2B05 Mesomorphic Phase Transitions Modified by Hydrogen Bond Interaction in Triphenylene Mesogens with the Terimnai Carboxylic Acid Groups

Abstract

A triphenylene mesogen having two carboxylic acids at the terminal position of the adjustsent peripheral chains was investigated on the mesomorphic phase transition behavior.. A Col_h mesophase is formed on cooling run from the isotropic liquid and the further cooling leads to crystallization into two types of the crystals. On heating run from the one cryastal phase into the Col_h mesophase, a slow maturing of the more highly ordered mesophase was found, which does no longer recrystallization on cooling up to 0℃ and the same temperature of the clearing point, but with a far larger transition enthalpy. This mesophase is highly viscous and the formation of this phase is related to the hydrogen bond interaction among the carboxylic acids, probably in an intercolumnar manner. This is an example that the hydrogen bond interaction as an intermolecular specific interaction leads to the formation of a more highly ordered mesophase by maturing the interaction.