Diverse architectures and luminescence properties of three low-dimensional Zn(II)/Cd(II) coordination polymers based on a pyridine-imidazole ligand

Abstract

Based on a rigid ligand 3,5-bis(imidazole-1-yl)pyridine (bip), three new low-dimensional Zn(II)/Cd(II) coordination polymers [Zn(bip)(Cl)2]n (1), [Zn(bip)(Cl)2]n (2) and [Cd(bip)(p-bdc)0.5(NO3)(H2O)·H2O]n (3) (p-H2bdc=1,4-benzenedicarboxylic acid) have been successfully obtained. Compounds 1 and 2 both feature zero-dimensional (0D) structures, whose asymmetric units are the same. Interestingly, the weak π-π stacking arrangement in 1 and 2 is significantly different in molecular orientation, resulting in two entirely different three-dimensional (3D) supramolecular structures. Compound 3 is characterized as an infinite one-dimensional (1D) chain structure formed by the linkage of Cd2(bip)2 units and linear p-bdc2− ligands, and is further extended into a 3D supramolecular architecture via weak π-π stacking interactions. It can be observed by careful investigation of the two structures that different packing modes in 1 and 2 can afford different networks. The photoluminescence of compounds 1–3 has been investigated in the solid state at ambient temperature.