Novel types of ionic thermotropic liquid crystals

Abstract

Liquid crystals are usually categorized as either lyotropic mesophases in which fluid anisotropy results from polar headgroup packing of amphiphilic molecules, or as thermotropic mesophases where the orientational order arises from interactions between partially rigid anisotropic molecules. The phase types exhibited by lyotropic and thermotropic liquid crystals have distinctive structures, optical textures and physical properties. Inclusion of a rigid anisotropic moiety into a lyotropic liquid crystal gives an additional source of orientational ordering, and can lead to phase behaviour encompassing both thermotropic and lyotropic liquid crystals. We have prepared a series of silver-containing thermotropic liquid crystals based on the bis(stilbazole) silver (I) cation. Some members of this series, in association with the amphiphilic counter-ion lauryl sulphate, form liquid crystal mesophases characteristic of both lyotropic and thermotropic liquid crystals.