Anion-dependent formation of four coordination polymers based on N,N′-di(3-pyridine) oxamide (DPOM): Crystal structures and luminescence

Abstract

Presented in this article are the anion-tuning formation, crystal structures and luminescent properties of four coordination polymers of N,N′-di(3-pyridine) oxamide (DPOM), including two one-dimensional (1D) chain/ladder polymers, [Ni(DPOM)(H2O)4]SO4·2H2O (1) and [Cd4(DPOM)6(NO3)8] (2), as well as two 3D coordination polymers, [Zn2(DPOM)(H2O)4(SO4)2] (3) and [Cd2(DPOM)(H2O)4(SO4)2] (4). The results of single crystal X–ray diffraction analyses indicate that in these coordination polymers, DPOM ligand serves as a bridge, connecting metal ions by both terminal pyridine N atoms. 1 is a 1D chain structure formed by the bridge of DPOM. 2 is a 1D ladder-like structure featuring Cd(NO3)2 structural units bridged by DPOM ligands. Both 3 and 4 are 3D pillar-layer structures with the 2D inorganic layer ZnSO4/CdSO4 pillared by DPOM ligands. The results of photoluminescent measurements illustrate that upon excitation, 2–4 can emit fluorescence in 408, 416, and 422nm in the solid state, respectively.