal, India
Quantification of Magnetic Interaction through
Spin Topology
11:00 -11:20 High Tea
Chair : Dr. Swapan Kumar Ghosh, BARC Mumbai
11:20-11:50 Prof. Nayanmoni Gogoi
Tejpur Univ., Assam, India
Modulation of Coordination Environment: A
convenient approach to Tailor Single Ion
Magnetic Anisotropy
11:50-12:20 Prof. A. K. Tyagi
BARC, Mumbai, India
Functional inorganic magnetic materials:
Synthesis, structure and application
12:20-12:50 Prof. Prasanna S. Ghalsasi
The MS Univ. of Baroda, India
Environmentally Conscious Structures:
Designing Molecular Magnets
12:50-14:20 Lunch
Chair : Prof. S. Maheswaran, IIT Bombay
Student Presentation
14:20-14:27 Amaleswari Rasamsetty University of Hyderabad, India
14:27-14:34 Asha Roberts Heidelberg University, Germany
14:34-14:41 Martin Amoza Dávila University of Barcelona, Spain
14:41-14:48 Mithun Chandra Majee IACS Kolkata, India
14:48-14:55 Mukesh Kumar Indian Institute of Technology Bombay, India
14:55-15:02 Ritwik Modak University of Calcutta, India
15:02-15:09 Sabyasachi Roy Chowdhury Indian Institute of Technology Kharagpur, India
15:09-15:30 High Tea
Chair : Dr. Sailaja Saha Sunkari, Banaras Hindu University
15:30-15:37 Sandeep K. Gupta Indian Institute of Technology Bombay, India
15:37-15:44 Shashi Kant Indian Institute of Technology Kanpur, India
15:44-15:51 Shefali Vaidya Indian Institute of Technology Bombay, India
15:51-15:58 Shuvankar Mandal University of Calcutta, India
15:58-16:05 Soumava Biswas IISER Bhopal, India
16:05-16:12 Sourav Biswas Indian Institute of Technology Kanpur, India
16:12-16:19 Tamal Goswami University of North Bengal, India
16:30-17:00 Concluding Remarks
17:00-17:20 Vote of Thanks
19:00-21:00 Dinner at Gulmohar Lawn
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Invited Lectures
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Dr. S. Ramasesha is Professor at Indian Institute
of Science, Bangalore, India. He obtained his M.Sc.
from Osmania University, Hyderabad, India, in 1977.
He received his Ph.D. degree from IIT kanpur. His
group has been developing novel techniques for
many-body models employed in the study of large
molecules and low-dimensional materials. His group
has extended exact diagonalization methods,
developed nonperturbative methods such as density
matrix renormalization group (DMRG) methods and
quantum Monte Carlo (QMC) methods to study large
systems. He has also extended the many-body
techniques to study real time dynamics. These techniques have been applied to
study, correlated electronic structure of C60 and its fragments, exciton binding
energy in conjugated polymers, relative ordering of one and two-photon states,
effects of quantum confinement, dynamics of electron-hole recombination and
triplet-triplet scattering. In spin systems, he has studied the quantum phases of
dimerized and frustrated spin chains, spin excitations and low-temperature
properties of alternating spin systems and spin ladders, low energy excitations and
quantum hysteresis in large spin clusters. Recently his group has developed a
model for understanding photomagnetism in the CuMo6 inorganic complex. We have
modeled superexchange interactions in A-B systems and have explained how,
contrary to Goodenough-Kanamori rules; the sign of exchange can switch from
ferromagnetic to antiferromagnetic depending upon system size, geometry and
chemical environment. For single molecule magnets they have recently developed
models for predicting magnetic anisotropy constants in systems with many spin
centers.
[for more details: http://sscu.iisc.ernet.in/s_ramasesha.html]
IIT Bombay MTMM 2016
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Magnetism in Fused Carbon Ring Systems
S.Ramasesha
Solid State and Structural Chemistry Unit
Indian Institute of Science, Bangalore 560 012, India
Fused organic ring systems are of great current interest as Graphene and related
systems belong to this class. Of particular interest are the fused systems made up
of rings with odd number of Carbon atoms. Typical of such systems are the fused
azulenes and fused cyclopentadienes. There are also Graphenenanoribbons which
belong to the class of fused ring systems. In polyacenes made up of fused benzene
rings, earlier DMRG studies had shown that the spin gap was low, almost a third of
the optical gap. We studied fused odd membered ring systems to explore the spin
gap when kinetic frustration is introduced into the system. Azulene is a classic
organic molecule where kinetic frustration leads to inter ring electron transfer
resulting in an dipole moment. So, we also wanted to explore if in the fused azulene
ribbons, if the electric dipole moment survives. Another class of systems we have
studied are the Graphenenanoribbons, with special emphasis on the role of different
edges on the electronic and magnetic properties. These have been studied using
symmetrized finite DMRG algorithm which has been found to be highly efficient and
accurate in yielding the desired electronic energy gaps in these systems.
IIT Bombay MTMM 2016
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Dr. V. Chandrasekhar is Professor at IIT Kanpur,
India and currently Director at NISER Bhubaneswar,
India. He obtained his M.Sc. from Osmania
University, Hyderabad, India, in 1977. He received his
Ph.D. degree in 1982 from the Indian Institute of
Science, Bangalore under the supervision of Prof. S.
S. Krishnamurthy. He worked as a post-doctoral
research associate with Professor R. R. Holmes at the
University of Massachusetts, Amherst, USA (1983-
1986) and then as a senior research officer in the
Indian Petrochemicals Corporation at Vadodara for a
year. He then joined the Department of Chemistry at the Indian Institute of
Technology, Kanpur in 1987 as an assistant professor. He became an associate
professor in 1991 and has been working as a full professor since 1995. His research
interests are in the area of inorganic rings and polymers, main group
organometallic chemistry, metal clusters and molecular materials. He has been a
recipient of several national and international awards and fellowships. His research
interests include Organometallic Chemistry, Inorganic-Cored Star Bursts,
Multinuclear Transition Metal Assemblies, Inorganic Rings and Polymers, Single
Molecule Magnets and Phosphoresent Organometallic Compounds.
[for more details: http://home.iitk.ac.in/~vc/]
Lanthanide ion-containing complexes as new examples of
molecular magnets
IIT Bombay MTMM 2016
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V. Chandrasekhar School of Chemical Sciences, National Institute of Science Education and Research
Bhubaneswar, Jatni-752050
Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208 016
[email protected];[email protected]
There has been a renaissance in the chemistry of lanthanide ion complexes in view
of their applications involving photophysical properties, magnetism and catalysis.
Both homometallic and heterometallic (3d/4f) lanthanide complexes are being
increasingly studied for their magnetic properties in general and as single-molecule
magnets in particular. In this talk we will present some of our work on trinuclear
3d/4f complexes which exhibit SMM properties.
References
[1]. Das, S.; Bejoymohandas,K. S.; Dey, A.; Biswas,S.; Reddy, M. L. P.; Morales, R.; Ruiz, E.; Titos-Padilla, S.; Colacio, E.; Chandrasekhar, V. Chem. Eur. J. 2015, 21, 6449-6464.
[2]. Goura, J.; Brambleby, J.; Goddard, P.; Chandrasekhar, V. Chem. Eur. J. 2015, 21, 4926-30
IIT Bombay MTMM 2016
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Dr. Keith S. Murray is an Adjunct Professor at
Monash University, Australia. He obtained his Ph.D. in
1966 from University of Manchester,UK. His research
interests are in the field of molecular magnetism
dealing with single molecule magnets (SMMs) and
spin-crossover species. He holds grants from the ARC
and the Australia-India AISRF program. Besides, he is
fascinated to the synthesis, structural,
magnetochemical, ESR, and Mössbauer spectral
studies of d-block compounds, molecular-based
magnetic materials of d-block and f-block
compounds, framework materials (covalent bridges and supramolecular) and spin-
crossover compounds of iron and cobalt. He is Member of Academic Board and
Science Faculty Board, Member of Chair Committees, Promotion Committees and
School Renovations staff liaison. He has 420 peer-refereed international
publications (May 11, 2012), with H-index of 58; being supported by the Australian
Research Council (ARC).
[for more details:
https://www.monash.edu/science/schools/chemistry/our-people/staff/murray]
IIT Bombay MTMM 2016
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Wheels and rings and toroidal states in 3d-4f clusters
Keith S. Murray,*a Kuduva R. Vignesh,b Alessandro Soncini,*c, Stuart K. Langleyd and Gopalan Rajaraman*b
a School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; b Department of Chemistry, IITB, Powai, Mumbai, India 400 076; c School of
Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia; d School of Science and the Environment, Chemistry Division, Manchester Metropolitan
University, Manchester, UK. e-mail: [email protected]
The ligands used are combinations of polypodal ligands such as triethanolamine or N-(R)-diethanolamine, and carboxylic acids such as benzoic or o-toluic acid. The nature of crystalline products isolated are often sensitive to mole ratios of reagents used and to the solvent employed. Beginning with Cr
III/Ln
III species of the
“butterfly’ type, [CrIII2LnIII
2(OMe) 2(mdea)2(O2CPh)4(NO3)2], Ln = Dy, Pr, Nd, Gd, Tb, Ho, and Er, the Dy family displays excellent SMM features including stepped magnetic hysteresis and large coercive fields, emanating from Cr-Dy exchange coupling of ~10 cm
-1. The isostructural Ln analogs show modified magnetic
features with the Tb and Ho compounds displaying SMM behaviour, with slightly smaller barrier heights compared to Dy but still displaying stepped hysteresis [1]. Changing reaction conditions in Cr
III/Dy
III chemistry led to formation of
[DyIII
6CrIII
(OH)8(o-tol)12(MeOH)5.5(NO3)0.5]∙3MeOH, which is a fascinating Cr-linked double Dy3-triangle heptanuclear (see Figure). Theoretical and experimental studies show that we have produced the first example of a dipolar-induced ferrotoroidically coupled molecular ground state, featuring con-rotating toroidal moments on the two triangles. Mn
III/Ln
III chemistry often leads to butterfly tetranuclears; here it
has yielded the largest Ln/d-block ‘wheel’ to date, viz. [Mn
III8Ln
III8(mdea)16(RCO2)8(NO3) 8]; Ln = Dy, Ho, Y, Yb, Er. The Dy example
shows possible toroidal moments [2].
References
[1]. Langley, S. K.; Wielechowski, D. P.; Chilton, N. F.; Moubaraki, B.; Murray, K. S. Inorg. Chem. 2015,54, 10497.
[2]. Vignesh, K. R.; Langley, S. K.; Moubaraki, B.;Murray, K. S.; Rajaraman, G. Chem. Eur. J, 2015, 21, 16364.
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IIT Bombay MTMM 2016
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IIT Bombay MTMM 2016
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Prof. Rodrigue Lescouezec is a Professor at
Université Pierre et Marie Curie, France. His research
interests include a) Molecular magnetic materials
(photo) switchable b) Paramagnetic NMR : structural
and magnetic probe c) Magnetic coordination clusters.
[for more details: http://www.ipcm.fr/LESCOUEZEC-Rodrigue?lang=fr]
IIT Bombay MTMM 2016
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Photomagnetic effects and SMM behaviour in cyanide-
bridged molecules
Rodrigue lescouezec
Université Pierre et Marie Curie, France.
Switchable Molecular Magnetic Materials have become an outstanding research
topic because of their potential applications as molecular memories, switches or
sensors. The cyanide-based coordination chemistryprovides various examples of
bistable systems, the Fe-Co Prussian Blue Analogue (AxCoy Fe(CN)6 z A is a cationic
ion) being one of the most emblematicphotomagnetic molecule-based material. In
these polymers, photo-induced electron transfer-coupled spin transition (ETCST)
can lead to a conversion of {FeIILS-CoIII
LS} diamagnetic pairs into {FeIIILS-CoII
HS}
paramagnetic ones.[1]In order to investigate more deeply the electronic and
structural parameters that influence this process, we have recently studied Fe-Co
molecular models.[2-4] Here, we will present an extension of this work toward the
synthesisand the study of new photomagneticmoleculesbased on {M-CN-M’} bridge which can also show SMM behaviour.
Figure: Examples of cyanide-based photomagneticcomplexes containing {W-CN-Co}, {Fe-
CN-Fe} or {Fe-CN-Co} units.
References
[1] O. Sato, T. Iyoda, A. Fujishima, K. Hashimoto, Science, 1996, 272, 704.[2] A. Mondal, Y. Li, P.
Herson, M. Seuleiman, M.L. Boillot, E. Rivière, M. Julve, L. Rechignat, A. Bousseksou, R. Lescouëzec,
Chem. Commun.2012, 48, 5653.[3]A. Mondal, Y. Li, M. Seuleiman, M. Julve, L. Toupet, M. Buron-
Lecointe, R. Lescouëzec, J. Am. Chem. Soc.2013, 135, 1653.[4] S. De, J. Jiménez, Y. Li, L.
Chamoreau, A. Flambard, Y. Journaux, A. Bousseksou, R. Lescouëzec, RSC Advances,2016, 6, 17456
- 17459.[5] A.Mondal, L.Chamoreau, Y. Li, M.Seuleiman, Y.Journaux, R.Lescouëzec, Chem. Eur. J.
2013, 19, 7682.[6] A. Mondal, Y. Li, L. Chamoreau, M. Seuleiman, L. Rechignat, A. Bousseksou, M.
Boillot, R. Lescouëzec, Chem. Commun.2014, 50, 2893.
IIT Bombay MTMM 2016
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Dr. Lorenzo Sorace is currently Associate
Professor at the Department of Chemistry of the
University of Florence, Italy, working in the
Laboratory of Molecular Magnetism. His main research
interest is in the use of multifrequency EPR
spectroscopy and magnetic measurements of
molecular materials. The specific focus of his work
has been on the origin and the control of the
anisotropy in these systems, a topic that led him to a
quite extensive use of Ligand field techniques and to
be interested in the magnetic properties, both static
and dynamic, of lanthanide based coordination compounds.
He received his Ph.D in 2001 from University of Florence under the supervision of
Prof. D. Gatteschi, after which he spent a postdoctoral period at Louis Neél and
HMFL laboratories (CNRS-Grenoble). He has published more than 170 peer-refereed
papers in international journals with total impact factor if 860.39. He refereed for
several internationally leading chemistry and physics journals (J. Am. Chem. Soc.,
Angew. Chemie, Phys. Rev. Lett., Chem. Eur. J., Chem. Commun., ACS Nano,
Chemical Science, Physical Chemistry Chemical Physics)
[for more details: http://www.lamm.unifi.it/STAFF/lorenzo_sorace.html]
IIT Bombay MTMM 2016
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Mononuclear vanadyl complexes as potential molecular
spin qubits
L. Sorace,1L. Tesi,1 M. Atzori,1 I. Cimatti,1 E. Lucaccini,1 E. Morra,2 M.
Chiesa,2 M. Mannini,1 R. Sessoli1
1 Dipartimento di Chimica “U. Schiff” and INSTM RU – Università degli Studi di
Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Italy. 2Dipartimento di Chimica & NIS Centre, Università di Torino, Via P. Giuria 7, I-
10125 Torino, Italy.
Email: [email protected]
Mononuclear coordination complexes of transition metal ions are particularly
appealing candidates for the implementation of a Quantum Information Processing
system, due to the relatively simple possibility of fine tuning their properties to
attainimproved performance and to their processability compared to spins in doped
semiconductors. On the other hand,the short lifetime of the quantum superposition
of states, Tm, poses significantlimitations to their actual implementation. Recently
promising results have been obtained on simple S = 1/2 complexes, with low
temperature Tm of the order of the milliseconds when V(IV) dithiolene complexes
are dispersed in nuclear spin-free solvents like CS2. The use of such systems as
viable qubits at higher temperature is however hampered by the rapid decrease, on
increasing the temperature, of the spin-lattice relaxation time, T1, which acts as a
limiting factor for Tm.[1]
We present here the results we recently obtained using a multi-technique
approach based on the combination of ac susceptometry and pulsed EPR techniques
to investigate T1and TmofS=1/2 molecular systems, which led us to identify
vanadylbased complexes as promising spin center for QIP applications. For such
systems, T1remains long over a broad range of temperatures and magnetic
fields.[2]Further, Rabi oscillations at room temperature have been observed in the
molecular semiconductor TiOPc (Pc=phthalocyanine) containing large concentration
(up to 10%) of VOPc. The combination of these features with its high thermal
stability and high processability makes these materials extremely appealing, as
they can be used as paramagnetic semiconductors in spintronics devices.[3]
References
[1]. Zadrozny, J. M. et al. ACS Central Sci.,2015. 1, 488.
[2]. Tesi, L. et al. Chem. Sci.,2016. 7, 2074.
[3]. Atzori, M. et al. J. Am. Chem. Soc. 2016, 138, 2154
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Dr. Sasankasekhar Mohanta passed B. Sc.
(Chemistry Honours) from Ramakrishna Mission
Residential College, Narendrapur (under University of
Calcutta) and M. Sc. (Inorganic Chemistry Special)
from University of Calcutta. He received his Ph. D.
degree on “Magnetic Properties of Phenoxo-Bridged
Polynuclear Macrocyclic Complexes”, working with Prof. Kamalaksha Nag, Department of Inorganic
Chemistry, Indian Association for the Cultivation of
Science, Kolkata. After working as a Lecturer in
Chemistry for few months in Ramakrishna Mission
Residential College, Narendrapur, he moved to University of Calcutta in 1997 as a
Lecturer in Chemistry and is working there now as a Professor. He worked as a
postdoctoral research associate with Prof. Ho-Hsiang Wei, Tamkang University,
Taiwan. He was selected for JSPS fellowship.
The research area of Prof. Mohanta includes magnetic properties (of 3d-3d
and 3d-4f systems), crystal engineering and biomimetic inorganic chemistry. He
has been exploring varieties of homo/heteronuclear systems derived from
single/double compartmental acyclic ligands and Robson type macrocyclic ligands.
He has reported works on magnetic exchange, double exchange, magneto-
structural correlations, single molecule magnets, rare examples of cocrystals of
metal complexes and functional models of metallo-proteins. He has published
around 100 papers in peer-reviewed journals of international repute.
[for more details:
http://www.caluniv.ac.in/cuchemistry/dr-sasankasekhar-mohanta/ ]
IIT Bombay MTMM 2016
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Some of Our Observations on Magnetic Exchange,
Double Exchange and Single Molecule Magnets
Sasankasekhar Mohanta
Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700 009, India
e-mail: [email protected]
This presentation will deal with: (i) First experimental and density functional
theoretical magneto-structural correlations in FeIII
NiII systems [1,2]; (ii) First example
of single-molecule magnetic (SMM) behavior through double-exchange – the concerned system is a Fe
2.5+Fe
2.5+ compound [3]; (iii)Understanding of the nature of magnetic
exchange interaction in series of CuIILn
III compounds, Ln = Ce–Yb [4]; (iv) Two
CoIII
DyIII
SMMs, each with twoslow relaxation branches [5]. Fe
IIINi
II systems: We have isolated a series of such compounds using few Robson
type macrocycles as the primary ligands and azide and few carboxylates as the secondary ligands to induce variation in structural and magnetic properties, and that has been achived.
(Fe2)V systems: Mössbauer and absorption spectral and magnetic studies of one
such system derived from a Robson type macrocyclic ligand have been undertaken in details to confirm the extent of double exchange. Interestingly, full electron delocatization in spite of crystallographic inequivalence of the two metal centers has been observed. The concerned system is also an SMM. Magnetic studies of an earlier closely similar compound have also been carried out, which does not exhibit SMM properties. Thus, remarkable effect in magnetic behavior as a result of slight change in ligand periphery has been observed.
CuIILn
III compounds: Understanding of the nature of magnetic exchange
interaction in most of the 3d-4f compounds (except those of GdIII
) is complicated due to population variance of Sratk levels. Utilizing empirical approach in which Ni
II(low-
spin)LnIII
systems have been used as reference compounds, the nature of exchange interaction in series of Cu
IILn
III compounds, Ln = Ce–Yb, derived from N2O2–O4
double-compartmental ligands have been understood. Co
IIIDy
III compounds: Two such compounds, derived from two N2O2–O4 double-
compartmental ligands, having bis-µ-phenoxido-bis-µ-acetate bridging moiety have been found to behave as SMMs with two relaxation branches. Remarkable effect in relaxation behavior as a result of slight change in ligand periphery has been observed. References
[1] Hazra, S.; Bhattacharya, S.; Singh, M. K.; Carrella, L.; Rentschler, E.; Weyhermüeller, T.; Rajaraman, G.; Mohanta, S. Inorg. Chem.2013, 52, 12881.[2] Sasmal, S.; Roy, S.; Carrella, L.; Jana, A.; Rentschler, E.; Mohanta, S. Eur. J. Inorg. Chem. 2015, 680.[3] Hazra, S.; Sasmal, S.; Fleck, M.; Grandjean, F.; Sougrati, M. T.; Ghosh, M.; Harris, T. D.; Bonville, P.; Long, G. J.; Mohanta, S. J. Chem. Phys.2011, 134, 174507. [4]Jana, A.; Majumder, S.; Carrella, L.; Nayak, M.; Weyhermüeller, T.; Dutta, S.; Schollmeyer, D.; Rentschler, E.; Koner, R.; Mohanta, S. Inorg. Chem.2010, 49, 9012. [5] Hazra, S.; Titiš, J.; Valigura, D.; Boča, R.; Mohanta, S. Dalton Trans. 2016, DOI: 10.1039/c6dt00848h.
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Dr. Viswanathan Baskar is an Associate Professor
at University of Hyderabad, India. He received his
Ph.D, from IIT Kanpur. Then, he stayed as AvH post-
doctoral fellow in Prof. Peter W. Roeskygroup, Freie
University Germany and EPSCR (RSC) post-doctoral
fellow in University of Manchester, UK with Prof. R. E.
P. Winpenny before moving to Hyderabad in 2007. His
interests can be broadly divided into two areas, firstly
in synthesizing and structurally characterizing
lanthanide based clusters with the aim of assembling
new single molecule magnets. Other research activity
is in synthesizing heavier main group based oxo clusters / polyoxometallates and
macrocycles and to employ them as proligands / cryptands for coordination to
transition metal ions and lanthanides.
For more details: [http://chemistry.uohyd.ac.in/~vb/index.html]
IIT Bombay MTMM 2016
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Unravelling the Coordination Chemistry of Organostibonic Acids
Viswanathan Baskar
School of Chemistry, University of Hyderabad,
Hyderabad 500046, India
e-mail: [email protected], [email protected]
Synthesis of arylstibonic acids (RSbO3H2) were first reported by Doak and Freedman in 1946 [1]. Organostibonic acids are insoluble, ill-defined, high molecular weight polymers whose solid state structures have been a matter of considerable debate. Recently in a break through work, Beckmann et al reported
the controlled hydrolysis of 2,6-Mes2C6H3SbCl4 under basic conditions leading to the isolation of the first molecular arylstibonic acid which crystalized as a dimer in solid state [2]. Our work in this field of research is primarily concerned with increasing the solubility of the organostbonic acids so as to use it as a versatile ligand for binding to transition metal ions and lanthanides. We have primarily used two methods to overcome this problem of insolubility. The first methods involves moderating the steric and electronic features of the organic part attached to antimony atom and the other method wherein these stibonic acids were subjected to reactions with various protic ligands with the aim of depolymerizing the starting precursor and isolating soluble discrete cluster forms [3-8]. The organostibonate clusters ability to act as pro-ligands for coordination to metal ions are also being investigated. References [1]. (a) Doak, G. O.; Steinman, H. G. J. Am. Chem. Soc. 1946, 68, 1987. (b) Doak, G.
O. J.Am. Chem. Soc.1946, 68, 1991. [2]. Beckman, J.; Finke, P.; Hesse, M.; Wettig, B. Angew. Chem., Int.Ed.2008, 47, 9982. [3]. Prabhu M. S. R.; Jami A. K.; Baskar. V. Organometallics2009, 28, 3953-3956. [4]. Jami A. K.; Prabhu M. S. R.; Baskar. V. Organometallics2010, 29, 1137-1143. [5]. Jami. A. K.; Baskar, V. Dalton trans,2012, 41, 12524. [6]. Kishore. P. V. V. N.; Baskar. V. Inorg. Chem. 2014, 53, 6737 [7]. Srungavruksham, N. K., Baskar, V. Dalton Trans. 2015, 44, 6358-6362. [8]. Ugandhar, U., Baskar, V., Dalton Trans.2016, 10.1039/C5DT03449C.
IIT Bombay MTMM 2016
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Dr. Ashutosh Ghosh is Professor at University of
Calcutta, India. He received his Ph.D, under the
supervision of Prof. N. RayChaudhuri. He also stayed
as UNESCO fellow, MONBUSHO Fellow, JSPS Fellow
in Prague, Czechoslovakia and Japan respectively
before moving to Calcutta. His research interests
include Homo- and heterometallic polynuclear
complexes of 1st transition metal ions: structural
characterization, magnetic properties and catalytic
activities. He is also recipient of several awards
notably CRSI Bronze Medal 2016. He has published
230 journals of international repute. Among these, 168 papers have been published
since he joined University of Calcutta in 1998 and started independent research.
For more details: [http://www.caluniv.ac.in/cuchemistry/dr-ashutosh-ghosh/]
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The making of a new family of Trinuclear Ni(II) Single-Molecule Magnets
Ashutosh Ghosh*
Department of Chemistry, University College of Science, University of Calcutta, 92, A.P.C. Road, Kolkata -700 009, India
e-mail: [email protected]
The N2Odonor Schiff bases (HL), the mono-condensation products of diamines and
salicylaldehyde or its derivatives are well known to produce diphenoxido bridged
dinuclear complexes with Ni(II). The variable temperature magnetic susceptibility
measurements reveal that these complexes are anti-ferromagnetically coupled,
which can be explained by the wide bridging angles (~1000) between the Ni(II)
centres. To decrease the bridging angle we introduced an additional water bridge
between the metal centers and succeeded to make the coupling ferromagnetic.
However, these dinuclear complexes do not exhibit slow relaxation of the
magnetization. Therefore, to increase the energy barrier that spins must overcome
when they switch from parallel alignment to antiparallel alignment and
consequently make the compound single-molecule magnet, we prepared both linear
and cyclic trinuclear Ni(II) complexes. The family of cyclic trinuclear complexes
having the general composition of [Ni3L3(OH)(X)](ClO4) where X is halide or
pseudohalide exhibit ferromagnetic coupling leading to S = 3 ground state in an
approximate equilateral triangle. Slow relaxation of the magnetization at low
temperatures is evident from frequency-dependence in the out-of-phase ac
susceptibilities. The pulsed-field magnetization recorded at 0.5 K shows clear steps
in the hysteresis loop in 0.5 to 1 T, being assignable to quantum tunneling and
characteristic of single-molecule magnets. Single-crystal magnetization
measurements for one of the complex clarify that the pseudo-three-fold axis of Ni3
corresponds to the magnetic easy axis. The compressed octahedral coordination
sphere of each Ni(II) ions agrees with the magnetic anisotropy observed.
