Novel liquid crystals having a thiocyano group at the terminal position

Abstract

This paper describes the preparation and thermal properties of some liquid crystalline materials having a thiocyano group at the terminal position. 4-Thiocyanophenyl 4-alkoxybenzoate derivatives are non-mesogenic. 4-Thiocyanophenyl 4-(4-alkoxybenzoyloxy)benzoate and 4-thiocyanophenyl 4-alkoxybiphenyl-4′-carboxylate derivatives show nematic and smectic A phases. The nematic-isotropic (smectic A-isotropic) transition temperatures are fairly low compared with those for the corresponding cyano compounds, and the smectic A phase commences from the early members. The thermal properties of the smectic A phase were examined by some binary phase diagrams, suggesting that the homologous members have two kinds of smectic A phase having different thermal properties, while the smectic-smectic transition was not detectable by either DSC or microscopic observations.