The nonlinear optical (NLO) properties of complex embody different characteristics with the traditional nonlinear materials due to the specificity of complex structures. Therefore, it has always been an important topic to research the influence factors of the nonlinear optical properties. By systematically investigating the influence of the metal ions or ligands on the third-order NLO properties of metal complexes, we found that both the metal ions and ligands could make important contributions to the NLO properties. The contribution that the metal ions and ligands make to the NLO properties could be determined by quantum chemical calculations,namely, their possession ratios in the frontier molecular orbital influence the nonlinear properties of complexes. In addition, our research revealed that Ag(I) complex possessed very strong third-order NLO properties,which points out the direction for the development of the third-order nonlinear optical materials.

Contents
1 The measurement of third-order nonlinear optical properties of complexes
2 The influence of the metal or ligand on the third-order nonlinear optical properties of metal complexes
3 The influence factors of third-order NLO performance for the metal complexes in theory
4 Ag complexes possess good nonlinear optical properties
5 Conclusion