Designing Structures of Molecular Magnets with A2CuCl4 (B) and A2Cu(N3)2(C) geometry.
References: Ghalsasi et al. Sci. Rep. (2015); CrystGrow. Des (2014).
IIT Bombay MTMM 2016
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Dr. Eliseo Ruiz is a Professor at the University of
Barcelona, Spain. He obtained his Ph.D. from
Barcelona under the supervision of Prof. Santiago
Alvarez. He did his postdoctoral work at Université de
Montréal with Prof. Dennis R. Salahub in 1993-44,
was appointed as Associate Professor at the
University of Barcelona in 2001 and became Professor
of Inorganic Chemistry in 2011. His actual research
interests are mainly centered in the use of theoretical
methods to study the magnetic and transport
properties of inorganic systems. In recent years he
has been involved in the synthesis and characterization of supramolecular systems
and hybrid systems of nanotubes with metal complexes. Since 1991 he has been
teaching different courses (Inorganic Chemistry, Supramolecular Chemistry,
Molecular Electronics,…) in the area of Inorganic Chemistry for graduate and undergraduate students in Chemistry, Physics and Geology. He has received
numerous awards for his significant contribution to theoretical chemistry. Moreover,
he has published 194 internationally peer-reviewed scientific journals possessing
overall citations of ~ 8724.
For more details:
[http://www.ee.ub.edu/index.php?option=com_content&view=article&id=85&Itemid=487 ]
IIT Bombay MTMM 2016
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Mononuclear Metal Complexes: From Single-Molecule
Magnets to Magnetoresistance Single-Molecule Devices
Eliseo Ruiz
Departament de QuímicaInorgànicaiOrgànica and Institut de QuímicaTeòricai
Computational, Diagonal 645, 08028 Barcelona, Spain
E-mail: [email protected]
Molecules that show high anisotropy are called single-molecule magnets (SMMs)
and they must contain metal centers with large spin-orbit effects. The progress of
Molecular Magnetism area covers a huge number of systems; from the first SMM
Mn12 to the latest lanthanide complexes with the highest reported anisotropy and
blocking temperatures around 40 K. We have studied some mononuclear transition
metal complexes that they exhibit single-ion magnet behavior. Our qualitative
approach is to present a well-defined route map to greatly enhance the magnetic
anisotropy of molecules containing only one paramagnetic center.[1,2] Also, in
order to calculate the zero-field splitting parameters, CASSCF(or CASPT2)-RASSI
calculations have been employed because they provide a quantitative estimation of
such parameters. Furthermore, we have focused our interest in mononuclear
complexes showing easy plane magnetization and the spin relaxation mechanism
involved in such systems.[3]
The second part of the presentation is devoted to the single-molecule devices, mononuclear complexes deposited on a gold substrate are in contact with magnetic Ni STM tip. Our first results provide a proof of concept strongly indicating that the STM conductance through FeII or CoII complexes (that are also spin-crossover system and single-molecule magnets, respectively) changes one order of magnitude with the direction of the Ni tip magnetic field. Our study shows a theoretical analysis and the practical implementation through two-terminal devices using STM equipment to achieve the room temperature molecular-based spintronic nanodevices.[4]
References
[1] S. Gómez-Coca, E. Cremades, N. Aliaga-Alcalde, E. Ruiz. "Mononuclear Single-Molecule Magnets: Tailoring the Magnetic Anisotropy of First-Row Transition-Metal Complexes". J. Am. Chem. Soc., 135, 7010-7018 (2013).[2] S. Gómez-Coca, D. Aravena, R. Morales, E. Ruiz. "Largemagneticanisotropy in mononuclear metal complexes". Coord. Chem. Rev., 289-290, 379-392 (2015).[3] S. Gomez-Coca, A. Urtizberea, E. Cremades, P.J. Alonso, A. Camon, E. Ruiz, E., F. Luis, Origin of slow magnetic relaxation in Kramers ions with non-uniaxial anisotropy. Nature Commun.5, 4300 (2014). [4] A. C. Aragonès, D. Aravena, J. I. Cerdá, Z. Acís-Castillo, H. Li, J. A. Real, F. Sanz, J. Hihath, E. Ruiz, I. Díez-Pérez (2015) Large Conductance Switching in a Single-Molecule Device through Room Temperature Spin-Dependent Transport”.Nano Letters, 16, 218-226 (2016).
34
IIT Bombay MTMM 2016
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Quantum Design India Pvt Ltd
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IIT Bombay MTMM 2016
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Dr. Mario Ruben is a Professor at Karlsruher
Institut für Technologie (KIT), Germany. He obtained
his Ph.D. in 1998 from University of Jena, Germany
under the supervision of Prof. D. Walther. After
postdoctoral position at the ISIS, Université Louis
Pasteur Strasbourg, France, he joined as a Research
group leader in KIT, Germany in 2001. He has
published 150 papers in international peer-reviewed
journals with H factor of 39. His research interests
deal with the design of functional nano-systems by
state-of-the-art organic/inorganic synthesis and
supramolecular self-assembly techniques. He is specilized in the interdisciplinary
research topics of Functional Molecules, Molecular Electronics and Carbon-based
Nanostructures.
[For more details:http://www.ruben-group.de/home.html]
IIT Bombay MTMM 2016
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Metal Complexes as Single Molecule Qubits
Mario Ruben,a,b*
aInstitut of Nanotechnology and Institut of Inorganic Chemistry, KIT, Karlsruhe
(Germany) bIPCMS, Université de Strasbourg, Strasbourg (France)
e-mail: [email protected]; web: www.ruben-group.de
Magnetic metal complexes have been proposed as Quantum Bits (Qubits)
candidates units for Quantum Computing (QC) and Quantum Information
Processing (QIP).1 Herein, we report on the implementation of metal complexes into
nanometre-sized (single-) molecular spintronic devices by a combination of bottom-
up self-assembly and top-down lithography techniques. The controlled generation of
magnetic molecular nanostructures on conducting surfaces and electrodes will be
shown, self-assembled on sp2-carbon nano-structures (SW-CNTs, graphene, etc.),
or inside nano-gap gold junctions. The quantum properties of the metal complexes
inside of the obtained supramolecular Quantum Devices (SMQD) are addressed at
the single molecule level in view of their I-V-characteristics by means of UHV- and
solution-based scanning probe and electromigration techniques.2-10
Figure 1 Artistic representation of aMolecular Spin Transistor based on a TbPc2 Single Molecule Magnet (SMM) acting as a molecular Qubit.9
References
[1]. M. Leuenberger, D. Loss, Nature2001, 410, 789; [2]. S. Kyatskaya et. al. J. Am. Chem. Soc. 2009, 131, 15143-15151. [3]. M. Urdampilleta et al. Nature Mater. 2011, 10, 502-506. [4]. J. Schwöbel et. al. Nature Comms.2012, 3, 953-956. [5]. R. Vincent et al. Nature2012, 488, 357-360. [6]. M. Ganzhorn et al. Nature Nano.2013, 8, 165–169. [7]. M. Ruben et. al. Nature Nano.2013, 8, 377–389. [8]. S. Wagner et. al. Nature Nano.2013, 8, 575–579. [9]. S. Thiele, et al. Science2014, 344, 1135-1138. [10]. M. Ganzhorn et. al. Nature Comm.2016, accepted.
IIT Bombay MTMM 2016
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Dr. S.M. Yusuf is currently the Head of the
Magnetism Section in Solid State Physics Division of
Bhabha Atomic Research Centre (BARC), Mumbai,
and Professor, Homi Bhabha National Institute,
Mumbai. He obtained his Ph. D (Physics) from
University of Mumbai. He was a post-doctoral fellow
at Argonne National Laboratory, USA, and a visiting
scientist at the Institute of Materials Science, Spain.
He was instrumental in setting up of the neutron
polarization analysis spectrometer at Dhruva reactor,
BARC for magnetic scattering studies, and a low
temperature laboratory for magnetization and magnetotransport studies in BARC.
He is the first person to have established and used neutron depolarization
technique in India. He is an active user of various international neutron scattering
facilities, such as ILL-Grenoble, PSI-Switzerland, LLB-Saclay and HMI-Berlin.
He has expertise in the area of advanced magnetic materials and neutron
scattering. His current research interests are in the field of magnetic nanoparticles,
multifunctional molecular magnetic materials, low dimensional magnetic materials,
high magnetocaloric materials, high spin polarization materials, etc. He has more
than 200 research publications in international journals, one international patent,
and several review articles and book chapters to his credit. He is a Ph. D guide of
(i) University of Mumbai, (ii) Homi Bhabha National Institute (HBNI), and (iii)
University of Pune (Co-guide). He has guided 9 Ph. D students, and delivered more
than 135 invited talks in various forums. He is a referee of the Nature publishing
Group, Physical Review Letters, and Physical Review B.
Dr. Yusuf is the recipient of MRSI-ICSC Superconductivity & Materials Science
Annual Prize, Raja-Ramanna Prize Lecture in Physics 2016, Dr. P. K. Iyenger
memorial award, Homi Bhabha Science & Technology Award, MRSI Medal, DAE SRC
outstanding research investigator award, DAE Group Achievement Award, N. S.
Sathya Murthy Memorial Award, and Indian Physical Society’s best young physicist
award. He is a member of various national and international professional bodies
including editorial advisory boards. He is a fellow of the National Academy of
Sciences, India.
[for more details: http://www.researchgate.net/profile/S_Yusuf2/ http://scholar.google.co.in/citations?user=Ml3ZmkIAAAAJ&hl=en]
IIT Bombay MTMM 2016
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Novel magnetism in Prussian blue, oxalate and
phenanthroline based molecular compounds S. M. Yusuf
Solid State Physics Division, Bhabha Atomic Research Centre,
Mumbai 400 085, India Email: [email protected]
Molecular magnetic materials are the subjects of active research because of their possible applications in future information processing and storing devices. We have investigated a large number of Prussian blue analogues (PBAs), such as Fe[Fe(CN)6].zH2O, {CoxNi1-x}1.5[Fe(CN)6]. zH2O (0≤x≤1), {CuxMn1-
x}1.5[Fe(CN)6].zH2O (0≤ x ≤1), RuxNi3-3/2x[Cr(CN)6]2.zH2O (0≤x≤1), and RbxBayMn[3-
(x-2y)]/2[Fe(CN)6].zH2O. A microscopic understanding of the novel phenomenon of magnetization reversal in {CuxMn1-x}1.5[Fe(CN)6]·zH2Ohas been achieved by employing reverse Monte Carlo (RMC) and Rietveld refinement techniques on neutron scattering data. Our work has also shown that the observed bipolar switching of magnetization can have novel applications in (i) volatile magnetic memory technology, (ii) thermo-magnetic switches, and (iii) a self-driven constant temperature bath. Besides, our work exploiting neutron diffraction on several molecular magnets has highlighted the role of structural defects and quenched disorder in controlling magnetism. For RuxNi3-3/2x[Cr(CN)6]2. zH2O (0 ≤ x ≤ 1) compounds, the role of the diffused 4d atomic orbital of Ru (as compared to the relatively localized 3d orbitals of Ni) in controlling the magnetic ordering has been brought out. We have even studied the nature of dynamical motions of both coordinated and un-coordinated water molecules that are present in the face centered cubic structure of such PBAs. An interesting magnetic field driven transition from an antiferromagnetic ground state to a ferrimagnetic state in (Rb/Ba/Mn)[Fe(CN)6]0.48H2O PBA has been established by performing neutron diffraction study under magnetic field. Such tunable PBAs which undergo controlled changes of their molecular states in response to external perturbations are suitable for applications in molecular electronics such as bi-stable memory devices. Our study on the oxalate (ox) and phenanthroline (Phen) ligands based spin chain molecular magnets,[{Fe(Δ)Fe(Λ)}1-x{Cr(Δ)Cr(Λ)}x(ox)2(phen)2]n(x = 0, 0.1, and 0.5) has revealed a giant coercivity of ~ 3.2 Tesla which opens up new opportunities to design very hard light weight (density: ~ 1gm/cc) magnets for practical applications. In my talk, some of these results will be presented in the light of importance of the studied molecular magnets for their practical applications.
[1] A. Kumar, S. M. Yusuf, et al.Phys. Rev. Lett. 101 207206 (2008).[2] M. D. Mukadam, A. Kumar, S. M. Yusuf et al. J. App. Phys. 103 123902 (2008).[3] S. M. Yusuf, A. Kumar, et al. Appl. Phys. Lett. 95, 182506 (2009).[4] S. M. Yusuf, N. Sharma, et al.J. Appl. Phys. 107, 053902 (2010)[5] P. Bhatt, S. M. Yusuf, et al. J. Appl. Phys. 108, 023916 (2010).[6] A. Kumar, S. M. Yusuf, et al. Phys. Rev. B 75 224419 (2007).[7] A. Kumar, S. M. Yusuf et al. Phys. Rev. B 71, 054414 (2005).[8] N. Thakur, S. M. Yusuf , et al. Phys. Chem. Chem. Phys, 12, 12208 (2010) .[9] V K Sharma, S Mitra A. Kumar, S M Yusuf et al., J. Phys.: Condens. Matter 23, 446002 (2011).[10] N. Thakur, S. M. Yusuf et al. J. Appl. Phys. 111, 063908 (2012).[11] S. M. Yusuf, N. Thakur, et al. J App. Phys. 112, 093903 (2012).[12]P. Bhatt, N. Thakur, M. D. Mukadam, S. Meena, and S. M. Yusuf, J. Phys. Chem. C117, 2676 (2013).[13]P. Bhatt, N. Thakur, S. S. Meena, M. D. Mukadam and S. M. Yusuf, J. Mater. Chem. C1, 6637 (2013).[14]P Bhatt, S Banerjee, S Anwar, MD Mukadam, SS Meena, SM Yusuf, ACS Appl. Mat.& Inter. 6, 17579(2014).[15] P Bhatt , N Thakur, M D Mukadam, SS Meena, and S M Yusuf, J. Phys.Chem. C118 , 1864 (2014).[16] V K Sharma, S Mitra, N Thakur, S M Yusuf, et al., J. Appl. Phys. 116, 034909 (2014).[17] A. Kumar, S. M. Yusuf, Physics Reports 556, 1-34 (2015).[18] P. Bhatt, A. Kumar, S. S. Meena, M. D. Mukadam, S. M. Yusuf, Chem. Phys. Lett. 2016 (in press).
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IIT Bombay MTMM 2016
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IIT Bombay MTMM 2016
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Dr. Talal Mallah is a Professor at Université Paris
Sud, France. His research interests include a)
Coordination nanoparticles b) Supramolecular routes
to nano-magnets and surface chemistry.
For more details: [http://www.icmmo.u-psud.fr/Labos/LCI/cv/tm.php]
IIT Bombay MTMM 2016
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Magnetic Anisotropy and Single Molecule Magnet behavior
in trigonal bi pyramidal mononuclear Co(II) complexes
T. Mallah*, L. Batchelor, F. Shao, G. Zakhia, R. Guillot, V. Campbell, R. Ruamps, N. Guihéry, A.-L. Barra, W. Wernsdorfer
Université Paris Sud, Laboratoire de Chimie Inorganique, ICMMO, CNRS, 91405, Orsay, France.
Laboratoire de Chimie et Physique Quantiques, Université de Toulouse III, 118, route de Narbonne, 31062 Toulouse, France.
Laboratoire National des Champs Magnétiques Intenses, UPR CNRS 3228, Université J. Fourier, 25, avenue des Martyrs, B.P. 166, 38042 Grenoble Cedex 9,
France. Institut Néel, CNRS, Université J. Fourier, BP 166 25, Avenue des Martyrs, 38405
Grenoble, France.
e-mail: [email protected]
One of the challenges in the field of molecular magnetism is to design stable molecular complexes based on transition metal ions possessing a blocking of the magnetization in the absence of a static magnetic field. This is a requirement if such molecules are to be used as single quantum bits for quantum information processing.1
Trigonal bipyramidal mononuclear Co(II) (S = 3/2) complexes of the general formula [Co(Me6tren)X](ClO4)2 (Me6tren is a tetradendate ligand) possess all the characteristics to present a blocking of the magnetization and an opening of the magnetic hysteresis loop at low temperature (Figure 1).2 The effect of the nature of the axial ligand X that has a structural and an electronic influence on the magnitude and the nature of the magnetic anisotropy will be discussed. The role of the transverse anisotropy in the case of these Kramers doublets ions will be discussed also.
Figure 1. (left) view of the molecular structure of the [Co(Me6tren)Cl]2+ complex; (middle) magnetic hysteresis loop of a diluted single crystal of [Co(Me6tren)Cl](ClO4) and (right) derivative of the central part of the M = f(µ0H) loop showing the hyperfine coupling between the electronic and the nuclear (I = 3/2) spins of Co(II).
References
[1] G. A. Timco, et al, Nat. Nanotech. 2009,4, 173. [2] R. Ruamps, et al, Chem. Sci.2014,5, 3418.
IIT Bombay MTMM 2016
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Dr. K. Gopal is an Assistant Professor at Central University of Rajasthan, India with expertise Inorganic chemistry: Crystal Engineering, Magnetic properties. He received his Ph.D from IIT Kanpur after which he stayed as Marie-Curie post-doctoral fellow in University of Manchester, UK and DST young scientist in IIT Bombay before moving to Rajasthan. He has published several papers in peer-refereed international journals.
[for more details: http://www.curaj.ac.in/Default.aspx?PageId=25 ]
IIT Bombay MTMM 2016
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Molecular Manganese Phosphonates
Dr. Gopal K
Department of Chemistry, Central University of Rajasthan, Ajmer, Rajasthan – 305 817, India
E-mail: [email protected]
The use of carboxylates as ligand for the synthesis of polynuclear metal complexes is a most successful strategy, seen in the past with numerous examples. Currently, the other synthetic approach involving phosphonate ligands (R-PO32-) are promising because of their ability to coordinate up to nine metal ions by three oxygen donors. In order to prepare the molecular metal-phosphonate cags over its preferred extended structures, several types ancillary ligands used such as pyrazoles, pyridines, pyridionates, etc.1-2 Similarly, in combination of carboxylates and phosphonates also gave interesting results. Some of them show interesting magnetic properties such as single molecule magnets (SMMs).1-4 A radically different approach – building larger cluster from smaller cages (bottom-up approach) with the help of phosphonates gave interesting results. Accordingly, a series of mixed-valent manganese phosphonate cage complexes synthesized from the reactions of tetranuclear Mn6O2-cored carboxylate cluster with various substituted phosphonic acids. Compounds synthesized are include MnII12MnIII8, MnII6MnIII10, MnII7MnIII9, etc. Priliminary magnetic studies show that some of the cages exhibits dominating intramolecular antiferromagnetic exchange interaction which leads to a small spin ground states.
Reference
[1]. Goura, J. and Chandrasekhar, V. Chem. Rev. 2015, 115, 6854-6965. [2]. Gopal, K.; Ali, S.; Winpenny, R. E. P. Structural Studies of Paramagnetic Molecular
Phosphonates. In Metal Phosphonate Chemistry: From Synthesis to Applications; Clearfield, A., Demadis, K., Eds.; Royal Society of Chemistry: Cambridge, U.K., 2012; pp 364−419.Shanmugam, M., Chastanet, G., Mallah, T., Sessoli, R., Teat, S. J., Timco, G. A., Winpenny, R. E. P. Chem. Eur. J. 2006, 12, 8777-8785.
[3]. Zheng, Y.-Z., Zhou, G.-J., Zhengab, Z. and Winpenny, R. E. P. Chem. Soc. Rev. 2014, 43, 1462-1475.
IIT Bombay MTMM 2016
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Dr. A. Sundaresan is a Professor at JNCASR,
Bangalore, India. He received his Ph.D fromIIT
Bombay followed by his post-doctoral position in
France and Japan before moving to Bangalore in
2004. His research interest is in the field of solid-
state chemistry and physics. Preparation and
characterization of various inorganic oxide materials,
including thin films, of both academic interest and
with technologically required properties have also
intrigued their group. Experimental techniques
involve solid state and chemical route of synthesis,
structural characterization (x-ray, neutron, and electron diffraction) and physical
property measurements (magnetic, electrical transport, and ferroelectrics). Their
aim is to correlate the structure and properties so that a material with required
property may be achieved.
[For more details: http://www.jncasr.ac.in/sundaresan]
IIT Bombay MTMM 2016
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Structure, Magnetism and Magnetodielectric Effect in A-
Site Ordered Chromate Spinel Oxides LiMCr4O8
(M= Ga, In, Fe)
A.Sundaresan
Chemistry and Physics of Materials Unit and International Centre for Materials
Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O.,
Bangalore 56064, India.
The compound ZnCr2O4 with cubic spinel structure (Fd-3m) undergoes
magnetostrutural transition at low temperaures due to magnetic Jahn-Teller
distortion. We have investigated the A-site ordered chromate spinels (LiMCr4O8, M
= Ga, In, Fe) where Li+ and Ga3+(In3+, Fe3+) replace Zn2+ ions and orders
alternatively in the tetrahedral sites leading to loss of inversion symmetry at the
Cr3+ site thereby reducing the crystal symmetry toF 3m. This A-site ordering
creates local non-centrosymmetric surroundings of magnetic ions which can give
rise to magnetoelectric effect. LiMCr4O8 (M=Ga & In) undergoes antiferromagnetic
ordering at ~ 14 K, while LiFeCr4O8 shows ferrimagnetic ordering at 95 K followed
by two other magnetic transitions at 60 and 23 K. Interestingly, we see that all
these compounds show dielectric anomalies at the temperatures where magnetic
anomalies are found. A sharp dielectric anomaly is observed at the broad magnetic
anomaly which is associated with opening of spin-gap (Tsg ~ 60 K) in LiInCr4O8 and
a broad dielectric anomaly at the onset of short range antiferromagnetic ordering
(Tso ~ 55 K) in LiGaCr4O8. This indicates that the origin of dielectric anomaly may be
associated with structural distortion which will facilitate to lift the magnetic
frustration. Moreover, all these compounds undergo a structural phase transition
from F 3m to I m2 at the lowest magnetic phase transition temperature. The
distortion of lattice at the magnetic ordering indicates a strong coupling between
spin and lattice degrees of freedom resulting in interesting magneto-dielectric
effect.
References:
[1]. Y. Okamoto, G. J. Nilsen, J. P. Attfield, and Z. Hiroi, Phys. Rev. Lett. 110, 097203 (2013) [2]. G. J. Nilsen, Y. Okamoto, T. Masuda, J. Rodriguez-Carvajal, H. Mutka, T. Hansen, and Z. Hiroi,
Phys. Rev. B 91, 174435 (2015) [3]. N. Ter-Oganessian, J. Magn. Magn. Mater. 364, 47 (2014)
IIT Bombay MTMM 2016
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Dr. Mahesh Sundararajan is an theoretical and
computational chemist working as a scientific officer
at Bhabha Atomic Research Centre, India. He works
on problems related to biological and environmentally
relevant molecules using electronic structure
methods. Using these methods, he tries to
understand the Structure-Function relationship of
complex chemical processess. He received his Ph.D
from University of Manchester, UK after which he
stayed as AvH post-doctoral fellow in Dr. Frank Neese
group before moving to BARC in 2010. His research
area incorporates Bio-Inorganic Chemistry, Supramolecular Chemistry, Actinide and
Environmental Chemistry, Nano Chemistry and Theoretical Spectroscopy. He has
published ~40 internationally peer-reviewed journals.
[For more details: http://maheshsundararajan.wix.com/mahesh
IIT Bombay MTMM 2016
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Molecular Magnetism involving Supramolecules
Mahesh Sundararajan
Theoretical Chemistry Section, Bhabha Atomic Research Centre,
Mumbai - 400 094, INDIA
e-mail: [email protected]
One of the important parameters involving single molecular magnets are zero field splitting (ZFS). Although single molecule magnets are known to function for information storage, a new paradigm has emerged recently which suggest each ion can function as magnets which are so called single ion magnet. Thus, several synthetic strategies are proposed to synthesize single ion magnets with large ZFS.
On the other hand, the formation of host-guest complexes can modulate unusual geometric and electronic structure. In this talk, we propose ions encapsulated within supramolecules can be used to alter the ZFS. As ZFS are very sensitive to geometries, encapsulated ions can be stabilized by both electrostatic hydrogen bonds and hydrophobic interactions significantly. These non-covalent interactions influences the ZFS significantly thus can open a new area in the field of Host-Guest Chemistry.
References
[1]. Comba, P.; Rajaraman, G. Inorg. Chem. 2008, 47, 78. [2]. Dybtsev, D. N.; Nuzhdin, A. L.; Chung, H.; Bryliakov, K. P.; Talsi, E. P.; Fedin V. P.;
Kim, K. Angew. Chem. Int. Ed.2006, 45, 916.
50
IIT Bombay MTMM 2016
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IIT Bombay MTMM 2016
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Dr. Rémi Maurice is currently at Laboratoire
SUBATECH, UMR CNRS 6457, (IN2P3/EMN
Nantes/Université de Nantes), Nantes, France. He
received his Ph.D from Toulouse, France and
Tarragona, Spain, followed by post-doctorate
activities in Groningen (The Netherlands) and
Minneapolis (USA). The main objective of his work is
to bring new insight in the physical and chemical
properties of molecules and materials with quantum
chemical methods. Besides, he is also fascinated to
understand magnetic, ferroelectric and photophysical
properties of ionic and molecular materials.
[For more details:https://www.researchgate.net/profile/Remi_Maurice]
IIT Bombay MTMM 2016
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Zero-Field Splitting in Transition Metal Complexes: Ab
initio calculations, effective Hamiltonians, and model
Hamiltonians
Rémi Maurice(a)*, Ria Broer(b), Coen de Graaf(c) and Nathalie Guihéry(d)
(a) SUBATECH, UMR CNRS 6457, IN2P3/EMN Nantes/Université de Nantes, Nantes, France (b) Zernike Institute for Advanced Materials, University of Groningen, Groningen, The
Netherlands (c) Departament de Química Física I Inorgànica, Universitat Rovira i Virgili, Tarragona, Spain
(d) Laboratoire de Chimie et Physique Quantiques, IRSAMC/UMR CNRS 5626, Université de
Toulouse 3, Toulouse, France e-mail: [email protected]
Theoretical calculations can be very helpful to analyse experimental data in terms of anisotropic spin Hamiltonians since they allow to (i) assess the validity of phenomenological Hamiltonians, (ii) discuss the parameter values that arise from experiment analyses, and (iii) rationalize these values from a more qualitative point of view e.g. by establishing magneto-structural correlations [1].
