1-D zigzag double-chain coordination polymers of transition metals derived from pyridine-2,3,5,6-tetracarboxylic acid

Abstract

Three new 1-D zigzag coordination polymers {[M2(pdtc)(bpy)2(H2O)3] · 4H2O} n [M = Zn (1), Ni (2), Co (3)] (H4pdtc = pyridine-2,3,5,6-tetracarboxylic acid, bpy = 2,2′-bipyridine) have been synthesized by the reactions of H4pdtc and corresponding metal salts in the presence of bpy at room temperature and characterized by elemental analyses, IR, TGA, fluorescence, and X-ray diffraction. The main structural feature of 1–3 is the presence of octahedrally coordinated M1(II) and M2(II) centers sequentially bridged by pdtc ligands; bpy acts as a blocking ligand to avoid further polymerization. These coordination modes lead to 1-D double-chain structures. The 2-D or 3-D supramolecular structures of 1–3 are built up by π ··· π and hydrogen-bond interactions. Two (H2O)3 clusters are observed in 1–3. The zinc complex shows strong fluorescent emission at 325 nm.