Three new 3D coordination polymers constructed by biphenyl-2,2′,4,4′-tetracarboxylic acid: Effect of metal ions and the second ligands

Three new coordination polymers with different architectures, {[Zn2(bta)(2,2′-bipy)2]·H2O}n (1), {[Cd2(bta)(2,2′-bipy)2(H2O)]·H2O}n (2) and [Cd3(bta)(Hbiim)2(H2biim)]n (3), where H4bta = biphenyl-2,2′,4,4′-tetracarboxylic acid, 2,2′-bipy = 2,2′-bipyridine and H2biim = 1H,1′H-2,2′-biimidazole, have been obtained by the reactions of metal nitrates, H4bta, the second ligands and H2O under similar hydrothermal conditions. All the polymers are three-dimensional (3D) constructions with different networks, in which 1, 2 and 3 exhibit a (42·84)-pts, (42·63·8)-sra and (416·65) topology, respectively. The bta ligands in 1–3 adopt η6,μ6-hexadentate, η8,μ5-tetradentate and η10,μ7-decadaldentate coordination modes, respectively, and the corresponding angles of two benzene rings in the ligand of each compound are 45.96°, 54.93° and 52.50°, respectively. This study indicates that the natures of metal ions and the second ligands are crucial factors for self-assemble of coordination polymers.