Design, Hydrothermal Synthesis, Crystal Structure And Properties Of Aromatic Carboxylic Acid Complexes

Rational design and construction of novel coordination polymers and investigation of their properties are the current interest in the field of superamolecular chemistry and crystal engineering, stemming from their various intriguing molecular topologies and potential applications as functional materials. The most effective strategy to construct novel coordination polymers is to select appropriate bridging ligands. As an important familiy of O-donor ligand, organic aromatic carboxylate ligands are good candidates for this purpose. Aromatic carboxylate ligands can exhibit diverse coordination fashions and bridge metal centers to assemble multidimensional architectures, they can also behave as various anions under different pH conditions and their degree of deprotonation would have great influence on the structure of the resulting coordination complexes.In view of reasons above and from the standpoint of molecular design, we select an aromatic dicarboxylate ligand(2,2'-oxydibenzoic acid) as bridging unit between metal ions, in combination with the use of pyridyl ligands as the second ligand, successfully synthesized a series of aromatic carboxylate coordinate complexes under hydrothermal conditions. These compounds were characterized by X-ray crystallography, spectroscopic, thermal properties. The main contents are described as following:(I)Under the conditions of hydrothermal sysnthesis, the 1D infinite chain coordination polymer {[Ba(Hodb)2]}n were prepared by reactions of 2,2'-oxydibenzoic acid and Ba(II) cation. And the complex structure was studied by X-ray, elemental analysis and IR spectra.( II ) The coordination polymers with the mixture of transitional metal ion, 2,2'-oxydibenzoic acid and the pyridyl ligands(5,5'-dimethyl-2,2'-bipyridine; 4,4'-dimethyl-2,2'-bipyridine; 2,2':6',2''-terpyridine; 1,2-di(4-pyridyl)ethylene) were prepared. Four novel compounds namely {[Cu(odb)(5,5'-dmbpy)H2O]}n(1), {[Zn(odb)(4,4'-dmbpy)]H2O}2(2), {[Zn(odb)(tpy)]}n(3), {[Cd(odb)(dpe)0.5H2O]}n(4), have been successfully constructed under hydrothermal conditions. Because of difficult dissolution ability of 2,2'-oxydibenzoic acid, the conditions of hydrothermal synthesis are severe. Especially, pH value of the reaction system, reaction temperature, crystallization time and temperature-descent rate affect the crystal structure.(III)Using mononuclear complex Na2CuTS·H2O and CeCl3·7H2O, we obtained the single-crystal of 3d-4f heterometallic hexanuclear complex {[CuTS(H2O)CeCuTS]2·2DMF·5H2O}(TS=N'N-bis(3-carboxylsaboxylsalidene)trimethylenediamine). Its crystal structure has been determined by X-ray analysis.