Supramolecular liquid-crystalline

Coco, S., Cordobilla, C., Dominguez, C. and Espinet, P. (2008) Luminescent gold(I) metallo-adds and their hydrogen bonded supramolecular liquid crystalline derivative s with decyloxystilbazole as hydrogen acceptor. Dalton Transactions, 48,6894—6900. 

Fouquey, C. Lehn, J.-M. Levelut, A.-M. Molecular recognition directed self-assembly of supramolecular liquid crystalline polymers from complementary chiral components. Adv. Mater. 1990, 2, 254-257. 

Gulikkrzywicki T, Fouquey C, Lehn JM. Electron-microscopic study of supramolecular liquid-crystalline polymers formed by molecular-recognition-directed self-assembly from complementary chiral components. Proc Natl Acad Sci USA 1993 90 163-167. 

Kato T. Supramolecular liquid-crystalline materials molecular self-assembly and selforganization through intermolecular hydrogen bonding. Supramol Sci 1996 3 53-59. 

Kato T, Kihara H, Ujiie S, Uryu T, Frechet JMJ. Structures and properties of supramolecular liquid-crystalline side-chain polymers built through intermolecular hydrogen bonds. Macromolecules 1996 29 8734-8739. 

Self-Organization of Supramolecular Liquid Crystalline Polymers from Complementary Components. If two (or more) complementary units e or 3 are grafted on a template T, mixing Te m with the complementary T3m may lead to the hetero-self-assembly of a linear or cross-linked, main-chain supramolecular copolymer species (Te m, Tsw), whose existence is conditioned by the molecular recognition-directed association between the e and a groups. 

It is reasonable to assume that the complementary units form the expected triply hydrogen bonded pairs, so that the entirely different behaviour of the pure compounds and of the 1 1 mixtures may be attributed to the spontaneous association of the complementary components into a polymolecular entity based on hydrogen bonding. The overall process may then be described as the self-assembly of a supramolecular liquid-crystalline polymer based on molecular recognition (Figure 40). The resulting species (TP2, TU2) is represented schematically by structure 174. 

Molecular recognition directed self-assembling of organized phases has been described recently in the formation 1) of mesophases by association of complementary molecular component, as in 13 (23) 2) of supramolecular liquid crystalline polymers of type 14 (24) and 3) of ordered solid state structures, such as that represented by 15 (25). In all these cases, the incorporation of NLO active groups may be expected to produce materials whose SHG properties would depend on molecular recognition induced self-organization. 

Stoddart et al.l<,lb have reported the self-assembly of branched [njrotaxanes in an investigation aimed at the preparation of larger, dendritic rotaxanes. Kato et al. 9lcl have reported the preparation of supramolecular liquid crystalline networks based on self-assembly of carboxylic acid-based, trigonally branched, //-bonding donors and bipyridine-type //-bonding acceptors. 

T. Gulik-Krzywicki, C. Fouquey, J.-M. Lehn, Electron Microscopic Study of Supramolecular Liquid Crystalline Polymers Formed by Molecular-Recognition-Directed Self-Assembly from Complementary Chiral Components , Proc. Natl. Acad. Sci. USA, 90, 163 (1993)... 

Fig. 2 A selection of early examples of supramolecular liquid crystalline polymers designed by Frechet and Kato [42-45], Lehn [46-50] and Griffin [51-54]...

Fig. 3 Schematic representations of some possible supramolecular liquid crystalline polymer architectures, a-e Different classes of main-chain structures, f-i Different side chain polymers, j-m Different types of networks...

Fig. 9 A halogen-bond mediated main-chain supramolecular liquid crystalline polymer 11-4...

Fig. 3. Supramolecular liquid-crystalline complex 1 obtained by the formation of hydrogen bonding between benzoic acid and pyridine moieties...

Fig. 5. Plot of transition temperatures for supramolecular liquid-crystalline complex 10 as a function of chain length (n) of the stilhazole moiety...

Double hydrogen bonding has been used for molecular recognition and organization [60]. Doubly H-bonded supramolecular liquid-crystalline complexes based on 2,6-bis(acylamino)pyridines show unique mesomorphic behavior. Complexes 21 exhibit monotropic crystal B phases [61, 62]. 

Fig. 10. Schematic illustration of supramolecular liquid-crystalline polymeric complexes I side-chain type II main-chain type III combined type and IV network type...

Fig. 11. Self-assembly of supramolecular liquid-crystalline side-chain polymer 30 consisting of polymer 29 and stilbazole 3...

The use of hydrogen bonding for mesogenic network formation has been expected for the formation of dynamic mesomorphic states due to the induction of dynamic properties, e.g. reversibility and fast exchange of the H-bonding [108-111]. Supramolecular liquid-crystalline networks have been prepared by the self-assembly of a polyacrylate with a benzoic acid moiety and 4,4 -bipyridine [108]. Complexes 46 form dynamically cross-linked structures obtained by the complexation of a carboxyl-functionalized polyacrylate and a mixture of a stilbazole, which has the single H-bond acceptor, and a bipyridine, which has the two acceptors. 

Fig. 15. Reversible phase transition of supramolecular liquid-crystalline network 46...

The topic of hydrogen bonded liquid crystalline materials has been reviewed by several groups [2,27,29-31]. Herein only the important and recent development on hydrogen bonded supramolecular low molecular weight LCs will be introduced. Supramolecular liquid crystalline polymers will not be included in this chapter. 

Zettsu N, Ogasawara T, Mizoshita N, Nagano S, Seki T. 2008. Photo triggered surface relief grating formation in supramolecular liquid crystalline polymer systems with detachable azobenzene unit. Adv Mater 20 516 521. 

Ciferri A. Supramolecular liquid crystallinity as a mechanism of supramolecular polymerization. Liq. Cryst. 

Kihara, H., Kato, T., Utyu, T., Frechet, J.M.J., 1996. Supramolecular liquid-crystalline networks built by self-assembly of multifunctional hydrogen-bonding molecules. Chem. Mater. 8, 961-968. 

H.F. Yu, H. Liu, T. Kobayashi, Fabrication and photoresponse of supramolecular liquid-crystalline microparticles. ACS Appl. Mater. Interfaces 3, 1333-1340 (2011)... 

Zettsu, N. Ogasawara, T. Mizoshita, N. Nagano, S. Seki, T. (2008). Photo-Triggered Surface Relief Grating Formation in Supramolecular Liquid Crystalline Polymer Systems with Detachable Azobenzene Units. Adv. Mater., 2008, 20, 516-521. 

MOLECULAR RECOGNITION DIRECTED SELF-ASSEMBLY OF SUPRAMOLECULAR LIQUID CRYSTALLINE POLYMERS... 

Scheme 7. Generation of a supramolecular liquid crystalline polymer.

B. Generation of Supramolecular Liquid-Crystalline Polymers and Fibers... 

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