Effect of Metal Ions on the Structures of Coordination Polymers Based on Biphenyl-2,2′,4,4′-Tetracarboxylate

Two new coordination polymers, {[Cd2(btc)(2,2′‐bpy)2]·H2O}n (1) and [Zn2(btc)(2,2′‐bpy)(H2O)]n (2) (H4btc = biphenyl‐2,2′,4,4′‐tetracarboxylic acid, 2,2′‐bpy = 2,2′‐bipyridine), were synthesized hydrothermally under similar conditions and characterized by elemental analysis, IR spectra, TGA, and single‐crystal X‐ray diffraction analysis. In complexes 1 and 2, the (btc)4– ligand acts as connectors to link metal ions to give a 2D bilayer network of 1 and a 3D metal‐organic framework of 2, respectively. The differences in the structures are induced by diverging coordination modes of the (btc)4– ligand, which can be attributed to the difference metal ions in sizes. The results indicate that metal ions have significant effects on the formation and structures of the final complexes. Additionally, the fluorescent properties of the two complexes were also studied in the solid state at room temperature.