Zinc(II) and Cadmium(II) Complexes with 1,3,5-Benzenetricarboxylate and Imidazole-Containing Ligands: Structural Variation via Reaction Temperature and Solvent

Five new metal complex, [Zn-3(L1)(2)(BTC)(2)]center dot 6H(2)O (1), [Zn-3(L1)(BTC)(2)] (2), [Cd-3(L1)(BTC)(2)] (3), [Cd-3(L2)(BTC)(2)]center dot 4H(2)O (4), and [Cd-3(L2)(BTC)(2)(H2O)(2)] (5), have been successfully synthesized by solvothermal reactions of corresponding metal salts with 1,3,5-benzenetricarboxylic acid (H3BTC) and imidazole-containing ligands 1,3,5-tris(imidazol-1-ylmethyl)benzene (L1) and 3,3',5,5'-tetra(imidazol-1-yl)-1,1'-biphenyl (L2). The structures of the complexes were determined by single crystal X-ray diffraction analysis. Complexes 1 and 2 obtained at different reaction temperatures show different structures: 1 is a three-dimensional (3D) net with Zn-BTC3- layers pillared by L1 ligands, while 2 has a 3D structure with a Zn-BTC3- framework and Zn-L1 chain. Complexes 2 and 3, which contain different metal centers, have similar framework structures but different coordination modes of carboxylate groups. 4 and 5 that were prepared from different solvents show different 3D structures. The thermal stability, photoluminescence, and sorption properties of the complexes were investigated.