synthesis of binaphthyl-based push-pull chromophores with supramolecularly polarizable acceptor ends

Research ArticleSynthesis of Binaphthyl-Based Push-Pull Chromophores withSupramolecularly Polarizable Acceptor Ends

Carmine Coluccini12 Giancarlo Terraneo3 and Dario Pasini14

1Department of Chemistry University of Pavia Viale Taramelli 10 27100 Pavia Italy2IMDEA Materials C Eric Kandel 2 Tecnogetafe Getafe 28906 Madrid Spain3Dipartimento di Chimica Materiali ed Ingegneria Chimica ldquoG Nattardquo Politecnico di Milano Via L Mancinelli 7 20131 Milano Italy4INSTM Research Unit University of Pavia Italy

Correspondence should be addressed to Carmine Coluccini carminecolucciniimdeaorg andDario Pasini dariopasiniunipvit

Received 11 December 2014 Revised 19 February 2015 Accepted 23 February 2015

Academic Editor Narcis Avarvari

Copyright copy 2015 Carmine Coluccini et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

We report on the design and synthesis of new enantiopure binaphthyl derivatives in which electron-donating and electron-withdrawing substituents are placed in direct conjugation to create push-pull dyes potentially active forNLOapplicationsThedyesunprecedentedly extend their 120587-bridge from the 331015840 positions of the binaphthyl units and incorporate as acceptors 13-dicarbonyland tetrafluorobenzene units useful for further supramolecular polarization of the chiral dyes

1 Introduction

Conjugated organic compounds and polymers are employedin many technological applications and widely studied eitherin solution or in bulk [1] Secondharmonic generation (SHG)a nonlinear optical property which is at the foundation foradvanced technologies in materials science and biologicalimaging requires a fully conjugated organic structure atthe molecular level and the absence of a center of symme-try in the bulk [2ndash6] Centrosymmetrical molecules needstringent conditions in the self-assembly process in orderto generate efficient materials for SHG [7 8] On the otherhand molecular chirality offers simple design principlesfor push-pull and noncentrosymmetric molecules and thenanostructuring via self-assembly of chiral organic dyes hasbeen shown to have pronounced effects and amplificationsof their SHG response [9] Binaphthyl compounds havebeen exploited for the realization of second-order nonlinearoptical (NLO) materials having the combined advantagesof being chromophores and carrying the required elementof chirality for bulk anisotropy [10ndash17] In fact binaphthylsystems such as that shown in Figure 1 are composed of twochromophores joined through an aryl-aryl bond which is theelement (axis) of chirality with dihedral angles usually close

to 90∘ so that interchromophoric conjugation is not efficientThe application of the binaphthyl compounds in the field ofnanosciences is recent and not yet fully explored [18ndash29] Inall previously reported examples of binaphthyl dyes for NLOapplications the molecular design expressing the push-pullconcept was developed by placing electron donating groupsin the 221015840 positions and the electron accepting units in the661015840 positions (Figure 1) [10ndash17]

Our research group studied various compounds in whichan electron donating group is conjugated through a 120587-bridgeto an electron accepting group which is a 13-dicarbonyl unitable to undergo further polarization by coordination withLewis-like metal ions [30ndash35] Examples of chromophoresable to undergo polarization and head to tail orientation uponthe use of specific supramolecular interactions are known[36ndash38] In this work we present our synthetic approachfor the obtainment of enantiopure binaphthyl systems ofnovel design and conception in which the 120587-bridge isextended through the 331015840 position The electron deficientmoieties in the form of 13-dicarbonyl units for compounds1 and iodotetrafluorobenzene units for compounds 2 canbe in principle further polarized by means of complexationwith metal cations in the former case or halogen bondingacceptors (eg pyridines) in the latter case (Figure 2)

Hindawi Publishing CorporationJournal of ChemistryVolume 2015 Article ID 827592 7 pageshttpdxdoiorg1011552015827592

2 Journal of Chemistry

+

+OO

Chiral axis

Chiral axis

O2N

O2N

minus

minus

Figure 1 The molecular design for push-pull chiral binaphthyl derivatives [16]

OMeOMe

O O

OO

O

O

O

O1a1b

n

n

Cationcomplexation

Cationcomplexation

n = 1n = 0

(a)

n

n

OMeOMe

F

FF

F

FF

FF

2a2b

I

I

Halogenbonding

Halogenbonding

n = 1n = 0

(b)

Figure 2 Target compounds subject of this paper

2 Results and Discussion

21 Synthesis of the Molecular Modules In our design strat-egy the electron-donating alkoxy substituents in the 221015840positions are in an ortho relationship with respect to thegrowing 120587-bridge in the 331015840 position achieving efficientconjugation with the 120587-bridge The synthesis of the key com-pounds is shown in Scheme 1 Enantiopure starting materialsfor this work were obtained via multistep syntheses startingfrom the commercially available enantiopure (R)-BINOLwhich was chemically transformed under nonracemizingconditions