In this talk, we will introduce the effective Hamiltonian theory and apply it to extract anisotropic spin Hamiltonians from the outcomes of contracted spin-orbit coupling configuration interaction (c-SOCI) calculations.
We will consider various examples, including mononuclear dn complexes [2], d9-d9 binuclear systems [3,4], and a d8-d8 binuclear complex [5,6]. In each case, we will introduce theoretically justified model Hamiltonians and compare to the most accurate experimental data when available. Challenges and perspectives will be finally highlighted.
References
[1]. Maurice, R.; de Graaf, C.; Guihéry, N. Phys. Chem. Chem. Phys. 2013, 15, 18784. [2]. Ruamps, R.; Batchelor, L. J.; Maurice R.; Gogoi N.; Jiménez-Lozano, P.; Guihéry, N.; de Graaf,
C.; Barra, A.-L.; Sutter, J.-P.; Mallah, T. Chem. Eur. J. 2013, 19, 950. [3]. Maurice, R.; Sivalingam, K.; Ganyushin, D.; Guihéry, N.; de Graaf, C.; Neese, F. Inorg. Chem.
2011, 50, 6229. [4]. Maurice, R.; Pradipto, A. M.; Guihéry, N.; Broer, R.; de Graaf, C. J. Chem. Theory Comput.
2010, 6, 3092. [5]. Maurice, R.; Guihéry, N.: Bastardis, R.; de Graaf, C. J. Chem. Theory Comput. 2010, 6, 55. [6]. Maurice, R.; de Graaf, C.; Guihéry, N. Phys. Rev. B 2010, 81, 214427.
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Dr. Nathalie Guihéry is a Professor of the University of Toulouse 3 Paul Sabatier in section 31 in France. She obtained her Ph.D. in 1995 under the superviison of Jean- Paul and Daniel Malrieu Maynau in the laboratory of Quantum Physics (UMR5626) of the University Paul Sabatier, France. Then, she acted as a temporary Teaching, Research Attaché (ATER) and lecturer in section 31 of the Paul Sabatier University. Afterwards, she has done Internship laboratory Fundamental Interactions Physics of the Instituto Superior Técnico of Lisbon, Portugal ,
together with Vitor Rocha and Pedro Viera Sacramento. In 2001-2003, she enacted as a director of the team "extended system and magnetism" and member of the scientific council of the laboratory. Since, 2009, she is a Professor of the University of Toulouse 3 Paul Sabatier in section 31. Her main Fields of interest is Simultaneous treatment methods of non-dynamic and dynamic correlations. The works undergone in her lab include: i) self-consistent and coherent approaches using the Heisenberg Hamiltonian (single-reference SC2 and multi-reference MRSC2) ii) ab initio methods in localized orbitals; to test a new technique for locating and selecting configurations on related compounds and to conduct systematic analysis of the different contributions of electron correlation; iii) spin-orbit coupling and spin-spin in the two-stage procedures of type to calibrate the methods programmed in Molcas and ORCA testing systematically the effects of the base, the number of states involved in the interaction, the extension of the active space, variational perturbation treatment or of correlation, etc. to reproduce the EPR parameters accurately; iv) obtaining good quality magnetic orbitals in order to reduce the computational cost of post-processing of electronic correlation, especially in the organic magnetic systems.
[For more details: http://www.lcpq.ups-tlse.fr/spip.php?rubrique420&lang=fr]
IIT Bombay MTMM 2016
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Magnetic anisotropy in mono- and bi-nuclear complexes:
theoretical insight and prospects
Nathalie Guihéry,(a)* Rémi Maurice, (b) Renaud Ruamps(a) and Coen de Graaf(c)
(a) Laboratoire de Chimie et Physique Quantiques, UMR5625, University of Toulouse 3, Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France;
(b) SUBATECH, IN2P3/EMN Nantes/University of Nantes, 4 rue Alfred Kastler, BP 20722 44307, Nantes, Cedex 3, France,
(c) University Rovira i Virgili, Marcel·li Domingo s/n, 43007 Tarragona, Spain (a)
e-mail: [email protected]
Magnetic anisotropy is the origin of the single molecule magnet (SMM)
behavior which is manifested by a slow relaxation of the magnetization and a
blocking of the magnetization for low enough temperatures. Since this bistable
behavior may lead to possible technological applications in the domain of data
storage and quantum computing, the understanding of the microscopic origin of
magnetic anisotropy has received a considerable interest during the last two
decades.
Mono-nuclear complexes having exotic coordination of the metal ion have recently
been shown to exhibit a very large magnetic anisotropy. A first study will be
devoted to the rationalization of the magnitude and nature of single ion anisotropy
from theoretical calculations. It will be shown that the competition between
relativistic effects and Jahn Teller distortion may lead to very large magnetic
anisotropy.
The overall magnetic anisotropy of a poly-nuclear complex comes from both the
local anisotropies of paramagnetic ions and their interactions. The second part of
this presentation will focus on the understanding of synergistic effects between local
anisotropies in bi-nuclear species for which we have both tuned the local
anisotropies by imposing peculiar geometries and combined various types of local
anisotropies.
The theoretical results presented here are published in various articles [1].
References
[1] J. of Chem. Theo. Comp., 2009 5, 11 2977; J Chem. Theor. Chem 2010 6 1, 55;J. Chem. Theor.
Chem.2010610, 3092; Phys. Rev. B, 2010 81 21, 214427; J. Chem. Phys.2010133, 084307; Inorg.
Chem.2011 50 13, 6229; Phys. Rev. B2012, 85,014409; Phys. Rev. B2012, 86, 024411; Chem.
Euro. J.2013, 19, 950; R. Ruamps et al. J. Am. Chem. Soc. 2013, 135, 3017A, Phys. Chem. Chem.
IIT Bombay MTMM 2016
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Dr. Annie K. Powell is a Professor at the University of Karlsruhe (now KIT), Germany. She obtained her Ph.D. in 1985 from the under the supervision of Dr. M. J. Ware from Manchester University, UK. After post-doctoral position in University of Freiburg, Germany she joined as Lecturer, Reader, Professor in UK before eventually moving to University of Karlsruhe in 1999. She has 400 peer-reviewed international publications. Besides, she has received several notable awards and visiting professor fellowship. She had been member and
reviewer for all leading international ACS, RSC, Wiley-VCH, Science and Nature journals. Her main Fields of interest includes synthesis of coordination complexes possessing mixed metal ions and also mixed oxidation states. In order to increase the versatility of these species we have discovered both how to produce clusters containing lanthanide ions – these can show fascinating magnetic properties – and also mixed 3d/4f clusters. She is at the forefront of research into the synthesis and properties of 3d/4f clusters in terms of variety and scope of the systems. An important underlying theme in their research has been the investigation of the magnetic properties using routine SQUID measurements as well as in collaboration for more exotic measurements. This work has been supported over the years through an EU RTN, an EU centre of excellence, a DFG collaborative “Schwerpunkt Programm” and a DFG centre of excellence (the Center for Functional Nanostructures). In addition to her chair at the South Campus of KIT (formerly the University) she has a position and a group at the North Campus at the Institute for Nanotechnology where research is supported through the Helmholtz Society. So, ongoing core research activities of her group comprise synthesis of Molecular Magnets, MOFs, SMOFs, Biomimetics, and multifunctional materials.
[for more details: http://ak-powell.chemie.uni-karlsruhe.de/]
IIT Bombay MTMM 2016
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Chirality and its Role in Coordination Chemistry – the
Jekyll and Hyde Behaviour of Metal Ions in Separating the
Left and Right Sides of the World
Annie K. Powell
Institute of Inorganic Chemistry and Institute of Nanotechnology, Karlsruhe
Institute of Technology, 76131 Karlsruhe Germany.
Email: [email protected]
The concepts of coordination chemistry developed by Alfred Werner at the beginning of the 20th century were finally substantiated by the realisation that a metal centre can invoke chirality by providing a central anchor-point to fix achrial ligands into a chiral structure. This is demonstrated easily with bidentate ligands which form tris-chelates, adopting either left- or right-handed propeller structures. On the other hand, a metal centre can provide an activation point for the inversion of the implied chirality of both pro-chiral and chiral ligands and lead to racemisation processes. Thus metal centres play an important role in terms of influencing the potential chirality of a given system.
This lecture will take examples from some of our recent work to illustrate these fascinating, but sometimes challenging, points. For example, intriguing chiral separations can be achieved when racemates of chiral ligands are used.[1] Furthermore, in addition to structural chirality induced by the presence of metal ions,[2] we can consider the implications for the fourth dimension in terms of time-reversal symmetry with a particular perspective on magnetic behaviour.[3]
[1]. Ringing the changes in FeIII/YbIII cyclic coordination clusters, A. Baniodeh, C. E. Anson, A. K. Powell, Chem. Sci., 2013, 4, 4354–4361.
[2]. [LnNa(PhCO2)4] (Ln = Ho, Dy): The first examples of chiral srs 3D-networks constructed using the monotopic benzoate ligand, Z. Majeed, K. C. Mondal, G. E. Kostakis, Y. Lan, C. E. Anson, A. K. Powell, Chem. Comm., 2010 46, 2551-2553 (b) Spontaneous resolution in homochiral helical [Ln(nic)2(Hnic)(NO3)] coordination polymers constructed from a rigid non-chiral organic ligand, I. Mihalcea, N. Zill, V. Mereacre, C. E. Anson, A. K. Powell, Crystal Growth & Design, 2014, 14, 4729–4734.
[3]. (a) Spin chirality in a molecular dysprosium triangle. The archetype of the noncollinear Ising model, J. Luzon, K. Bernot, I.J. Hewitt, C. E. Anson, A. K. Powell, R. Sessoli, Phys. Rev. Lett., 2008, 100, 247205; (b) Heterometallic CuII/DyIII 1D chiral polymers: chirogenesis and exchange coupling of toroidal moments in trinuclear Dy3 single molecule magnets, G. Novitchi, G. Pilet, L. Ungur, V. V. Moshchalkov, W. Wernsdorfer, L. F. Chibotaru, D. Luneau, A. K. Powell, Chem. Sci,, 2012, 3, 1169-1176; (c) Ligand field variations: tuning the toroidal moment of Dy6 rings, A. Baniodeh, N. Magnani, S. Bräse, C. E. Anson, A. K. Powell, Dalton Trans. 2015, 44, 6343-6347.
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Dr. Federico Totti is currently an Associate
Researcher at University of Florence, Italy and
belongs to the LaMM (Laboratory of Molecular
magnetisM). His expertise are in Physical &
Computational Chemistry, Inorganic Chemistry, and
Materials Chemistry. He received his Ph.D in 2000
from University of Florence, Italy followed by FIRB
position at the same university (2005-2006). He has
published 50 peer-refereed international journals with
total impact factor if 338.87 on the following topics:
Molecular Orbital Theory applied to the study of the
reaction mechanisms of compounds containing Transition Metals and to the
description of the magnetic interaction in clusters containing Transition Metals
belonging to the first and second series; Description of excited states by DFT and
post-HF methods. Elaboration of Force Fields both for Periodic Systems and for
Isolated ones DFT characterization of electronic and magnetic interactions between
surfaces and magnetic clusters;DFT and P-DFT characterization on the structural,
electronic, and magnetic interactions between metallic and/or magnetic surfaces
and single molecule magnets He developed and/or he has in action scientific
collaborations with: Alessandro Bencini, Luigi Messori and Andrea Bencini
(University of Florence), Vincenzo Barone (Scuola Normale of Pisa), Piercarlo
Fantucci (University of Milano-Bicocca), MarcellaIannuzzi (University of Zurich),
Sebastian Loth (Max Planck Institute),Stefano Sanvito (Trinity College of Dublin),
Jean-Paul Costes and Boris Le Guennic (CNRS), Maria Vaz (University Federal
Fluminense), Miguel Novak (University of Rio de Janeiro), and Gopalan Rajaraman
(IIT of Mumbai). He has refereed for several internationally leading chemistry and
physics journals i.e. Nature Communications, Angewandte Chemie, Nanoscale,
Langmuir, Chemistry, Chemical Communications, Inorganic Chemistry, Physical
Review Letters and Physical Review B, and for European Institutions i.e. PRACE and
DFG.
[for more details: http://www.unifi.it/p-doc2-2015-0-A-2c2a352d332b-1.html]
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Molecular magnets and their journey fromisolated
clusters to self-assembled-monolayers: the key role of
computational methods
F. Totti , A. Lunghi, S. Ninova, G. Fernandez Garcia, and R. Sessoli
Dipartimento di Chimica “U. Schiff”, Sesto F.no, Italy
E-mail: [email protected]
The race to the miniaturization of electronical devices pushed the scientific communities to explore the amazing world at the nanoscale level. However, it is not easy to have a clear picture of properties and behaviors taking place at this lenght scale at the experimental level. Moreover, the necessity to have a fine tuning on them is becoming mandatory to substantially improve the nanodevice performances. In this framework, monolayers of magnetic molecules adsorbed on different types of surfaces showing ad hoc or novel properties have becoming more and more important in crucial fields as, for instance, spin valves,1 qubits for quantum computing2 or memory storage devices.3 However, to have an accurate structural and magnetic characterization of SMMs (Single Molecule Magnets) on a surface the synergic contributions of several experimental techniques supported by in silico approaches are required.4-9 In this framework, the key role of the computational methods will be illustrated presenting an overview of the recent results obtained to model and characterize the geometrical features and magnetic properties of SMM@surface through Density Functional approaches. Reerences
[1] Rocha, A. R.; García-Suárez, V. M.; Bailey, S. W.; Lambert, C. J.; Ferrer, J.; Sanvito, S. Nat. Mater., 4, 335–339 (2005).
[2] Wernsdorfer, W. Nat. Mater., 6, 174–176 (2007). [3] Mannini, M.; Pineider, F.; Sainctavit, P.; Danieli, C.; Otero, E.; Sciancalepore, C.; Talarico, A.
M.; Arrio, M.-A.; Cornia, A.; Gatteschi, D. et al. Nat. Mater., 8, 194–197 (2009) [4] M. Mannini, F. Pineider, C. Danieli, F. Totti, L. Sorace, Ph. Sainctavit, M.-A. Arrio, E. Otero, L.
Joly, J. C.Cezar, A. Cornia, and R. Sessoli, Nature, 468, 417 (2010). [5] A. Lunghi, M. Iannuzzi, R. Sessoli, F. Totti J. Mat. Chem. C, 3,7294-7304(2014). [6] S. Ninova, V. Lanzilotto, L. Malavolti, L. Rigamonti, B. Cortigiani, M. Mannini, F. Totti, R. Sessoli
J.Mat. Chem. C, 2, 9599 - 9608(2014). [7] L. Malavolti, V. Lanzilotto, S. Ninova, L. Poggini, I. Cimatti, B. Cortigiani, L. Margheriti, D.
Chiappe, E.Otero, P. Sainctavit, F. Totti, A. Cornia, M. Mannini, and R. Sessoli Nano Lett., 15, 535–541 (2015).
[8] A. Caneschi, D. Gatteschi and F. Totti Coord. Chem. Rev., 289-290, 357-378 (2015).
[9] G. Fernandez Garcia, A. Lunghi, F. Totti, R. Sessoli, J. Phys. Chem. Lett. Submitted (2016).
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Prof. Peter Comba is a Professor at the Institute of
Inorganic Chemistry, University of Heidelberg,
Germany. He obtained his Ph.D. in 1981 from the
University of Neuchatel, Switzerland. After postdoctoral
positions at the Australian National University and the
University of Lausanne and the habilitation at the
University of Basel, he moved in 1992 to Heidelberg.
He received the Humboldt South Africa Research Award
in 2000 and had visiting professorships at the
Universities of Leiden, ANU, Pretoria, Brisbane and
Osaka. His main Fields of interest include theoretical
inorganic chemistry, fundamental co-ordination chemistry, biomimetic nonheme
iron chemistry, halogenation of organic substrates, radiopharmaceutical chemistry,
co-ordination chemistry of cyclic peptides, purple acid phosphate model chemistry,
EPR spectroscopy, single-molecule magnetism.
[For more details: [http://www.uni-heidelberg.de/comba-group]
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Magnetic interactions in oligonuclear 3d-4f complexes –
synthesis, magnetism spectroscopy and theory.
Peter Comba
Universität Heidelberg, Anorganisch-Chemisches Institut andInterdisciplinary Center
for Scientific Computing (IWR), Im Neuenheimer Feld 270, 69120 Heidelberg,
Germany
http://www.uni-heidelberg.de/comba-group
Single-molecule magnets (SMMs) have sizable relaxation barriers between the two
degenerate states of opposite electron spin and therefore are of fundamental
interest and have also attracted attention for various possible applications. Reasons
for problems to design and prepare SMMs with accurately predicted and large
relaxation barriers are that the efficient and accurate theoretical description of the
magnetic anisotropy and its dependence from structure (magneto-structural
correlations) have only recently started to become available, and the prediction and
enforcement of coordination geometries of lanthanides are much less developed
than those of transition metal ions.
On the basis of three series of complexes (see Figure), the solid state structures,
magnetic and spectroscopic properties (MCD, HF-EPR and NMR) will be discussed
and used to validate a well-establishedcomputational scheme to compute the
electronic ground state, magnetic exchange and relaxation pathways, based on
broken symmetry DFT as well as on an ab initio CASSCFwavefunction, spin-orbit
coupling via the restricted active space state interaction method (RASSI) and an
analysis of the multiplet splitting derived from the Lines model and a ligand field
analysis involving extended Stevens operators.
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Dr. Helene Bolvin is a Senior Researcher at the Laboratorie de Chimie et de Physique Quantiques, Universite Paul Sabatier Toulouse, France. She obtained her Ph.D. in 1993 from the Université d’Orsay, France under the supervision of Olivier Kahn. After postdoctoral positions at the Laboratoire de Physique Quantiques Université Paul Sabatier, Toulouse, France, Institutt for kjemi Universitetet i Tromso, Norway and Laboratoire de Chimie Quantique Université de Strasbourg, France she moved to Toulouse,France. Her main Fields of interest is to calculate the magnetic properties of lanthanides and
actinides using first-principles methods including both correlation and relativistic effects: (SO-CASSCF, SO-CASPT2, SO-DDCI). Studied molecules include one or two heavy atoms as lanthanide or actinide. The calculated properties are compared to the experimental data, usually EPR parameters (g factors), magnetization and susceptibility curves.
For more details: [http://www.lcpq.ups-tlse.fr/spip.php?rubrique374&lang=eny/]
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Magnetic properties of actinide complexes probed by pNMR
spectroscopy : a theoretical contribution.
Matthieu Autillo†, Claude Berthon† and Hélène Bolvin*‡
†CEA, Nuclear Energy Division, RadioChemistry & Processes Department, DRCP,
France.
‡Laboratoire de Physique et de Chimie Quantiques, Université Toulouse 3, France.
e-mail: [email protected]
Paramagnetic NMR spectroscopy permits to probe the magnetic properties of
actinide complexes. The presence of a paramagnetic center modifies the NMR
spectrum and brings numerous informations about the structure and the bonding of
the complex. Two mechanisms determines this paramagnetic shift : the contact
shift which results from the spin polarisation through the bonding skeleton and the
pseudocontact term which is related to the anisotropic properties of the
paramagnetic center.
The Evans method permits to determine the magnetic susceptibility of the actinide
cation from the pNMR shift. In this presentation, we will analyze the susceptibility of
aqueous Ac(III), Ac(IV), Ac(V) and Ac(VI) complexes, both from experimental data
and from SO-CASPT2 calculations. For the Ac(III) and Ac(IV) complexes, we will
show that the magnetic susceptibility is smaller than the one expected from the LS
scheme due to different contributions : the coupling with exciting J states, the
delocalization of the magnetic density due to bonding, and mostly, to the large zero
field splitting leading to the non saturation of the magnetization at room
temperature. For Ac(V) and Ac(VI) complexes, we will show how the dependence in
temperature permits to determine the nature of the groudn state.
The differentiation between the contact and the pseudocontact terms is usually
performed through the tempearture dependence of the magnetization. This is based
on a work made by Bleaney in the 70's. We will question the availibility of this
model for the actinide complexes by interpolating experimental data and the
calculation of the model parameters by SO-CASPT2 in a series of dipicolinate
complexes of both lanthanide and actinide complexes.
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Dr. Mark Murrie FRSC is a Professor at the
University of Glasgow, UK. He obtained his Ph.D.
from the University of Manchester, UK. His research
interests are in the synthesis and characterisation of
molecular materials and nanomaterials that display
novel magnetic, optical or switching properties and
have huge potential applications. These can be
broadly split into three areas: a) Molecular
nanomagnets / single-molecule magnets; b)
Nanomaterials (d- and f-block metal oxides); c) The
effect of high pressure on molecular materials.
[For more details: http://www.chem.gla.ac.uk/staff/markm/]
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Probing the magnetic anisotropy in trigonal bipyramidal 3d
single-ion magnets
Mark Murrie*
WestCHEM, School of Chemistry, University of Glasgow, G12 8QQ (UK)
e-mail: [email protected]
The ability to control and increase magnetic anisotropy is one of the key targets in
the development of single-molecule magnets. Monometallic complexes of
paramagnetic transition metal ions in certain coordination environments can exhibit
appreciably enhanced magnetic anisotropy due to stabilisation of an unquenched
orbital moment.[1] This behaviour is complex, with symmetry, coordination
geometry, crystal field, ligand donor strength, crystal packing and intermolecular
interactions all contributory factors.[2][3]
High-field EPR studies of [Ni(MDABCO)2Cl3]ClO4 (1, MDABCO+ = 1-Methyl-4-aza-1-
azoniabicyclo[2.2.2]octanium cation) give an axial zero-field splitting parameter (D)
in the range from −400 to −535 cm−1.[4] This unprecedented giant magnetic
anisotropy arises because of the combination of large Cl ligands in the equatorial
positions along with rigid, bulky MDABCO+ ligands in the axial positions. These
prevent Jahn-Teller distortions away from trigonal geometry which would lead to a
quenching of the first order spin-orbit coupling.[5]
We have begun to examine the correlation between structure and magnetic
properties in {Ni(II)-RDABCO} systems via the use of applied hydrostatic pressure.
Comparison of the pressure response in these systems will reveal whether Jahn-
Teller distortions can be induced and how this is influenced by crystallographic
symmetry. These studies, when combined with high-pressure magnetic and high-
pressure high-field EPR studies, will allow us to gain a much deeper understanding
of the factors controlling both the magnetic anisotropy and the unwanted under
barrier relaxation mechanisms.
References
[1] Gomez-Coca, S.; Cremades, E.; Aliaga-Alcalde, N.; Ruiz, E. J. Am. Chem. Soc. 2013, 135,
7010.[2] Freedman, D. E.; Harman, W. H.; Harris, T. D.; Long, G. J.; Chang C. J.; Long, J. R. J. Am.
Chem. Soc.2010, 132, 1224.[3] Craig, G. A.; Murrie, M. Chem. Soc. Rev.2015, 44, 2135. [4]
Marriott, K. E. R.; Bhaskaran, L.; Wilson, C.; Medarde, M.; Ochsenbein, S. T.; Hill, S.; Murrie, M.
Chem. Sci.2015, 6, 6823.[5] Gruden-Pavlović, M.; Perić, M.; Zlatar, M.; García-Fernández, P. Chem.
Sci. 2014, 5, 1453.
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Dr. Sambhu N. Datta is a Professor Emeritus at
IIT Bombay, India, with expertise in Theoretical
Chemistry. He received his Ph.D. degree from
University of Virginia, USA in 1976. It was followed
by post-doctoral works in University of Utahin 1976
and Vanderbilt University in 1977. Since 1978 he has
been in IIT Bombay. He has published more than 100
articles and reviews in peer reviewed international
journals and written several book chapters. His
research has been focused in three areas, namely,
(a) Aspects of Relativistic Quantum Chemistry:
Minmax principle; exact solutions; relativistic Hamiltonian operator (b) Molecular
magnetism:Magnetic molecules; magnetic molecular crystals and polymers;organic
ferromagnets, super-paramagnets and spin-glass; silicon based polyradicals;
photo-magnetic molecules and spin crossover; ferromagnetic and antiferromagnetic
molecular solids (c) Aspects of photosynthesis: exciton-phonon coupling; energy
migration; growth rate of green plants; electron transfer reactions involved in Z-
scheme.
[for more details : http://www.chem.iitb.ac.in/people/Faculty/prof/snd.html]
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Organic Molecular Magnets – A Reality Sambhu N. Datta*
Chemistry Department, Indian Institute of Technology Bombay, Powai, Mumbai E-mail: [email protected]
Molecule-based magnets have recently grown in importance in the fields of magneto-optics and spintronics. Organic magnetic materials are usually synthesized by molecular engineering that often leads to fancier properties [1]. Mataga was the first to predict ferromagnetic coupling in repeating radical systems [2]. Yoshizawa and Hoffmann contended that certain paradoxical requirements are necessary for ferromagnetic interaction between unpaired electrons [3]. Matsuda and Iwamura demonstrated the preparation of super high-spin radicals by attaching radical centers to pi-conjugated polymers [4]. Rajca et al. have synthesized several high-spin polyradicals at ambient conditionsto obtain the desired spin states [5], such as poly-xylylene radicals, Schlenk radicals, and macrocyclic ring based organic super-paramagnets and even spin-glass. Aqualitative understanding of these spin systems is obtained from Spin Alternation rule in UDFT [6] while a quantitative rationalization requires calculations involving the broken symmetry methodology [7]. Radical length and coupler aromaticity are important factors for the design of molecular magnets. Quantum chemical calculations have so far identified a large number of ferromagnets [8]. These are to be discussed here.
Spin can be controlled through structure such as by ensuring translational
periodicity [2] with proper intermolecular magnetic interaction [3], or by an external stimulus that is photo-induced, electrochemical, and thermal or pressure-induced, and also often by chemical treatments like doping. Exotic examples of the external control include spin state change on excitation [9], photo-magnetism that is based on the photochromic effect [10], redox-modulated spin change [11], and even spin crossover in organic systems. Our theoretical studies on some of these phenomena[12] will be discussed.
