Rare Earth Carboxylic Acid Coordination Polymers To Build, Structure And Nature

In recent years, the most important subjects of intensively current research in the cross domain of coordination chemistry, supermolecular chemistry and crystal engineering have focused on building novel metal-organic coordination polymers through metal-ligand coordination and intermolecular interactions (hydrogen bonds,π–πstacking, etc.) between ligands. Design and synthesis of rare earth organic complexes are of great interest at present, due to their novel topological structures and many merits such as high luminescent intensity, good monochromaticity, non-oxidate and so forth. With these aims, four rare earth coordination polymers have been synthesized by solvent method or hydrothermal method in this paper, with the first ligands 2,4-dichlorobenzoic acid, 4,4'-oxybis(benzoic acid), 2,2'-biphenyldicarb- oxylic acid and the second ligand 1,10-phenanthroline. The crystal structures of these complexes were determined by X-ray diffraction, and the properties were characterized by IR, fluorescence spectra , DTA - TG analysis.1. A new coordination polymer [Eu(2,4-DClBA)3(CH3CH2OH)2]n(2,4-HDClBA = 2,4-dichlorobenzoic acid)with 2,4-H2DClBA ligands was prepared by solvent method. In the complex, each Eu3+ ion is eight-coordinated and surrounded by eight oxygen atoms, of which four oxygen atoms are from four bidentate-bridging 2,4-DClBA anions, two oxygen atoms from one bidentate-chelating 2,4-DClBA anion, and other two oxygen atoms provided by two ethanol molecules. The neighboring Eu3+ ions are linked by two 2,4-DClBA groups in bidentate-bridging coordination mode to form an infinite 1-D chain. The fluorescence spectrum of the complex shows the characteristic emission of Eu3+ ion.2. Two new coordination polymer {[Sm(OBA)1.5(phen)]·11H2O}n (1) and {[Dy2(OBA)3(H2O)4]·H2O}n (2) [H2OBA = 4,4'-oxybis(benzoic acid)] with OBA ligands were synthesized by hydrothermal method. The coordination modes of all central Sm3+ ions in the complex 1 are identical, which are linked by OBA ligands to form a 3-D network; Complex 2 exists two crystallographically independent Dy3+ ions, one of them is eight-coordinated, the other is seven-coordinated. Complex 2 is a 3-D supermolecular complex through OBA ligands connecting with Dy3+ ion to be a 2-D network and complicated intermolecular hydrogen bonds interactions. The fluorescence spectra of the two complexes show the characteristic emission of Sm3+ ion and Dy3+ ion.3. A new coordination polymer [Y2(BPDA)3(H2O)2]n (H2BPDA = 2,2'-biphenyldica- rboxylic acid) with BPDA ligands was prepared by hydrothermal method. In the complex, 1-D chains are constructed by BPDA ligands bridging center Y3+ ions, which are further formed to be a 3-D supermolecular complex though strongπ–πinteraction owing to interactional phenyl rings of BPDA ligands. There are two types of Y3+ ions in the complex, one of them is coordinated with eight carboxyl oxygen atoms of BPDA ligands, but the other is coordinated by six carboxyl oxygen atoms of BPDA ligands and two oxygen atoms of two water molecule.