Synthesis, characterization and theoretical investigations of the structure, electronic properties and third-order nonlinearity optics (NLO) of M(DPIP)2

• Metal-2-(4,5-diphenyl-1-H-imidazole-2-yl)-phenol complexes have been synthesized.
• Structures have been determined by the X-ray diffraction technique.
• The geometry and molecular orbitals are calculated based on B3LYP/LANL2DZ.
• The third nonlinear optical properties were measured by the Z-scan technique.

Three complexes of M(DPIP)2 (M = Cu, Co, Zn as 1, 2, 3) were synthesized and characterized by elemental analysis, IR, UV–Vis, thermogravimetry, and X-ray diffraction. Their nonlinear optical properties were measured by the Z-scan technique and yielded a normalized transmittance of about 70% for complex 1 (45 μJ pulse), and 93% for complex 3 (68 μJ pulse at the focus point). The nonlinear absorption coefficient, β, is 1.4 × 10−11 m/W for 1 and 5.6 × 10−13 m/W for 3, and the third-order nonlinear refraction index, n2, is 1.0 × 10−18 m2/W for 3. Complex 1 shows self-defocusing property, while complex 3 exhibits self-focusing property. The thermogravimetric results show that the frame structure of compounds 1–3 begin to collapse at 400, 250 and 280 °C, respectively, which suggests that they elicit excellent thermal stability. This research aims to provide better understanding of these compounds, and offer preliminary explanations for the significant differences between compounds 1–3, in order to potentially help in the designing of future novel materials with NLO properties.

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