References: 1. Datta, S.N.; Trindle, C.O.; Illas, F. Theoretical and computational aspects of magnetic organic molecules, 1st edition, Imperial College
Press, London, 2014.2. Mataga, N. Theoret. Chim.Acta1968, 10, 372.3. Yoshizawa, K.; Hoffmann, R. Chem. Eur. J. 1995, 1, 403.4. Matsuda, K.; Iwamura, H. Current Opinion in Solid State Materials Science1997, 2, 446.5. (a) Rajca, A.; Rajca, S.; Desai, S. R. J. Am. Chem. Soc.1995, 117, 806. (b) Rajca, A.; Wongsriratanakul, J.; Rajca, S. J. Am. Chem. Soc.2004, 126, 6608.6. Trindle, C.; Datta, S.N.; Mallik, B. J. Am. Chem. Soc. 1997, 119, 12947.7. (a) Noodleman, L.; Baerends, E. J. J.Am. Chem. Soc. 1984, 106, 2316. (b) Noodleman, L.; Peng, C.Y.; Case, D. A.; Mouesca, J. M. Coord. Chem . Rev. 1995, 144, 199.8. (a) Ali, Md. E.; Datta, S.N.; J. Phys. Chem. A 2006, 110, 13232. (b) Pal, A. K.; Datta, S. N. J. Phys. Chem. C2014, 118, 27599. (c) Hansda, S.; Pal, A. K.; Datta, S. N. J. Phys. Chem. C, 2015, 119, 3754. (d) Pal, A. K.; Hansda, S.; Datta, S. N. J. Phys. Chem. A 2015, 119 (10), 2176. (e) Pal, A. K.; Kumar, A.; Datta, S. N. Chem. Phys. Lett. 2016, 648, 189.9. Teki, Y.; Miyamoto, S.; Nakatsuzi, M.; Miura, Y. J. Am. Chem. Soc.2001, 123, 294.10. Boggio-Pasqua, M.; Bearpark, M. J.; Robb, M. A. J. Org. Chem. 2007, 72, 4497. 11. Ito, A.; Kurata, R.; Sakamaki, D.; Yano, S.; Kono, Y.; Nakano, Y.; Furukawa, K.; Kato, T.; Tanaka, K. J. Phys. Chem. A. 2013, 117, 12858.12. (a) Saha, A.; Latif, I. A.; Datta, S. N. J. Phys. Chem. A 2011, 115, 1371. (b) Sadhukhan, T.; Hansda, S.; Latif, l. A.; Datta, S. N. J. Phys. Chem. A 2013, 117, 13151. (c) Sadhukhan, T.; Dutta, A.; Datta, S. N. J. Phys. Chem. A 2015, 119, 9414. (d) Sadhukhan, T. Ph.D. Dissertation, IIT-Bombay, 2015 (Supervisors: Dutta A. and Datta, S. N.).
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Dr. Anirban Misra is a Professor of Chemistry at University of North Bengal, India. He received his Ph.D from IIT Bombay followed by post-doctoral position in Texas A & M University at Galveston before moving to Bengal, India. He received IBM-Lowdin Award at Sanibel 2003. He has published papers in several peer-refereed international journals and written a book chapter. His research interest include theoretical chemistry and quantum chemistry.
[For more details: http://northbengal.academia.edu/AnirbanMisra]
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Quantification of Magnetic Interaction through Spin
Topology
Anirban Misra Department of Chemistry, University of North Bengal, Darjeeling 734013, India
Email: [email protected]; Phone: +919434228745
A simple formalism is developed to quantify the interaction among unpaired
spins from the ground state spin topology[1]. Magnetic systems where the spins
are coupled through direct exchange and superexchange are chosen. Starting from
a general Hamiltonian, an effective Hamiltonian is obtained in terms of spin density
which is utilized to compute exchange coupling constants in magnetic systems
executing direct exchange. On the other hand, a perturbative approach is adopted
to address the superexchange process. Spin transfer in between the sites in the
exchange pathway is found to govern the magnetic nature of a molecule executing
superexchange. The metal-ligand magnetic interaction is estimated using the
second order perturbation energy for ligand to metal charge transfer and spin
densities on the concerned sites. Using the present formalism, the total coupling
constant in a superexchange process is also partitioned into the contributions from
metal-ligand and metal-metal interactions. Sign and magnitude of the exchange
coupling constants, derived through the present formalism, are found to be in
parity with those obtained using well-known spin projection technique. Moreover, in
all the cases the ground state spin topology is found to complement the sign of
coupling constants. Thus, the spin topology turns into a simple and logical means to
interpret the nature of exchange interaction. The spin density representation in the
present case resembles McConnell’s spin density Hamiltonian and in turn validates it [2]. Through this formalism the metal-ligand interaction is estimated in systems
like Mn2O¯, Cr2O¯ and Cu2Cl6
2– where the superexchange is operative. Among these
three, Cu2Cl62– has confronted several ab initio studies, which accurately estimates
exchange-coupling constants. This approach is further tested on a few charge
transfer complexes [3, 4] and again these rigorously obtained values and the
experimental results are found to be concordant with the coupling constant values
estimated through our approach and hence solicits for the present theoretical
construction.
References
[1] Paul, S.; Misra, A. J. Chem. Theory Comput. 2012, 8, 84.
[2] McConnell, H. M. J. Chem. Phys.1963, 39, 1910.
[3] Shil, S.; Paul, S.; Misra, A. J. Phys. Chem. C 2013, 117, 2016.
[4] Goswami, T.; Paul, S.; Misra, A. RSC Adv. 2014, 4, 14847.
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Dr. Nayanmoni Gogoi is currently working as
Assistant Professor at Tezpur University, India. He
received his Ph.D. from IIT Bombay followed by post-
doctoral studies in LCC, Toulouse before moving to
Tezpur, Assam, India. His primary research goal is to
develop Single Molecule Magnets which show slow
relaxation of magnetization at higher temperatures.
For this purpose, they design molecules with large
uniaxial anisotropy and strong magnetic exchange
interaction. Apart from the above, Dr. Gogoi’s
research group is also working towards the
development of robust Metal Organic Frameworks as heterogeneous catalyst for
important chemical transformations.
[For more details: http://tezu.ernet.in/dcs/people/faculty/~ngogoi/index.htm]
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Modulation of Coordination Environment: A Convenient
Approach to Tailor Single Ion Magnetic Anisotropy
Mamon Dey and Nayanmoni Gogoi
Department of Chemical Sciences, Tezpur University, Napaam, Sonitpur, Assam-
784028
e-mail: [email protected]
Control of magnetic anisotropy has emerged as a highly formidable challenge that needs to be addressed for effectively increasing the energy barrier for magnetization reversal in Single Molecule Magnets. During this presentation, a unique, convenient and rational approach to modulate single ion anisotropy in high coordinate complexes in a predetermined way by simple and subtle modification of the coordination environment will be elaborated. This approach to modulate magnetic anisotropy is based on dictating the contribution of second order perturbation to spin–orbit coupling through rationally controlling the mixing of ground state with orbitally degenerate excited states. It is shown that, by appropriately changing the energy of the excited states involved in spin-orbit coupling through rational modification of coordination environment, the axial zero field splitting parameter of seven coordinate cobalt complexes can be changed in a predetermined fashion.
References
[1] Neese, F.; Pantazis, D. A. Faraday Discuss.2011, 148, 229.
[2] Waldmann, O. Inorg. Chem.2007, 46, 10035.
[3] Dey, M.; Gogoi, N. Angew. Chem. Int. Ed.2013, 52, 12780.
[4] Dey, M.; Dutta, S.; Sarma, B.; Deka, R. C.; Gogoi, N. Chem. Commun., 2016, 52, 753-756.
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Dr. A. K. Tyagi is presently heading the Solid State
Chemistry Section, Chemistry Division, BARC and is
also a Professor at HBNI. He received his PhD from
Mumbai University and did postdoctoral research from
Max-Planck Institute, Stuttgart, Germany. He has
published large number of papers in international
journals and written several book chapters. His
research interests are in the field of nanomaterials,
functional materials and nuclear materials. In
recognition of his work, he has been conferred with
several awards such as Homi Bhabha Science &
Technology Award, MRSI Medal, CRSI Medal, INS Gold Medal, RajibGoyal Prize,
Prof. CNR Rao National Prize in Chemical Sciences and MRSI-ICSC senior award. He
is a Fellow of National Academy of Sciences, Indian Academy of Sciences and Royal
Society of Chemistry
[For more details: http://www.hbni.ac.in/faculty/BARC/barcm_chem_tyagi_ak.html]
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Functional inorganic magnetic materials: Synthesis, structure and applications
A. K. Tyagi
Chemistry Division,
Bhabha Atomic Research Centre
Mumbai - 400 085, India
(Email: [email protected])
Functional materials have assumed prominent position in several areas. Such
materials are not classified on the basis of their origin, nature of bonding or
processing techniques but are classified based on the functions which they can
perform. This is a significant departure from the earlier schemes in which materials
were described as metals, alloys, ceramics, polymers, glass etc. The synthesis of
such materials has been a challenge and also an opportunity to chemists. New
functional materials can be designed by interplay of synthesis protocol and
crystallographic structure. In my group various functional materials are being
designed by interplay of synthesis and crystallographic structure. The role
preparation and structure, in particular size, doping and defects on magnetic
properties of materials will be explained in this talk. The role of chemical bonding
on magnetic properties will be focused. Some typical materials which will be
discussed in are La1-xCexCrO3, RECrO3, CeScO3 and RECrO4 (RE = rare-earths).
Some recent results on double perovskites will also be discussed. The effect of size
confinement on magnetic properties of some of these materials will also be
discussed. Recent results on several applications of magnetic materials in drug
delivery, hyperthermia and separation will be briefly covered.
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Dr. Prasanna Shridhar Ghalsasi is a Professor at MS University of Baroda, India with expertise in Materials Chemistry. He received his Ph.D from University Department of Chemical Technology, Mumbai followed by post-doctoral position in USA and Japan for ~4-5 years before moving to Baroda. He has published several peer-refereed international journals. He is keenly interested in chemistry education (Olympiad activity) and undergraduate research.
[For more details: [http://www.msubaroda.ac.in/faculty.php?action=show_staff_detail&id=201]
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Environmentally Conscious Structures: Designing
Molecular Magnets
Prasanna S. Ghalsasi, Hemant M. Mande, Ashok K. Vishwakarma
Department of Chemistry, Faculty of Science, The M. S. University of Baroda, Vadodara Gujarat, India. 390 002.
Email: [email protected]
Designing of materials has always remained at the realm of synthetic scientific research. Traditionally, design strategies are based on our surrounding nature, and/or living systems. Today we are surrounded by ‘pollution’!
Porous Structures-storage: HCl gas was main byproduct during Leblank process in late 1800 century, chlor-alkali industry. HCl gas was vented directly into an atmosphere in those days thus triggering concept of environmental safety. This has resulted in the use of concept of ‘sorption’ of gases at industrial level. Sorption requires porous structures, which were found in coal, and minerals. This has started emergence in designing of porous structures. The designing development was not limited to activated charcoal but many inorganic structures in zeolite to purely organic structures for energy crisis.
Non-porous structures-function: I will present my group’s work in designing of molecular magnets using today’s surrounding! In this direction we designed non-porous solid structures for ‘sorption’ of environmental waste from gases as well as liquids. Sorbed structures imparted technologically important properties. These structures are based on Cu(II) complexes. The ‘sorption’ at solid-state not only removes environmentally toxic gases such as ‘HCl’ but also removes ‘azide’ from liquid, as shown in scheme-1. More interestingly, the ‘sorbed’ structures showed ‘selectivity’, ‘molecular recognition’ along with interesting magnetic behavior which will be discussed in detail.
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Invited Chair Person
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Dr. Sourav Pal is presently a Professor (HAG) in
IIT Bombay, Mumbai, India. He received his PhD
from IACS Kolkata before moving to NCL, Pune, India
as Scientist. He had his post-doctoral research
experience from University of Florida, USA and
University of Heidelberg, Germany. He has published
about 250 papers in internationally peer-reviewed
journals and guided about 30 PhD thesis. Apart from
research, he has been involved with several
administrative responsibilities at NC: and scientific
decision making in the country. He eventually
became the Director of NCL, Pune. His research interests are in the field of Frontier
Theoretical Development on Molecular Electric Properties, Theoretical investigation
of Hard-Soft Acid-Base relation, study of electron-molecule scattering as well as
resonance and molecular decay, development and application of molecular
dynamics and density functional response approach for molecular properties. He is
recognized as a leader in the above areas and has delivered several invited/
keynote/ plenary lectures in international conferences. In recognition of his work,
he has been conferred with several awards such as Shanti Swarup Bhatnagar Prize,
SASTRA-CNR Rao Award, Sadhan Basu Memorial lecture award of INSA, CRSI Silver
Medal, Bimla Churn Law memorial Lecture Award, RPG Life Sciences Padma
Vibhushan Prof M M Sharma Medal, and various others. He has also delivered
Charles A Coulson lecture of University of Georgia USA. He is DST J C Bose National
Fellow and a Fellow of Indian National Science Academy, Indian Academy of
Sciences, National Academy of Sciences and Royal Society of Chemistry. A special
issue of Molecular Physics was published in his honor on his 60th birthday in the
year 2015. He is currently the President of CRSI is elected as a member of the
Exceutive Council of Federation of Asian Chemical Societies. He is also a
Distinguished Visiting Professor of IIT Kharagpur.
[for more details: http://www.chem.iitb.ac.in/people/Faculty/prof/spal.html]
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Dr. M. S. Balakrishna is presently a Professor in IIT
Bombay, Mumbai, India. He received his PhD from
IISc Bangalore, India. He then did his post-doctoral
studies from Canada and USA before moving to
Bombay. His research interests are designing new
mutlifunctional, multidentate phosphorus, nitrogen
and silicon based ligands, organo phosphorus
compounds and the transition metal organometallic
chemistry, designing new type of water soluble
phosphine ligands for medicinal and catalytic studies,
Inorganic rings, cages and clusters and their
transition metal chemistry, Inorganic materials and polymers, Thermo chemical and
electrochemical studies of phosphine bound organometallics, Homogeneous
catalysis and Spectroscopy.
[for more details: http://www.chem.iitb.ac.in/people/Faculty/prof/msb.html ]
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Dr. Debabrata Maiti is presently an associate
Professor in IIT Bombay, Mumbai, India. He received
his PhD from John Hopkins University, USA and post-
doctoral studies from MIT, USA before moving to
Mumbai. He has published several internationally
peer-reviewed journals with high impact factor. His
research interests are a) Metal catalyzed C-H
activation b) C-H functionalization c) Metal mediated
defunctionalization and d) Bio-inspired catalysis. He is
recipient of several awards i.e. a) Alkyl Amines
Young Scientist Award b) INSA-Young Scientist Award
c) ISCB Young Scientist Award d) AVRA Young Scientist Award, e) CRSI Young
Scientist Award, 2014 f) Thieme Chemistry Journal Award, 2013 g) IIT Bombay-
IRCC Young Scientist Award, 2013
[for more details: http://www.chem.iitb.ac.in/~dmaiti/index.html]
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Dr. Prasenjit Ghosh is presently a Professor in IIT
Bombay, Mumbai, India. He received his PhD from
Columbia University, USA. He has published several
internationally peer-reviewed journals with high
impact factor. His research interests are designing
"molecules with purpose", his research aims at
discovering new catalytic or biomedical applications of
organometallic complexes particularly of the N-
heterocyclic carbenes. Through this endeavor, they
also intend to obtain an understanding of the key
attributes of the N-heterocyclic carbene ligands that
are largelybehind their unprecedented success in homogeneous catalysis. He is
recipient of several awards i.e. i) CRSI Bronze medal ii) Miller Teaching Award iii)
RSC West India Young Scientist Award iv) Ajit Memorial Lecture Award.
[for more details: http://www.chem.iitb.ac.in/~pghosh/index.html]
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Prof. P. Venuvanalingam is currently a CSIR
Emeritus Scientist at School of Chemistry,
Bharathidasan University, Tiruchirappalli, India. He
obtained his Ph.D. degree in 1982 from Madurai
Kamaraj University, Madurai. He joined Madurai
Kamaraj University P. G. Centre, Tirunelveli as
Lecturer in Physical Chemistry in 1982 and moved to
Bharathidasan University in 1988 as Reader. He
became a full Professor in 1994 and then elevated as
Senior Professor in 2013 and retired in that year. He
was UGC Emeritus Fellow in the same Institution for
one year in 2014. He was awarded Tamil Nadu Best Scientist Award for Chemical
Sciences in 2000 for his contributions in Computational Chemical Graph Theory and
Weak Interactions. He has guided 15 PhDs and currently three are working for PhD.
He has operated 8 funded projects, published so far 123 papers in peer reviewed
journals including two book chapters and delivered more than 100 invited lectures
in India and abroad. He has several research collaborations within and outside India
and is a reviewer for ACS, RSC and Elsevier Journals. He has Guest Edited an issue
of J.Chem.Sci. published by the Indian Academy of Sciences in 2007. He is basically
a theoretical and computational chemist and has research interests in Modeling
Reaction Intermediates and Transition States, Reactions in Solution and
Catalysis and Bio-catalysis, Weak Interactions, Host-Guest Chemistry,
Computational Bioinorganic and Oraganometallic Chemistry, Computational
Chemical Graph Theory and Artificial Intelligence.
[for more details:
http://www.bdu.ac.in/schools/chemistry/chemistry/dr_p_venuvanalingam.php]
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Dr. C. P. Rao is an Institute Chair Professor in the
Department of Chemistry, IIT Bombay. He received
his PhD from IISc., Bangalore, and post-doctoral
training from Harvard University and MIT, USA before
moving to IIT Bombay. His research interests are
Bioinorganic and Supramolecular Chemistry of
Carbohydrate- and Calix[n]arene based scaffolds,
Nano structures, Protein/enzymes &
isolation/purification, metallation of proteins and
metal-protein nanoparticles, and Computational
docking studies of the conjugates of carbohydrates
with lectins and glycosidases. He is recipient of J.C. Bose National Fellowship,
Bronze Medal of CRSI. He is a fellow of Indian National Science Academy, Indian
Academy of Sciences, Bangalore, National Academy of Sciences, Allahabad and
Andhra Pradesh Academy of Science.
[for more details: http://www.chem.iitb.ac.in/~cprao/index.html]
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Dr. H. B. Singh is a Professor in IIT Bombay, India.
He received his PhD from Lucknow University. He
worked as Postral Fellow in Aston University,
Birmingham, Engalnd. His research interests are
design, synthesis and structural studies of novel
organometallic derivatives of sulphur, -selenium and -
tellurium as well as their applications. He is recipient
of several awards and fellowships i.e. Ramanna
Fellowship, J C Bose National Fellowship, CRSI Silver
Medal 2012 etc.
[for more details: http://www.chem.iitb.ac.in/~chhbsia/webpage/home.htm]
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Prof. Raghavan B. Sunoj received his Ph.D. from the Indian Institute of Science Bangalore. After a couple of years of postdoctoral research at the Ohio State University (USA), he returned to India in 2003 as an assistant professor in the department of chemistry, IIT Bombay. He was promoted to a full professor in 2012. He is an elected member of the board of World Association of Theoretical and Computational Chemists (WATOC) and a fellow of the Royal Society of Chemistry (London). He has won several national awards as well as the excellence in
teaching award from the IIT Bombay. He has published well over hundred research papers in the area of reaction mechanism and asymmetric catalysis. His current research interests are in the domain of computational organic chemistry with emphasis on transition state modeling in asymmetric catalysis, mechanisms of multi-catalytic reactions, and computational design of catalysts.
[For more details: http://www.chem.iitb.ac.in/~sunoj]
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Dr. Swapan K. Ghosh is currently Raja Ramanna
Fellow at BARC and was earlier Head of Theoretical
Chemistry Section, BARC, Mumbai, India. He is also
Senior Professor at HBNI, Mumbai, and adjunct
Professor at UM-DAE-Centre for Excellence in Basic
Sciences, Mumbai. His research interests include
Theoretical and Computational Chemistry,
Computational Materials Science, Soft Condensed
Matter Physics, Density Functional Theory and Muti-
scale Modeling of Molecules and Materials,
Nanomaterials, Dynamical Processes in Solution, etc.
He is recipient of several awards including the Third World Academy of Sciences
(TWAS) prize in Chemistry, CRSI silver medal, A.V.Rama Rao Prize, etc. He is a
Fellow of TWAS, Trieste, Indian Academy of Sciences, Bangalore, Indian National
Science Academy, New Delhi, and National Academy of Sciences, Allahabad. .
[for more details:
http://www.hbni.ac.in/faculty/BARC/barc_chem_ghosh_swapan.htm]
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Dr. Sailaja S. Sunkari is an Assistant Professor in
the Department of Chemistry, Mahila Mahavidyalaya,
Banaras Hindu University, India. She obtained her
Ph.D from Hyderabad Central University in 2003 and
did her JSPS Post-doctoral studies from The University
of Tokyo, Tokyo. Her research interests are in the
fields of Supramolecular chemistry, Molecule based
magnetism and small molecule crystallography.
[for more details:http://www.sailajasunkari.com/Dr.%20SailajaS.%20Sunkari.html]
IIT Bombay MTMM 2016
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IIT Bombay MTMM 2016
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Name Institute
Amaleswari Rasamsetty University of Hyderabad, India Asha Roberts Heidelberg University, Germany Martin Amoza Dávila University of Barcelona, Spain Mithun Chandra Majee IACS Kolkata, India Mukesh Kumar Indian Institute of Technology Bombay, India Ritwik Modak University of Calcutta, India Sabyasachi Roy Chowdhury Indian Institute of Technology Kharagpur, India Sandeep K. Gupta Indian Institute of Technology Bombay, India Shashi Kant Indian Institute of Technology Kanpur, India Shefali Vaidya Indian Institute of Technology Bombay, India Shuvankar Mandal University of Calcutta, India Soumava Biswas IISER Bhopal, India Sourav Biswas Indian Institute of Technology Kanpur, India Tamal Goswami University of North Bengal, India
Student Presentations
94
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Poster Presentations
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Poster
No. Name Title
Page
No.
P1 Sailaja S. Sunkari Novel 3d Metal - Schiff base Supramolecular Systems for Magnetic Applications
99
P2 Amaleswari Rasamsetty
Synthesis, Characterization and Magnetic properties of Tetranuclear and Dinuclear Ln(III) Complexes
100
P3 Sudeshna Bhattacharya
Pyridine-Pyrazole Based Lanthanide Organic Frameworks (Ln = GdIII and DyIII ) Showing Magnetocaloric Effect and Single Molecular Magnetic Behavior
101
P4 Shuvankar Mandal A Series of MIICuII
3 Stars (M = Mn, Ni, Cu, Zn, Cd) Exhibiting Unusual Magnetic Properties
102
P5 Sandeep K. Gupta An Air-Stable Dy(III) Single-Ion Magnet with High Anisotropy Barrier and Blocking Temperature
103
P6 Ritwik Modak Family of MnIII
4LnIII2 (LnIII= SmIII, GdIII, DyIII)
coordination clusters: experimental and theoretical investigations
104
P7 Arun Kumar Bar Mononuclear Complexes as Ising−Type Anisotropic Building Units to Construct Single Molecule Magnets
106
P8 Dhrubajyoti Mondal
Pentametallic ‘Bowl’-Shaped Nickel(II) Complexes Involving Pyrazolido- Bridge in a Rare 3-η
1:η1:η1 Mode: Synthesis, Crystal Structures and Magnetic Properties
107
P9 Tamal Goswami Electric field modulation of magnetic anisotropy of a series of first row transition metal complex
108
P10 Soumya Mukherjee
Influence of Tuned Linker Functionality on Modulation of Magnetic Properties and Relaxation Dynamics in a Family of Six Isostructural Ln2 (Ln=Dy, Gd) Complexes
109
P11 Vijay Singh Parmar
Tetrahedral CoII based binuclear double-stranded helical single-ion-magnet
110
P12 Mithun Chandra Majee
Pentanuclear 3d−4f Heterometal Complexes of MII
3LnIII2 (M = Ni, Cu, Zn and Ln = Nd, Gd, Tb)
Combinations: Syntheses, Structures, Magnetism, and Photoluminescence Properties
111
P13 Manasi Roy
Systematic study of mutually inclusive influences of temperature and substitution on the coordination geometry of Co(II) in a series of coordination polymers and their properties
112
P14 Anoop Kumar Gupta
Magnetic Properties of Metal−Organic Hybrid Materials of Co(II) Using Flexible and Rigid Nitrogen Based Ditopic Ligands as Spacers
114
P15 Arun K. Pal
Geometrical Structure of meta-Xylylene Based Asymmetric and Symmetric Polyradicals and their Magnetic Nature: A Density Functional Study
115
P16 M.Deepankumar Computational Design Of Ionic Liquids Based Catalysts For Pechmann Condensation Reaction
116
P17 Sukhen Bala
Construction of Polynuclear Lanthanide (Ln= DyIII, TbIII and NdIII) Cage Complexes using Pyridine-Pyrazole based ligands: Versatile Molecular Topologies and SMM behavior
117
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Poster
No. Name Title
Page
No.
P18 Soumava Biswas Squarato-bridged Gadolinium Based Metal−Organic Frameworks (MOFs) for Efficient Magnetic Refrigeration
118
P19 Debashis Saha
Field-Induced Single-Ion-Magnetic Behaviour of Octahedral CoII in a Two Dimensional CoordinationPolymer
119
P20 Mukesh Kumar Singh
Weak Intermolecular Interaction As A Tool For The Generation Of Single Molecular Magnets: Going From Traditional To Non-traditional Molecules
120
P21 Bijoy Dey A ferromagnetically coupled squashed Ni4( 3-OCH3)4 cubane based 3D metal organic framework
121
P22 Manoj Majumder A Theoretical study on the polyfunctional materials based on organic diradicals
122
P23 Asha Roberts Experimental Verification of Computational Methods to Describe the Magnetic and Electronic Properties of SMM Systems
123
P24 Chitranjan Sah Bimolecular reactions of pyridine and pyridine-N-oxide radicals with small molecules
124
P25 Murugesan Panneerselvam
Theoretical investigations on the Kinetic Aspects of Anation Mediated Hydrogen Oxidation by Pentapyridyl Metal Complexes
125
P26 Mayank Saraswat A Theoretical Investigation on the Unimolecular Decomposition Pathways of Pyridine and Pyridine-N-oxide Radicals
126
P27 Nicheal Michael Kaley
Finding Exchange couplings for a series of 3d Transition Metals Tetramers
127
P28 Sourav Biswas Compartmental ligand based Polynuclear Ensembles having 3d/4f metal ions: Single Molecule Magnet property
128
P29 Lilit Jacob Electronic structure of pyridine and pyridine-N-oxide radicals
129
P30 K. Jagan Catalyst for Hydrogen Generation and Storage From Formic Acid Decomposition
130
P31 Sabyasachi Roy Chowdhury
Magnetic Anisotropy Barriers in Linear Transition Metal Complexes
131
P32 Apoorva Upadhyay Enhancing Anisotropic Energy Barrier of Lanthanide by Exploiting A Diamagnetic Zn(II) Ion
132
P33 Rashmi Gupta Design and development of magnetic nanomaterials based on multichelating ligand functionalized MWCNTs
133
P34 Shefali Vaidya Control of Magnitude and Sign of Magnetic Anisotropy in Co(II) tetrahedral complexes by Synthetic approach
134
P35 Naushad Ahmed
Magnetic exchange coupling influencing the SMM properties of Nickel(II)-Lanthanide(III) complexes and making Ferric wheel {Fe8} complex for a precursor of Qubit
135
P36 Tulika Gupta Deciphering Prerequisites To Fine Tune Energy Barrier and Exchange Harnessing Theoretical Tools
136
P37 Arup Sarkar Ab-initio Studies On The Spin Hamiltonian Parameters Of First Row Mononuclear Transition Metal Complexes
138
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Poster
No. Name Title
Page
No.
