Synthesis And Magnetic Studies Of Bis-Schiff Base Ligand Bridged Lanthanide Complexes

In recent years,the fluorescence and molecular magnetism of Schiff base bridged lanthanide complexes have attracted unprecedented attention and interest of scientists.This thesis focuses on the research hotspot of single-molecule ma gnets.Using Schiff base ligands N¹,N⁴-bis（pyridine-2-methylene）benzene-1,4-dia mine（L1）、N¹,N⁵-bis（2-pyridinyl methylene）-1,5-naphthalenediamine（L2）and N¹,N⁵-bis（2-quionlinyl methylene）-1,5-naphthalenediamine（L3）to combline different lanthanide ions,twenty binuclear lanthanide complexes were successfully synthe sized.The structures of the complexes were characterized by elemental analysis and infrared spectroscopy.The fluorescence and magnetic properties of some complexes were tested and analyzed.The main contents are as follows:1.A series of eight-coordinated dinuclear lanthanide complexes were synthesized by using Schiff base N¹,N⁴-bis（pyridine-2-methylene）benzene-1,4-diamine（L1）as the main ligand and hexafluoroacetylacetone（hfac）as the auxiliary ligand to combline lanthanide ions.Fluorescence spectra show that complexes 1（Dy）and 2（Tb）can emit the corresponding characteristic peaks of lanthanide ions.The magnetic test results show that the complex[Dy₂（hfac）₆（L1）]（1）has single-molecule magnet behavior,U_eff/k _B=44.01 K,τ₀=1.34×10^-6 s.2.A series of eight-coordinated dinuclear lanthanide complexes were synthesized by using Schiff base N¹,N⁵-bis（2-pyridinyl methylene）-1,5-naphthalenediamine（L2）as the main ligand and hexafluoroacetylacetone（hfac）as the auxiliary ligand to combline lanthanide ions.Fluorescence spectra show that complexes 6（Dy）and 7（Tb）can emit the corresponding characteristic peaks of lanthanide ions.The magnetic test results show that the complex[Dy₂（hfac）₆（L2）]（6）has single-molecule magnet behavior,U_eff/k _B=38.50 K,τ₀=1.70×10^-6 s.3.A series of eight-coordinated dinuclear lanthanide complexes were synth esized by using Schiff base N¹,N⁵-bis（2-quionlinyl methylene）-1,5-naphthalenedi amine（L3）as the main ligand and hexafluoroacetylacetone（hfac）as the auxiliar y ligand to combline lanthanide ions.Fluorescence spectra show that complexes11（Dy）and 12（Tb）can emit the corresponding characteristic peaks of lanthani de ions.The magnetic test results show that the complex[Dy₂（hfac）₆（L3）]（11）has single-molecule magnet behavior,U_eff/k _B=20.86 K,τ₀=9.20×10^-7 s.4.A series of eight-coordinated dinuclear lanthanide complexes were synth esized by using Schiff base N¹,N⁴-bis（pyridine-2-methylene）benzene-1,4-diamine（L1）as the main ligand and trifluoroacetylacetone（tfa）as the auxiliary ligand to combline lanthanide ions.Fluorescence spectra show that complexes 16（Dy）and 17（Tb）can emit the corresponding characteristic peaks of lanthanide ions.The magnetic test results show that the complex[Dy₂（tfa）₆（L1）]（16）has single-molecule magnet behavior,U_eff/k _B=53.51 K,τ₀=5.16×10^-6 s.