Synthesis, crystal structures and properties of Cu(II) and Cd(II) complexes with 4,4′-oxybis(benzoic acid)

Three novel complexes, [Cu(phen)(oba)]2·(DMF)2(H2O) (1), {[Cu(2,2-bipy)2(Hoba)][Cu(2,2-bipy)2(oba)]2·(nitrate)(H2O)13} (2) and [Cd(oba)(ptca)]·(DMA)2 (3) (H2oba = 4,4′-oxydibenzoic acid, H2ptca = terephthalic acid, 2,2-bipy = 2,2′-dipyridylamine, DMA = dimethylamine, phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, infrared spectrum and X-ray crystal diffraction. Strong hydrogen bonds play central roles in the formation of the 3D structure, the combined influence of the weak interactions such as C–H…O, carbonyl…π and C–H…π interactions are also evident in the structures. Complex 1 shows 1D helix structure which is shaped by intermolecular and intramolecular π…π stacking. Complex 2 displays a interesting water morphology based on the lattice water molecules while Complex 3 shows 2-fold (4,4)-net vertical interpenetrating structure. The preliminary investigations on the fluorescence property of the complexes are presented.