Liquid crystalline properties of 4-alkoxyphenyl 3-fluoro- and 3-methyl-4-thiocyanatophenyl terephthalates

The preparation and thermal properties of homologous series of 4-alkoxyphen yl 3-fluoro- and 3-methyl-4-thiocyanatophenyl terephthalates are described. Both homologous series show nematic phases; smectic A and C phases are als o formed in the higher homologous. The methyl group and fluorine atom adjac ent to the thiocyanate group lower the clearing points, in comparison with the unsubstituted compounds. The layer structures for both smectic A and C phases were characterized by X-ray diffraction experiments. The effects of the substituents on liquid crystalline properties are discussed.