P38 Shashi Kant Magnetostructural Aspects of Polynuclear complexes of Carboxylate-Appended (2-Pyrydyl)alkylamines
139
P39 Archana Velloth Theoretical study on Co mononuclear and dinuclear complexes toward exploring single molecular magnets
140
P40 Martin Amoza Theoretical study of low spin (S=1/2) single-ion magnets
141
P41 Priyanka Pandey Structural and Magnetic Studies of Copper – Azido Assemblies with Symmetric Amines
142
P42 Vignesh R Kuduva Heterometallic 3d-4f Single Molecule Magnets: Experiment and Theory
143
P43 T. Rajeshkumar Ab-intio Calculations on Heterometallic {Ln-Ln’} Complexes for Quantum Information Processing
144
P44 Subrata Tewary Spin-State Energetics and Spin Crossover Phenomena in Octahedral Fe(II) Complexes- Through DFT and Ab initio CASSCF Studies
145
P45 Mursaleem Ansari Oxidation of methane by an N-bridged high-valent diiron–oxo species: electronic structure implications on the reactivity
146
P46 Pragya Shukla Role of first row transition metal in modification of exchange interaction with the Lanthanide ions
147
P47 Shalini Tripathi Synthesis and characterization of Phosphorous based monomeric Cobalt complexes
148
P48 Mohd Waseem Macrocyclic Schiff base-Lanthanide complex SMMs for molecular spintronics application
149
P49 R.Ranjith Synthesis of nano sized TiO2 and its application in Adsorption removal of methylene blue and Antimicrobial activity
150
P50 A.G.Bharathi Dileepan
Synthesis and Characterization of N-Heterocyclic Carbene Dinuclear Silver(I) and Copper(I) Complexes
151
P51 Rajesh kumar M. Synthesis, Characterization and Photoluminescence Properties of Cu(II), Ni(II), Co(II), and Zn(II) Complexes of Isatin Derivatives
152
P52 Senthamizh Selvan
Phytochemical Screening, GC-MS Analysis and Pharmacological Activity of Shuteria Involucrata
153
P53 S.Steplin paul Selvina
Structurally Engineered Cysteine Capped ZnO/GO Nanocomposites for Photocatalytic Degradation of Rhodamine B under Visible Light
154
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Novel 3d Metal - Schiff base Supramolecular Systems for
Magnetic Applications
Sailaja S. Sunkari*a, Nidhi Dwivedi,a,b Priyanka Pandeya
aDepartment of Chemistry, Mahila Mahavidyalaya, Banaras Hindu University bDepartment of Chemistry, Institute of Science, Banaras Hindu University
Varanasi 221 005 [email protected]
Research in the domain of transition metal supramolecular assemblies is intriguing as they offer myriad applications in fields as diverse as biology, physics, chemistry, materials, theory etc. Molecular magnetism is one core application of transition metal assemblies, with wide range of applications as in quantum computing, magnetic refrigeration, molecular electronics, high density information storage and so on, of contemporary relevance. The ease in tunability of the magnetic properties by structural modification, coupled with increased access to SQUID magnetometers worldwide has resulted in increased research contributions in this field of molecular magnetism in recent years. Among the diverse type of ligands used to assemble metal ions, schiff bases and pseudo halides are most popular in magneto chemistry. Owing to their versatile coordinating tendencies, it is not easy to predetermine the final structure (and associated magnetic behaviour), because of the competition between structure directing non-covalent forces and large number of external parameters that direct the final solid formation. Moreover, obtaining single crystals for large assemblies is very tricky and not always fruitful. With an interest to generate novel polymeric systems with promising magnetic properties, our efforts with Mn(II) & Cu(II), Schiff bases and pseudohalides have resulted in interesting polymeric systems whose structural details will be presented. Because of limited access to SQUID magnetometers in India, the magnetic studies are not yet complete and we look forward for collaborations.
Ortep of [Mn(saldab)N(CN)2]n showing atoms as 30% probability ellipsoids. i = x+1, y, z
Ortep of [Mn(naphtdab)N(CN)2CH3
OH] showing atoms as 30% probability ellipsoids. Solvent CHCl3 omitted for clarity
Ortep of Cu4(saldab)2(N3)4 showing atoms as 30% probability ellipsoids. i = -x+1, -y, -z+1
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Synthesis, Characterization and Magnetic properties of
Tetranuclear and Dinuclear Ln(III) Complexes
Amaleswari Rasamsetty,a Chinmoy Das,b Maheswaran Shanmugam,b E. Carolina Sañudo,c and Viswanathan Baskar*a
School of Chemistry, University of Hyderabad , Gachibowli-500046.
e-mail: [email protected] (9 PT)
In the past two decades there has been an increasing interest in the synthesis of single molecular magnets (SMM), since the discovery of first SMM Mn12 acetate.1 SMM behavior has been correlated to the presence of a large magnetic anisotropy and large ground state spin. Recently many 4f-based polynuclear SMMs with high energy barriers have been reported due to their large magentic anisotropy. Among them, a tetranuclear Dy complex [Dy4K2O(O-tBu)12] exhibit highest barriers of energy for reversal of magnetization 842K.2 So here in, we synthesized a series of lanthanide complexes. The reaction of bifunctionalized -diketone(LH) and pivallic acid(pivH) in the presence of triethyl amine with LnCl36H2O salts in 1:1:1 ratio affords a series of tetranuclear Ln(III) coordination compounds, [Ln4(µ3-OH)4(L)4(µ2-piv)4(MeoH)4] [Ln = Gd(III), Tb(III), Dy(III) and Ho(III)]. X-ray diffraction reveals that molecular structure contains a distorted cubane like core, which is formed by the coordination action of the ligands. By changing the coligand(pivH) with LH3’ (2,6-Bis(hydroxyl methyl)p-cresol) leads to the formation of a dinuclear cluster [Ln2(L)4(µ2-LH2’)2]4DMF [Ln = Gd(III), Dy(III) and Ho(III)] and their magnetic behavior has been studied
References
[1] (a) Li, Q.; Vincent, J. B.; Libby, E.; Chang, H. R.; Huffman, J. C.;Boyd, P. D. W.; Christou, G.;
Hendrickson, D. N. Angew. Chem., Int. Ed.1988, 27, 1731–1733. (b) Sessoli, R.; Gatteschi, D.;
Caneschi, A.;Novak, M. A. Nature 1993, 365, 141–143.[2] Blagg, R.J.; Ungur, L.; Tuna, F.; Speak, J.; Comar, P.; Collison, D.; Wernsdorfer, W.; McIness, E. J. L.; Chibotaru, L.F.; Winpenny, R. E. P. Nature Chemistry 2013, 5, 673-678.
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Pyridine-Pyrazole Based Lanthanide Organic Frameworks
(Ln = GdIII and DyIII ) Showing Magnetocaloric Effect and
Single Molecular Magnetic Behavior
Sudeshna Bhattacharya and Raju Mondal*
Department of Inorganic Chemistry, Indian Association for the Cultivation of Science 2A & 2B Raja S.C.Mullick Road,Jadavpur,Kolkata-700032 West Bengal,
India
e-mail: [email protected]
Two multifunctional metal-organic frameworks (MOFs) has been synthesized using a new ligand, 4-(3-(pyridin-2-yl)-1H-pyrazol-5-yl)benzoic acid (H2PPBA), comprising of two contrasting coordination compartments, a chelating pyridine-pyrazole moiety and one carboxylic acid group. The MOFs (Ln= Gd (1), Dy (2)) are isostructural and exhibit interesting graphite like architecture with presence of distinct nanoporous channels inside the network, further confirmed by reasonably high surface area and N2 and CO2 gas adsorption. The MOF-1 provides us a nice example of a case where reasonably strong magnetocaloric effect[1] was observed for a mononuclear gadolinium compound with magnetic entropy change (−ΔSm ) of 10 J kg−1 K−1 at T = 2 K and ΔH = 5 T. Another aspect of this work is the occurrence of underexplored SMM behavior[2] of ferromagnetic Dy(III) MOFs (MOF-2) , confirmed by AC susceptibility measurement with energy reversal barrier of ~12.13 K. The MOFs also show some interesting spectroscopic property.
References
[1]. a) Li, D.-P. ; Wang, T.-W. ; Li, C.-H. ; Liu, D.-S. ; Li, Y.-Z. ; You, X.-Z. , Chem. Commun. 2010, 46, 2929. b) Sessoli, R.; Powell, A. K. Coord. Chem. Rev.2009, 253, 2328.
[2]. (a) Woodruff, D. N. ; Winpenny, R. E. P. ; Layfield, R. A. , Chem. Rev., 2013, 113, 5110. (b) Trifonov, A. A. , Shestakov, B. ; Long, J.; Lyssenko, K.; Guari, Y. ; Larionova, J. , Inorg. Chem., 2015, 54, 7667.
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A Series of MIICuII3 Stars (M = Mn, Ni, Cu, Zn, Cd)
Exhibiting Unusual Magnetic Properties
Shuvankar Mandal and Sasankasekhar Mohanta*
Department of Chemistry, University of Calcutta, 92 A. P. C. Road,
Kolkata - 700 009 e-mail: [email protected]
This presentation deals with five tetrametallic stars of composition [MII(CuIIL)3](ClO4)2 (1, M = Mn; 2, M = Ni; 3, M = Cu; 4, M = Zn; 5, M = Cd), where H2L is the single-compartment Schiff base ligand N,N'-bis(salicylidene)-1,4-butanediamine [1,2]. The central metal ion (MII) resides in between the three [CuIIL] moieties and is bonded with all the six phenoxo oxygen atoms, resulting in the formation of a star-shaped system. The title compounds are rare or sole examples of stars having such metal ion combinations. Such a series of stars from the same ligand is interesting. ESI-MS positive spectral study has been undertaken for 1–4. The variable-temperature / variable-field magnetic studies reveal that MnIICuII
3 compound 1 exhibits ferromagnetic interaction with J = 1.02 cm−1, NiIICuII3
compound 2 and ZnIICuII3 compound 4 exhibits weak/very weak antiferromagnetic
interaction with J = –3.53 and –1.4 cm–1, respectively, and CuIICuII3 compound 3
exhibits moderate antiferromagnetic interaction with J = –35.5 cm−1. The magnetic behaviour of these systems is surprisingly different from that expected on the basis of known governing parameters (phenoxo bridge angle, out-of-plane shift of phenyl groups, Cu–O–M–O dihedral angle) and it seems therefore that such anomaly is related to the distorted coordination environment of the peripheral copper(II) centers (intermediate between square planar and tetrahedral). The DFT-computed J values are quantitatively (for 1) or qualitatively (for 2 and 3) matched well with the experimental values. Spin densities and magnetic orbital (NBOs) correspond well with the trend of observed/computed magnetic exchange interactions.
Reference:
[1] Mondal, S.; Mandal, S.; Carrella, L.; Jana, A.; Fleck, M.; Köhn, A.; Rentschler, E.; Mohanta, S. Inorg. Chem. 2015, 54, 117 131.
[2] Mondal, S.; Mandal, S.; Jana, A.; Mohanta. S. Inorg. Chim. Acta 2014, 415, 138 145.
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An Air-Stable Dy(III) Single-Ion Magnet with High
Anisotropy Barrier and Blocking Temperature
Sandeep K. Gupta and Ramaswamy Murugavel*
Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India
e-mail: [email protected]
In the recent past there has been resolute efforts worldwide to find suitable high temperature molecular magnets by pushing up magnetization reversal barrier (Ueff) and blocking temperature (TB). Although there are several literature reports of single-molecule magnets (SMMs) with either high Ueff and TB, their stability under ambient aerobic conditions remains as a major concern for exploitation towards end-user applications. Further many of the SMMs reported lack coercivity, a characteristic of the hard magnets. Herein we report an air-stable Dy(III) single-ion magnet (SIM) with pseudo-D5h symmetry, synthesized from a sterically encumbered phosphonamide, tBuPO(NHiPr)2, which exhibits a magnetization blocking (TB) up to 12 K, definite from zero-field cooled magnetization curve, with an anisotropy barrier (Ueff) as high as 735.4 K. Dy(III)-SIM exhibits a magnetic hysteresis up to 12 K (30 K) with a large coercivity of ~ 0.9 T (~ 1.5 T) at a sweep rate of ~ 0.0018 T s-1 (0.02 T s-1). These high values combined with persistent stability under ambient conditions, render this system as one of the best-known SIMs. Ab initio calculations have been used to establish the connection between higher-order symmetry of the molecule and quenching of QTM effects. The relaxation of magnetization is observed via the second excited Kramers doublet owing to pseudo high-order symmetry, which quenches the quantum tunneling of magnetization. This study highlights fine-tuning of symmetry around the lanthanide ion to obtain new generation SIMs and offers further scope for pushing the limits of Ueff and TB using this approach.
Acknowledgement: We thank Mr. T. Rajeshkumar and Prof. G. Rajaraman for collaborative work on theoretical models for this study.
Fig. 1. (a) Molecular structure of 1. Lattice water molecule and most of the
H-atoms have been omitted for clarity. The H-atoms of the water molecules
are hydrogen bonded to the three iodide anions and two lattice phosphonic
diamide ligands. (b) Polyhedron showing D5h symmetry around DyIII
ion.
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Family of MnIII4LnIII
2 (LnIII= SmIII, GdIII, DyIII) coordination
clusters: experimental and theoretical investigations
Ritwik Modak,† Yeasin Sikdar,† Alina Bieńko,§ Maciej Witwicki,§ Maria Jerzykieiwcz,§ and Sanchita Goswami*,†
†Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata –
700009, India § Faculty of Chemistry, University of Wroclaw, 14 F. Joliot - Curie, 50-383 Wroclaw,
Poland e-mail: [email protected]
The present work introduces a family of MnIII4LnIII
2 (LnIII = SmIII, GdIII, DyIII) coordination clusters having a multisite hydroxyl rich ligand, H3Vapd, 3–[(2–Hydroxy–3–methoxy–benzylidene)–amino]–propane–1,2–diol, namely, [MnIII
4SmIII2(Vapd)4(OAc)6]4H2O (1), [MnIII
4GdIII2(Vapd)4(OAc)6]4H2O (2) and
[MnIII4DyIII
2(Vapd)4(OAc)6]4H2O (3). The SmIII analogue is the first example of Mn4Ln2 species reported so far.1,2,3 The similarities and differences in terms of structure, topology and magnetic behaviors within the series are investigated extensively. DFT computations were carried out to address the experimentally challenging questions regarding the nature of magnetic interactions in the MnIII
4LnIII2 family coordination clusters.
1,2,4M6-1 [MnIII4SmIII
2] 1,2,4M6-1 [MnIII4GdIII
2] 1,2,3M6-1[MnIII4DyIII
2]
References
[1]. H. Ke, L. Zhao, Y. Guo, J. Tang, Dalton Trans. 2012, 41, 2314. [2]. Shiga,T.; Hoshino, N.; Nakano, M.; Nojiri, H.; Oshio, H. Inorg. Chim. Acta. 2008, 361, 4113. [3]. Boron III, T. T.; Kampf, J. F.; Pecoraro, V. L. Inorg.Chem. 2010, 49, 9104.
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JEOL designs and manufactures integrated
scientific instrumentations for high-level research
and development activities.
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Point resolution : 0. 08 nm (STEM) 0.
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The JXA-8530F features the improved hardware that is used
in the JXA8500F (the first FE-EPMA in the world). The FE gun of the JXA-8530F provides not only a spatial
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IIT Bombay MTMM 2016
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Mononuclear Complexes as Ising−Type Anisotropic Building Units to Construct Single Molecule Magnets
Arun Kumar Bar, Celine Pichon, Ramasesha Suryanarayana Sastry,
Jean-Pascal Sutter, Vadapalli Chandrasekhar*
School of Chemical Sciences, NISER, Bhubaneswar 752050, India e-mails: [email protected], [email protected]
Uni-axial zero-field splitting parameter (D) in conjunction with spin ground state plays crucial role in governing the energy barrier for magnetization reversal in molecule-based magnets. It has long been challenging for chemists to rationally control the single-ion magnetic anisotropy by chemical design. Recent investigations revealed that deviation from hexa-coordination and adaptation of non-conventional coordination geometry can induce significantly large magnetic anisotropy in mononuclear complexes with appropriate 3d transition metal ions.[1] Moreover, association of such Ising-type anisotropic mononuclear complexes with metallo-ligands could lead to polynuclear systems with large spin ground state as well as high energy barrier for magnetic relaxation. We have been considering hepta-coordinate 3d transition metal ions (FeII, CoII and NiII) as anisotropic building units.[2] In this presentation, we will discuss the magnetic behaviors of such mononuclear complexes, self-association of such mononuclear complexes with cyanometallates (ca. Scheme 1) and their magnetic features.
Scheme 1. Schematic representation of the association of a mononuclear heptacoordinate FeII complex with [W(CN)8]
3- towards the formation of Fe3W2 SMM
References
[1]. Bar, A. K.; Pichon, C.; Sutter, J.-P. Coord. Chem. Rev. 2016, 308, 346. [2]. Bar, A. K.; Pichon, C.; Gogoi, N.; Duhayon, C.; Ramasesha, S.; Sutter, J.-P. Chem. Commun.
2015, 51, 3616; (b) Venkatakrishnan, T. S.; Sahoo, S.; Bréfuel, N.; Duhayon, C.; Paulsen, C.; Barra, A.-L. Ramasesha, S.; Sutter, J.-P. J. Am. Chem. Soc., 2010, 132, 6047; (c) Ruamps, R.; Batchelor, L. J.; Maurice, R.; Gogoi, N. Chem. Eur. J., 2013, 19, 950
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Pentametallic ‘Bowl’-Shaped Nickel(II) Complexes
Involving Pyrazolido- Bridge in a Rare μ3-η1:η1:η1 Mode:
Synthesis, Crystal Structures and Magnetic Properties
Dhrubajyoti Mondal, Manoranjan Maity and Muktimoy Chaudhury*
Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata 700 032, India
e-mail: [email protected]
Two pentametallic nickel(II) compounds [Ni5(L1)(µ3-OH)(µ4-
OH)(Hpz)2(pz)4.75(NO3)0.25] (NO3) (1) and [Ni5(L2)(µ3-OH)(µ4-
OH)(Hpz)2(Pz)4.75(OH)0.25(H2O)0.25](NO3) (2) with metal centers and donor atoms
topology close to a ‘bowl’ shape have been synthesized following a single pot protocol using hexadentate bisphenolate N2O4 pro-ligands (H2L
1 and H2L2) together with
pyrazole and hydroxide as bridging co-ligands. ESI-MS and single-crystal X-ray
diffraction analyses have been used to characterize these compounds. One of the
pyrazolido- ligands (pz) in these compounds actually binds three metal centers in a rare
3-η1:η1:η1- mode which is unprecedented in 3d-metal chemistry. This pyrazolido ligand
interestingly has a disordered structure in both the compounds with a fractional
occupancy of 0.75. While in compound 1 the residual occupancy (0.25) is fulfilled by a
bridging NO3- anion, the corresponding bridging anion in compound 2 is a hydrogen
bonded aqua-hydroxido [H-O…H-O-H]- ligand, connected to three adjacent metal
centers (Ni1, Ni2 and Ni5). Four nickel centers (Ni1, Ni2, Ni3, and Ni4) of these
pentametallic cores are lying on a rectangular plane and connected together by a
hydroxido ligand [O6] in a rare µ4- mode. The fifth nickel center Ni5 is lying above this
plane and together these metal centers are arranged to form a distorted tetragonal
pyramid. An extensive magnetic study at variable temperatures (1.8 – 300 K) indicates
an overall antiferromagnetic exchange interaction in these compounds which can be
interpreted satisfactorily following a three-J model with J1/hc = –88.3 cm–1, J2/hc = –25.8 cm–1, J3/hc = +2.11 cm–1, g = 2.350, and D/hc = –6.06 cm–1 for 1 with S = 1
ground state. Corresponding values for 2 are J1/hc = –88.6 cm–1, J2/hc = –26.0 cm–1,
J3/hc = +2.50 cm–1, g = 2.484, and D/hc = –6.14 cm–1.
References: [1] (a) Sorace, L.; Benelli,C.; Gatteschi, D. Chem. Soc. Rev. 2011, 40, 3092. (b)
Sessoli, R.; Powell, A. K. Coord. Chem. Rev. 2009, 253, 2328.
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Electric field modulation of magnetic anisotropy of a series
of first row transition metal complex Tamal Goswami and Anirban Misra*
Department of Chemistry, University of North Bengal, Darjeeling - 734013 , West Bengal, India
e-mail: [email protected]
Single Molecule Magnets (SMMs) are important apparatus in the domain of data storage[1]. and quantum computing [2]. SMMs are often characterized by a large easy-axis-type magnetic anisotropy and concomitant high energy barrier (U), which restricts the reversal of the magnetization from +Ms to −Ms. The barrier U can be given by |D|S2 for molecules with integer spins and |D|(S2 −1/4) for molecules with half integer spins. Here, D is the zero-field splitting (ZFS) parameter and S is the ground-state spin. The large negative ZFS parameter (D) causes the spin (S) of the molecule to point along a preferred easy-axis and makes it a nanomagnet. The modulation of the ZFS parameter by ligand substitution has recently been studied in the framework of DFT [3]. Structural modification in an octahedral CrIII system can switch the magnetization behavior of a molecule from easy-plane to easy-axis type. Although the bulk properties of SMMs are well documented in their unperturbed state [4], the study of the effect of an external electric field on the magnetization of SMMs is relatively recent. To control magnetization, the use of an electric field is highly advantageous [5]. In a previous study it has been shown that an external static electric field can alter the nature of magnetism in an paramagnetic molecule and make it an SMM [6]. Herein, we investigate the effect of an external electric field on the ZFS parameter of a series of pseudo-octahedral [MIICl(pz4lut)]+ (M= Mn, Fe, Co and Ni) complexes (dmphen=α,α,α ,α -tetra(pyrazolyl)lutidine)[7] that are important for studies in fundamental coordination chemistry.
References
[1] Mannini, M.; Pineider, F.; Sainctavit, P.; Danieli, C.; Otero, E.; Sciancalepore, C.; Talarico, M.;
Arrio, M. A.; Cornia, A.; Gatteschi, D.; Sessoli, R. Nat. Mater. 2009, 8, 194 – 197.[2] Ardavan, A.;
Rival, O.; Morton, J. J. L.; Blundell, S. J.; Tyryshkin, A. M.; Timco, G. A.; Winpenny, R. E. P. Phys.
Rev. Lett. 2007, 98, 057201.[3] Goswami, T.; Misra, A. J. Phys. Chem. A 2012, 116, 5207 – 5215.
[4] Accorsi, S.; Barra, A. L.; Caneschi, A.; Chastanet, G.; Cornia, A.; Fabretti, A. C.; Gatteschi, D.;
Mortalo, C.; Olivieri, E.; Parenti, F.; Rosa, P.; Sessoli, R.; Sorace, L.; Wernsdorfer, W.; Zobbi, L. J.
Am. Chem. Soc. 2006, 128, 4742 – 4755.[5] Chiba, D.; Sawicki, M.; Nishitani, Y.; Nakatani, Y.;
Matsukura, F.; Ohno, H. Nature 2008, 455, 515 – 518. [6] Goswami, T.; Misra, A. Chem. Eur. J.
2014, , 20, 13951 – 13956. [7] Morin, T. J.; Bennett, B.; Lindeman, S. V.; Gardinier, J. R. Inorg.
Chem. 2008, 47, 7468-7470.
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Influence of Tuned Linker Functionality on Modulation of
Magnetic Properties and Relaxation Dynamics in a Family
of Six Isostructural Ln2 (Ln=Dy, Gd) Complexes Soumya Mukherjee,a Jingjing Lu,b G. Velmurugan,c Shweta Singh,a G.
Rajaraman,c Jinkui Tangb* and Sujit K. Ghosha*
aIndian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Pashan, Pune-411008, India.
e-mail: [email protected]
bState Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. cDepartment of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai,
Maharashtra, India-400076. A coordination cluster family comprising of six new dinuclear symmetric lanthanide complexes, were isolated employing a mixed-ligand strategy stemming out of a strategic variation of the functionalities introduced among the constituent schiff-base linkers. The purposeful introduction of three diverse auxiliary groups with delicate differences in their electrostatic natures affects the local anisotropy and magnetic coupling of LnIII ion-environment in the ensuing Ln2 dinuclear complexes, consequentially resulting into distinctly dynamical magnetic behaviours among the investigated new-fangled family of isostructural Ln2 complexes. Among the entire family, subtle alterations in the chemical moieties render two of the Dy2 analogues to behave as single molecule magnets (SMMs), while the other Dy2 congener merely exhibits slow relaxation of the magnetization. The current observation marks one of the rare paradigms,[1] wherein magnetic behaviour modulation has been achieved by virtue of the omnipresent influence of subtly tuned linker functionalities among the constituent motifs of the lanthanide nanomagnets.[2]
References
[1]. Joarder, B.; Mukherjee, S.; Xue, S.; Tang, J.; Ghosh, S. K., Inorg. Chem. 2014, 53, 7554-7560. [2]. Mukherjee, S.; Lu, J.; Velmurugan, G.; Singh, S.; Rajaraman, G.; Tang, J.; Ghosh, S. K., Under
Revision.
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Tetrahedral CoII based binuclear double-stranded helical
single-ion-magnet
Vijay Singh Parmar¥, Amit Kumar Mondal and Sanjit Konar*
Department of Chemistry, IISER Bhopal, Bhopal, MP, India.
e-mail: [email protected]
A Recent approach towards Single Molecule Magnets (SMMs) considers magnetic properties to be arising from a single first row transition metal (TM) ion in a suitable ligand field that creates magnetic anisotropy. In the literature, these are often
referred to as single-ion magnets (SIMs) [1]. Moving forward with this approach, A rare class of dinuclear double-stranded helicates having tetrahedral CoII centres with formulae of [Co2(L
1)2]·2(CH3CN)(1), [Co2(L2)2]·5 (CH3CN)·(CH3OH) (2) [2],
were synthesized and characterized. Detailed dc and ac magnetic susceptibility measurements reveal the presence of field induced slow magnetic relaxation behaviour in the high spin tetrahedral CoII centres with an easy-plane magnetic anisotropy. Complexes 1 and 2 are the rare examples of transition metal based helicates showing such behaviour. The effect of the peripheral ligand functionalisation in the magnetic relaxation behavior in 1 and 2 was also examined.
