Synthesis and mesomorphic characterization of novel liquid crystals derived from bioactive natural sterols

Abstract

Steroids are one of the prominent categories of secondary metabolites that are renowned for their biological activities. The steroidal derivatives are well known for their inherent potential to exhibit diverse mesophases. In this report, we have shown the mesomorphic behavior of some novel 4-mercaptoalkyl benzoates of cholesterol, stigmasterol and ergosterol. This study mainly focuses on the effect of the steroidal skeleton, as well as the effect of replacement of oxygen with the sulfur atom in the side chains on their mesogenic behavior. The cholesteryl analogs were found to show smectic, cholesteric and blue phases; whereas the stigmasterol and ergosterol derivatives were found to be smectogenic in nature. The stigmasterol derivatives were found to exhibit significantly lower clearing temperatures compared to corresponding cholesterol and ergosterol analogs. Also, the replacement of the oxygen atom with sulfur in the cholesteryl derivatives resulted in a considerable reduction in their clearing temperatures.