Three AgI, CuI and CdII 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

Abstract

The new asymmetrical organic ligand 2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole (L, C17H13N5O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft AgI, CuI and CdII 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)]PF6} n , 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], {[Cu2I2(L)2]·C4H8O2} n , 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)2(NO3)2]·2CH4O·0.65H2O} n , were obtained. The experimental results show that ligand L coordinates easily with linear AgI, tetrahedral CuI and octahedral CdII 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.