Supramolecular assembly of double-stranded chains, helical chains and catenane-like layers with flexible ligands

Four new transition metal coordination polymers, [Co(bpndc)(phen)(H2O)](n) (1), [Co-3(bpndc)(3)(2,2'-bpy)(2)]n(center dot)0.5n(i-C3H7OH) (2), and [M(bpndc)(2,2'-bpy)(2)](n) (M = Zn, 3; Cu, 4; H(2)bpndc = benzophenone-4,4'-dicarboxylic acid; phen = 1, 10-phenanthroline; 2,2'-bpy = 2,2'-bipyridine) have been synthesized by the hydrothermal reactions and characterized by single crystal X-ray diffraction, elemental analysis, and IR spectrum. Because of the introduction of different terminal auxiliary ligands, bpndc ligands in complexes 1 and 2 adopt different coordination modes. In complex 1, bpndc ligands act as tridentate ligand and bridge Co-II ions into 1D double-stranded chains; while complex 2 possesses 2D (4,4) grids, where bpndc ligands adopt tetradente and pentadentate modes. Two such grids interpenetrate to form a novel catenane-like layer. Complexes 3 and 4 are isostructural. Bpndc ligands adopt tetradentate mode and bridge metal ions forming 1D helical chains.