Synthesis and Crystal Structure of a New Cadmium（Ⅱ） Supramolecular Network Containing Chelating Imidazole-4-carboxylate Ligand

A new complex, [Cd（Himc）2（H2O）2] 1, obtained from imidazole-4-carboxylatic acid （H2imc） and Cd（ClO4）2·6H2O, has been synthesized. The crystal structure was determined by X-ray diffraction. The title compound crystallizes in the orthorhombic system, space group Pccn, with a = 7.4886（11）, b = 11.9667（18）, c = 13.550（2） A, V= 1214.3（3） A3, Z = 4, Mr= 370.60, Dc = 2.027 mg/m3, F（000） = 728,μ （MoKa） = 1.829 mm^-1, the final R = 0.0243 and wR = 0.0591 for 1150 unique reflections with I 〉 2σ（I）. The cadmium（II） center in the title complex is coordinated with two oxygen and two nitrogen atoms from two bidentate chelated imidazole-4-carboxlate ligands together with two water molecules, giving a distorted octahedral coordination geometry. A one-dimensional hydrogen bonding chain is formed via intermolecular O-H...O hydrogen bonds, and such adjacent chains are further stacked through intermolecular π-π and hydrogen bonding interactions to form a 3D supramolecular framework. Complex 1 exhibits a fluorescent emission band at 290 nm （λex = 236 nm） in the solid state.