Chiral esters and their mixtures with stable S_C* phase at ambient temperature

Abstract

Calculated and experimental phase diagrams of binary mixtures of the homologous series of (S) (+)-4-(2′-methylbutyl)-benzoate esters of the 4-n-alkoxybenzoic acids were compared. Eutectics occured if the length ratio of the components were smaller than r=0.9. If r⩾0.9, co-crystallizations were detected. In mixtures of neighbouring homologues even the rule of additivity was valid for the melting curve (r=0.93–0.96, isomorphous systems). Eutectic mixtures of the n=8 and n=7 homologues (exhibited stable chiral smectic C phase around room temperature) were proved in spite of their length ratio of 0.96. Spontaneous polarization and helical pitch were measured both in the single compounds as well as in their mixture.