New bifluorinated liquid-crystal compounds with broad mesomorphic ranges

Abstract

A new family of bifluorinated liquid crystal compounds of general formula

has been prepared. Their mesomorphic properties were measured. When n = 1 and A is cyclohexyl, phenyl, 3-bromophenyl or bicyclo[2.2.2]octane, these compounds are characterized by a wide nematic range. Some nematic mixtures with these materials were prepared and their physical properties were measured. These mixtures have a high birefringence (0.16–0.19), a negative dielectric anisotropy (- 2-7), and a large value of the elastic-constant ratio K₃₃/K₁₁ (1.7 at 20°C). In addition when n = 2 and R₂ is a chiral chain, compounds (I) show a wide chiral smectic C range, of about 100°C.