Syntheses, crystal structures, and optical properties of a series of transition metal coordination polymers with chelidamic acid and 4,4′-bipyridine

A series of transition metal (Zn, Cu, Mn) complexes with chelidamic acid (2,6-dicarboxy-4-hydroxypyridine, H3CAM) and 4,4′-bipyridine (bipy), [Zn2(bipy)Cl2] n (1), {[Zn2(HCAM)(H2CAM)2] · (bipy) · 3.5H2O} n (2), [Mn3(HCAM)3(H2O)7] · (bipy) · 3H2O (3), [Mn2(HCAM)2(bipy) · (H2O)2] · 4H2O (4), [Cu2(HCAM)2(bipy) · (H2O)2] · 4H2O (5), and Cu2(HCAM)2(bipy) · (H2O)2 (6), have been synthesized by hydrothermal or solution methods and characterized by single-crystal X-ray diffraction. The structural analyses reveal that 1 exhibits a zigzag chain of Zn(II), Cl−, and 4,4′-bipyridine. In 2, a 1-D polymeric [Zn2(HCAM)(H2CAM)2] n chain and a discrete 4,4′-bipyridine assemble into a 2-D supramolecular network via H-bonds. Complex 3 consists of asymmetric units of Mn3(HCAM)3(H2O)7 that are linked by hydrogen bonds to form a 2-D H-bonded network. Complexes 4–6 are isomorphous and possess discrete structures. The photoluminescent properties of 1–6 at room temperature were studied.