Syntheses, crystal structures, third-order nonlinear optical properties and thermal properties of two infinite (6, 3) net complexes

Two new complexes {[Co(bbbm)1.5(NO3)2]·H2O}n (1) and [Cd(bbbm)1.5(NO3)2]n (2) (bbbm = 1,1’-(1,4-butanediyl)bis-1H-benzimidazole) have been synthesized and structurally characterized. Both complexes are built up by two-dimensional coordination networks with (6, 3) nets. The third-order nonlinear optical (NLO) properties of the two complexes are determined and the results show that they not only possess large third-order NLO absorptive effects, but also display strong refractive behaviors. The hyperpolarizability |γ| values are 2.2 × 10−29 esu for complex 1, and 1.6 × 10−30 esu for complex 2. The NLO effective of complex 1 is stronger than that of 2 due to the decreased π back-donation capacity from Co(II) to Cd(II). Thermal analysis studies show that complex 1 is less stable and begins to decompose at 131 °C. While complex 2 is stable up to 257 °C.