A series of 1-D to 3-D metal-organic coordination architectures assembled with V-shaped bis(pyridyl)thiadiazole under co-ligand intervention

Six new coordination polymers based on V-shaped linkage 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and transition metal ions, [Co(bpt)(pm)(0.5)(H2O)]n center dot 3nH(2)O (1), [Cu-2(bpt)(pm)(H2O)(4)](n) (2), [Co(bpt)(pydc)](n) center dot 2nCHCl(3) center dot nH(2)O (3), [Cu-2((b)pt)(pydc)(2)(H2O)(2)](n) (4), [Cu-2(bpt)(pydco)(2)(H2O)(2)](n) center dot nH(2)O (5) and [Cd(bpt)(pydco)](n) (6) (H(4)pm = pyromellitic acid, H(2)pydc = pyridine-2,6-dicarboxylic acid, H(2)pydco = pyridine-2,6-dicarboxylic acid N-oxide), have been synthesized under the intervention of various polycarboxylate ligands. Complex 1 exhibits a 3-D 4-connected structure with 1-D nanosized open channels encapsulated lots of water molecules. Complex 2 represents a 2-D grid containing two types of rectangular windows. When pydc and pydco instead of pm, complexes 3 and 6 were obtained with highly undulated 2-D layers. The interlayers of 3 are filled with two kinds of solvent molecules, whereas 6 is a double-layered framework without free molecules. Complexes 4 and 5 consist of two distinct 1-D infinite chains held together to form different 2-D supramolecular networks. Importantly, bpt spacer shows changeful conformational geometries and generates complicated crystalline architectures with the introduction of polycarboxylate ligands. Additionally, thermal stability of complexes 1, 3 and 5, fluorescent properties of 6 and X-ray powder diffraction of 1 have also been investigated. (C) 2008 Elsevier B. V. All rights reserved.