| In recent years,the potential applications of rare earth single-molecule magnetsin quantum computing and information storage have received extensive attentio-n from scientists.According to current research hotspots,this thesis selects Schiff base 8-hydroxyquinoline derivatives with multiple coordination sites as organic ligands,and adjusts the concentration,ratio,reaction time,p H value and other reaction conditions of the reactants.10 multi-nuclear rare earth-based complexes were synthesized and characterized by single crystal X-ray diffraction and PXRD,and the magnetic properties and luminescence properties of some complexeswere studied.The specific work is as follows:1?Three kinds of Schiff base 5-(benzylideneamino)quinolin-8-ol(HL1),5-((4-ethylbenzylidene)amino)quinolin-8-ol(HL2)and 5-(4-methylbenzylidene)-8-hydroxylquinoline(HL3)were synthesized by aldehydeamine condensation reaction.2?Choosing 5-(benzylideneamino)quinolin-8-ol(HL1)as the ligand and1-phenylbutane-1,3-dione rare earth salt as raw material,three rare earth complex[Ln4(L1)6(pbd)4(?3-OH)2]·2CH3CN(Ln=Gd(1),Tb(2),Dy(3))were synthesized by solvent evaporation.The results of single crystal structure analysis show that the complexes 1-3 are rare earth-based complex with centrosymmetrical square anti-prism structure.It can be obtained from the magnetic test results that the complex1 has a magnetocaloric effect,and its maximum magnetic entropy becomes-?Sm=21.41J·kg-1·K-1.Complex 3 has a single-molecule magnet behavior and slow magnetic relaxation,the effective energy barrier is(Ueff/k BT)is 81.48 K,and the exponential factor?0=6.48×10-8s.3?Choosing 5-((4-ethylbenzylidene)amino)quinolin-8-ol(HL2)as the ligand,and rare earth 2,2,6,6-tetramethylheptane3,5-dione salt as the auxiliary ligand to design and synthesize three rare earth complexes[Ln4(L2)6(tmhd)4(?3-OH)2]·2CH3CN(Ln=Gd(4),Tb(5),Dy(6))and characterize its structure and magnetic properties.The results show that compounds 4 and 5 are in the P21/C space group with Z=2,and complex 6 is in the P?space group with Z=1,but their structures are similar.They all have centrosymmetric square anti-prismatic structure.Magnetic studies show that the complex 4 has magnetocaloric effect,and the maximum magnetic entropy becomes-?Sm=18.02 J·kg-1·K-1,the AC susceptibility test proves that complex 6 has a single-molecule magnet behavior,and the effective energy barrier(Ueff/k BT)is 83.1 K after fitting with the pre-referential factor?0=4.18×10-8s.4?Four rare earth polynuclear compounds[Ln4(dbm)4(L3)6(?3-OH)2]·CH3CN(Ln=Eu(7),Tb(8),Dy(9)and Ho(10))were synthesized by the reaction of5-(4-methylbenzylidene)-8-hydroxylquinoline(HL3)and rare earth salt of diphthalylmethane,and volatilize at room temperature.Single crystal X-ray diffraction shows that complexes 7-10 are all eight-coordinated.The optical and magnetic research found that complex 4 and complex 5 have potential application value in the field of luminescence.The frequency-dependent signal of complex 9indicates that it shows the behavior of single-molecule magnet with slow magnetic relaxation,the Arrhénius equationcan be used to obtain a potential energy barrier of(Ueff/k BT)of 116.7 K,and an exponential factor of?0=1.05×10-8s. |
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