Liquid Crystals Derived from Semifluorinated Alkoxybenzoyl Hydrazines

Abstract

A variety of liquid crystals with semifluorinated tails including 4-alkoxybenzoic acids (1d–h), 4-alkoxybenzoyl hydrazines (2d–h), and N,N′-bis(4-alkoxybenzoyl) hydrazines (3d–m) have been synthesized, and their properties are compared with their perhydrogenated analogs. Semifluorination in compounds 1d–h suppressed nematic phases, and semifluorinated compounds 2d–h exhibit mesogenic behavior where none is found in their perhydrogenated counterparts. Compounds 3a–c with perhydrogenated chains display Cub and SmC phases. Introduction of one semifluorinated chain, 3d–h suppresses the Cub phase but induces a SmA phase, with lower melting but higher clearing temperatures compared to compounds with two semifluorinated chains, 3i–m. The mesogenic properties of some selected binary mixtures of these compounds 3a–d and some lateral fluoro substituted N,N′-bis (4-alkoxybenzoyl) hydrazines 7–9 are also discussed.