A Nematic Gap in Binary Mixtures of Compounds without a Strong Polar Group

Phase diagrams are determined of binary-mixtures composed of azo-and azoxyarylethanes with smectic A and C phases. 1, 2-bis butylbenzenoyloxy-azobenzene-4 ethane compound 1 revealing the smectic C phase yields mixtures characterized by a wide nematic gap separating the smectic phases of the pure components. It has been found by X-ray diffraction that the smectic C phase in compound 1 reveals a two-dimensional ordering similar to that observes in compounds with the antiphase [Ctilde]. It is suggested that the observed destabilization of the smectic C phase in the mixtures of the tested compound is due to the difference in the ordering of the smectic C phase of the mixture components.