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Structure formation control of disc-shaped molecules

: Janietz, D.


Molecular Crystals and Liquid Crystals 396 (2003), S.251-264
ISSN: 0026-8941
ISSN: 1542-1406
Fraunhofer IAP ()

Supramolecular assemblies of radial multialkynylbenzene derivatives are presented which arise either from specific interactions with interfaces or from the covalent linkage of different molecular fragments. Surface-assisted molecular orientation control was investigated at the air/water interface, on photo-oriented azobenzene films and on rubbed polyimide orientation layers, respectively. Surface alignment generates edge-on or tilted orientations of the aromatic discs. Two- and three-dimensional architectures are formed which differ remarkably from the nematic-discotic bulk phases of the compounds. On the other hand, linking chemically a pentaalkynylbenzene donor moiety with an intramolecular acceptor function leads to charge-transfer mesogens, displaying novel types of mesophases which cannot be achieved with binary mixtures of flat donor and acceptor components.