Syntheses and characterizations of four metal coordination polymers constructed by the pyridine-3,5-dicarboxylate ligand

A series of metal-organic frameworks, namely [Ni(PDB)(H2O)](n) (1), [Pb(PDB)(H2O)] center dot (H2O) (2), [Co-2(PDB)(2)(bpy)(2)(H2O)(4)] center dot 4H(2)O (3) and [CO2(PDB)(2)(phen)(2)](n) (4) (H2PDB = pyridine-3,5-dicarboxylic acid, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline), have been synthesized based on pyridine-3,5-dicarboxylate acid and two neutral chelate ligands, with different metal ions such as Ni-II, Co-II and Pb-II, under hydrothermal conditions. The framework structures of these polymeric complexes have been determined by the Xray single crystal diffraction technique. In the four complexes, the pyridine-3,5-dicarboxylate acid ligand exhibits diverse coordination modes, which play an important role in the construction of metal-organic frameworks. The thermal analyses of these four complexes have been measured and discussed. In addition, complex 2 shows strong phosphorescent emission at room temperature and the magnetic measurement of the polymer of 4 reveals a typical antiferromagnetic exchange. (c) 2007 Elsevier Ltd. All rights reserved.