Synthesis, Structures, And Catalytic Properties Of Complexes Based 1,3-xylenediamine N,N,N~',N~'-tetraacetic Acid

The design and construction of novel coordination polymers have been one of the most important research fields on coordination chemistry, supramolecular chemistry and crystal engineering, due to their beautiful topological structures and potential applications on ion-exchange, adsorption, enantioselective catalyst, electrics, magnetism, H₂-storage, molecular recognition and catalytic fields. Dinuclear complexes that capable of dioxygen activation and DNA cleavage are one of the most active research topics in current chemistry research due to their theortical and wide application.In this dissertation, chelete ligand 1,3-xylenediamine N,N,N',N'-tetraacetic acid and its complexes were synthesized and characterized by nuclear magnetic resonance spectroscopy, infrared spectroscopy, elemental analysis. Its complexes were synthesized and characterized through TG, single crystal x-ray diffraction and PXRD in solid state. Its solution chemistry were studied using potentiometric titration, UV-vis, Raman Spectroscopy and electrospray ionization mass spectrometry. Main research conclusions are as follows:1: The title ligand, Li_0.5H_3.5L·H₂O was synthesized through condensation of 1,3-xylenediamine and bromoacetic acid in the presence of LiOH. Crystal of ligand H₄L.H₂O {C₁₆H₂0N₂O₈·H₂O}_n was obtained in dilute acidic solution. H₄L.H₂O is a inner salt. The two iminoaiacetic moieties are on the same side of the central benzene plane. 3D coordination polymers, {[Zn₂(μ₁₀-L)( H₂O)₂]·2H₂O}_n(1) and {[Co₂(μ₁₀-L)(H₂O)₂]·2H₂O}_n(2) were synthesized hydrothermally as well as static volatile methods. Research indicated that the fluorescence of the complexes can be designed to ligand emission. Thermogravimetric analysis agrees well with the crystal structure on coordination and crystalline water molecules. Both IR and PXRD indicate that complex 1, 2 and Mn(â…¡) analog are amphorous. Both 1 and 2 can catalytic the oxidation of colorless 1,5-diphenylcarbonohydrazide into red diphenylcarbazone in ethanol solution hetergenously in the presence of excess H₂O₂ at room temperature. The catalytic effect of 1 is 33 times that of 2 in identical reaction conditions.. 2: Potentiometric titration indicate that H₄L has four proton process. The first two steps are the protonation of iminodiacetate nitrogen atom, protonation constants are similar to N-substituted iminodiacetic acid. The third and fourth protonation are <3 and <2 respectively. Temperature dependence protonation constants indicate that the protonation process is exothermic. The species and its stability constants of Cu(â…¡) and Zn(â…¡) complexes were also determined. In neutral aqueous solution, Cu₂L(H₂O)₂(OH)₂^2- is the main specie. While for Zn(â…¡) complexes, Zn₂L ,Zn₂L(OH)-are the main species in neutral aqueous solution. The stability of Cu(â…¡) complexes are obviously larger than corresponding Zn(â…¡) complexes. Electrospray mass spectra agrees well with the titration data.Copper((â…¡) complex can activate dioxygen and catalytic the oxidation of colorless 1,5-diphenylcarbonohydrazide into red diphenylcarbazone. Red diphenylcarbazone can be further oxidized into colorless product. The whole catalytic process is a consecutive first-order process. Dinuclear zinc complexes in weak basic aqueous solution can catalyticly hydrolysis bis(p-nitrophenol) phosphate diester).