Synthesis and mesomorphic properties of liquid crystals containing a perfluorinated segment via different linkers

Abstract

This study presents the synthesis and mesomorphic properties of a series of biphenyl benzoate liquid crystals carrying a perfluorinated segment, via three uncommon flexible linkers. In particular, a (E)-2-propenyloxy linker was used which was issued from an elegant regioselective dehydrohalogenation reaction. The remarkable microsegregation effect of the perfluorinated segment, led to the formation of highly stable untilted smectic mesophases. For all mesophases, the molecular packing corresponds to a monolayer arrangement of the mesogenic parts and a partial intercalation of the perfluorinated chains, measured by a intercalation ratio parameter τF. Geometrical calculations based on Xrays data led to τF comprised between 1.48 and 1.68 depending of the mesophase and temperature.