Compound (R)-1b (Scheme 1 top) was synthesized usinga Knoevenagel condensation reaction between elongatedrecently reported dialdehyde (R)-3b [39] and dimethylmalonate 4 The reaction was carried out under classi-cal conditions (piperidine as the catalyst continuous H

2O

removal with a Dean-Stark apparatus) the compound wasisolated in good yield after column chromatography andfully characterized (see Appendix) On the contrary usingidentical conditions compound (R)-1a could not be obtainedfrom dialdehyde (R)-3a It is likely that the enhanced sterichindrance caused by the presence of the methoxy grouportho to the aldehyde functionality is responsible for the

Journal of Chemistry 3

O

OO

O+

O O

OO

R

567

PiperidineOMeOMe

O O

OO

O

O

O

O

OMeOMe

O

O

+NaH

DMFrtOMeOMe

O

O

F F

FF OMeOMe

F

FF

F

FF

FF

4

8

n

n n

nn

n n

n

3a3b n = 1

n = 0

3a3b n = 1

n = 0

1b n = 1 (50)

9b n = 1 (69)9a n = 0 (20)

BenzeneΔ

R = BrR = PO(OEt)2R = P(Ph)3

+Brminus

P(Ph)3+Brminus

Scheme 1 Synthesis of the molecular modules described in this paper

reduced reactivity in this case We also explored alternativereaction approaches to the synthesis of (R)-1b by means ofolefination reaction (Wittig or Horner-Wadsworth-Emmonsmethodologies) involving binaphthyl dialdehyde derivative(R)-3a in combination with 120587-extended phosphonate 6 orphosphonium salt 7 In both cases however decompositionof 6 or 7 occurred in the presence of the strong basesrequired for Wittig or HWE reactions presumably becausea carbon-carbon double bond which is highly activatedtowards nucleophilic attack is present in the 120587-extendedstructures

Reaction of (R)-3a and (R)-3b with phosphonium salt8 using standard Wittig conditions (NaH DMF) affordedcompounds (R)-9a and (R)-9b in acceptable yields Thestereochemistry of the newly carbon-carbon double bondwas determined to be stereopure trans by NMR spectroscopy

With the aim to expand the supramolecular functional-ities of 9b we targeted the formation of halogen bondingdonor sites by adding an iodine atom for each tetrafluo-rophenyl ring It is known that iodine atoms when theyare covalently bound to strong electron-withdrawing groupssuch as fluorinated residues function as very efficient elec-tron density acceptor sites [40] The iodination reaction onthe partially fluorinated rings in 9b was carried out at lowtemperature (minus78∘C) by using BuLiI

2in dry THF under

N2atmosphere Unfortunately the addition in para position

of the iodine atom occurred partially and a mixture ofthe starting material 9b and the iodinated product 2b wasrecovered as confirmed by analysis of 19F-NMR spectrum(see Figure S1 in Supplementary Material available onlineat httpdxdoiorg1011552015827592) In the region ofminus140 ppm the presence of two signals minus140 and minus144 ppm


300 400 500

A

0

2

1b(10120583M)1b(10120583M) + Eu(OTf)3 (15 eq)

120582 (nm)

(a)

300 400 500

A

00

02

9b

120582 (nm)

(b)

300 400 500

0

20

9b

120582 (nm)

minus20

Δ120576

(Mminus

1 cmminus1)

(c)

Figure 3 (a) Titration experiment of 1b with Eu(OTf)3in MeCN ((b) and (c)) UV and CD spectra of 9b (1 120583M MeCN)

respectively confirmed the occurrence of unreacted startingmaterial 9b while the presence of the peak at minus123 ppmcharacteristic for fluorine atoms on an aromatic moiety inortho position to an iodine atom suggested the formationof small amount of iodinated system Other small peaks atminus136 and minus121 ppm which were detected in the spectrumhighlighted the possible formation of different side productsarising from the iodination reaction The best ratio betweenhydrogenated and iodinated compound was 10 3 Severalattempts to purify this mixture have been carried out usingstandard chromatography crystallization and cocrystalliza-tion methods however neither a fully purification nor anenrichment in the mixture of the iodinated compound wasobtained Further attempts have been made to obtain thetarget halogen bonding donor compound by chaining theexperimental conditions mainly the temperature howeverpure iodinated system was never isolated

22 Absorption Complexation and Chiroptical PropertiesWe have recently reported on the characterizationof supramolecular complexes involving push-pullchromophores in which the electron-withdrawing molecularfragment is a malonate moiety and we have demonstratedthat this moiety is able to form supramolecular reversiblecomplexes with metal cations (such as lanthanides) behavingas Lewis Acids [30ndash35] The peculiar nature of thesecomplexes is testified by a large red shift (ca 100 nm) of theintramolecular charge-transfer absorption band (ICT) uponcomplexation In order to verify the potential of compound1b for complexation and supramolecular polarization weperformed titrations in MeCN using our previously usedprobes Eu3+ and Sc3+ as trifluoromethanesulfonate saltssince they are readily dissolved in MeCN As shown inFigure 3(a) the addition of up to 15 equivalents of Eu(OTf)

