Hainan Poly Pharm. Co., Ltd.

Three Ni(II) complexes with phenanthroline-based ligands were synthesized and characterized by UV-visible, IR, MS, and elemental anal.Their off-resonance 3rd-order nonlinear optical (NLO)properties were measured using a fs laser and the degenerate 4-wave mixing technique.The 3rd-order NLO susceptibilities χ⁽³⁾ were 3.45-4.37 × 10^-13 esu.The 2nd-order hyperpolarizabilities γ of the mols. were 3.46-4.36 × 10^-31 esu.The response times were 50-74 fs.The influence of the mol. structure on the 3rd-order optical nonlinearity was analyzed.Highly polarizable delocalized π-conjugated electron system is the key factor leading to strong 3rd-order optical nonlinearity.