Theoretical study on second-order nonlinear optical properties of 1,10-phenanthroline Ru(Ⅱ) complexes

The dynamic first hyperpolarizabilities of a series of 1,10-phenanthroline Ru（II） complexes were carried out using density functional theory （DFT）. The results indicate that these complexes have large second-order nonlinear optical （NLO） responses. Specially, complex 6b has a maximal first hyperpolarizability βtot value. The first hyperpolarizabilities can be tuned by changing the ancillary ligand, introducing electron-acceptor group NO2 and/or increasing r-conjugation on phenanthroline. Calculations on absorption spectra demonstrate that the second-order NLO responses of complexes in series a are ascribed to the intraligand charge transfer （ILCT）, while the complexes in series b exhibit metal-to-ligand charge transfer （MLCT） and lig- and-to-ligand charge transfer （LLCT） transition at relatively low-energy absorptions.

The dynamic first hyperpolarizabilities of a series of 1,10-phenanthroline Ru(Ⅱ) complexes were carried out using density functional theory(DFT).The results indicate that these complexes have large second-order nonlinear optical(NLO) responses.Specially,complex 6b has a maximal first hyperpolarizability βtot value.The first hyperpolarizabilities can be tuned by changing the ancillary ligand,introducing electron-acceptor group NO2 and/or increasing π-conjugation on phenanthroline.Calculations on absorption spectra demonstrate that the second-order NLO responses of complexes in series a are ascribed to the intraligand charge transfer(ILCT),while the complexes in series b exhibit metal-to-ligand charge transfer(MLCT) and ligand-to-ligand charge transfer(LLCT) transition at relatively low-energy absorptions.