Synthesis of nickel(II) complexes containing modified phenanthroline ligands for potential nonlinear optical applications

•Three nickel(II) complexes were synthesized and characterized. Two of them are new.•The third-order optical nonlinearities of these complexes were investigated.•The relationships between molecular structure and optical property were analyzed.

Three nickel(II) complexes containing modified phenanthroline ligands were synthesized and characterized by UV–visible, IR, MS and elemental analysis. Their off-resonant third-order nonlinear optical properties were measured using femtosecond laser and degenerate four-wave mixing technique. The third-order nonlinear optical susceptibilities χ(3) were 3.74–4.23 × 10−13 esu. The nonlinear refractive indexes n2 were 6.88–7.77 × 10−12 esu. The second-order hyperpolarizabilities γ of the molecules were 3.74–4.22 × 10−31 esu. The response times were 58–75 fs. The results show that these complexes have potential nonlinear optical applications.

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