Syntheses and characterization of six coordination polymers of zinc(II) and cobalt(II) with 1,3,5-benzenetricarboxylate anion and bis(imidazole) ligands

Six new coordination polymers, namely [Zn-1.5(BTC)(L-1)(H2O)(2)]center dot 1.5H(2)O (1), [Zn-3(BTC)(2)(L-2)(3)] (2), [Zn-3(BTC)(2)(L-3)(1.5)(H2O)]center dot H2O (3), [Co-6(BTC)(4)(L-1)(6)(H2O)(3)]center dot 9H(2)O (4), [Co-1.5(BTC)(L-2)(1.5)]center dot 0.25H(2)O (5), and [Co-4(BTC)(2)(L-3)(2)(OH)(2)(H2O)]center dot 4.5H(2)O (6), where L-1 = 1,2-bis(imidazol-1-ylmethyl)benzene, L-2 = 1,3-bis(imidazol-1-ylmethyl)benzene, L-3 = 1,1'-(1,4-butanediyl)bis(imidazole), and BTC = 1,3,5-benzenetricarboxylate anion, were synthesized under hydrothermal conditions. In 1-6, each of L-1-L-3 serves as a bidentate bridging ligand. In 1, BTC anions act as tridentate ligands, and compound 1 shows a 2D polymeric structure which consists of 2-fold interpenetrating (6, 3) networks. In compound 2, BTC anions coordinate to zinc cations as tridentate ligands to form a net with (6(4)center dot 8(2))(2)(8(6))(6(2)center dot 8)(2) topology. In compound 3, BTC anions act as tetradentate ligands and coordinate to zinc cations to form a net with (4 center dot 6(2)center dot 8(3))(2)(8 center dot 10(2))(4 center dot 6 center dot 8(3)center dot 10)(2) topology. In compound 5, each BTC anion coordinates to three Co cations, and the framework of 5 can be simplified as (6(4)center dot 8(2))(2)(6(2)center dot 8(2)center dot 10(2))(6(3))(2) topology. For 4 and 6, the 2D cobalt-BTC layers are linked by bis(imidazole) ligands to form 3D frameworks. In 6, the Co centers are connected by mu(3)-OH and carboxylate O atoms to form two kinds of cobalt-oxygen clusters. Thermogravimetric analyses (TGA) for these compounds are discussed. The luminescent properties for 1-3 and magnetic properties for 4-6 are also discussed in detail.