Nonlinear optical properties of azo sulfonamide derivatives

The present work deals with the linear and nonlinear optical properties such as the dipole moment, polarizability, total hyperpolarizability, electric field–induced second harmonic generation, and hyper-Rayleigh scattering first hyperpolarizability of four heterocyclic azo compounds containing the sulfonamide group considered promise in nonlinear optic. The obtained polarizability and hyperpolarizability were supported by the frontier molecular orbital analysis. The properties have been effectively estimated and thoroughly examined to shed light on the nonlinear optical activity based on the density functional theory. The observed results show a high total first hyperpolarizability \({\beta }_{{\text{tot}}}\) ${\beta }_{\text{tot}}$ up to 2503 a.u. and a low energy gap \({E}_{{\text{g}}}\) $E_{\text{g}}$ less than 1.41 eV. An inverse relationship has been obtained between the \({\beta }_{{\text{tot}}}\) ${\beta }_{\text{tot}}$ and \({E}_{{\text{g}}}\) $E_{\text{g}}$ . The calculated \({E}_{{\text{g}}}\) $E_{\text{g}}$ values confirm that charge occurs within the azo sulfonamides. The new study provides a promising avenue for the development of these azo sulfonamides as novel NLO materials.

The molecular modeling and the theoretical studies were performed with Gaussian software packages. The B3LYP/6–311 + G** level was used for optimization. All the linear and nonlinear optical properties reported here are obtained using the DFT. The optimized structures and their frontier molecular orbitals were plotted using the GaussView 5.1 program.