Synthesis, structure and thermal stability of ternary metal complexes based on polycarboxylate and N-heterocyclic ligands

The reactions of metal salts with pyrazine-2,3-dicarboxylic acid (H(2)pzdc), pyridine-2,5-dicarboxylic acid (H(2)pydc), pyrazine-2,3,5,6-tetracarboxylic acid (H(4)pztc). 4,4'-bipyridine (bipy) and 1,10-phenanthroline (phen) afforded four new ternary complexes, namely [CO2(pzdc)(2)(bipy)(H2O)(2)](n)center dot 3nH(2)O (1), [Zn-2(pzdc)(2) (bipy)(H2O)(2)](n)center dot 3nH(2)O (2), [Co(pydc)(2)(H2O)(2)](H(2)bipy) (3) and [Cu-2(pztc)(phen)(2)(H2O)(2)]center dot 2HNO(3)center dot 2H(2)O (4). The metal centers are all six-coordinated. Compounds (1 and 2 are 21) coordination polymers exhibiting wave-like polymeric networks. The 2D layers are stacked in an interpenetrating mode to form double-layered frameworks, which possess similar to 8 angstrom x 6 angstrom tunnels Occupied by (H2O)(6) Clusters. Compound 3 is a mononuclear supramolecular compound in which 4,4'-bipyridine is protonated and acted as a cationic building block. Compound 4 is a centro-symmetric binuclear complex. Pztc(4-) as a hexadentate ligand coordinates to two Cu(II) ions to form four chelating rings. Phen are arranged in an ABAB parallel fashion to form a supramolecular architecture incorporating HNO3 lattice molecule. The thermal stabilities of 1-4 and luminescence of zinc complex 2 were also investigated. (c) 2008 Elsevier B.V. All rights reserved.