References
[1]. Craig, G. A.; Murrie, M. Chem. Soc. Rev. 2015, 44, 2135 [2]. Parmar, V. S.; Mondal, A. K.; Biswas, S.; Konar, S. Dalton Trans. 2016, 45, 4548.
Fig. 2 Out-of-phase (χM″) AC magnetic susceptibility plots for complex 1(left) and complex 2(right) at 1000 Oe.
Fig. 1 View of the molecular structures of complex 1
(left) and complex 2 (right) illustrating double-stranded helicate formation. The two strands are differently coloured and hydrogen atoms are omitted for clarity
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Pentanuclear 3d−4f Heterometal Complexes of MII3LnIII
2
(M = Ni, Cu, Zn and Ln = Nd, Gd, Tb) Combinations:
Syntheses, Structures, Magnetism, and Photoluminescence
Properties
Mithun Chandra Majee, Manoranjan Maity and Dr. Muktimoy Chaudhury*
Department of Inorganic Chemistry, Indian Association for the Cultivation of Science,
Kolkata-700032, West Bengal, India e-mail: [email protected]
The study of lanthanide complexes covalently linked to transition metal centers
(providing 3d-4f interactions) is an area of contemporary research interest due to
their intriguing magnetic as well as luminescent properties1. These observations
have motivated synthetic coordination chemists to develop protocols for the
syntheses of hetero-metallic 3d-4f compounds. In this presentation we have
reported the syntheses and X-ray structures of a new family of isostructural
LnIII2M
II3-type pentanuclear complexes of molecular formula [LnIII
2(MIIL)3( 3-O)3H]
(ClO4)·xH2O (1 −5) [Ln = Nd, M = Zn, 1; Nd, Ni, 2; Nd, Cu, 3; Gd, Cu, 4; Tb, Cu,
5] using the ligand N,N-bis(2-hydroxy-3-methoxy-5-methylbenzyl)-N/,N/-
diethylethylenediamine (H2L) that fits our approach. The compounds have been
prepared for comparison studies in order to check how the individual metal ions
(both 3d and 4f types) influence the magnetic and photophysical properties of the
combined system. For the isotropic CuII–GdIII compound 4, is the only member of
this triad, showing a tail of an out-of-phase signal in the ac susceptibility
measurement. Among the three NdIII2M
II3 (M = ZnII, NiII, and CuII) complexes,
only the ZnII analogue (1) displays an NIR luminescence due to the 4F3/2→ 4I11/2
transition in NdIII when excited at 290 nm.
References
[1]. (a) Lehn, J.-M. Supramolecular Chemistry: Concepts and Perspectives; VCH: Weinheim,
Germany, 1995. (b) Piguet, C.; Bünzli, J. –C. G. Chem. Soc. Rev. 1999, 28, 347.
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Systematic study of mutually inclusive influences of
temperature and substitution on the coordination
geometry of Co(II) in a series of coordination polymers
and their properties
Manasi Roy and Raju Mondal*
Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata-700032, West Bengal, India
e-mail: [email protected]
During last two decades the synthesis and design of metal-organic frameworks (MOFs) has flourished as an emerging area of research because of their promising application in gas separation, magnetism, catalysis etc1. Recently there has been a great deal of interest in designing magnetic MOFs through the assembly of organic ligands and paramagnetic metal centers. Of particular interest is the molecular-based magnetic materials having a cryogenic magnetocaloric effect (MCE), because of their potential application as a magnetic refrigerant material. Accordingly, a series of Co(II) MOFs are synthesized which showed different coordination geometries such as octahedral, tetrahedral, sq pyramidal, trigonal bipyramidal, and sq planar, controlled by external physical stimuli like temperature(Fig.1). All the MOFs show photocatalytic degradation of toxic dye molecules (Fig.2). On the other hand, magnetic behaviours specially to explore MCE in non-cluster-based SBU type Co MOF (MOF-2) have also been investigated (Fig.3).2
References
[1]. Tranchemontagne, D. J.; Mendoza-Cortés, J. L.; O’Keeffe, M.; ″aghi, O. M. Chem. Soc. Rev. 2009, 38, 1257-1283.
[2]. Roy, M; Mondal, R. (Manuscript under revision)
HN
N N
NH
R
HOOC COOH
+ Co2++
800C 1200C
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Magnetic Properties of Metal−Organic Hybrid Materials of Co(II) Using Flexible and Rigid Nitrogen Based Ditopic
Ligands as Spacers
Anoop Kumar Gupta, Musheer Ahmad and Parimal K. Bharadwaj*
Department of Chemistry, IIT-Kanpur, Kanpur, Uttar Pradesh e-mail: [email protected]
Studies on coordination polymers have witnessed an upsurge in recent years
due to their novel architecture as well as potential applications as functional
materials. In particular, these materials can be engineered via ligand design to
impart useful magnetic properties.1 Coordination polymers of paramagnetic metal
ions have led to an interesting range of systems exhibiting magnetic phenomena
such as ferromagnetism, antiferromagnetism, spin-canting, metamagnetism,
single-chain magnetism, and so on. It has been our interest to construct
coordination polymers with interesting magnetic properties using carboxylate as
well as mixed carboxylate and nitrogen donor linkers. We have utilized a
tricarboxylate ligand with different N-donor co-ligands and Co(II) metal nodes to
construct coordination polymers with multinuclear clusters of Co(II) capable of
magnetic interactions.2
References:
[1]. - - - Inorg. Chem. 2011, 50, 6850.
[2]. Ahmad, M.; Sharma, M. K.; Das, R.; Poddar, P.; Bharadwaj, P. K. Cryst. Growth Des. 2012, 12, 1571
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Geometrical Structure of meta-Xylylene Based Asymmetric
and Symmetric Polyradicals and their Magnetic Nature: A
Density Functional Study
Arun K. Pal† and Sambhu N. Datta*, ‡
† Department of Chemistry, Indian Institute of Technology, Kharagpur-721302, India‡
Department of Chemistry, Indian Institute of Technology, Mumbai-400076, India *Email: [email protected]
Quantum chemical investigations on unsymmetrical (with –CR2 group at one end and phenyl ring at the other) [1] and symmetrical (phenyl groups at both terminals and –CR2 groups as the radical sites) [2] polyradicals of meta-xylylene chains are done using unrestricted DFT – broken symmetry formalism [3], to determine the geometrical differences, and their possible magnetic characteristics.
This gives rise to a more or less linear chain for the unsymmetrical cases (Figure 1a). We have used CRYSTAL09 package for calculations on the infinitely long one dimensional and periodic polyradical chains. The coupling constants estimated from the periodic calculations are quite large at about 500 cm−1 and somewhat greater than the limiting values calculated for the polyradicals with an increasing number of phenylene groups.
The geometrical features of symmetrical polyradicals are interestingly different from those of the unsymmetrical polymers (Figure 1b). The successive phenyl rings are surprisingly found to be twisted in a corkscrew fashion in the same direction so as to form a somewhat rope-like curved chain. The polyradicals form molecular wires of the Crown shape. Because of the irregularity of twist angles, a periodic chain would certainly not form, and a larger chain (n > 6) with twist in the same direction may be sterically prohibited.
Each polyradicals (asymmetric and symmetric) has a coupling constant larger than thermal energy. For each group of polyradicals, the coupling constant has been found to exponentially decrease with increase in the number of phenylene groups. The Heisenberg-Dirac-Van Vleck (HDVV) coupling constants are generally large. The polymers are predicted to be very strong paramagnets [1-2].
R = H R = Me R = H R = Me
(a) Asymmetric polyradicals (n = 5) b) Symmetric polyradicals (n = 5)
Fig 1. UM062X/6-31G(d,p) level high-spin optimized geometry for pentaradicals. References:
[1] Pal, A. K.; Hansda, S.; Datta, S. N. J. Phys. Chem. A 2015, 119, 2176–2185. [2] Pal, A. K.; Kumar, A.; Datta, S. N. Chem. Phys. Lett. 2016, 648, 189-194. [3] Datta, S.N.; Trindle, C.O.; Illas, F. Theoretical and computational aspects of magnetic organic
molecules, 1st edition, Imperial College Press, London, 2014.
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Computational Design Of Ionic Liquids Based Catalysts For
Pechmann Condensation Reaction
M.Deepankumar, MadhavanJaccob
Department of chemistry, Loyola, Chennai 600034, India
In recent years,many researchers are aiming to develop an efficient and re-usablegreen catalyst for the Pechmann condensation without using large amount of harmful solvents. In such cases ionic liquids(IL) can play a vital role for many organic transformations in synthetic organic chemistry.Among the many chemical reactions,Pechmann condensation is one of the important reactionto prepare the coumarin derivatives which is very useful in biology and medicine. In recent times, choline based ionic liquidswere foundto be a effective catalyst for the Pechmann condensation. In order to develop the ionic liquid based efficient green catalyst for Pechmann condensation, thorough understanding of their reaction mechanism is needed. So we are aiming to perform the detailed quantum chemical calculations on Pechmann condensation on considering all the possible reaction mechanisms. Based on the computed results, most favourable pathway and essential features of IL based catalysts for Pechmann condensation will be discussed.
Scheme 1:Pechmann condensation mechanism
Reference
[1]. Daru,J. ;Stirling,A. J. Org. Chem.,2011, 76 (21), pp 8749–8755.
[2]. Stephen Tyndall.; Koon Fai Wong.; and Melissa, A.; VanAlstine-Parris, J. Org. Chem.,2015, 80 (18), 8951-8953.
[3]. Deepankumar,D.; Jaccob,M. (unpublished results)
OO
H3C
O
C2H5
HOHO
H
NH
CH3
CH3O
H
H2PO
4
HC
OO OH
NH
CH3
CH3
O
H
H2PO4
CH3
H
Scheme-1
Scheme-2
Scheme-3
1. Trans-esterification
2. Electrophilic attack
3. Water elimination
1. Electrophilic attack
2. Water elimination
3. Trans-esterification
1. Electrophilic attack
2. Trans-esterification
3. Water elimination
Reactant Product
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Construction of Polynuclear Lanthanide (Ln= DyIII,
TbIII and NdIII) Cage Complexes using Pyridine-
Pyrazole based ligands: Versatile Molecular Topologies
and SMM behavior
Sukhen Bala and Raju Mondal* Department of Inorganic Chemistry, Indian Association for the Cultivation of
Sceience, Jadavpur, Kolkata-700032, India e-mail: [email protected]
Lanthanide cages are of unabated research interest because of their potential applications in SMMs1, magnetocaloric effects2 and in luminescence studies.3 Here we explore three octanuclear lanthanide (III) (Ln = Dy, Tb) cage compounds and one hexanuclear neodymium (III) coordination cage with two different pyridyl-pyrazolyl based ligands, exhibiting versatile molecular architectures including a butterfly core. Relatively less common semi-rigid pyridyl-pyrazolyl based asymmetric ligand systems show an interesting trend of forming polynuclear lanthanide cage complexes with different coordination environments around the metal centres. The resultant multinuclear lanthanide complexes show interesting magnetic features originating from different spatial arrangements of the metal ions. Alternating current (ac) susceptibility measurements of the two dysprosium complexes display frequency- and temperature-dependent out-of-phase signals in zero and 0.5T dc field, a typical characteristic feature of Single-Molecule Magnet (SMM) behaviour,4 and indicating different energy reversal barriers due to different molecular topologies. Another aspect of this work is the occurrence of the not-so-common SMM behaviour of the terbium complex, further confirmed by ac susceptibility measurement.
References
[1]. Dearden, A. L; Parsons, S; Winpenny, R. E. P. Angew. Chem. Int. Ed. 2001, 40, 151-154. [2]. Zheng, Y.-Z; Evangelisti, M; Winpenny, R. E. P. Angew. Chem. Int. Ed. 2011, 50, 3692-3695. [3]. Yang, X; Schipper, D; Jones, R. A; Lytwak, L. A; Holliday, B. J; Huang, S. J. Am. Chem. Soc.
2013, 135, 8468–8471.[4] Bala, S; Bishwas, M. S; Pramanik, B; Khanra, S; Fromm, K. M; Poddar, P; Mondal, R. Inorg. Chem., 2015, 54, 8197–8206.
0 5 10 15 20 25 300
20
40
60
80
100 163 Hz
467 Hz
845 Hz
1176 Hz
T(K)
'/cm
3m
ol-
1
0 T
0 5 10 15 20 25 30
1
2
3
4
163 Hz
845 Hz
467 Hz
1176Hz
T(K)
''/cm
3m
ol-
1
0.5 T
0 5 10 15 20 25 30
15
20
25
30
35 163 Hz
467 Hz
845 Hz
1176 Hz
T(K)
'/cm
3m
ol-
1
0.5 T
0 5 10 15 20 25 30
0
4
8
12
16 467 Hz
845 Hz
1176 Hz
163 Hz
T(K)
''/cm
3m
ol-
1
0 T
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Squarato-bridged Gadolinium Based Metal−Organic Frameworks (MOFs) for Efficient Magnetic Refrigeration
Soumava Biswas, Amit K. Mondal and Sanjit Konar*
Department of Chemistry, IISER Bhopal, Bhopal, M.P. India
e-mail: [email protected]
Exploration of the magnetocaloric effect (MCE) of molecular magnetic materials has attracted immense interest in recent years. [1] It has been claimed that gadolinium based molecular materials showing magnetic refrigeration can potentially replace the conventional compressor based refrigerants for ultralow-temperature applications because of their environment friendliness and economic advantages. [1]. In this context, we reported three densely packed squarato-bridged gadolinium based metal−organic frameworks (MOFs) [Ln5( 3-OH)5( 3-O)-
(CO3)2(HCO2)2(C4O4)(H2O)2] (1), [2] [Gd(C4O4)(C2O4)0.5(H2O)2] (2) [3] and
[Gd(C4O4)(OH)(H2O)4]n (3). [4] The structural analyses (for 1 and 2) reveal that the 3D framework consists of extended gadolinium cube whereas 3 have a 2D layered structure. Magnetic investigations confirm that complex 1 exhibits one of the largest cryogenic magnetocaloric effects among the molecular magnetic refrigerant
materials reported so far (−ΔSm = 64.0 J kg−1
K−1
for ΔH = 9 T at 3 K). The cryogenic cooling effect (of 1) is also quite comparable with that of the commercially used magnetic refrigerant gadolinium−gallium garnet. For 2 and 3, the maximum magnetic
entropy change (−ΔSm) found to be 44.0 J kg−1
K−1
(for ΔH = 7 T at 3 K) and 47.3 J
kg−1
K−1
(for ΔH = 9 T at 3 K) respectively.
References
[1]. Zheng, Y.-Z.; Zhou, G.-J.; Zheng, Z.; Winpenny, R. E. P. Chem. Soc. Rev. 2014, 43, 1462 [2]. Biswas, S.; Mondal, A. K.; Konar, S. Inorg. Chem. 2016, 55, 2085 [3]. Biswas, S.; Jena, H. S.; Adhikary, A. Konar, S. Inorg. Chem. 2014, 53, 3926 [4]. Biswas, S.; Adhikary, A.; Goswami, S.; Konar, S. Dalton Trans. 2013, 42, 13331.
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Field-Induced Single-Ion-Magnetic Behaviour of
Octahedral CoII
in a Two Dimensional CoordinationPolymer
Debashis Saha, Amit Kumar Mondal, Sanjit Konar*
Department of Chemistry, IISER Bhopal, Bhopal 462066, MP, India.
e-mail: [email protected] A novel 2D coordination polymer was synthesized employing a V-shaped flexible terpyridine-based ligand L (L = 4 -(4-methoxyphenyl)-4,2 :6 ,4 -terpyridine) as
linkers and MII (M = Co
II) as nodes. Structural analysis of the complex revealed the
formation of a rare [4+4] metallocyclic unit and the extension of these cyclic units into two dimensions give rise to an interdigitated 2D sheet structure where the methoxy group of the ligand oriented above and below the sheet forming crests and troughs. Detailed dc and ac magnetic susceptibility measurements reveal the presence of field induced slow magnetic relaxation behavior of the magnetically
isolated six-coordinate CoII center with an easy-plane magnetic anisotropy.
Figure1. A novel Co
II based two-dimensional coordination polymer exhibiting field-induced single-ion-magnet
behavior SIM-type field-induced slow relaxation behavior of the magnetically isolated six-
coordinate CoII centers in a 2D coordination polymer was observed. The best fits of
the reduced magnetization data gave axial ZFS parameter, D = 41.6 cm−1
and the
effective energy barrier (Ueff) was found to be 36.9 K, which is the highest value
reported so far among 2D CoII-based single-ion-magnets.
References
[1] Craig, G.A.; Murrie, M. Chem. Soc. Rev. 2015, 44, 2135. [2] Vallejo, J.; Fortea-Perez, F. R.; Pardo, E.; Benmansour, S.; Castro, I.; Krzystek, J.; Armentanoc, D.; Cano, J. Chem. Sci. 2016, 7, 2286.
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Weak Intermolecular Interaction As A Tool For The
Generation Of Single Molecular Magnets: Going From
Traditional To Non-traditional Molecules
Mukesh Kumar Singh, Aparna G. Nair and Gopalan Rajaraman*
Chemistry Department, IIT Bombay, Powai, Mumbai 400076
e-mail: [email protected]
Magnetic exchange propagating through weak - and CH- stacking interactions has been witnessed in several cases, but the mechanism of such coupling is not fully understood from Single Molecular Magnetic point of view. Our group is actively involved in computing the magnetic exchange interaction of weakly coupled systems using density functional method and here we have attempted to shed light on the magnetic coupling mediated through - and CH- stacking interactions using DFT. Our initial attempt was to explore the weak π-π interaction as possible interaction to build SCMs in tradition transition metal complexes. Magnetic studies indicate that complexes with only π-π interaction always exhibit weak anti-ferromagnetic interaction, whereas complexes with only CH- stacking interactions can exhibit both ferromagnetic and anti-ferromagnetic interactions based on the transition metal present in the complexes.[1] But as the experimental designing of a complex with only CH- stacking interaction is a difficult task so we have tried to explore the weak π-π interaction as possible interaction to build Single Chain Magnets (SCMs) in non-tradition transition metal complexes like Ferrocene and endohedral metallo-fullerenes (EMFs) where ligand field is expected to be weaker than traditional transition metal complexes.[2]
References
[1] Singh, M. K.; Yadav, N.; Rajaraman, G. Chem. Commun. 2015, 51, 17732. [2] Singh, M. K.; Yadav, N.; Rajaraman, G. Chem. Eur. J. 2015, 21, 980.
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A ferromagnetically coupled squashed Ni4(μ3-OCH3)4 cubane based 3D metal organic framework
Bijoy Dey, Debashis Saha, Soumava Biswas and Sanjit Konar*
Department of Chemistry, IISER Bhopal, Bhopal 462066, MP, India.
e-mail: [email protected]
Fabrication of magnetically important MOF is a synthetic chalange because
intermetallic distance in most of the MOFs are larger than considered for good
exchange interaction so one strategy is to use multinuclear metal assembly as
nodes in the framework. So, considering this strategy a novel three-dimensional
(3D) Ni(II) based metal organic framework (MOF) with nicotinate-N-oxide as ligand
(L) {[Ni(L)( 3OCH3)]n・n(CH3OH)・3n(H2O)} (1) has been synthesized and
characterized. Single crystal structure analysis reveals the 3D framework of 1
originates from the self-assembly of the propeller shaped secondary building units
(SBU) made of Ni4( 3-OCH3)4 cubane(fig.1). Detailed magnetic studies show that 1
exhibits a dominant intra-cubane ferromagnetic interactions between Ni(II)
centres(fig.2). References [1] Balagu, A. P.; Piligkos, S.; Teat, S. J.; Costa, J. S.; Shiddiq, M.; Hill, S.; Castro, G. R.;
Escorihuela, P. F.; Sanudo, E. C. Chem. Eur. J. 2013,19, 9064. [2] Canaj, A. B.; Tzimopoulos, D. I.; Philippidis, A.; Kostakis, G. E.; Milios, C. J. Inorg. Chem.
2012, 51, 10461
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A Theoretical study on the polyfunctional materials based
on organic diradicals
Manoj Majumder and Anirban Misra*
Department of Chemistry, University of North Bengal, Darjeeling - 734013 , West
Bengal, India
e-mail: [email protected]
We have designed and theoretically studied different sets of diradicals by coupling azulene with nitronyl nitroxide radicals and with (2,2,6,6-Tetramethylpiperidin-1-yl) oxyl (TEMPO) radicals [1]. To begin with, the geometries of all these diradicals have been optimized at high spin (HS) state in the gas phase. With these optimized geometries the magnetic exchange coupling constant (J) values are estimated for these diradicals using the broken symmetry (BS) approach in an unrestricted DFT framework [2]. Among the designed diradicals some are found to be ferromagnetic and rests are antiferromagnetic. We have also calculated the zero field splitting (ZFS) parameter (D) with the ferromagnetic one [3]. In this note, we have theoretically evaluated second-order ( ) and third-order ( ) nonlinear optical (NLO) responses [4]. All of the studied systems are found to be NLO active. From our calculations we ambitiously expect the usefulness of these materials as a potent, non-hazardous polyfunctional materials that may have potential use in the areas such as telecommunications, electric optical devices, light modulators and information storage and as well as have some biomedical application also [5].
References
[1]. [1] Bhattacharya, D.; Shil, S.; Goswami, T.; Misra, A.; Panda, A.; Klein, D. J. Comp. Theo. Chem. 2013,1024, 15.
[2]. Yamaguchi, K.; Takahara, Y.; Fueno, T.; Nasu, K. Jpn. J. Appl. Phys. 1987, 26, L1362. [3]. Goswami, T.; Misra, A. J. Phys. Chem. A, 2012, 116, 5207. [4]. (a) Nakano, M.; Shigemoto, I.; Yamada, S.; Yamaguchi, K. J. Chem. Phys. 1995, 103, 4175. (b)
Nakano, M.; Kiribayashi, S.; Yamada, S.; Shigemoto, I.; Yamaguchi, K. Chem. Phys. Lett. 1996, 262, 66.
[5]. Ray, P.C. Chem. Rev. 2010, 110, 5332.
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Experimental Verification of Computational Methods to
Describe the Magnetic and Electronic Properties of SMM
Systems
Asha Roberts, Michael Großhauser, Dennis Müller, Lena Daumann and Peter Comba*
Institute of Inorganic Chemistry and Interdisciplinary Center for Scientific
Computing, Heidelberg University
Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
e-mail: [email protected]
In the pursuit of a rational approach to designing new SMM systems, the need for accurate computational methods cannot be understated. Through the combination of computational and experimental methods a thorough understanding of the required electronic and magnetic properties can be obtained. A necessary part of this understanding is determining how the ligand field influences these properties and how it can be optimised.
Experimental and computational methods have been combined to give a thorough description of the electronic and magnetic properties of a range of complexes. Heteronuclear DyIIIMII complexes (M = Ni, Co) were synthesised using the dinucleating cyclene-based ligand (1,4,7,10-tetraazacyclododecan-1,4,7,10-tetrayl)-tetrakis-(methylen))-tetrakis(2-methoxy-4-methylphenol) H4L. The ligand was designed to provide a preorganised N4O2 site for the M(II) ion, with the DyIII coordinated in the O4 site with pivalates and solvent molecules completing the coordination sphere. While SMM behaviour was displayed by the DyIIINiII complex, no SMM behaviour was observed in the CoII analogue. Ab initio calculations indicated that conformational differences in the crystal structures at both metal sites might be the reason for the discrepancies in magnetic properties. The excellent agreement between computed and experimental parameters (Squid magnetometry, MCD, NMR, HF-EPR) supports the quality of the ab initio approach used.
In order to elucidate the subtle effects of the ligand field on the magnetic properties, a series of mononuclear lanthanide complexes has been synthesised. The ligands employed are comprised of two bidentate donors (1-hydroxy-pyridine-2-one, 1,2-HOPO) with a linking chain of various lengths. Depending on the identity and length of the chain, a different geometry can be enforced. The geometry of the complexes differ only slightly across the series and preliminary calculations of the DyIII complexes indicate that these geometrical changes have a significant impact on the magnetic properties. Additionally, conformational changes within a single complex reveal high sensitivity of the first excited state to the ligand field, with the ground state remaining largely unchanged. Despite the small ligand field of lanthanides, it is clear that it is of central importance for molecular magnetism.
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Bimolecular reactions of pyridine and pyridine-N-oxide radicals with small molecules
Chitranjan Sah, Lilit Jacob, Mayank Saraswat, Sugumar Venkataramani*
Department of chemical sciences, Indian institute of Science Education and research Mohali
Email. [email protected]
Free radicals are very important reactive intermediates. A widespread attention on free radicals transpired after the finding of their potential application in making organic molecular magnets. Molecular magnets are either isolated molecules or assemblies of molecule with one or more magnetic centre. In this regard, free radicals have been explored as building blocks for molecular magnets. To achieve the goal, it is necessary to understand the electronic structural and the stability aspects of several radicals. Reactivity studies of radicals are one of the foremost features in understanding the latter aspect. Besides reactions involving free radicals are inevitable in different areas such as organic synthesis, polymer chemistry, and atmospheric chemistry.[1] In the field of organic synthesis, several radical based reactions such as photoredox catalysis, radical addition and radical cyclization are well-known.[2] Most of the radical based reactions possess extremely fast kinetics with a wide range of time scale indicating smaller barriers. Due to the tremendous growth in modern synthetic methodologies, chemoselectivity, regioselectivity and stereoselectivity in radical reactions are also vastly improved.[3]
In our lab, we are currently focused on the structural, stability and reactivity aspects of heterocyclic radicals. In a series of studies, we are exploring the above-mentioned features of pyridine-N-oxide radicals in comparison with pyridine radicals. We are particularly interested in the influence of N-oxide moiety in the stability of the pyridine radical. Bimolecular reactions, in particular, with small molecules that are commonly occurring in atmosphere will provide useful insights in to the stability prospects of such radicals. The key reaction partners that we consider are water, oxygen, hydrogen, carbon dioxide, carbon monoxide, and methanol etc. Various channels during the bimolecular reactions and their corresponding barriers are the major emphasis of this study. Preliminary results in this regard will be the part of this contribution.
