Hydrothermal synthesis, structure and property of transition metal(Mn, Zn, Cd or Pb) coordination frameworks using quinoline-8-oxy-acetate acid and dicarboxylic acid as ligands

Abstract

Five transition metal coordination compounds, [Mn2(8-qoac)2(bdc)(H2O)4](1)(8-qoacH=quinoline-8-oxy-acetate acid, H2bdc=benzene-1,4-dicarboxylic acid), [Zn4(8-qoac)4(bdc)2] n (2), {[Cd2(8-qoac)2(Hip)2(H2O)2]·(H2O)4} n (3)(H2ip=benzene-1,3-dicarboxylic acid), [Pb3(8-qoac)2(bdc)1.5(H2O)Cl] n (4) and [Zn2(8-qoac)(8-ql)(bdc)] n (5)(8-Hql=8-hydroxyquinoline), were synthesized by hydrothermal syntheses of metal salts with benzenedicarboxylic acid and 8-qoacH. Compound 1 possesses a discrete dimer bridged by bdc2− ligand. Compound 2 presents a 2D layer network constructed from bdc2− linkers and 1D infinite ribbons, in which Zn(II) centers are bridged by 8-qoac− with a tetradentate binding mode. Compound 3 displays a 1D zigzag chain, with adjacent chains further connected via extensive O-H…O hydrogen bonds to generate a 3D supramolecular structure. Compound 4 shows a 3D framework containing trinuclear lead secondary building units and bdc2− linkers, in which a new coordination mode of 8-qoac− ligand is observed. In compound 5, Zn(II) ions are simultaneously bridged by 8-qoac−, 8-ql− and bdc2− ligands to form tetranuclear zinc units, which are further interlinked by bdc2− linkers to yield a 2D wave-like layer. Based on intraligand(IL)(π-π*) fluorescent emission, compounds 1–5 possess strong purple fluorescent emissions. In addition, the thermal stabilities of compounds 1–5 were studied.