Translational and rotational phase ordering of symmetric dimer mesogens: Molecular rigidity effect

Abstract

A theoretical approach towards molecular rigidity and mesogenic behaviour of symmetric dimer molecules viz., α,ω-bis (4-cyanobiphenyl-4′-yloxycarbonyl) propane (3dimer) and α,ω-bis (4-cyanobiphenyl-4′-yloxycarbonyl) hexane (6dimer) has been analysed with regard to orientational and translational motions. The crystallographic information files of these molecules have been used to report the structures. The formalism of CNDO/2 approach has been executed to estimate the charges and dipole moment components of all atoms. Total configurational interaction energies have been estimated using Rayleigh-Schrodinger perturbation theory. These energy data have been utilized to estimate the configurational probability using the formula given by Maxwell-Boltzmann at phase transition temperature. The translational/ rotational ordering of different configurations has been analysed. The mesogenic behaviour of these compounds has been explained according to their relative order that helps in establishing molecular mesogenic models. As the manipulation of a molecular configuration is significant from the view point of photonics, this manuscript is expected to provide a route in understanding in this feature depending on the parameters reported in this manuscript. The impact of rigidity and aspect ratio upon the liquid crystal transitions has been discussed.