Zinc(II) and cadmium(II) coordination polymers with bis(4-pyridyl)benzylamine: structure and photoluminescence

Two coordination polymers, [(bpba)Zn(CH3COO)2]n (1) and [(bpba)3Cd2(NO3)4]n·nMeOH·4nH2O (2) (bpba = bis(4-pyridyl)benzylamine), were obtained using Zn(CH3COO)2·2H2O/Cd(NO3)2·4H2O and bpba in a mixture of solvents, and were further characterized. The zinc(II) ion of 1 showed a tetrahedral geometry with two oxygen atoms of the acetate ligands and two pyridine groups of the bpba ligands, and it is linked to the neighboring zinc(II) ions through the bpba ligands, giving rise to an interesting one-dimensional helical structure. Contrastingly, the cadmium(II) ion of polymer 2 was bonded by three pyridine groups of three different bpba ligands and four oxygen atoms of two nitrate ligands, exhibiting a T-shaped geometry. Thus, polymer 2 forms a two-dimensional wave-like structure by the coordination of cadmium(II) ion and bpba ligand to each other. Polymers 1 and 2 showed strong UV emissions depending on the metal ions and are red-shifted, compared to the bpba ligand.