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

Abstract

Five new metal complexes, [Zn3(L1)2(BTC)2]·6H2O (1), [Zn3(L1)(BTC)2] (2), [Cd3(L1)(BTC)2] (3), [Cd3(L2)(BTC)2]·4H2O (4), and [Cd3(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.