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 complexes, [Zn 3 (L1) 2 (BTC) 2 ]·6H 2 O ( 1 ), [Zn 3 (L1)(BTC) 2 ] ( 2 ), [Cd 3 (L1)(BTC) 2 ] ( 3 ), [Cd 3 (L2)(BTC) 2 ]·4H 2 O ( 4 ), and [Cd 3 (L2)(BTC) 2 (H 2 O) 2 ] ( 5 ), have been successfully synthesized by solvothermal reactions of corresponding metal salts with 1,3,5-benzenetricarboxylic acid (H 3 BTC) 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-BTC 3– layers pillared by L1 ligands, while 2 has a 3D structure with a Zn-BTC 3– 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.