Synthesis, Structures And Properties Of Lanthanide Metal Complexes With 6-Hydroxynicotinate

In this thesis, eight novel lanthanide metal complexes with 6-hydroxynicotinate as ligand were obtained in aqueous solution. The crystal structures of these complexes have been determined by X-ray single-crystal diffraction. The complexes were characterized by IR spectrometry, UV spectrometry, fluorescence spectrometry and TG The main contents are described as following:1. Eight lanthanide metal complexes showed two structures of 1D and 2D. Complexes 3,4,5,6 and 7 are isostructure with 1D chain-structure; Complexes 1,2 and 8 are isostructure with 2D plane-structure.The structure investigation indicated that, eight complexes belong to triclinic crystal system, space group P-1. Each lanthanide metal was nine-coordinated and formed distorted monocapped square antiprism geometry. The variation of average Ln-O bond length in two groups well reflected the lanthanide contraction effect. Ligand exhibits five kinds of coordination mode in complexes, listing as monodentate mode, didentate-bridging mode, chelating-bridging didentate mode, tridentate-bridging mode and chelating-bridging tridentate mode.2. The UV spectrometry showed that UV absorption of the eight complexes dominated by ligand absorption. The absorption intensities of the complexes were stronger than ligand because the conjugatin degree was increased after coordination.3. The fluorescent property of the eigth complexes were investigated by the fluorescent spectrophotometer. The fluorescent spectra of complexes 1,3,5,6 and 7 were domintaed by fluorescent emission of ligand. The luminescent of complex 4 showed the characteristic peaks of the weak fluorescent lanthanide metal ions. Complex 4 displayed stronger fluorescent than the ligand because of the efficient energy transfer from the ligand to the lanthanide metal ions. The emission spectra of complexes 2 and 8 were due to 4f→5d transition of lanthanide metal ions. Water molecules in complexes only affected the emission peak intensities of the metal ions, not changed the emission peak position. 4. TG analysis indicated that the 2D complexes showed stronger thermal stability than 1D complexes. The variation of termal stability in two groups well reflected the lanthanide contraction effect.