3

resulted in negligible changes in the UVVis spectra


Essentially identical results were obtained with Sc(OTf)3

This could be caused by an inefficient complexation ofthe conjugated malonate moiety in 1b with the metalcenter in these conditions In any case since the red shiftpreviously observed is completely lacking the utility of1 as supramolecularly polarizable dyes is reduced TheUV spectrum of ligand 1b alone showed the low energyabsorption band attributable to the Intramolecular ChargeTransfer band at 358 nm which is similar to that obtained for9b (361 nm) and to those obtained for pyridine-terminatedanalogous compounds [39] The CD spectra of 9b showedthe classical exciton couplet signature typical of binaphthylsystems centered at 360 nm coincident as expected withthe ICT 120582max of the compound

3 Conclusions

We have reported the synthesis and experimental character-ization of binaphthyl-based push-pull dyes of novel concep-tion The synthetic methodologies building on enantiopureknown binaphthyl derivatives have been demonstrated tobe viable for the construction of the 120587-bridge with therequired stereospecificity regarding the newly formed doublebond In the case of dyes 1 a more thorough study ontheir inability to give the expected UVVis response uponinteraction with the metal cation will be carried out inthe near future Regarding dyes 2 the failure of the finaliodination step suggests the possibility of the introductionof a fully functional supramolecular unit from a suitableiodinated phosphonium salt through theWittig reaction Weare currently developing this synthetic approach

Appendix

Experimental

General Experimental All available compounds were pur-chased from commercial sources and used as receivedCompounds 3a [41] 3b [39] 5 [42] and 8 [43] wereprepared as previously described THF (Na benzophenone)Et2O (Na benzophenone) and CH

2Cl2(CaH2) were dried

and distilled before use Analytical thin layer chromatog-raphy was performed on silica gel chromophore loadedcommercially available plates Flash chromatography wascarried out using silica gel (pore size 60 A 230ndash400mesh)1H and 13C NMR spectra were recorded from solutionsin CDCl

3on 200 300MHz or 500MHz spectrometer with

the solvent residual proton signal or tetramethylsilane as astandard The UVVis spectroscopic studies were recordedusing commercially available spectrophotometers Opticalrotations were measured on a polarimeter in a 10 cm cellwith a sodium lamp (120582 = 589 nm) and are reported asfollows [120572]rtD (c = mg(mL)minus1 solvent) CD spectra wererecorded at 25∘C at a scanning speed of 50 nmminminus1 andwere background corrected Each spectrum is the instrumentaverage of four consecutive scansMass spectrawere recordedusing an electrospray ionization instrument (ESI)

General Procedure for the Titration ExperimentsThe titrationexperiments were conducted as follows to a stock solutionof the ligand (solution A) in MeCN (UVVis spectroscopicgrade) several aliquots of the guest (solution B) were addedSolution B is formed by the lanthanide triflate at higherconcentration dissolved in solution A in order to maintainthe ligand always at the same constant concentration

Compound 1b A solution of 3b (58mg 0101mmol)dimethyl malonate 4 (43mg 032mmol) and three dropsof piperidine in benzene (5mL) was stirred at reflux witha Dean-Stark apparatus for 15 h The solvent was removedin vacuo and the reaction mixture was then treated withH2O (10mL) at room temperature extracted with AcOEt

(3 times 20mL) and dried (Na2SO4) The reaction mixture

was purified by flash column chromatography (SiO2 hex-

aneAcOEt 11 to 37) to afford 1b as a yellow solid (40mg50) MS(ESI) mz 825 ([M + Na]+ 100) 1627 ([2M +Na]+ 100) 1H NMR (CDCl

3 300MHz 25∘C) 120575 = 829

(s 2H -CH=C(COOMe)2) 797 (d 2H binaphthyl) 780 (s

2H -binaphthyl) 774 (d 2H -CH-vinyl J = 16Hz) 763 (d4H -ArH) 75ndash71 (m 16H -CH-binaphthyl -CH-vinyl andArH) 391 (s 6H -COOMe) 388 (s 6H -COOMe) 343(s 6H -OCH

3) 13C NMR (CDCl

3 75MHz 25∘C) 120575 = 1672

(C=O) 1645 (C=O) 1544 (Cq) 1423 (CH) 1401 (Cq) 1338(Cq) 1318 (Cq) 1307 (Cq) 1305 (Cq) 1300 (CH) 1293(CH) 1282 (CH) 1269 (CH) 1265 (CH) 1260 (CH) 1256(CH) 1252 (CH) 1251 (CH) 1247 (Cq) 613 (CH