References
[1]. Chrsky, P. Zahradnik, R. Acc. Chem. Res. 1976, 9, 407-411 [2]. Oderinde, S. Frenette, M. J. Am. Chem. Soc. 2016, 138, 1760−1763 [3]. Matyjaszewski, K. Macromolecules 1998, 31, 4710-4717
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Theoretical investigations on the Kinetic Aspects of Anation Mediated Hydrogen Oxidation by Pentapyridyl
Metal Complexes
Murugesan Panneerselvam1, Madhavan Jaccob1* 1Department of Chemistry, Loyola College, Chennai 600 034, India
E-mail: [email protected]
Molecular electrocatalyst is the one who involves mainly the conversion of chemical energy into electrical energy occurred by the electrochemical oxidation of hydrogen using a metal. Detailed investigation of their mechanistic and kinetic aspects of reaction mechanism is necessary to develop the molecular electrocatalyst which can perform such catalytic reactions under laboratory conditions. Among the several molecular electrocatalyst, pentadentate polypyridyl ligand (PY5Me2) based cobalt complexes provide a better platform for competent hydrogen-producing electrocatalyst under soluble, diffusion-limited conditions in both organic and aqueous media. In this particular catalytic reaction, two kind of mechanistic pathways were observed. One of the pathways occurring from an acetonitrile-bound CoII/I couple and another pathway operating from an anation assisted pathway. So, this background is tempted us to rise a question of what reason makes the involvement of anions in the hydrogen oxidation process using a molecular electrocatalyst. In order to understand this, we have aimed to perform the detailed quantum chemical calculations on the reaction mechanism of hydrogen reduction with different anion substituted cobalt pentapyridine complexes.
References
[1]. A. E. King, Y. Surendranath, N. A. Piro, J. P. Bigi, J. R. Long, C. J. Chang, Chem. Sci.
2013, 4, 1578–1587. [2]. M. Panneerselvam, M. Sankaralingam, M. Jaccob (unpublished results)
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A Theoretical Investigation on the Unimolecular Decomposition Pathways of Pyridine and
Pyridine-N-oxide Radicals
Mayank Saraswat, Chitranjan Sah, Lilit Jacob, Sugumar Venkataramani* Department of Chemical Sciences, IISER Mohali, Mohali
Email id: [email protected]
Aromatic hydrocarbons containing hetero atoms are part of the heavy fuels, such as coal and coal-derived liquids [1]. The combustion of them are very important processes in the petroleum industries, andalso used as a source of energy in many power plants.In particular, pyridine, the benzene analogue with nitrogen atom in the core is one of the important sources for the fuel-bound nitrogen. [2,3]. Thermal decomposition of pyridine has been the subject of many detailed experimental and theoretical investigations.Under shock tube pulsed pyrolysis condition, hydrogen cyanide was observed at a temperature above 650 °C, and complete cleavage of the pyridine ring was observed above 900 °C [4].Along with hydrogen cyanide the prominent pyrolytic products were found to be acetylene, cyanoacetylene, diacetylene, methane and hydrogen etc.The thermal decomposition is interpreted as a chain reaction initiated primarily by a C-H bond scissionleading to a pyridine radical [5]. (Scheme 1)
A C-H bond scission in pyridine can potentially lead to three unique radicals. Similar to pyridine, pyridine-N-oxide is equally interesting, if we consider the fact that oxidation of pyridine may lead to the latter. Hence, we consider them as model compounds for studying the complex chemical reactions that occur when heavy fuels undergo pyrolysis and combustion. We, therefore, decided to carry out a detailed theoretical investigation on theunimolecular decomposition pathways of pyridine and pyridine-N-oxide radicals.Thiscurrent investigation is aimed atthe characterization of stationary points on the potentialenergy surfaces, including the transition states to understand the reaction mechanism. The transition states have beenverified by analysing the intrinsicreaction coordinate (IRC). Various channels under unimolecular decomposition pathways for each isomeric pyridine-N-oxide radicalsin comparison with the pyridine radicals will be presented in this contribution.
Scheme1: Possible pathways for o-pyridyl radical ring opening products based on literature[5].
References :
[1]. Unsworth, J. F. In Coal Quality and Combustion Performance; Unsworth, J. F., Barrat, D. J., Robert, P. T., Eds.; Elsevier Science Publishers: Amsterdam, 1991.
[2]. Snyder, L. R., Anal. Chem.1969, 41, 314. [3]. Brandenburg, C. F.; Latham, D. R. J. Chem. Eng. Data1968, 13, 391. [4]. Dubnikova, F.; Lifshitz, A. J. Phys. Chem. 1998, 102, 10880. [5]. Liu R. J. Phys. Chem. A2000, 104, 8368-8374.
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Finding Exchange couplings for a series of 3d Transition
Metals Tetramers
Nisheal Michael Kaley and Swapan K. Pati
Theoretical Sciences Unit, JNCASR, Bangalore.
e-mail: [email protected]
The magnetic properties of 3 d transition metal complexes are quite important for designing magnetic materials. We have selected the 3d metal acetate tetramers for our current study. This tetramer is linked within its neighbouring dimers through a double oxo-bridge. The coupling essentially takes place through this bridge via super-exchange interactions. We have varied the metal atom through the 3d series and used Constrained Density Functional Theory [1] and Broken Symmetry approaches to compute the exchange coupling values. Following this we have also tried to establish a relationship between the coupling constants and the magnetic moment of each of the 3d transition metals tetramers. These results will be presented. References
[1]. Rudra, I.; Wu, Q.; Voorhis, T. V. J. Chem. Phys. 2006, 124.2, 024103.
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Compartmental ligand based Polynuclear Ensembles
having 3d/4f metal ions: Single Molecule
Magnet property
Sourav Biswas, Prasenjit Bag and Vadapalli chandrasekhar*
Chemistry, IIT Kanpur, Kanpur, 208016
e-mail: [email protected]; [email protected] Polynuclear 3d/4f complexes have been receiving a great deal of attentions in recent years because of their not only intriguing structural topologies but also wide range of applications in the field of catalysis1, luminescence2, molecular magnetism3 etc. In particular, their interest in the field of molecular magnetism is because they can behave as single molecule magnets (SMM) or single chain magnets (SCM) due their large ground state spin and Ising type anisotropy, arising from strong spin-orbit coupling. One of the challenging things in this field is to design a proper ligand which can hold the 3d and 4f metal ions simultaneously and at the same time promotes the significant exchange interactions. Therefore proper synthetic route in this field is very appealing. We have been working for some time on 3d/4f complexes and able to assemble various homometallic lanthanide complexes by employing multidentate Schiff base ligands.4 However, the limitations of those ligands prompted us to search for alternative design. Upon the employment of compartmental Schiff base ligands, we are able to assemble a series of pentanuclear {Cu2Ln3}, hexanuclear {Cu4Ln2} and octanuclear {Ni4Ln4} complexes. Interestingly, each of the three series represents entirely new structural topology and their Dy3+ analogues exhibit slow relaxation of magnetization at low temperature.
References [1]. Pohlki, F.; Doye, S. Chem. Soc. Rev. 2003, 32, 104. [2]. Santos, C. M. G.; Harte, A. J.; Juinn, Q. S.; Gunnlaugsson, T. Coord. Chem. Rev. 2008, 252,
2512. [3]. Gatteschi, D.; Caneschi, A.; Pardi, L.; Sessoli, R. Science 1994, 265, 1054. [4]. Das, S.; Dey, A.; Biswas, S.; Colacio, E.; chandrasekhar, V. Inorg. Chem. 2014, 53, 3417.
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Electronic structure of pyridine and pyridine-N-oxide radicals
Lilit Jacob, chitranjanSah, MayankSaraswat, SugumarVenkataramani*
Department of Chemical Science, IISER Mohali, Mohali, Punjab
mail:[email protected]
Free radicals– one of the key reactive intermediates with an unpaired electron –play essential roles in organic synthesis, polymer chemistry, atmospheric chemistry and biochemistry.[1] Besides, they are also significant in material chemistry, in particular, as building blocks in constructing organic molecular magnets, which shows potential applications in data storage, magnetic shielding, and magneto-optical switching.[2, 3]One among the several reported strategies in such construction is to attain a strong magnetic coupling between many mono- and/or poly-radical units to achieve ferri- or ferromagnetic ordering. As a result, high magnetic ordering will be obtained; where the coupling must not be compensated, otherwise antiferromagnetic ordering will occur.[4]In this regard,extensive studies have been carried out to understand the electronic structural aspects of free radicals. Our group’s research interests in volvethe studies on heterocyclic radicals using matrix isolation and computations. One of the prototypical heterocyclic radicals, namely, pyridine radical has been well studied.[5] However, the studies on other heterocyclic radicals and their derivatives are largely unexplored. In this context, we investigate on pyridine-N-oxide radical, which is an interesting molecule as it pocesses an unique functionality that can effectively act as a push electron donor and as a pull electron acceptor group.[6]The preliminary computational results on electronic structural and stability aspects of the three isomericpyridine-N-oxide radicals in comparison with pyridine radicals will be presented. (Scheme 1)
Scheme 1. Isomeric pyridine and pyridine-N-oxide radicals
Reference
[1]. Petr Chrsky and Rudolf Zahradnik, Acc. Chem. Res. 1976, 9, 407-411.
[2]. Tamura M et al, Chem. Phy. Lett, 1991, 186, 5, 401-404.
[3]. Miller J S and Epstein A J, J. Chem. Soc., Chem. Commun. 1998, 1319.
[4]. Hosokhoshi Y et al, J. Am. Chem. Soc. 2001, 123, 7921.
[5]. Vernon R. Morris, Energy & Fuels, 1991, 5, 126-133.
[6]. Ikuo Nakanishi et al, Org. Biomol. Chem.2005, 3, 3263-3265.
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Catalyst for Hydrogen Generation and Storage From Formic Acid Decomposition
K. Jagan, M. Jaccob
Computational Chemistry Laboratory, Department of Chemistry, Loyola College,
Chennai – 600 034 E-mail:[email protected]
Hydrogen is an alternative energy resource for solving severe energy crisis and environmental problems. Currently, the production of hydrogen is largely obtained from decomposition of formic acid, which is nontoxic, biodegradable, environmental friendly. Several metal based molecular electro-catalysts were used for decomposition of formic acid leads to the production of hydrogen. Among these, bipyridine based iridium complexes were found to be efficient catalyst for formic acid decomposition leads to the formation of hydrogen. In order to develop the efficient molecular electro catalysts, a detailed quantum chemical calculation is warranted. So we are aiming to perform the detailed DFT calculations to explore the potential energy surfaces for all the possible reaction mechanisms and key intermediates and transition states. Based on the computed results, most favorable pathway and key features for the efficient catalyst will be discussed.
(R=OH, OMe, F, NH3. , X=Cl, H2O) References
[1]. Wang, W.-H.; Ertem, M. Z.; Xu, S.; Onishi, N.; Manaka, Y.; Suna, Y.; Kambayashi, H.; Muckerman, J. T.; Fujita, E.; Himeda, Y. ACS Catal. 2015, 5 (9), 5496–5504.
[2]. Jagan, K.; Jaccob, M.; Panneerselvam, M. (unpublished results)
Ir
N
NX
R
R
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Magnetic Anisotropy Barriers in Linear Transition Metal Complexes
Sabyasachi Roy Chowdhury, Sabyashachi Mishra
Department of Chemistry, IIT Kharagpur
email: [email protected]
__________________________________________________________________ Linear bicoordinated mononuclear complexes have received wide attetion as single molecule magnets due to the unquenched orbital angular momentum of the metal center. The spin-orbit coupled orbital angular momentum of metal center on interaction with ligand field, produces large magnetic anisotropy. A series of linear complex of transition metals with varying ligand field have been studied employing ab initio electronic structure calculations to evaluate effective magnetic anisotropy barrier. The scalar-relativistic electronic states obtained from state-averaged CASSCF calculations are treated as N-electron basis to obtain spin-orbit coupled states and Kramer's pairs. The transition magnetic moment matrix elements among the Kramer's pairs are analyzed to predict the mechanism of relaxation of magnetization and effective magnetic anisotropy barrier. The strong correlation between the geometry at the metal center and the mechanism of relaxation of magnetization is highlighted.
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Enhancing Anisotropic Energy Barrier of Lanthanide by
Exploiting A Diamagnetic Zn(II) Ion
Apoorva Upadhyay and Maheswarn Shanmugam*
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, India- 400076
E-mail: [email protected]
Unquenched orbital angular momentum constitutes large magnetic anisotropy in lanthanide ions which is evident from the mononuclear teribium phthalocyanin single molecule magnet reported by Ishikawa about a decade ago. Several efforts (such as substituent position on the ligating atom, geometry etc.) been made to enhance the energy barrier of the SMM, however we have shown for the first time by exploiting a diamagnetic zinc ion near vicinity of anisotropic lanthanides increases the effetive enerrgy barrier. To this contribution we have synthesized Dy(III) monomer and a heteronucler dimer of Dy(III)-Zn(II) with molecular formula [Dy(HL)2(NO3)3] (1) and [ZnDy(NO3)2(L
-)2(CH3CO2)] (2) respectively (where L is a Schiff base ligand namely[2-methoxy-6-[(E)-phenyliminomethyl]phenol]). Near fivefold increase in Ueff in 2 compared to 1 is rationalized by detailed ab initio calculations.1 We aim to show the importance of 4d transition metal ions in building SMM, where from largest exchange can be harvested due to the diffused nature of the 4d orbitals. We did present in this poster, one of the largest ruthenium cluster based on carboxylate ligand [Ru6
III(µ3-O)2(µ-OH)2((CH3)3CCO2)12(py)2], which is registered with largest exchange (800 cm-1) known for any transition metal cluster so far. Theoritical calculations shed light on the origin of largest exchange in this ruthenium cluster.2
References
[1]. A. Upadhyay, S. K. Singh, C. Das, R. Mondol, S. K. Langley, K. S. Murray, G. Rajaraman, and M. Shanmugam, Chem. Commun.,2014, 50, 8838.
[2]. A. Upadhyay, J. S. Rajpurohit, M. K. Singh, R. Dubey, A. K. Srivastava, A. Kumar, G. Rajaraman and M. Shanmugam, Chem.-Eur. J.,2014,20,606
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Design and development of magnetic nanomaterials based
on multichelating ligand functionalized MWCNTs
Rashmi Gupta, Sachin Kumar Singh, Bachcha Singh*
Department of Chemistry (Centre of Advanced Study), Institute of Science
Banaras Hindu University, Varanasi 221 005, India
We are describing a new approach to design magnetic nanomaterials via decoration of covalently functionalized multichelating organic moieties to the surface of MWCNTs. On association with the metal ions, these organic-nanomaterial hybrids generate multinuclear metal centre on surface of carbon nanotubes. These newly synthesized hybrid materials were then characterized by FTIR, XPS, SQUID and suitable techniques. Carbon nanotubes are good candidates to promote communication between paramagnetic centers at large distances through a highly delocalized π system [1]. Due to their large chemically active surface and highly conjugated π – electron framework, metal decorated MWCNTs leads to exhibit unprecedented magnetic properties [2].
References
[1]. Si, M.S; Xue, D. S. Applied Physics Lett. 2008, 92, 081907. [2]. Georgakilas, V.; Gournis, D.; Tzitzios, V.; Pasquato, L.; Guldi, D. M.; Prato, M. J. Mater. Chem.
2007, 17, 2679.
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Control of Magnitude and Sign of Magnetic Anisotropy in
Co(II) tetrahedral complexes by Synthetic approach
Shefali Vaidya,1 Subrata Tewary, 1 Yanhua Lan 2, Wolfgang Wernsdorfer2, Gopalan Rajaraman1, and Maheswaran Shanmugam*1
1 Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai,
Maharashtra, India-400076
Email: [email protected] 2 Institut Néel, CNRS and Université Grenoble Alpes, BP 166, 25 Avenue des
Martyrs, 38042 Grenoble Cedex 9, France.
The majority of SMM or SIM compounds reported in the literature have been serendipitously obtained. Due, often, to the lack of systematic studies, very little is known about the factors that influence the magnitude and sign of the D value for any metal ion. This is particularly true for 3d-transition metal complexes, as the orbital angular momentum is quenched by the ligand field. Hence, a very limited number of SIMs has been synthesized based on 3d metal ions. Based on direct current (dc), alternating current (ac), hysteresis magnetic measurements and supported by theoretical calculations, we have detailed, not only how to control the sign of D, but also the factors that significantly affect the magnitude of -D in tetrahedral (Td) Co(II) SIMs that have A ground states. The proposed novel synthetic approach offers a way to enhance the D-value (thus increased Ueff) and to achieve a new generation of Co(II) tetrahedral single-ion magnets in a rational approach with the improved magnetic behavior.
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Magnetic exchange coupling influencing the SMM
properties of Nickel(II)-Lanthanide(III) complexes and
making Ferric wheel {Fe8} complex for a precursor of
Qubit
Naushad Ahmed and Maheswaran Shanmugam Chemistry Department, Indian Institute of Technology Bombay,
Powai, Mumbai 40076, India e-mail: [email protected]
The lanthanide(III) ion because of the unquenched orbital angular momentum impose a large magnetic anisotropy which inturn increase the energy barrier for relaxation of magnetization. The continuous breaking of the record of energy barrier reported for {Dy4K2} and related complexes by various means of synthetic strategy, still the blocking temperature not exceeded 14K. This is due to the Quantum tunneling of magnetization which is significantly faster than the Orbach process. Several efforts have been made to quench the QTM like incorporation of radical system and transition metal ions with lanthanide by enhancing the magnetic interaction. We have designed a suitable Schiff bas ligand 2-methoxy-6-[(E)-2’- hydroxymethyl-phenyliminomethyl]-phenolate to combine the transition and lanthanide metal ions and isolated [Ni2Ln2(CH3CO2)3(HL)4(H2O)2]
3+. Among these complexes, {Ni2Dy2} was found to show out of phase susceptibility signals in which QTM was fully suppressed/quenched to a maximum extent. In the line of interest in Quantum information process we have also isolated novel carboxylate free redox active ferric wheel complex with record exchange antiferromagnetic interaction (J= -170 cm-1) between oxo bridged Fe(III) ions with the same Schiff base ligand.
References
[1]. N. Ahmed, C. Das, S.Vaidya, S. K. Langley, K. S. Murray, M. Shanmugam, Chem. Eur. J. 2014, 20, 14235 – 14239.
[2]. N. Ahmed, C. Das, S. Vaidya, S. K. Langley, K. S. Murray, A. K. Srivastava. M. Shanmugam, Dalton Trans. 2014, 43, 7375–17384.
[3]. N. Ahmed, A. Upadhyay, T. Rajeshkumar, S. Vaidya, J. Schnack, G. Rajaraman, M. Shanmugam. Dalton Trans. 2015, 44, 18743–18747
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Deciphering Prerequisites To Fine Tune Energy Barrier and Exchange Harnessing Theoretical Tools
Tulika Gupta and Gopalan Rajaraman*
Department of Chemistry, IIT Bombay,Powai,Mumbai-400076,India; e-mail: [email protected]; [email protected]
Enhanced energy barrier (Ueff) for magnetization reorientation in Molecular
Nanomagnets (MNMs) are driven by the presence of large ground spin state with a
uniaxial magnetic anisotropy. Lanthanide based SMMs are the most promising in
this arena as they offer a large magnetic anisotropy due to the presence of strong
spin-orbit coupling.
Despite innumerous synthesis of lanthanide-based SMMs or SIMs or SCMs, explicit
understanding of the origin of the slow relaxation of the magnetization and the
mechanisms of the Quantum Tunneling of the Magnetization (QTM) still remains
scarce. We have undertaken detailed2 ab initio calculations within the
CASSCF/RASSI/SINGLE_ANISO/POLY_ANISO approach as implemented in MOLCAS
8.0 suite. We attempted to answer the following intriguing questions: i) Can we
validate experimental anisotropy barrier through elucidation of relaxation
mechanism? ii) Can we extend our study beyond the experimental prejudice? iii)
Can we tune anisotropy by varying basis set/active space? iv) Which diamagnetic
metal ion plays proactive role in governing the barrier of Ln-complexes ? Is it
number of diamagnetic metal ion or its position or nature of 4f electron dentiy-
which one is crucial one dictate magnetic anisotropy behaviour?
References
[1]. M. N. Leuenberger, D. Loss, Nature 410 (2001) 789. [2]. (a)T.Gupta and G. Rajaraman, J. Chem. Sci. 126 (2014),1569. (b) S. K. Singh, T.Gupta,
M.Shanmugam and G. Rajaraman,Chem. Commun. 50 (2014), 15513 (c) S. K. Singh.T.Gupta and G. Rajaraman, Inorg. Chem. 53 (2014), 10835.
-4 -2 0 2 4
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0.51|+5/2>+0.49|+3/2>0.51|-1/2>+0.49|-3/2>
0.98|+15/2>+0.02|+13/2>0.98|-15/2>+0.02|-13/2>
En
ergy (
cm
-1)
M(
DyIIIOb late
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late
ZnIIZnII
Position of Zn???
Zn
Zn
Dy
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137
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138
Ab-initio Studies On The Spin Hamiltonian Parameters Of First Row Mononuclear Transition Metal Complexes
Arup Sarkar, Saurabh Kumar Singh and Gopalan Rajaraman
Department of Chemistry, Indian Institute of Technology Bombay
Email: [email protected]
Zero-field splitting (ZFS) in transition metal ions mainly arises due to the spin-orbit coupling with the excited state of systems having S 1. First row metal complexes have very weak spin-orbit coupling but have significant ligand field effect. And also symmetry and geometric distortions play an important role. The ligand field and geometric distortions determine the final electronic energy levels in these metal coordination complexes. For many years, chemists tried to make molecule-based magnets having high axial anisotropy (large |D| value), which is one of the prime requirements in designing single molecule magnets.1 This work, presents a theoretical study of spin Hamiltonian parameters (g, D, E) of the first row mononuclear transition metal complexes. A very reliable ab initio method, CASSCF/NEVPT2 has been proposed based on the different basis set evaluations.2 The detailed investigation on the roles of d-orbital energy levels and electronic transitions were discussed.
References
[1]. Gatteschi, D., Sessoli, R. & Villain, J. Molecular Nanomagnets (Oxford Univ. Press, 2006). [2]. Singh, S. K.; Gupta, T.; Badkur, P.; Rajaraman, G. Chem. Eur. J. 2014, 20, 10305-10313.
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Magnetostructural Aspects of Polynuclear complexes of
Carboxylate-Appended (2-Pyrydyl)alkylamines
Shashi Kant, R.N. Mukherjee*
Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016,
India
e-mail: [email protected]
Magnetostructural studies on polynuclear complexes, aimed at understanding the underlying structural factors that govern the magnetic exchange interaction between paramagnetic centres mediated by ligand bridge(s), continue to be of interest.1–3 Polynuclear metal carboxylates4 are good candidates for the investigation of the magnetic exchange interaction between adjacent metal ions. It is well known that the carboxylate group can bridge metal ions to give rise to a variety of polynuclear transition metal complexes, ranging from discrete entities to three-dimensional systems.5-7
From the perspective of generating discrete closed oligomeric structures8 we have chosen the carboxylate-appended (2-pyridyl)alkylamine ligands have been considered in this work.
Four new complexes [discrete pentanickel(II), tridecanickel(II), tetracobalt(II) and tridecacobalt(II) cluster] supported by carboxylate-appended (2-pyridyl)-alkylamine ligands have been synthesized and structurally characterized.
References
[1]. O.Kahn, Molecular Magnetism,VCH publishers, Weinheim, Germany,1993. [2]. O. Kahn, Adv. Inorg. Chem., 1995, 43, 179. [3]. K. S.Murray, Adv. Inorg. Chem., 1995, 43, 261. [4]. (a) C. Ruiz-P´erez, ″. Rodr´ıguez-Mart´ın, M. Hern´andez-Molina, F. S. Delgado,
Pas´an, J. Sanchiz, F. Lloret and M. Julve, Polyhedron, 2003, 22, 2111; (b) L. Caadillas-Delgado, O. Fabelo, J. Pasn, F. S. Delgado, F. Lloret,M. Julve and C.Ruiz-Prez, Inorg. Chem., 2007, 46, 7458.
[5]. R. J. Doedens, Prog. Inorg. Chem., 1976, 21, 209. [6]. S. J. Rettig, R. C. Thompson, J. Trotter and S. Xia, Inorg. Chem., 1999, 38, 1360,
and references therein. [7]. V. Tangoluis, G. Psomas, C. Dendrinou-Samara, C. P. Raptopoulou, Terzis and D. P.
Kessissoglou, Inorg. Chem., 1996, 35, 7655. [8]. H. Arora, F. Lloret and R. Mukherjee, Dalton Trans., 2011, 40, 10055.
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Theoretical study on Co mononuclear and dinuclear
complexes toward exploring single molecular magnets
Archana Velloth1 , Yutaka Imamura1 , Hiroshi Sakiyama2 and Masahiko
Hada1*
1Department of Chemistry, Tokyo Metropolitan University, Japan
2Department of Material and Biological Chemistry, Yamagata University, Japan e-mail: [email protected]
For designing novel single molecule magnets1 (SMMs), a high spin ground state and a large magnetic anisotropy are the key components, predominantly the magnetic anisotropy play a pivotal role. Among the 3d transition metal complexes, high spin Co(II) complexes are of particular interest due to its high spin ground state (S) and single ion anisotropy (D).1 Here, in order to understand the magnetic properties and the origin of anisotropy in the selected high spin Co(II) complexes, we performed ab initio calculations on cobalt complexes at the CASSCF level, including the spin-orbit coupling within the SORASSI approach. We have considered both mononuclear as well as dinuclear complexes of cobalt and have explored the single ion and the cluster anisotropy for these systems. For the mononuclear complexes, we were able to correlate between the coordination sphere and the zero field splitting parameter (D) for the complexes. For the dinuclear complexes, the exchange interaction was computed within the Lines model by using POLY_ANISO2 program and the fit of magnetic susceptibility is in good agreement with the experimental data. Even if there is a significant single ion anisotropy for the cobalt, the antiferromagnetic coupling between the ions make the exchange coupled ground state nonmagnetic. Hence from the studied complexes, mononuclear units were highly anisotropic compared to the dinuclear complex which suggests that mononuclear counterparts may be the best candidate to exhibit SMM behaviour.
References
[1]. R. Sessoli, D. Gatteschi, A. Caneschi, M. A. Novak, Nature, 1993, 365,141–143 [2]. J. M. Zadrozny, J. R. Long, J. Am. Chem. Soc., 2011, 133, 20732. [3]. L. F. Chibotaru, L. Ungur, The computer programs SINGLE_ANISO and POLY_ANISO. University of
Leuven, 2012.
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Theoretical study of low spin (S=1/2) single-ion magnets
Martín Amoza and Eliseo Ruiz*
Departament de Química Inorgànica i Orgànica, Institut de Química Teòrica i Computacional
e-mail: [email protected]
One of the main investigation lines in molecular magnetism is the study of Single-Molecule Magnets (SMMs). This systems are characterize for having a slow magnetic relaxation at molecular level due to the presence of an anisotropy energy barrier between the different ±Ms degenerate spin states that depend both of the ground state spin S and its axial zero field splitting parameter D.
