Nonlinear optical properties of dihydrobenzothiazolylidene and dihydroquinoinylidene compounds

Abstract

The geometrical parameters, absorption spectra and first hyperpolarizability of BTZ (12a, 12c) and QUIN (13a, 13c) compounds have been studied with quantum chemistry methods. The hyperpolarizability β and transition energy were determined by density functional theory (DFT) and time-dependent DFT (TD-DFT). Electric field was considered to study the dependence of transition energy on electric field and to fit state-to-state dipole moment. DFT calculation and visualized methods (charge different density and molecular orbital analysis) provided an insight into the relationship between structure and first hyperpolarizability. In addition, two-photon absorption character of them has been firstly studied with the response theory approach. Results demonstrated that 12c and 13c with same electron-withdrawing substitution display obvious nonlinear optical response, and larger value of two-photon absorption sections suggest that they are good candidates for NLO materials.