Prediction of Nematic Mesomorphism. Compounds with Disclike Molecules.

Molecular parameters for 136 compounds with disclike molecules and known phase diagrams were calculated and analyzed by a procedure proposed previously in order to improve the method for predicting possible types of mesomorphism from molecular characteristics. A correlation between the value of the molecular parameter M_m and the existence of a nematic liquid crystal is established. An analysis of calculated values of M_m for 27 new molecules of similar structure yielded compounds that are likely to form nematic liquid crystals. To verify the prediction, one of these compounds — 1,3,5 cyclohexanebenzoatebenzene — was synthesized and its phase diagram was studied. The prediction results agree with experimental data: the range of existence of a nematic mesophase was established (130.5–134.5°). Rapid cooling followed by prolonged storage of samples at room temperature without mechanical deformation led to vitrification of the samples ith preserved mesophase texture. Mechanical deformation of vitrified samples resulted in their transition to the crystal phase. [ABSTRACT FROM AUTHOR]