An investigation on spectroscopic, linear and nonlinear optical parameters of a potential NLO compound

In this study, the theoretical calculations on 2-[2-(2,4-dimethoxy-phenyl)-vinyl]-1-ethyl-pyridinium iodide (DMPI), which was previously synthesized and experimentally examined, were performed and compared with the corresponding experimental results. The optimized geometrical parameters, vibrational frequencies, ¹H and ¹³C-NMR chemical shifts, HOMO-LUMO and the optical band gap energies of DMPI compound were obtained theoretically by using B3LYP and HSEh1PBE methods with LANL2DZ basis set. The other important optical properties such as refractive index, extinction coefficient, conductivity, dielectric constant, VELF and SELF were investigated using experimental and theoretical spectra. The dipole moment, the mean polarizability, the third-order susceptibility, first and second-order hyperpolarizabilities and nonlinear refractive index parameters were also computed at HSEh1PBE/LANL2DZ and B3LYP/LANL2DZ levels respectively. According to the values of theoretical NLO parameters, DMPI compound indicates high NLO efficiency, as expressed in the experimental study. Hence DMPI appears to be a promising candidate for electro-optic, photonic and NLO applications.

Graphical abstract