A comprehensive study of linear and non-linear optical properties of novel charge transfer molecular systems

Abstract

A comprehensive investigation of the class of compounds shown in Fig. 1 has been carried out at the semi-empirical level of the theory to determine their linear and non-linear optical properties. These molecular systems show very large non-linear optical activity. Geometries of all molecules were optimized at the semi-empirical level of the theory using AM1 Hamiltonian by MOPAC 6.0 computational package. The heats of formation, dipole moments (D), polarizabilities (α), static hyperpolarizabilities (β) and frontier molecular orbital energies are calculated as a function of the twist angle (1234), between the diaminomethylene unit and the six membered fused rings as shown in Fig. 1 using AM1 Hamiltonian using MOPAC 6.0 computational chemistry package. All β values that we report here are the magnitude of static hyperpolarizability. The frontier molecular orbital calculations clearly show the inverse relationship of HOMO–LUMO gap with the total static hyperpolarizability. The enormous enhancement of the hyperpolarizability for a particular dihedral angle of these designed novel molecular systems is also reported. The study reveals that these classes of organic compounds show very large non-linear optical properties and hence in general may influence in finding and developing potential non-linear optical materials.