Vibrational Circular Dichorism and Non Linear optics of Azobenzene Derivatives; A Theoretical Study

The present work reports a theoretical study on vibrational spectra and nonlinear optical properties of azobenzene derivatives. The theoretical geometrical parameters in the ground state have been investigated by density functional method using B3LYP functional and 6-311G++ (d, p) basis set. The analysis of calculated IR and VCD indicates that the binaphthyl and alkoxy side chain of azobenzenes derivatives contribute differently to spectral line shape. The out-of-phase bending and twisting of azobenzene rings, out-of-phase stretching of binaphthyl substituent and wagging of hydrogen atoms present on the alkoxy side chain vibrational modes dominate display distinct bands in spectra. To investigate nonlinear optical behavior, the electric dipole moment, the polarizability and the hyperpolarizability were computed using DFT/B3LYP/6-311G++ (d,p) level of theory. The results reveal that there is a potential rise in nonlinear optical character of azobenzene derivatives on account of binaphthyl substitution, due to extend in p-conjugation length