Theoretical calculation of the optical anisotropy of substituted cyclohexanes and associated bisphenyl molecules using experimentally derived group polarizabilities

Abstract

A general method for the formulation of polarizability tensor and computation of optical anisotropy of a series of substituted cyclohexanes and their bisphenyl fragments, which are model analogues of corresponding polymers is presented. The calculation makes use of the molecular geometry and conformations from force-field simulations and the anisotropic polarizability tensors of the constituent groups derived from experiments reported in the literature. Cyclohexanes with phenyl group substitution show higher anisotropy than those with methyl substituents. For the same substitution, a higher optical anisotropy is observed for equatorial orientation than axial. The optical anisotropy for the cyclohexanes is dependent on the orientation of the substituent group rather than on its position, whereas for the bisphenyl fragments the anisotropy is dependent on both these factors along with the conformation of the whole molecule. All the cyclohexyl substituted bisphenyl fragments show lower optical anisotropy than diphenylpropane, a model analogue of bisphenol A polycarbonate that is widely used in optical applications. The results presented here have implications and potential applications in the design of molecules as well as polymers for optical media.