Torsional Energy and Nonlinear Optical Properties of 2-, 3-R-4-Phenylpyridine (R = CH3, NH2 and NO2)

Abstract

In this study, the torsional dependence of the electronic energy and nonlinear optical properties of some derivatives of 4-phenylpyridine were calculated by using HF theory and Becke three parameter functional (B3LYP) hybrid approaches within the density functional theory with the 6-31++G(d,p) basis set. We investigated global minimum energy, electric dipole moment (μ), first static polarizability (a), polarizability of anisotropy (Da), first static hyperpolarizability (b) and optical band gap (E_HOMO-LUMO). The CH₃, NH₂ and NO₂ substitution effect on the physical properties of title compounds compared with 4-phenylpyidine results. Torsional energy calculations were performed with HF/6-31++G(d,p) and B3LYP/6-31++G(d, p) levels of theory. The nonlinear optical properties performed with only at the B3LYP/6-31++G(d, p) and B3LYP/ 6-311++G(2d, 2p) levels of theory. In our calculations we have found that substitution of CH₃ on the 4-phenylpyridine does not display the dramatic increasing in polarizability and first hyperpolarizability values whereas NH₂ and especially NO₂ generate three times large nonlinearity compared with 4-phenylpyridine.