Molecular Twisting Power of Cholesteryl Propionate, Nonanoate and Myristate

Abstract

We have measured the pitch of cholesteryl propionate-nonanoate mixture at different weight ratio for various temperature. The pitch of ternary mixture, cholesteryl propionate, nonanoate and myristate, was also measured as a function of temperature and concentration of cholesteryl myristate when the weight ratio of propionate and nonanoate is kept equal. The molar twisting power (β) was calculated by employing Bak and Labes’ equation and the relation between twisting power and temperatures is found to be linear for cholesteryl propionate, nonanoate and myristate in the temperature range away from transitions.

For the mixture with smectic mesophase the temperature coefficient of the pitch is anomalous. The v (critical exponent describing the divergence of the smectic correlation length) for cholesteryl nonanoate is found to be 0.611 which is in excellent agreement with de Gennes’ prediction.