Effect of synthetic conditions on the structures and properties of metal complexes with chelidamic acid and 4,4′-bipyridyl

Through controlling the temperature, pH value, solvent and added metal salts, six new zinc(II) and cobalt(II) coordination polymers with different structural features, formulated as {[Zn-2(HCAM)(2)(bipy)]center dot 2H(2)O}(n) (1), {[Co-3(CAM)(2)(bipy)(2)center dot(H2O)(4)]center dot 16/3H(2)O}(n) (2), {[Co(HCAM)(bipy)]center dot 19/6H(2)O}(n) (3). {4(H2O)-[Co(biPY)center dot(H2O)(4)](bipy)[Co(HCAM)(2)]}(n) (4), Zn-2(HCAM)(2)(bipy)center dot(H2O)(2) (5), and 2(H2O)center dot[Co-2(HCAM)(2)(bipy)center dot(H2O)(4)] (6) (bipy = 4,4'-bipyridyl), have been synthesized based on reaction between chelidamic acid (2,6-dicarboxy-4-hydroxypyridine, called as H(3)CAM) and 4,4'-bipyridyl. For 1 and 3, metal ions connected by the carboxylate O atoms to form a one-dimensional chain, which was then further linked by 4,4'-bipyridyl to form 2D coordination polymers. In 2, the Co(II) ions and chelated chelidamic acid ligands are interconnected by the hydroxyl oxygen atom to form a nearly linear chain and are further assembled into a 2D coordination polymer via the [Co(bipy)(2)center dot 4H(2)O)(2+) units. In 4, there exist a one-dimensional polymeric [Co(C10N2H8)center dot(H2O)(4)](n)(2+) chain and a discrete [Co(HCAM)(2)](2-) anion, and then further assemble into a 2D supramolecular network via H-bonds and pi-pi stacking interactions. And compounds 5 and 6 are iso-structural and possess discrete structures. The solid-state photoluminescence, magnetic properties and IR of 1-6 have been investigated. (C) 2012 Elsevier Ltd. All rights reserved.