Construction of three new coordination polymers based on 5-ethyltetrazole (ET) generated via in situ cycloaddition reaction

By the addition of different secondary ligands, three new d10 metal coordination polymers, [M2(ET)(pzdc)(μ3-OH)] [M = Cd(1), Zn(2)] and [Zn(Et)(Hbic)] (3) (ET = 5-ethyltetrazole; H2pzdc = Pyrazine-2,3-dicarboxylic acid; Hbic = 1H-benzimidazole-5-carboxylic acid), have been successfully prepared under hydrothermal reactions and structurally characterized by single-crystal X-ray diffraction analysis. The ET ligand in compounds 1–3 is in situ generated from the [2 + 3] cycloaddition reaction of the precursor propionitrile and NaN3 in water with the aid of zinc/cadmium salt. Compounds 1 and 2 present three-dimensional (3D) (4,4,4,4)-connected net based on O-centered M3 isosceles triangle. Compound 3 exhibits a 3D diamond framework constructed by infinite –ET–Zn–ET– 1D zigzag chains and Hbic as bridging coligand. Furthermore, the thermal stabilities of compounds 1–3 and the luminescence properties of compounds 1 and 2 have been investigated.