Synthesis,Luminescence And Magnetic Properties Of Rare Earth Metal Complexes

In recent years,complexes have developed rapidly and become an important research topic in the field of coordination chemistry.Rare-earth metal ions have a special 4f-layer electronic structure,and the rare-earth metal complexes formed by those metal ions have also received increasing attention from researchers.Rare-earth metal complexes are widely used in magnetics,catalysis,fluorescence,adsorption,biomedicine,etc.Rare earth luminescent materials and single-molecule magnets are the most popular research topics.Lanthanide ions(Gd³⁺,Tb³⁺,Dy³⁺,Ho³⁺,Er³⁺,Yb³⁺and so on)are usually used in the rare earth complexes.Based on such research background,lanthanide metal ions were selected to synthesize 9 new rare-earth metal complexes,and their optical and magnetic properties were studied.The main contents are as follows:In the thesis,with 2-[[（4-nitrophenyl）imino]methyl]-8-hydroxyquinoline（HL1）as the ligand and dibenzoylmethane as the co-ligand,seven dinuclear rare-earth metal complexes of no reported were synthesized:[Ln₂（dbm）₄（L1）₂]（Ln=Gd（1）,Tb（2）,Eu（3）,Er（4）,Yb（5）,Dy（6））and[Nd₂（dbm）₄（L1）₂]·2.5CH₃CN（7）.The crystal structure was measured by X-ray single crystal diffraction,and the structural characterization was performed by elemental analysis,X-ray powder diffraction analysis,infrared spectroscopy,ultraviolet absorption spectroscopy,and thermogravimetry.And the related complexes were tested by near infrared fluorescence,magnetic testing,etc.The crystal structure results indicate that the complexes 1-7 are isomorphic and belong to the triclinic system and Pīspace group.The near-infrared luminescence spectra of complexes 4,5,and 7 show that they all emit characteristic peaks of their metal ions.The excitation wavelength（470 nm）of complex 7 is in the visible region.The magnetic properties of complexes 1 and 6 show that complex 1 has a magnetocaloric effect.The maximum magnetic entropy change is 14.36 J kg^-11 K^-1under T=4 K,ΔH=7 T conditions.The complex 6 has a typical single-molecule magnet behavior,which means that the pre-factorτ₀ is 5.10×10^-77 s and the effective energy barrierΔE/k_B is 62.42 K.With N’-（3-methylthiophene-2-methylene）-2-mercaptopropionyl hydrazide（HL2）as the ligand and dibenzoylmethane as the co-ligand,new two rare earth complexes were synthesized:[Ln₂（dbm）₄（L2）₂]（Ln=Er（8）,Yb（9））.The crystal structures were measured and characterized.X-ray single crystal diffraction data reveals that the complexes 8-9 crystallize in the triclinic Pīspace group.