Synthesis And Characterization Of Mixed Complexes Of Lanthanide

The research on complexes of rare earth has been of increasing significance due to their wide use in biology, material and medicine. But the mechanism of chemical constitution and property is still unknown. Abundance of data were provided in this experiment which can been used for the structural and coordinate analyses in order to synthesize correctly in practice, predict new phenomemon and make sure the relation between various coordination mode and its property.This three series containing 18 mixed complexes with one neutral ligand of phen and anion ligands of p-nitrobenzoic acid, 1-benzoylacetone, alcohol and nitrate radical have been synthesized with new methods from the solution of slight acidity, 8-hydroxyquinoline being the acidity conditioner. The complexes were characterized with elemental analysis, IR, UV, ¹H-NMR, TGA and fluorescence spectrum. Moreover the crystal structures of the mixed complexes [Ce（p-NBA）₃（phen）]₄·4（H₂O）, [La（p-NBA）₃（C₂H₅O）（H₂O）]₂bipy,Eu（NO₃）₂（phen）₂（BZA）·0.5（NO₃） were obtained.The main conclusions are as follows:（1） The pH of solution is convenient to be control by 8-hydroxyquinoline for its weaker basicity comparing to some strong bases （e.g. NaOH）. Furthermore a little polar solvent （e.g. water） that been added in the solution will improve the crystal form of complex, which fits to be tested by X-ray single crstal diffraction.（2） The coordinating to the central ion of ligands, the reasons for the shifting direction of the proton and the vibrations of the red shifting for the complexes in UV spectrum have been investigated by means of IR、UV、¹H-NMR. The properties of all the ligands of the complexes could be presented by those spectral figures. Nevertheless there was not totally the same with the free ligands. This is helpful to determine if the products were the very complexes.（3） The thermal decomposition mechanism was studied by TGA. The results show that the ability to coordinate was as follow: p-nba/bza>NO₃^->bipy/phen> alcohol>H₂O.（4） The results of X-ray single crstal diffraction show that the complex [Ce（p-NBA）₃（phen）]₄·4（H₂O） crystallizes in the triclinic and the coordination number is eight. [La（p-NBA）₃（C₂H₅O）（H₂O）]₂·bipy also in the same crystal system. In the two single crystal, phen is chelating and P-NO₂C₆H₄COO^- shows bidentate bridging only. Alcohol and water coordinate La³⁺ ion by one oxygen atom. Crystal of Eu（NO₃）₂（phen）₂（BZA）·0.5（NO₃） crystallizes in the monoclinic and Eu³⁺ ion is ten-coordinate. Phen, bza and NO₃- all chelate to the metal center.（5） Eu（Ⅲ） complexes in the DMF solution have been investigated by the fluorescent spectra at room temperature （λex=400nm）.The results show that the complexes belongs to m^*�'m brighteners. Effect of ligands on the complexes’ emission properties has also been studied.