3) 527

(COOCH3) 526 (COOCH

3)

Compound 6 A solution of 5 (586mg 187mmol) andtriethyl phosphite (157 g 943mmol 50 eq) was refluxed intoluene (60mL) for 24 h After cooling the solvent and excessphosphite were removed under vacuo and the product waspurified by column chromatography (hexaneethyl acetate14 to 19) to yield compound 6 as a yellow oil (559mg81) 1H NMR (CDCl

3 300MHz 25∘C) 120575 = 775 (s 1H

Ar-CH=C(COOMe)2) 740ndash728 (m 4H ArH) 400 (m

4H P(O)OCH2CH3) 385 (s 6H -COOCH

3) 317 (d 2H

ArCH2P(O)OEt) 127 (t 6H P(O)OCH

2CH3) 13CNMR

(CDCl3 75MHz 25∘C) 120575 = 1671 1644 1423 1347 1312

1302 1295 1251 621 526 346 328 163

Compound 7 A solution of PPh3(295mg 113mmol) and

5 (344mg 110mmol) was refluxed in toluene (3mL) for6 h After cooling the precipitate was filtered off to yieldcompound 7 as an orange solid (310mg 49) 1H NMR(CDCl

3 300MHz 25∘C) 120575 = 782ndash760 (m 16H ArH) 722ndash

713 (m 4H ArH) 566 (d 2H ArCH2PPh3) 385 (s 3H

-COOCH3) 383 (s 3H -COOCH

3) 13C NMR (CDCl

3

75MHz 25∘C) 120575 = 1668 1642 1417 1349 1344 1325 13211303 1301 1300 1294 1260 1181 1170 527 307 301

Compound 9aNaH (5mg 02mmol) was added to a solutionof the phosphonium salt 8 (80mg 016mmol) in dry DMF(2mL) After stirring for 30min at room temperature asolution of compound 3a (27mg 007mmol) in dry DMF(1mL) was added After stirring at 40∘C for 15 h H

2O was

added and the mixture was extracted with CH2Cl2 The


organic phase was dried (Na2SO4) and the reaction mixture

purified by flash chromatography (SiO2 hexaneCH

2Cl273)

to yield 9a as a white solid (10mg 20) MS(ESI) mz 663([M + H]+ 100) 685 ([M + Na]+ 97) 1347 ([2M + Na]+40) 1H NMR (CDCl

3 200MHz 25∘C) 120575 = 830 (s 2H

binaphthyl) 803 (d 2H -CH-vinyl J = 16Hz) 801 (d 2Hbinaphthyl) 749ndash716 (m 10H binaphthyl and -CH-vinyl)696 (m 2H -CH- tetrafluorophenyl) 345 (s 6H -OCH

3)

Compound 9b NaH (45mg 176mmol) was added to asolution of the phosphonium salt8 (593mg 117mmol) in dryDMF (2mL) After stirring for 30min at room temperaturea solution of compound 3b (337mg 059mmol) in dry DMF(3mL) was added After stirring at 40∘C for 15 h H

2O was

added and the mixture was extracted with Et2OThe organic

phase was dried (Na2SO4) and the reaction mixture purified

by flash chromatography (SiO2 hexaneCH

2Cl273) to yield

9b as a yellow solid (350mg 69) [120572]25D = minus5056∘ (c =00016 CH

2Cl2) MS(ESI) mz 866 ([M + H]+ 100) 1H

NMR (CDCl3 300MHz 25∘C) 120575 = 830 (s 2H binaphthyl)

796 (d 2H binaphthyl) 771ndash757 (m 10H -ArH- and -CH-vinyl) 751ndash741 (m 6H binaphthyl and -CH-vinyl) 726ndash710 (m 6H binaphthyl and -CH-vinyl) 696 (m 2H -CH-tetrafluorophenyl) 345 (s 6H -OCH

3) 13C NMR (CDCl

3

75MHz 25∘C) 120575 = 1544 (Cq) 1470 (CF) 1440 (CF) 1383(Cq) 1369 (Cq) 1359 (Cq) 1337 (Cq) 1308 (Cq) 1298(CH) 1281 (CH) 1273 (2CH) 1270 (2CH) 1263 (CH) 1262(CH) 1256 (CH) 1251 (CH) 1246 (CH) 1136 (CH) 1130(Cq) 1040 (CH) 1036 (CH) 613 (CH

3)

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

Support from the University of Pavia MIUR (Programs ofNational Relevant Interest PRIN Grants 2004-033354 and2009-A5Y3N9) from CARIPLO Foundation (2007ndash2009)and in part from INSTM-Regione Lombardia (2010ndash2012and 2013ndash2015) is gratefully acknowledged The authors wishto thank Stefano Colombo for early experimental involve-ment in this work

