Molecular Recognition Directed Self-Assembly of Supramolecular Liquid Crystals

Abstract The first part of this paper discusses the molecular design of selected examples of structural units containing taper shaped exo-receptors and various crown ether, oligooxyethylenic, and H-bonding based endo-receptors, which self-assemble into cylindrical channel-like architectures via principles resembling those of tobacco mosaic virus (TMV). The ability of these structural units to self-assemble via a delicate combination of exo- and endo-recognition processes will be presented. A comparison between various supramolecular (generated via H-bonding, ionic, and electrostatic interactions) and molecular “polymer backbones” will be made. The formation of columnar hexagonal (Φh), nematic and re-entrant isotropic phases by selected self-assembled systems will be discussed. The present limitations concerning the ability to engineer the structural parameters of these supramolecular channel-like architectures and some possible novel material functions derived fiom them will be briefly mentioned. The second part of this paper discusses the molecular design of a novel class of macrocyclics which self-assemble via intramolecular recognition processes into supramolecular “rod-like” collapsed macrocyclics which display thermotropic liquid crystalline mesophases. It will be demonstrated that these macrocyclics have a higher ability to form liquid crystalline phases than the corresponding linear compounds which have identical or even higher degrees of polymerization. Therefore, they represent the ideal molecular architectures which generate nematic and smectic phases. The third part presents the concept and the synthesis of willow-like thermotropic dendrimers.