Preparation and Thermal Properties of Liquid Crystals Having a Thiocyanato group and a Fluorine Substituent at the Terminal Position

Abstract

Some liquid crystalline materials having a thiocyanato group and a fluorine substituent at the terminal position were prepared and investigated the thermal properties. The transition temperatures and the latent heats were measured by the polarized microscope and the differential scanning calorimeter. 4-thiocyanatophenyl 4-(4-alkoxybenzoyloxy)benzoate derivatives showed nematic and smectic A phases. On the other hands, 4-alkoxyphenyl 4-thiocyanatophenyl terephthalate derivatives showed smectic B or C phase, as well as nematic and smectic A phases. The layer spacings of the smectic phases were examined by X-ray diffractions, suggesting that the short alkoxy derivatives have a mono-layer arrangement, but the long alkoxy derivatives have a partially bilayer one.