References

[1] A C Grimsdale K L Chan R E Martin P G Jokisz and AB Holmes ldquoSynthesis of light-emitting conjugated polymers forapplications in electroluminescent devicesrdquo Chemical Reviewsvol 109 no 3 pp 897ndash1091 2009

[2] S R Marder ldquoOrganic nonlinear optical materials where wehave been and where we are goingrdquo Chemical Communicationsno 2 pp 131ndash134 2006

[3] T Verbiest S Sioncke A Persoons L Vyklicky and T J KatzldquoElectric-field-modulated circular-difference effects in second-harmonic generation from a chiral liquid crystalrdquo AngewandteChemie International Edition vol 41 no 20 pp 3882ndash38842002

[4] H Kang A Facchetti H Jiang et al ldquoUltralarge hyperpolariz-ability twisted 120587-electron system electro-optic chromophoressynthesis solid-state and solution-phase structural charac-teristics electronic structures linear and nonlinear opticalproperties and computational studiesrdquo Journal of the AmericanChemical Society vol 129 no 11 pp 3267ndash3286 2007

[5] P A Sullivan and L R Dalton ldquoTheory-inspired develop-ment of organic electro-optic materialsrdquo Accounts of ChemicalResearch vol 43 no 1 pp 10ndash18 2010

[6] U Gubler and C Bosshard ldquoA new twist for nonlinear opticsrdquoNature Materials vol 1 no 4 pp 209ndash210 2002

[7] G J Ashwell ldquoCentrosymmetric molecules for second har-monic generationrdquo Advanced Materials vol 8 no 3 pp 248ndash250 1996

[8] F Wurthner J Schmidt M Stolte and R WortmannldquoHydrogen-bond-directed head-to-tail orientation of dipolarmerocyanine dyes a strategy for the design of electroopticalmaterialsrdquo Angewandte Chemie International Edition vol 45no 23 pp 3842ndash3846 2006

[9] T Verbiest S van Elshocht M Kauranen et al ldquoStrongenhancement of nonlinear optical properties throughsupramolecular chiralityrdquo Science vol 282 no 5390 pp913ndash915 1998

[10] M Caricato A K Sharma C Coluccini andD Pasini ldquoNanos-tructuring with chirality binaphthyl-based synthons for theproduction of functional oriented nanomaterialsrdquo Nanoscalevol 6 no 13 pp 7165ndash7174 2014

[11] G Yang Y Si and Z Su ldquoChiroptical linear and second-ordernonlinear optical properties of binaphthol derivativesrdquoOrganicand Biomolecular Chemistry vol 10 no 42 pp 8418ndash8425 2012

[12] D Cornelis E Franz I Asselberghs K Clays T Verbiest andG Koeckelberghs ldquoInterchromophoric interactions in chiralX-type 120587-conjugated oligomers a linear and nonlinear opticalstudyrdquo Journal of the American Chemical Society vol 133 no 5pp 1317ndash1327 2011

[13] G Koekcelberghs T Verbiest M Vangheluwe et al ldquoInfluenceof monomer optical purity on the conformation and propertiesof chiral donor-embedded polybinaphthalenes for nonlinearoptical purposesrdquo Chemistry of Materials vol 17 no 1 pp 118ndash121 2005

[14] G Koeckelberghs M Vangheluwe I Picard et al ldquoSynthesisand properties of new chiral donor-embedded polybinaph-thalenes for nonlinear optical applicationsrdquo Macromoleculesvol 37 no 23 pp 8530ndash8537 2004

[15] B J Coe E C Harper K Clays and E Franz ldquoThe synthesisof chiral cationic nonlinear optical dyes based on the 111015840-binaphthalenyl unitrdquoDyes and Pigments vol 87 no 1 pp 22ndash292010

[16] H-J Deussen C Boutton N Thorup et al ldquoNew chi-ral bis(dipolar) 661015840-disubstituted binaphthol derivatives forsecond-order nonlinear opticsrdquo ChemistrymdashA European Jour-nal vol 4 no 2 pp 240ndash250 1998

[17] H-J Deussen E Hendrickx C Boutton et al ldquoNovel chiral bis-dipolar 661015840-disubstituted binaphthol derivatives for second-order nonlinear optics synthesis and linear and nonlinearoptical propertiesrdquo Journal of the American Chemical Societyvol 118 no 29 pp 6841ndash6852 1996

[18] A Bencini C Coluccini A Garau et al ldquoA BINOL-based chiralpolyammonium receptor for highly enantioselective recogni-tion and fluorescence sensing of (SS)-tartaric acid in aqueoussolutionrdquoChemical Communications vol 48 no 84 pp 10428ndash10430 2012


[19] M Caricato A Delforge D Bonifazi D Dondi A Mazzantiand D Pasini ldquoChiral nanostructuring of multivalent macro-cycles in solution and on surfacesrdquo Organic amp BiomolecularChemistry 2015