This behavior was first notice by Gatteschi & coworkers [1] in 1993 in a Mn12 complex where the antiferromagnetic coupling between 8 MnIII and 4 MnIV leads to a S = 10 ground state. After this discovery many SMMs have been synthesize following different strategies to increase the energy barrier. At first the research aimed at increase the total spin of the systems by couplings between transition metals producing large families of TM-SMMs [2]. The later discovery of the TBA[TbPc2] complex by Isikawa & coworkers [3] showed that anisotropy could be the key factor for larger energy barrier rather than larger spins and give cause for Ln-based SMM and mononuclear SMM (also known as Single-Ion Magnet, SIM). In 2010 this behavior was also shown for TM-SIM in a high-spin FeII trigonal pyramid complex [4].
This work theoretically studies some of these last TM-complexes with just one unpaired electron leading to a low spin value (S=½) and compare with the available experimental data. The three different complexes of FeIII, CoII and MnIV were studied with MOLCAS code following a CASSCF/CASPT2+RASSI and ORCA following a CASSCF/NEVPT2+QDPT methodology. We demonstrate that the simplest FeIII sandwich-type complex has a field-induced single-ion magnet behavior and made a preliminary study of it analogous complex with CoII. Finally we have justified the magnetic properties of the MnIV complex.
References
[1]. Sessoli, R.; Gatteschi, D.; Caneschi, A.; Novak, M. A. Nature 1993, 141. [2]. Aromí, G.; Brechin, E. K. Synthesis of 3 D Metallic Single-Molecule Magnets 2006. [3]. Ishikawa, N.; Sugita, M.; Ishikawa, T.; Koshihara, S. Y.; Kaizu, Y. J. Am. Chem. Soc,
2003, 125, 8694. [4]. Freedman, D. E.; Harman, W. H.; Harris, T. D.; Long, G. J.; Chang, C. J.; Long, J. R.
J. Am. Chem. Soc. 2010, 132, 1224.
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Structural and Magnetic Studies of Copper – Azido Assemblies with Symmetric Amines
Priyanka Pandey, Sailaja S. Sunkari*
Department of Chemistry, Mahila Mahavidyalaya, Banaras Hindu University, Varanasi 221 005
Molecular magnetic systems are much sought after material attributes of supramolecular assemblies with applications ranging from quantum computing, magnetic refrigeration, molecular electronics, high density information storage and so on, which are of contemporary relevance.1 Transition metal - azide systems, (were)are ideal candidates for magnetic studies, as the bridging azido unit (unique bridging moiety in magneto chemistry) can effectively lead to large assemblies or clusters of organized spins provided by the metal centers, under self assembling conditions. While single crystal structure determination is necessary for correlating the magnetic properties, in the absence of structural data (a common feature with large assemblies), spectroscopic signatures of azide binding helps in predicting the structure and understanding the observed magnetic behaviours. With above background, we would be discussing the structural, spectral and magnetic properties of novel Copper(II) - azido assemblies with amino based ligands.
Figure1. Ortep of (i) [{Cu2(1,3-dap)2(N3)4}2] (1); (ii) [{Cu(en)2(N3)2}] (2) & (iii) Cu(det)(N3)2 (3).
References
[1]. (a) J. S. Miller and M. Drillon, Magnetism: Molecules to Materials, Wiley-VCH, Weinheim, Germany, 2002-2005, vol. I-V; (b) Themed issue on Molecule Based Magnets. Chem. Soc. Rev. 2011, 40.
1
2
3
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0.1 1 10 100 1000
0.0
0.5
1.0
1.5
2.0
2.5
'' cm
3 m
ol-1
Frequnecy(Hz)
2 K
3 K
4K
5K
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
Ueff=87Ka) b) c)
Heterometallic 3d-4f Single Molecule Magnets: Experiment and Theory
Vignesh R Kuduvaa, G Rajaramanb*, Keith S Murrayc*
aIITB-Monash Research Academy, IIT Bombay,Mumbai-400076 bDepartment of Chemistry, IIT Bombay, Mumbai-400076
cSchool of Chemistry, Monash University, Victoria, Australia-3168 e-mail: [email protected] & [email protected]
Complexes which exhibit slow relaxation of magnetization, even in the
absence of a magnetic field, are called Single Molecule Magnets(SMMs) and these molecules can act as magnets below their blocking temperature(TB).
[1] To date, the search for SMMs was based primarily on the use of 3d metal ions.[2a] Recently, the design and synthesis of heterometallic 3d-4f clusters have caught great attention since the discovery that such complexes are potential SMMs.[2b-c] We herein report the synthesis, magnetic properties and theoretical studies of a new molecular wheel of core type {MnIII
8LnIII8} and butterfly {CoIII
2LnIII2}complexes. The {MnIII
8LnIII8}
wheels represent the largest MnIII-LnIII heterometallic wheels thus far reported. A non-zero out-of-phase component is observed for Dy and Y analogue, however, no maxima are observed in AC measurements. The MOLCAS[3]calculation in line with the experimental prediction and the Dy complex has SMM behavior but slow magnetic relaxation of the molecule is not observed due to the large transverse components (gx and gy). The {CoIII
2DyIII2} complex is showing maxima in the AC
measurements and results the energy barrier of 87K.
Figure. Molecular Structure of a) {MnIII
8DyIII8} b) {CoIII
2DyIII2} complexes and c) Frequency and
temperature dependence of χM '' for CoIII2DyIII
2 complex.
References
[1]. Sessoli,R.; Gatteschi,D.; Caneshi,A.; Novak,M.A. Nature, 1993, 365, 141. [2]. a) Milios,C.J.; Inglis,R.; Vinslava,A.; Bagai,R.; Wernsdorfer, W. S. Parsons, S. P. Perlepes, G.
Christou, E. K. Brechin, J. Am. Chem. Soc., 2007, 129, 12505. (b) Andruh, M.; Costes, J. P.; Diaz, C.; Gao, S. Inorg. Chem. 2009, 48, 3342. (c) Sessoli, R.; Powell, A. K. Coord. Chem. Rev. 2009, 253, 2328. [3] Aquilante,F.; De Vico,L.; Ferre,N.; Ghigo,G.; Malmqvist, P.A.; Neogrady,P.; Pedersen, T.B.; Pitonak, M.; Reiher, M.; Roos, B.O.; Serrano-Andres, L.; Urban, M.; Veryazov, V.; Lindh, R.; J. Comput. Chem. 2010, 31, 224
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Ab-intio Calculations on Heterometallic {Ln-Ln’} Complexes for Quantum Information Processing
Thayalan Rajeshkumar and Gopalan Rajaraman*
Department of Chemistry, IIT Bombay, Mumbai-400076, India
e-mail:[email protected]
Single Molecule Magnets (SMMs) are of interest to co-ordination chemist because of its interesting magnetic properties and their wide range of applications such as memory storage devices, molecular refrigeration, quantum computing and so on[1]. Recently Guillem and co-workers have synthesized a series of lanthanide ions containing homometallic {Ce2, Er2} and heterometallic complexes {Ce-Y, La-Er, Ce-Er} and in which {Ce-Er} complex is found to be a valid candidate as CNOT gate in quantum information processing. Ab-intio calculations have been carried out on the Homometallic {Ln-Ln} and Hetetometallic {Ln-Ln’} complexes using Molcas Package to understand the magnetic energy levels of the lanthanide ions. The role of co-ordination environment and symmetry around the lanthanide ions are understood using model complexes. Further exchange values between the lanthanide ions are evaluated and the reason behind the preference of heterometallic {Ln-Ln’} complex rather than homometallic {Ln-Ln} complexes have been explored.
References
[1]. Rinehart, J. D.; Long, J. R. Chem. Sci., 2014, 53, 2485–2488. [2]. Aguila, D.; Barrios, L. A.; Velasco, V.; Roubeau, O.; Repolles, A.; Alonso, P. J.; Sese, J.; Teat,
S. J.; Luis, F.; Aromi, G. J. Am. Chem. Soc. 2014, 136, 14215-14222
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a) b) c)
Spin-State Energetics and Spin Crossover Phenomena in
Octahedral Fe(II) Complexes- Through DFT and Ab initio
CASSCF Studies
Subrata Tewary and Gopalan Rajaraman*
Indian Institute of Technology Bombay, Mumbai- 400076, India Email: [email protected]
Spin-crossover (SCO) is generally observed for d4 to d7 metal ions of 1st row transition metals in an octahedral coordination environment. The SCO is a subtle property influenced by small structural/electronic changes.[1] Spin states switch in such complexes can be driven thermally[1], by pressure[2a] and light irradiation.[2b] The spin transition temperature (T1/2) which is characteristic to the SCO properties may differ on heating, T1/2 ↑, compare to that on cooling, T1/2 ↓, which leads to the
hysteresis.[3a] This hysteresis is due to intermolecular cooperative effects[3b] and confers the bistability or “memory effect” which is critical to many practical applications such as display and memory devices.[4] The most studied spin crossover systems were based on Fe(II) complexes[5] and hence a series of Fe(II) spin crossover systems have been studied using standard density functional (DFT) methods and ab initio methods. Highly correlated wave function based methods such as CASSCF (Complete Active Space Self Consistent Field) and MP2 have shown promising results in terms of accuracy but remains computationally expensive. On the other hand DFT is relatively cheap, but its reproducibility depends on whether a particular method is happening correctly.
Figure: a) B3LYP optimized structure b) computed spin density plot and c) MO plot for dx
2-y
2 orbital of [Fe(bik)3](BF4)2 [where bik- bis(1-methylimidazol-2-yl)ketone]
References
[1] P. Gütlich, A. Hauser, H. Spiering, Angew. Chem. Int. Ed., 1994, 33, 2024-54. [2](a)S. Decurtins, P. Gütlich, K. M. Hasselbach, H. Spiering, A. Hauser, Inorg. Chem., 1985, 24, 2174. (b) H. G. Drickamer, Angew. Chem., 1974, 86, 61.[3] (a) J. Kro ber, E. Codjovi, O. Kahn, F. Groliere, C. Jay, J. Am. Chem. Soc., 1993, 115, 9810−11. (b) O. Kahn, C. J. Martinez, Science, 1998, 279, 44−48. [4] P. Gütlich, A. Hauser and H. Spiering, Angew. Chem., Int. Ed., 1994, 33, 20.[5] P. Gütlich, Y. Garciaa, H. A. Goodwinb, Chem. Soc. Rev., 2000, 29, 419–427.
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Oxidation of methane by an N-bridged high-valent diiron–oxo species: electronic structure implications on the
reactivity
Mursaleem Ansari, Gopalan Rajaraman*
Department of Chemistry, Indian Institute of Technology Bombay
e-mail: [email protected]
High-valent iron–oxo species are key intermediates in C–H bond activation of several substrates including alkanes. The heme and non-heme mononuclear Fe(IV)=O complexes cannot easily activate inert C–H bonds such as those of methane. In this context dinuclear complexes have gained attention, particularly -nitrido dinuclear iron species [(TPP)(m-CBA)Fe(IV)( -N)Fe(IV)-(O)(TPP•+)]− reported[1] lately exhibits remarkable catalytic abilities towards substrates such as methane. Here using DFT methods, we have explored the electronic structure and complex spin-state energetic present in this species. To gain insights into the nature of bonding, we have computed the absorption, the EPR the Mössbauer parameters and J vales. We have also probed the mechanism of methane oxidation by the dinuclear Fe(IV)=O species. Calculated results are in agreement with the experimental data and our calculations predict that in [(TPP)(m-CBA)Fe(IV)( -N)Fe(IV)(O)(TPP•+)]− species, the two high-spin iron centres are antiferromagnetically coupled leading to a doublet ground state. Our calculations estimate an extremely low kinetic barrier of 26.6 kJ mol−1[2] (at doublet surface) for the C–H bond activation of methane by the dinuclear Fe(IV)=O species. Besides these mechanistic studies on the methane activation reveal the unique electronic cooperativity present in this type of dinuclear complex.
References
[1]. Kudrik, E. V.; Afanasiev, P.; Alvarez, L. X.; Dubourdeaux, P.; Clémancey, M.; Latour, J.-M.; Blondin, G.; Bouchu, D.;
Albrieux, F.; Nefedov S. E.; Sorokin, A. B. Nat. Chem., 2012, 4, 1024–1029.
[2]. Ansari, M.; Vyas, N.; Ansari A.; Rajaraman, G. Dalton Trans., 2015, 44, 15232–15243.
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Role of first row transition metal in modification of
exchange interaction with the Lanthanide ions
Pragya Shukla and Maheswaran Shanmugam
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai,
Maharashtra, India-400076
email:[email protected]
The magnetic properties of molecular materials has attracted conceivable interest in last few decades. Molecular magnetism is delegate of various research areas which focus on the avocation of molecular approaches to design, study and use new classes of magnetic material in which the properties can be adjust at the molecular level. Single molecule magnets (SMM) are extensive class of nanosized magnetic molecules.
The synthesis of hetero-metal complexes containing both 3d and 4f have attracted attention because of their application in several areas. Lanthanide ions provide significant large anisotropy which lead to a 3d-4f SMMs with properties remarkably different from homo-metallic 3d and 4f ones.1 In order to further understand and improve 3d-4f heterometallic behaviour, we have synthesized a series 4f mononuclear complexes and 3d-Ln hetero-metallic complexes. From magnetic measurement it is confirm that the observed χMT values are in good agreement with the calculated values for Ln monomers and the same has been observed in case of 3d-4f heterometalic. In case of Ni-Ln series Ni-Gd/Dy and Ni-Ho shows ferromagnetic and anti-ferromagnetic interaction at low temperature respectively.
Reference
[1]. a) Yajie Gao et.al. Inorg. Chem. 2011, 50, 1304–1308. b) Zhao-Sha Meng et. al. Dalton Trans., 2012, ,
2320– 2329. c) Maheswaran and co-workers Dalton Trans., 2016, 45,3616-3626.
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Synthesis and characterization of Phosphorous based
monomeric Cobalt complexes
Shalini Tripathi and Maheswaran Shanmugam
Indian Institute Of technology Bombay, Powai, Mumbai – 400076
E-mail: [email protected]
Molecules which tend to retain their magnetization even in the absence of magnetic field are termed as Single Molecule Magnet (SMM) [1]. For such molecules the magnetization relaxation depends on the effective energy barrier, which is significantly altered by the anisotropic parameter and spin ground state [2]. As an excellent candidate for SMM, Co (II) may exhibit large magnetic anisotropy with flexible zero field splitting parameter that mainly depends on its coordination geometry and the degree of their distortions [3]. Previously, it was also predicted that increasing the softness of the ligating atom (from O to S) increases the value of anisotropy [4]. This transpires that nature and covalency of Metal-Ligand bond plays a crucial role for the estimation of magnetic anisotropy. In the same line of study some P- based ligands{1,2 bis(diphenylphosphino)ethane; triethylphosphite} are chosen for present work such that along with the impact of soft nature of the ligand, effect of various geometries and chelation on magnetism can be further studied.
Figure 1Crystal structure of A). [Co(Cl)2(dppe)2] B). [CoCl(Dppe)2].SnCl3C). [Co{P(OEt)3}5].BPh4
Reference
[1]. R. Sessoli, D. Gatteschi, A. Caneschi and M. A. Novak, Nature (London)1993, 365, 141-143. [2]. 2.Guo Y.-N., Xu G.-F, Gamez P., Zhao L., Lin S.-Y., Deng R., Tang J., Zhang H.-J.. J. Am. Chem.
Soc.,2010, 132, 8538–8539. [3]. 3. -
, J. Am. Chem. Soc., 2013, 135, 15880. [4]. 4. S. Vaidya, A. Upadhyay, S. K. Singh, T. Gupta,S.Tewary, S. K. Langley, J.P. S. Walsh, K.
S.Murray, G.Rajaraman and M.Shanmugam, ChemCommun. ,2015 , 51(18), 3739-3742 (b) J. M. Zadrozny and J. R. Long, J. Am. Chem. Soc.2011, 133, 20732-20734.
A) B) C)
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Macrocyclic Schiff base-Lanthanide complex SMMs for
molecular spintronics application
Mohd Wasim and Maheswaran Shanmugam* Indian Institute of Technology, Bombay, Powai, Mumbai- 400076
e-mail:[email protected]
Single Molecule Magnets (SMMs) since its discovery in Mn12complex in early 1990s, has attracted increasing interestdue to its fascinating application in storing and processing high density information and in molecular spintronics [1-4]. However the limitation associated with SMMs is its low blocking temperature, and loss of its SMM behaviour when functionalised on surface.Lanthanides take advantage over transition metals due to their large spin and highly anisotropic nature needed for higher blocking temperature but the disadvantage includes quantum tunnelling of magnetisation(QTM) which is more prominent in lanthanideSMMs.Recently Long et al. have observed that presence of bridging N2
3-radical can increase exchange interaction up to approximately fifty times in lanthanide dimer complexes which not only supresses QTM but also increases the blocking temperature.[5-7]So owing to these observations we have synthesised mononuclear as well as peroxo bridged binuclear lanthanide complexes containing macrocyclic Schiff base ligand with extended conjugation. We are expecting that these complexes would show good SMM behaviour which can be tuned due to the redox activity of conjugated macrocyclic ligand. Our future plan is to functionalise these complexes on gold and carbon nanotube through different covalent and noncovalent linkage and to observe the transport phenomenon through the assembly to explore its application in
molecular spintronics.
References
[1]. Sessoli,R.;Gatteschi,D.;Caneschi,A.;Novak,M.A.Nature1993, 365, 141-143. [2]. Sessoli, R.;Tsai,H.L.;Schake, A.R.; Wang, S.; Vincent, J.B.;Folting, K.;Gatteschi, D.; Christou, G.;
Hendrickson,D. N.J. Am. Chem. Soc.1993, 115, 1804-1816. [3]. Gatteschi,D.;Caneschi, A.;Pardi, L.;Sessoli, R.Science1994, 265, 1054-1058. [4]. Bogani,L.;Wersdorfer, W.Nature mat.2008, 7, 179-186 [5]. Rinehart,J.D.; Long, J. R.Chem. Sci.2011, 2, 2078-2085. [6]. Rinehart, J.D.; Fang, M.; Evans, W.J.; Long, J. R. J. Am. Chem. Soc.2011,133, 14236-14239. [7]. Rinehart, J.D.; Fang, M.; Evans, W.J.; Long, J. R. Nat. Chem.2011,3,538-542.
Crystal structure of complexes [Ce(MeL1)(NO3)3], [Gd(L1) (NO3)2(DMF)]
+ and [Ln2(L1)2(NO3)2(O2)]
2+(Where
Ln=Dy or Ho). Colour scheme red,blue and gray for oxygen, nitrogen and carbon respectively.
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Synthesis of nano sized TiO2 and its application in Adsorption removal of methylene blue and
Antimicrobial activity
R. Ranjith, S. Priscilla Prabhavathi, D. Maruthamuthu, Shameela Rajam*
Research Department of Chemistry Bishop Heber College
Tiruchirappalli-620017, Tamilnadu, India
email: [email protected]
Titanium dioxide is a versatile heterogeneous catalyst. Absorption of light by a TiO2 nanoparticles leads to the formation of an electron–hole pair. 2. Adsorption study is carried out on methylene blue. The TiO2 nanoparticles were synthesized via Sol-gel route from precursors TiCl4 and ethanol. The attempt has been made to develop more faster and economical removal of methylene blue dye from aqueous solution. The material is analysed by FT-IR, UV, SEM-EDS, XRD and TEM techniques. The antimicrobial activity of the nanoparticles s ware investigated by their capability to inactivate Escherichia coli (E. coli) in an actual food packaging application test under various conditions, including types of light (fluorescent and ultraviolet (UV)) and the length of time the nanoparticles ware exposed to light. The antimicrobial activity of the TiO2 nanoparticles - exposed under both types of lighting was found to increase with an increase in the TiO2 nanoparticles concentration and the light exposure time. It was also found that the antimicrobial activity of the films exposed under UV light was higher than that under fluorescent light. The developed nanoparticles has the potential to be used as a food packaging nanoparticles that can extend the shelf life, maintain the quality, and assure the safety of food.
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Synthesis and Characterization of N-Heterocyclic Carbene
Dinuclear Silver(I) and Copper(I) Complexes
Bharathi Dileepan A.G, Maruthamuthu D, Ranjith R, Shameela Rajam*
PG Research and Department of Chemistry, Bishop Heber College, Affiliated Bharathidasan University, Trichy, India
E-mail: [email protected]
The modification of dinuclear silver and copper metallcycles is described. Reaction of benzimidazole with 1,2-dibromoethane gives 1,2-bis(1H-benzo[d]imidazole-1-yl)ethane (L). The dibenzimidazolium salts react with AgCl/CuCl to give the dinuclear silver(I)/copper(I) tetracarbene metallacycles
Ag(1)/Cu(2) in high yield. Irradiation (UV light, 365 nm) of Ag and Cu in [D6] ACETONE resulted in rapid conversion into the corresponding dinuclear bridged-carbon complexes Ag(3) and Cu(4) quantitatively. The carbon-bridged precursors were isolated in good yields as their tetrabenzimidazolium salts.
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Synthesis, Characterization and Photoluminescence
Properties of Cu(II), Ni(II), Co(II), and Zn(II) Complexes
of Isatin Derivatives
Rajesh Kumar M, Violet Dhayabaran V,* Muthulakshmi R, Malathi M
P.G and Research Department of Chemistry, Bishop Heber College, Trichy-620017.
Tamil Nadu, India
e-mail: [email protected]
This research focuses on the preparation, characterization, and photoluminescence
properties of new Co(II), Ni(II), Cu(II) and Zn(II) complexes of isatin derivatives.
The ligand and metal complexes were characterized by spectroscopic studies such
as IR, UV/Vis, NMR, photoluminescence spectroscopy and molecular docking
studies. The ligand and the metal complexes gave intense emissions ( max= 267-
297 nm) upon irradiation by ultraviolet light. The photoluminescence quantum
yields and long excited-state lifetimes of the ligand The photoluminescence
intensities and quantum yields of the metal complexes changed upon complexation
with various metals ( max: Ni= 361 nm, Zn= 363 nm, Cu= 375 nm, Co= 370 nm)
and ( max: Ni= 361 nm, Zn= 351 nm, Cu= 354 nm, Co= 352 nm). Drug designing
against breast cancer as they are exhibiting excellent binding property with the
BCAR1 protein. These novel complexes may be of interest as organic emitting
material for electroluminescent devices.
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Phytochemical Screening, GC-MS Analysis and Pharmacological Activity of Shuteria Involucrata
Senthamizh Selvan. N, Isaiah. S*
PG & Research Department of Chemistry, Bishop Heber College (Autonomous),
Tiruchirappalli-620017, Tamilnadu, India
e-mail: [email protected] (Isaiah. S)
In the present work, leaf and stem extract of Shuteria involucrata plant were
prepared by soxhlet apparatus using various solvents such as chloroform, ethanol,
n-Hexane, methanol, petroleum ether and water. The extracts were screened for
major phyto constituents using established procedures. Around fifteen phyto
constituents were identified to be present. The antimicrobial activity was carried out
by disc diffusion technique against the six selected pathogens. Among the six S.
auereus, P. aeruginosa and C. albicans were more susceptible to the extract,
whereas the others are less susceptible. The extracts were also tested for the anti-
cancer activity against (HeLa) the human cervical cancer cell line using MTT assay.
The results revealed that the extracts exhibit appreciable antiproliferative against
the HeLa cells. The ethanol fraction of the Shuteria involucrata was taken for GC-
MS analysis. The GC-MS analysis exhibited peaks of six different phytochemical
compounds. The presence of various bioactive compounds confirms the application
of Shuteria involucrata for various ailments by traditional practioners.
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Structurally Engineered Cysteine Capped ZnO/GO
Nanocomposites for Photocatalytic Degradation of
Rhodamine B under Visible Light
S.Steplin paul Selvina, N.Radhikaa, I.Sharmila Lydiaa*
a PG and Research Department of Chemistry, Bishop Heber College, Tiruchirappalli -
620017, Tamil Nadu, India
Email: [email protected]
L-cysteine capped ZnO nanoparticles (CCZ-NP) were synthesized by microwave
assisted chemical precipitation method. They were immobilized on to a graphene
oxide (GO) matrix by sonochemical method. CCZ-NP and immobilized CCZ-GO were
spectrochemically characterized using FT-IR, diffuse reflectance UV-Vis., powder-
XRD, Surface morphology of nanoparticles was studied by SEM technique. The
crystal structure ((hexagonal wurtzite) and average particle size of capped ZnO
nanoparticles were identified by powder-XRD data. In the degradation of
Rhodamine-B (RhB) under visible light, both CCZ-NP and immobilized CCZ-GO
composites were exhibited good photocatalytic activity upto 98.13% in 45 min.
Last but not the least its Bhangra which is a lively form of folk music and dance that originates from
Punjab. People traditionally perform bhangra celebrating harvest. During bhangra people sing Punjabi
boliyaan and at least one person plays the Dhol drum. All forms of Bhangra singers employ a high,
energetic tone of voice. Singing ercely and with great pride, they typically add nonsensical, random
noises to their singing, the dance moves involve raising the arms above the shoulders. Some of the
steps mimic actions related to harvesting. While bhangra begins as a part of harvest festival celebrations
it eventually became a part of such diverse occasions like weddings and New Year celebration.
We here at Department of Chemistry, IIT Bombay take great pride in showcasing the quality
and variety of Indian Culture in given short span of time.
The performance will start with playing sitar by Sagar Joshi which includes alaap: it is an
opening section of the performance; alaap actually sets the mood for raag followed by jhala: it
is a fast paced conclusion of classical compositio n before the gat part starts. Gat which refers
to the speed of the rhythm and is used when the musical composition is in full swing will be
presented after after jhala. Next composition is based on teen taal, which is a rhythmic cycle of
16 beats with four equal divisions. Indian musicians believe that teen taal in the king of taal-s.
After that yaman raga will be presented which is considered to be one of the most fundamental
ragas in Hindustani Classical tradition. This raga is traditionally sang during evening time. After
this it's time for a natyasangeet based on raag todi. Natyasangeet is a form of Indian semi
classical music originated in Maharashtra.
Next performance is by Ranjana phadke invoking the sun god- suryastuti followed by traditional
routine in kathak, from the Sanskrit word katha meaning "story", and katthaka in Sanskrit means
"he who tells a story", or "to do with stories". The structure of a conventional kathak performance
tends to follow a progression in tempo from slow to fast, ending with a dramatic climax. After that
in abhinaya paksha we will see a picturesque presentation of the colourful festival of Holi- a semi
classical form potraying the festival of vibrance, moods and energy.
Third half of the programme will compromise of two well-known folk dances of India – Bihu and
Bhangra.
The bihu dance is a folk dance from the indian state of assam related to bihu festival. This joyous
dance is performed by both young men and women. Like some other Indian festivals, Bihu (all three)
is associated with farming; as the traditional Assamese society is predominantly agricultural. The
Rongali bihu or Bohag bihu is an important festival of assam, celebrated with fun in abundance by all
assamese people irrespective of caste, creed and belief.
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