Assembly of Zn(II) and Cd(II) coordination polymers based on a flexible multicarboxylate ligand and nitrogen-containing auxiliary ligands through a mixed-ligand synthetic strategy: syntheses, structures and fluorescence properties.

The structures of coordination polymers are strongly influenced by the organic ligands and metal ions used for their construction, so it is important to choose suitable ligands and metal ions and appropriate synthetic processes. Two novel d(10) coordination polymers, namely poly[[diaquabis(2,2'-bipyridine)[μ4-4,4'-(1,4-phenylenedioxy)bis(benzene-1,2-dicarboxylato)]dizinc(II)] dihydrate], {[Zn2(C22H10O10)(C10H8N2)2(H2O)2]·2H2O}n, (1), and poly[[diaquabis(1,10-phenanthroline)[μ4-4,4'-(1,4-phenylenedioxy)bis(benzene-1,2-dicarboxylato)]dicadmium(II)] dimethylformamide disolvate], {[Cd2(C22H10O10)(C12H8N2)2(H2O)2]·2C3H7NO}n, (2), have been synthesized from 4,4'-(1,4-phenylenedioxy)bis(benzene-1,2-dicarboxylic acid) (H4L) and two different N-containing auxiliary ligands through a mixed-ligand synthetic strategy under a solvothermal environment. The structures were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis and IR spectroscopy. Compounds (1) and (2) both present one-dimensional chain structures and two-dimensional supramolecular layer structures constructed by weak hydrogen bonds. It is interesting to note that the carboxylate ligands reveal stable trans configurations in both compounds. The fluorescence properties of (1) and (2) in the solid state were also investigated.