[20] A Saad O Jeannin and M Fourmigue ldquoA binaphthol-substituted tetrathiafulvalene with axial chirality and its enan-tiopure TCNQF4 charge-transfer saltsrdquo New Journal of Chem-istry vol 35 no 5 pp 1004ndash1010 2011

[21] S Colombo C Coluccini M Caricato C Gargiulli G Gattusoand D Pasini ldquoShape selectivity in the synthesis of chiralmacrocyclic amidesrdquo Tetrahedron vol 66 no 23 pp 4206ndash4211 2010

[22] C Coluccini A Mazzanti and D Pasini ldquoLocked chro-mophores as CD and NMR probes for the helical conformationof tetraamidic macrocyclesrdquo Organic amp Biomolecular Chem-istry vol 8 no 8 pp 1807ndash1815 2010

[23] S Y-L LeungWH Lam andVW-WYam ldquoDynamic scaffoldof chiral binaphthol derivatives with the alkynylplatinum(II)terpyridine moietyrdquo Proceedings of the National Academy ofSciences of the United States of America vol 110 no 20 pp7986ndash7991 2013

[24] A Shockravi A Javadi and E Abouzari-Lotf ldquoBinaphthyl-based macromolecules a reviewrdquo RSC Advances vol 3 no 19pp 6717ndash6746 2013

[25] M Caricato N J Leza K Roy et al ldquoA chiroptical probefor sensing metal ions in waterrdquo European Journal of OrganicChemistry no 27 pp 6078ndash6083 2013

[26] M Caricato A Olmo C Gargiulli G Gattuso andD Pasini ldquoAlsquoclickedrsquomacrocyclic probe incorporating Binol as the signallingunit for the chiroptical sensing of anionsrdquo Tetrahedron vol 68no 38 pp 7861ndash7866 2012

[27] M Caricato C Coluccini D Dondi D A V Griend andD Pasini ldquoNesting complexation of C

60with large rigid D

2

symmetrical macrocyclesrdquo Organic amp Biomolecular Chemistryvol 8 no 14 pp 3272ndash3280 2010

[28] C Coluccini D Dondi M Caricato A Taglietti M Boiocchiand D Pasini ldquoStructurally-variable rigid and optically-activeD2and D

3macrocycles possessing recognition properties

towards C60rdquo Organic and Biomolecular Chemistry vol 8 no

7 pp 1640ndash1649 2010[29] A Moletti C Coluccini D Pasini and A Taglietti ldquoA chiral

probe for the detection of Cu(ii) by UV CD and emissionspectroscopiesrdquo Dalton Transactions no 16 pp 1588ndash15922007

[30] C Coluccini A K Sharma M Caricato et al ldquoSwitchingof emissive and NLO properties in push-pull chromophoreswith crescent PPV-like structuresrdquo Physical Chemistry ChemicalPhysics vol 15 no 5 pp 1666ndash1674 2013

[31] C Coluccini A K SharmaDMerli DVGriend BMannucciand D Pasini ldquoSpectroscopic and electrochemical sensingof lanthanides with 120587-extended chromophores incorporatingferrocenes and a coordinative endrdquoDalton Transactions vol 40no 44 pp 11719ndash11725 2011

[32] M Caricato C Coluccini D A V Griend A Forni and DPasini ldquoFrom red to blue shift switching the binding affinityfrom the acceptor to the donor end by increasing the120587-bridge inpush-pull chromophores with coordinative endsrdquo New Journalof Chemistry vol 37 no 9 pp 2792ndash2799 2013

[33] D Pasini P P Righetti and V Rossi ldquoMalonate crown ethersas building blocks for novel D-120587-A chromophoresrdquo OrganicLetters vol 4 no 1 pp 23ndash26 2002

[34] L Garlaschelli I Messina D Pasini and P P RighettildquoFullerene ylidene malonate supramolecular triadsrdquo EuropeanJournal of Organic Chemistry no 20 pp 3385ndash3392 2002

[35] C Coluccini PMetrangoloM Parachini D Pasini G Resnatiand P Righetti ldquolsquoPush-pullrsquo supramolecular chromophoressupported on cyclopolymersrdquo Journal of Polymer Science PartA Polymer Chemistry vol 46 no 15 pp 5202ndash5213 2008

[36] J M Klopp D Pasini J D Byers C Grant Willson and JM J Frechet ldquoMicrolithographic assessment of a novel familyof transparent and etch-resistant chemically amplified 193 nmresists based on cyclopolymersrdquo Chemistry of Materials vol 13no 11 pp 4147ndash4153 2001

[37] A Facchetti E Annoni L Beverina et al ldquoVery large electro-optic responses in H-bonded heteroaromatic films grown byphysical vapour depositionrdquoNature Materials vol 3 no 12 pp910ndash917 2004

