PB19 Highly ordered liquid crystal phases by intermolecular hydrogen bonding

Abstract

Rod-like liquid crystalline compounds 1 possessing an amide group and a m-substituted alkoxy chain were synthesized and their thermodynamic behaviors and organizations were investigated. Compounds 1a (R^1 = R^2 = n-C_4H_9) and 1c (R^1 = n-C_4H_9, R^2 = n-C_<12>H_<25>) exhibited only smectic A phases. On the other hand, compounds 1b (R^1 = n-C_<12>H_<25>, R^2 = n-C_4H_9) and 1d (R^1 = R^2 = n-C_<12>H_<25>) showed both smectic A and smectic C phases. In X-ray diffraction and temperature-variable FT-IR spectroscopy it was found that the molecules possessing a short R^2-chain dimerized in an antiparallel manner, while the molecules possessing a long R^2-chain were organized in a synparallel manner in the smectic layer with the intermolecular hydrogen bonding. Thus, compounds 1b and 1d could generate effectively stable smectic phases despite the lateral intermolecular hydrogen bonding between their amides.