DFT Studies on second-order nonlinear optical properties of mono (salicylaldiminato) Nickel(II) polyenyl Schiff base metal complexes

Density function theory (DFT) B3LYP/6-31g(d)-finite field (FF) method was employed to investigate the second-order nonlinear optical (NLO) properties of Nickel(II) polyenyl Schiff base complexes and its polyenyl ligands. It is found that the complexes display higher second-order NLO responses than their ligands. An enhancement of second-order NLO properties of complexes because the Ni2+ ion increased the electron densities distribution of coordinated atoms and adjacent carbon atoms in frontier molecular orbitals, and reduced the gaps between occupied and unoccupied orbitals. Thus the metal complexes display better second-order NLO responses.