The Research Of Rare Earth Complexes Based On 8-hydroxyquinoline Schiff Base And β-diketones

8-hydroxyquinoline and its derivatives are known as a class of highly fluorescent materials as well as promising materials for nonlinear optical properties and electroluminescent applications.Taking advantage of the versatile coordination modes,8-hydroxyquinoline and its derivatives have been utilized to ligate to transition metals.These complexes have the features of good electronic transmission performance,widely high luminous efficiency,easy purification,good film-forming,high glass transition temperature and so on.Recently,rare earth complexes based on 8-hydroxyquinoline have been the most promising electroluminescence material and the magnetic properties of them have intrigued the great interest of many researchers.β-diketonates are not only ideal candidates as light-harvesting chromospheres,but also suited to the investigation in the field of SMMs.Such ligands have potential applications in theoretical and practical studies.In particular for acetylacetonate（acac）,it has a significant impact in the magnetic fields of complexes.Therefore,a total of β-diketones ligands are widely used for studying the magnetic and fluorescence of complexes.In this thesis,twelve rare earth complexes [RE₄（acac）₄（L）₆（μ₃-OH）₂]（1-7）（RE = Y（1）,Eu（2）,Gd（3）,Tb（4）,Dy（5）,Tm（6）,Lu（7））and [RE₄（dbm）₄（L）₆（μ₃-OH）₂]（8-12）（RE = Y（8）,Eu（9）,Tb（10）,Dy（11）,Lu（12））based on 5-（4-fluorobenzylidene）-8-hydroxylquinoline have been synthesized by heating reflux method or mixing at room temperature.They have been investigated by single crystal X-ray diffraction,elemental analysis,X-ray power diffraction,thermal gravimetric analysis,IR,UV-vis,fluorescence measurement and magnetic measurement.Complexes [RE₄（acac）₄（L）₆（μ₃-OH）₂]（RE = Y（1）,Eu（2）,Gd（3）,Tb（4）,Dy（5）,Tm（6）,Lu（7）,acac = acetylacetone）have been prepared by heating reflux method.The photoluminescence of complexes 1,2,4,5,7 were tested at room temperature.Complexes 3-6 were measured by the temperature dependence of the magnetic susceptibilities.Complexes 4 and 5 were characterized at the indicated frequencies by the temperature dependence of ac magnetic susceptibilities and complex 4 did not show the frequency dependence,indicating it should not be a SMM.Complex 5 became frequency-dependent and exhibited multiple zero-field slow magnetic relaxation processes typical for Single Molecular Magnets（SMMs）.Two distinct slow magnetic relaxation processes,with effective energy barriers Ueff = 48 K for slow relaxation（SR）process and Ueff = 121 K for fast relaxation（FR）process.The magnetocaloric effect（MCE）was detected with-ΔSm（T）= 20.8 J·kg-1·K-1 for complex 3.Complexes [RE₄（dbm）₄（L）₆（μ₃-OH）₂]（RE = Y（8）,Eu（9）,Tb（10）,Dy（11）,Lu（12）,dbm = 1,3-diphenyl-1,3-propanedione）have been constructed by stiring at ambient temperature.The photoluminescence of complexes 8-12 were investigated at room temperature.Complexes 10 and 11 were characterized by the temperature dependence of the magnetic susceptibilities and the temperature dependence of ac magnetic susceptibilities at the indicated frequencies,indicating that complex 10 did not show the frequency dependence and complex 11 displayed single molecular magnet behavior,with the effective anisotropy barrier U_eff = 56 K and τ₀ = 2.64×10^-7s.