Syntheses, Structures and Third-Order Nonlinear Optical Properties of Two-Dimensional Rhombohedral Grid Coordination Polymers: [Cd(imz)3]2(BTC)•0.5H2O and [Cu4(H2O)2(imz)8](BTC)2•7H2O(BTC=1, 2, 4, 5-benzenetetracarboxylate anion, imz = imidazole)

Hydrothermal reactions of 1, 2, 4, 5-benzenetetracarboxylic acid (H4BTC) with cadmium acetate and copper acetate in the presence of imidazole (imz) resulted in two new coordination polymers, namely, [Cd(imz)(3)](2)(BTC)center dot 0.5H(2)O 1, [Cu-4(H2O)(2)(imz)(8)](BTC)(2)center dot 7H(2)O 2. Two compounds have been characterized structurally using single-crystal diffraction, elemental analysis, and FT-IR spectrum. In compound 1, the hexa-coordinated Cd(II) ions are bridged by BTC to form two-dimensional rhombohedral grid sheets. In compound 2, the coordination polyhedrons [CuO4N2] and [CuO3N2] are bridged by BTC to lead to a 2D framework with rectangular-shaped cavities. Two compounds of third-order nonlinear optical (NLO) properties were determined by Z-scan technique in DMSO solution. The results showed that two compounds exhibited strong NLO absorption and strong self-focusing effects. The third-order NLO absorptive coefficients beta(MKS) are 5.45 x 10(-11) m W-1 for 1 and 9.81 x 10(-11) m W-1 for 2. The refractive indexes gamma(MKS) are 3.96 x 10(-18) m(2) W-1 for 1 and 7.60 x 10(-18) m(2) W-1 for 2. The third-order NLO susceptibility chi((3)) are calculated to be 1.25 x 10(-11) for 1, 2.32 x 10(-11) esu for 2, respectively. These values are larger than those of metal coordination polymers reported. Two novel two-dimensional transition metal coordination polymers have been reported. Two compounds exhibit strong NLO absorption and strong self-focusing effects. The third-order NLO susceptibility chi((3)) are calculated to be 1.25 x 10(-11) for 1, 2.32 x 10(-11) esu for 2, respectively.