Molecular Ordering of 4-Acetyl-2'-Nitrobiphenyl - A Computational Analysis

Abstract

Abstract The molecular ordering of some biphenyl derivatives like 4-acetyl-2'-nitrobiphenyl (ANBP), 4-nitro-2-biphenylamine (NBPA) and 4-acetyl-3'-chlorobiphenyl (ACBP) has been examined using basic con-cepts of quantum mechanics and intermolecular forces. The CNDO/2 method has been employed to compute the net atomic charge and atomic dipole components at each atomic centre. The modified Ray-leigh-Schrödinger perturbation theory along with the multicentred-multipole expansion method has been employed to evaluate long-range interactions while a '6-exp' potential function has been assumed for short-range interactions. Accuracies upto 0.1 A in translation and 1° in rotation have been achieved. Probability of occurrence of a particular configuration has been calculated using MB-statistics. On the basis of stacking and in-plane interaction energy calculations, all possible geometrical arrangements between molecular pairs have been considered and a most favorable configuration of pairing has been obtained. A comparative picture of molecular parameters like total energy, binding energy, total dipole moment etc. has been given. An attempt has been made to develop a molecular model correlated with the liquid crystalline property exhibited by this class of molecules.