Three Ag, Cu and Cd coordination polymers based on the new asymmetrical ligand 2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole: syntheses, characterization and emission properties.

The new asymmetrical organic ligand 2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole (L, CHNO), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft Ag, Cu and Cd metal ions was investigated and three new coordination polymers (CPs), namely, catena-poly[[silver(I)-μ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole] hexafluoridophosphate], {[Ag(L)]PF}, catena-poly[[copper(I)-di-μ-iodido-copper(I)-bis(μ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole)] 1,4-dioxane monosolvate], {[CuI(L)]·CHO}, and catena-poly[[[dinitratocopper(II)]-bis(μ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole)]-methanol-water (1/1/0.65)], {[Cd(L)(NO)]·2CHO·0.65HO}, were obtained. The experimental results show that ligand L coordinates easily with linear Ag, tetrahedral Cu and octahedral Cd metal atoms to form one-dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π-π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.