Small molecule based five-membered heterocycles: A view of liquid crystalline properties beyond the biological applications

Liquid crystal (LC) is an intermediate phase of matter with the physical attributes of liquid, and a high-level of orientational order of solids. This property of LCs has been widely utilized for the development of LC displays and other industrial applications. The research in the past few decades shows the substantial increase in the exploring of applications of five-membered liquid crystalline heterocydes in photovoltaic devices, organic light-emitting technologies, and biological systems. In this article, we have discussed the history, classification, synthetic strategies, physical parameters and mesomorphic studies of five-membered heterocycles beyond biological applications. The liquid crystalline heterocycles that are covered in the review include imidazoles, isoxazoles, isoxazolines, pyrazoles, pyrazolines, thiazoles, thiophenes, 1,2,3- and 1,2,4-triazoles, 1,2,4- and 1,3,4-oxadiazoles, and 1,3,4-thiadiazoles. Overall, the review provides a comprehensive profile of the mesomorphic properties of five-membered heterocydes. (C) 2019 Elsevier B.V. All rights reserved.