Molecular Crystals and Liquid Crystals, Vol.396, 251-264, 2003
Structure formation control of disc-shaped molecules
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.
Keywords:pentaalkynes;star-shaped oligo-nematogens;surface alignment;charge-transfer twins;disc-rod triple mesogens