Alkali-metal salts of aromatic carboxylic acids: Liquid crystals without flexible chains

Abstract

The alkali-metal salts of meta-substituted benzoic acids exhibit a smectic A mesophase at high temperatures. These compounds are examples of liquid crystals without terminal alkyl chains. The influence of the metal ion and of the type of substituents on the transition temperatures is discussed. Compounds with the substituent in the ortho- and para-positions are non-mesomorphic. The crystal structures of the compounds Rb(C7H4ClO 2)(C7H4ClO2H), Na(C 7H4IO2)(H2O), K(C7H 4ClO2)(C7H4ClO2H) and Rb(C7H4BrO2)(C7H4BrO 2H) have been determined by X-ray crystallography. These compounds possess a layerlike structure in the solid state. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.