Syntheses and characterization of two novel cadmium(II) coordination polymers derived from pyridyl substituted terpyridine and diphenate mixed ligands

Two metal-organic coordination polymers, [Cd(dpa)(pytpy)]center dot(H2O)(3) (1) and [Cd-3(dpa)(Pytpy)(2)(SO4)(2)]center dot(H2O)(3) (2), have been synthesized by the reactions of 4'-(3-pyridyl)-2,2':6',2 ''-terpyridine (pytpy), diphenic acid (H(2)dpa) with Cd(ClO4)(2)center dot 6H(2)O and CdSO4 center dot 8/3H(2)O, respectively, in the presence of base. Compound I is a one-dimensional helical chain, in which (dpa)(2-) as bridging ligand is responsible for the formation of the main framework and pytpy as chelating ligand grafts on one side of the helical chain and forms pi-pi stacking interactions with adjacent chains. This compound is further extended into a two-dimensional supramolecular framework through hydrogen bonds. Compound 2 is a one-dimensional chain simultaneously composed of bridging neutral organic ligand, bridging anionic organic ligand and bridging anionic inorganic ligand. The (dpa)(2-) and sulfate anions connect Cd-II atoms into neutral [Cd-3(dpa)(SO4)(2)] subunits and the trinuclear units are bridged by pytpy ligand into one-dimensional double-layer chain. This structure is further extended into two-dimensional layer architecture through face-to-face pi-pi interactions. (C) 2008 Elsevier B.V. All rights reserved.