Syntheses and crystal structures of three coordination polymers based on terphenyl-2,5,2',5'-tetracarboxylic acid

摘要

Solvothermal reactions of terphenyl-2,5,2',5'-tetracarboxylic acid (H_4qptc) and M~(II) (M=Co, Ni, Cu) in the presence of 2,2'-bipyridine (2,2'-bpy) afford three new coordination polymers, [M(qptc)_(0.5)(2,2'-bpy)(H_2O)]_n (M=Co (1), Ni (2)) and [Cu(H_2qptc)(2,2'-bpy)]_n (3). The structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR, and TGA. Complexes 1 and 2 are isostructural and display a 2-D layer wherein qptc~(4-) is a twisted H-shaped ligand connecting Co~(II) centers. Furthermore, 3-D structures in 1 and 2 are formed via inter-chain π...π interactions between neighboring 2,2'-bpy ligands, with the centroid-centroid distances of 3.619-3.822 A. In 3, two deprotonated carboxyl groups of H_2qptc~(2-) are a Z-shaped ligand linking Cu~(II) centers to a 1-D zigzag polymeric chain. A 2-D layer structure is built with the help of inter-chain π...π interactions between the 2,2'-bpy and H_2qptc~(2-).