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)(H 2 O) 4 ]SO 4 ·2H 2 O ( 1 ) and [Cd 4 (DPOM) 6 (NO 3 ) 8 ] ( 2 ), as well as two 3D coordination polymers, [Zn 2 (DPOM)(H 2 O) 4 (SO 4 ) 2 ] ( 3 ) and [Cd 2 (DPOM)(H 2 O) 4 (SO 4 ) 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(NO 3 ) 2 structural units bridged by DPOM ligands. Both 3 and 4 are 3D pillar-layer structures with the 2D inorganic layer ZnSO 4 /CdSO 4 pillared by DPOM ligands. The results of photoluminescent measurements illustrate that upon excitation, 2 – 4 can emit fluorescence in 408, 416, and 422 nm in the solid state, respectively.