[38] E Cariati A Forni S Biella et al ldquoTuning second-order NLOresponses through halogen bondingrdquo Chemical Communica-tions no 25 pp 2590ndash2592 2007

[39] C Coluccini M Caricato E Cariati A Forni and D PasinildquoSynthesis chiroptical and SHG properties of polarizable push-pull dyes built on 120587-extended binaphthylsrdquo RSC Advances vol5 no 28 pp 21495ndash21503 2015

[40] P Metrangolo F Meyer T Pilati G Resnati and G TerraneoldquoHalogen bonding in supramolecular chemistryrdquo AngewandteChemiemdashInternational Edition vol 47 no 33 pp 6114ndash61272008

[41] H T Stock and R M Kellogg ldquoSynthesis of enantiomericallypure thiocrown ethers derived from 111015840-binaphthalene-221015840-diolrdquoThe Journal of Organic Chemistry vol 61 no 9 pp 3093ndash3105 1996

[42] C Almansa L A Gomez F L Cavalcanti et al ldquoDiphenylpro-pionic acids as new AT1 selective angiotensin II antagonistsrdquoJournal of Medicinal Chemistry vol 39 no 11 pp 2197ndash22061996

[43] E Cariati G Cavallo A Forni et al ldquoSelf-complementarynonlinear optical-phores targeted to halogen bond-driven self-assembly of electro-optic materialsrdquo Crystal Growth amp Designvol 11 no 12 pp 5642ndash5648 2011

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+

+OO

Chiral axis

Chiral axis

O2N

O2N

minus

minus

Figure 1 The molecular design for push-pull chiral binaphthyl derivatives [16]

OMeOMe

O O

OO

O

O

O

O1a1b

n

n

Cationcomplexation

Cationcomplexation

n = 1n = 0

(a)

n

n

OMeOMe

F

FF

F

FF

FF

2a2b

I

I

Halogenbonding

Halogenbonding

n = 1n = 0

(b)

Figure 2 Target compounds subject of this paper

2 Results and Discussion

21 Synthesis of the Molecular Modules In our design strat-egy the electron-donating alkoxy substituents in the 221015840positions are in an ortho relationship with respect to thegrowing 120587-bridge in the 331015840 position achieving efficientconjugation with the 120587-bridge The synthesis of the key com-pounds is shown in Scheme 1 Enantiopure starting materialsfor this work were obtained via multistep syntheses startingfrom the commercially available enantiopure (R)-BINOLwhich was chemically transformed under nonracemizingconditions

Compound (R)-1b (Scheme 1 top) was synthesized usinga Knoevenagel condensation reaction between elongatedrecently reported dialdehyde (R)-3b [39] and dimethylmalonate 4 The reaction was carried out under classi-cal conditions (piperidine as the catalyst continuous H

2O

removal with a Dean-Stark apparatus) the compound wasisolated in good yield after column chromatography andfully characterized (see Appendix) On the contrary usingidentical conditions compound (R)-1a could not be obtainedfrom dialdehyde (R)-3a It is likely that the enhanced sterichindrance caused by the presence of the methoxy grouportho to the aldehyde functionality is responsible for the


O

OO

O+

O O

OO

R

567

PiperidineOMeOMe

O O

OO

O

O

O

O

OMeOMe

O

O

+NaH

DMFrtOMeOMe

O

O

F F

FF OMeOMe

F

FF

F

FF

FF

4

8

n

n n

nn

n n

n

3a3b n = 1

n = 0

3a3b n = 1

n = 0

1b n = 1 (50)

9b n = 1 (69)9a n = 0 (20)

BenzeneΔ


+Brminus

P(Ph)3+Brminus





2in dry THF under




300 400 500

A

0

2

1b(10120583M)1b(10120583M) + Eu(OTf)3 (15 eq)

120582 (nm)

(a)

300 400 500

A

00

02

9b

120582 (nm)

(b)

300 400 500

0

20

9b

120582 (nm)

minus20

Δ120576

(Mminus

1 cmminus1)

(c)




3





3 Conclusions


Appendix

Experimental











3 300MHz 25∘C) 120575 = 829



3) 13C NMR (CDCl

3 75MHz 25∘C) 120575 = 1672


3) 527

(COOCH3) 526 (COOCH

3)


3 300MHz 25∘C) 120575 = 775 (s 1H



3) 317 (d 2H


2CH3) 13CNMR

(CDCl3 75MHz 25∘C) 120575 = 1671 1644 1423 1347 1312

1302 1295 1251 621 526 346 328 163






3) 13C NMR (CDCl

3

75MHz 25∘C) 120575 = 1668 1642 1417 1349 1344 1325 13211303 1301 1300 1294 1260 1181 1170 527 307 301


2O was





2Cl273)


3 200MHz 25∘C) 120575 = 830 (s 2H


3)


