Computational analysis of ordering in higher homologous series of nBAC: The effect of a dielectric medium

Abstract

A computational analysis of ordering in higher homologous series of p-n-alkylbenzoic acids (nBAC) that have 7 (7BAC) and 9 (9BAC) carbon atoms in the alkyl chain has been carried out on the basis of quantum mechanics and intermolecular forces. The molecular geometry of 7BAC and 9BAC has been constructed on the basis of published crystallographic data with the standard values of bond lengths and bond angles. The evaluation of atomic charge and dipole moment at each atomic center has been carried out through the complete neglect differential overlap (CNDO/2) method. The configurational energy has been computed via the Rayleigh-Schrodinger perturbation method. The total interaction energy values obtained through these computations were used to calculate the probability of each configuration in a dielectric medium at the nematic-isotropic-transition temperature through the use of the Maxwell-Boltzmann formula. It has been observed that there is a considerable rise in the probability of interactions, although the order of preference remains the same. The present article offers theoretical support to the experimental observations. In addition, this provides a new way of looking at the liquid-crystalline molecules in a dielectric medium.