Metal-organic coordination polymers assembled from divalent transition salts with a flexible spacer ligand: Hydrothermal syntheses, crystal structures, and luminescent and magnetic properties

摘要

Seven new metal-organic coordination polymers, [M(tzda)(H2O)(4)](n) [M=Co(1), Ni (2) and Zn(3)], [Zn(tzda)(4,4'-bipy)](n) (4), [Cd(tzda)(4,4'-bipy)(0.5)(H2O)](n) (5) and [M(tzda)(4,4'-bipy)(H2O)](n) [M=Co(6), Ni(7)] [H(2)tzda=(1,3,4-thiadiazole-2,5-diyldithio)diacetic acid, 4,4'-bipy=4,4'-bipyridine] have been hydrothermally synthesized and structurally characterized by X-ray single crystal diffraction. Compounds 1-3 display similar 1D zigzag chain structure. Compound 4 possesses a 2D-layered architecture generated from [Zn(tzda)](n) moiety with double-chain structure cross-linking 4,4'-bipy spacers, while compound 5 consists of -Cd-O-CO-Cd-OCO- chains cross-linked through -CH2SC2-N2SSCH2- spacers of tzda anions and 4,4'-bipy, also showing a 2D-layered structure. The structures of 6 and 7 seem more complicated, in which the [M(tzda)](n) layered subunits are extended to unique 3D framework by the bridging 4,4'-bipy ligand. Photoluminescence investigations reveal that 4 and 5 both display strong blue emissions in the solid state at room temperature, which could be significant in the field of luminescent materials. The magnetic studies of 6 and 7 show both display the characteristics of a weak antiferromagnetic coupling between metal ions in the system mediated by carboxylate bridges.