Syntheses, Structures And Properties Of Coordination Compounds Based On Symmetrical Imidazole Dicarboxylic Acid And Asymmetric Nitrogen Heterocyclic Flexible Ligands

In this paper, fourteen novel complexes have been synthesized by reactions of a flexible dual-acid derivatives of imidazole 2,2'-(ethane-1,2-diyl)bis(1H-imidazole-4,5-dicarboxylic acid) (H6ebidc) and a semi-flexible asymmetric heterocyclic compounds 2-((benzoimidazol-yl)methyl)-1H-tetrazole (Hbimt) with metal center. And some complexes' thermal properties, fluorescence properties and biological activity have been studied. The whole dissertation is divided into four chapters.In Chapter 1, the research and applications of functional coordination complexes which are build of the imidazole dual-acid and its derivatives, or the asymmetric heterocyclic ligands have been primarily introduced. The significance of the article topic and the main researches of this paper were outlined.In Chapter 2, we preliminary investigated the regular pattern of the ligand 1,2-bis(2-4,5-imidazole dicarboxylic-yl)ethane (H6ebidc) coordinated with metal center. Eight novel metal complexes, namely, [Co(H4ebidc)(H2O)2] (1), [Ni(H4ebidc)(H2O)2] (2), [Cu(H4ebidc)H2O]·H2O (3), [Cu(H5ebidc)Cl]·1/2(dbz)·CH3OH (4), [Cu(H5ebidc)Br]·1/2(dbz)·CH3OH (5), [Cd(CH3OH)2(μ-H4ebidc)2Cd(CH3OH)2]·CH3OH (6),{[Cd (H6ebidc)1/2(Cl)(Ⅰ)]·CH3OH}n (7) and [Ce(H2ebidc)1/2SO4(H2O)5]n(8) have been synthesized by evaporation at room temperature and solvothermal reactions of Co(II), Ni(Ⅱ), Cu(Ⅱ), Cd(Ⅱ), Zn(Ⅱ) and Ce(Ⅳ) salts with 1,2-bis(2-4,5-imidazole dicarboxylic-yl)ethane (H6ebidc). Crystal structures have been determined by single crystal X-ray diffraction. Complexes 1-5 possess mononuclear structures,1,2 and are the same heterogeneous crystal structure with six-coordinated,4 and 5 are also the same heterogeneity crystal structure, and Cu (Ⅱ) are all five-coordinated; Complex 6 is a neutral binuclear structure and the ligand is bridged; Complex 7 exhibits one-dimensional chains structure by the interconnected ligands bridge and double Cl- bridge; Complexes 8 exhibits two-dimensional network structure through SO42- anion bridge and ligand bridge. During the experiment, we found it's very easy for H6ebidc to reaction with transition metal salts and forming insoluble polymer, but hard to obtain single crystal. Of the eight complexes obtained, single crystals of 1,2 and 4-7 were obtained through adding template. Although there many potential site in this ligand, Scheme 2-1, mode I dominated this chelating coordination mode. In the premise of the same other conditions, no matter how to increase the ratio of the metal ions and ligands, the structures of the complexes obtained are all the same. And even independent of the solvent and temperature. But with the increasing of metal ionic radius the ligand coordination mode tends to Scheme 2-1, ModeⅢ, indicating that the radius of metal ions plays a regulatory role on the ligand coordination mode. In addition, the thermal property of complex 8 and the fluorescence properties of complexes 6,7and 8 have been investigated.In Chapter 3, six novel complexes, [Ag(Hbimt)2]·NO3 (9), [Hg2(bimt)2Br2]·H2O (10), [Hg2(bimt)2I2](11), [Zn2(bimt)2(Ac)(OH)]n(12),{[Zn(Hbimt)2TPA]·H2O}n (13) and {[Zn1.5(Hbimt)(H2O)2BTC]·DMF}n (14) have been synthesized by reactions of a semi-flexible unsymmetrical N-heterocyclic ligand 2-((benzoimidazol-yl)methyl)-1H-tetrazole (Hbimt) with Hg(Ⅱ), Ag(Ⅰ), Zn(Ⅱ) salts by evaporation at room temperature and solvotherma. Crystal structures have been determined by single crystal X-ray diffraction. Complex 9 is a mononuclear structure; Complexes 10 and 11 possess binuclear structures and are the same heterogeneous crystal structure; Complex 13 exhibits one-dimensional structure by the dehydrogenation of organic anions (TPA) as bridge. Complex 14 is a one-dimensional ladder chain structure through the dehydrogenation of organic anions (BTC) as bridge which connected three metal centers. Complex 12 displays two-dimensional network structure through the ligand, AC- anions and OH- as bridges. In these complexes, Hbimt acts as monodentate or bidentate bridging ligand. The ligands are based on the N atom from benzimiazole involved in coordination, while the three potential N atoms of tetrazole are not involved in coordination no matter in which kind of ligand coordination mode. Compare with the work done of Xinjuan Wu in our team, we have known that in the ligand (Hbimt) the coordination ability of N atom from benzimidazole are rather strong than from tetrazole in the process of self-assembly formation complex.. And it's consistent with our calculated of the contributive percents of the nitrogen atoms in the frontier molecular orbits of the free ligand. In addition, the fluorescence properties of complexes 9-14 and the thermal properties and the thermal property of complexes 12 and 14 have been investigated.In Chapter 4, conclusion of this work is given.