2O was




2Cl273) to yield


2Cl2) MS(ESI) mz 866 ([M + H]+ 100) 1H



3) 13C NMR (CDCl

3


3)



Acknowledgments


References






























2






























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

OO

O+

O O

OO

R

567

PiperidineOMeOMe

O O

OO

O

O

O

O

OMeOMe

O

O

+NaH

DMFrtOMeOMe

O

O

F F

FF OMeOMe

F

FF

F

FF

FF

4

8

n

n n

nn

n n

n

3a3b n = 1

n = 0

3a3b n = 1

n = 0

1b n = 1 (50)

9b n = 1 (69)9a n = 0 (20)

BenzeneΔ


+Brminus

P(Ph)3+Brminus





2in dry THF under




300 400 500

A

0

2

1b(10120583M)1b(10120583M) + Eu(OTf)3 (15 eq)

120582 (nm)

(a)

300 400 500

A

00

02

9b

120582 (nm)

(b)

300 400 500

0

20

9b

120582 (nm)

minus20

Δ120576

(Mminus

1 cmminus1)

(c)




3





3 Conclusions


Appendix

Experimental











3 300MHz 25∘C) 120575 = 829



3) 13C NMR (CDCl

3 75MHz 25∘C) 120575 = 1672


3) 527

(COOCH3) 526 (COOCH

3)


3 300MHz 25∘C) 120575 = 775 (s 1H



3) 317 (d 2H


2CH3) 13CNMR

(CDCl3 75MHz 25∘C) 120575 = 1671 1644 1423 1347 1312

1302 1295 1251 621 526 346 328 163






3) 13C NMR (CDCl

3

75MHz 25∘C) 120575 = 1668 1642 1417 1349 1344 1325 13211303 1301 1300 1294 1260 1181 1170 527 307 301


2O was





2Cl273)


3 200MHz 25∘C) 120575 = 830 (s 2H


3)


2O was




2Cl273) to yield


2Cl2) MS(ESI) mz 866 ([M + H]+ 100) 1H



3) 13C NMR (CDCl

3


3)



Acknowledgments


References






























2






























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


300 400 500

A

0

2

1b(10120583M)1b(10120583M) + Eu(OTf)3 (15 eq)

120582 (nm)

(a)

300 400 500

A

00

02

9b

120582 (nm)

(b)

300 400 500

0

20

9b

120582 (nm)

minus20

Δ120576

(Mminus

1 cmminus1)

(c)




3





3 Conclusions


Appendix

Experimental











3 300MHz 25∘C) 120575 = 829



3) 13C NMR (CDCl

3 75MHz 25∘C) 120575 = 1672


3) 527

(COOCH3) 526 (COOCH

3)


3 300MHz 25∘C) 120575 = 775 (s 1H



3) 317 (d 2H


2CH3) 13CNMR

(CDCl3 75MHz 25∘C) 120575 = 1671 1644 1423 1347 1312

1302 1295 1251 621 526 346 328 163






3) 13C NMR (CDCl

3

75MHz 25∘C) 120575 = 1668 1642 1417 1349 1344 1325 13211303 1301 1300 1294 1260 1181 1170 527 307 301


2O was





2Cl273)


3 200MHz 25∘C) 120575 = 830 (s 2H


3)


2O was




2Cl273) to yield


2Cl2) MS(ESI) mz 866 ([M + H]+ 100) 1H



3) 13C NMR (CDCl

3


3)



Acknowledgments


References






























2






























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




3 Conclusions


Appendix

Experimental











3 300MHz 25∘C) 120575 = 829



3) 13C NMR (CDCl

3 75MHz 25∘C) 120575 = 1672


3) 527

(COOCH3) 526 (COOCH

3)


3 300MHz 25∘C) 120575 = 775 (s 1H



3) 317 (d 2H


2CH3) 13CNMR

(CDCl3 75MHz 25∘C) 120575 = 1671 1644 1423 1347 1312

1302 1295 1251 621 526 346 328 163






3) 13C NMR (CDCl

3

75MHz 25∘C) 120575 = 1668 1642 1417 1349 1344 1325 13211303 1301 1300 1294 1260 1181 1170 527 307 301


2O was





2Cl273)


3 200MHz 25∘C) 120575 = 830 (s 2H


3)


2O was




2Cl273) to yield


2Cl2) MS(ESI) mz 866 ([M + H]+ 100) 1H



3) 13C NMR (CDCl

3


3)



Acknowledgments


References






























2






























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




2Cl273)


3 200MHz 25∘C) 120575 = 830 (s 2H


3)


2O was




2Cl273) to yield


2Cl2) MS(ESI) mz 866 ([M + H]+ 100) 1H



3) 13C NMR (CDCl

3


3)



Acknowledgments


References






























2






























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of












2






























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

synthesis of binaphthyl-based push-pull chromophores with supramolecularly polarizable acceptor ends

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