Synthesis, Structures And Luminescent/Magnetic Properties Of Lanthanide Complexes Based On 8-Hydroxyquinoline And Its Derivatives

For rare earth elements and their compounds,due to their unique fluorescent and magnetic properties,they have an extensive value in utility,therefore,and become indispensable special materials in modern advanced science and technology.Currently,research on luminescent materials and single molecule magnets all have become a research hot spot.In this paper,8-hydroxyquinoline&its derivatives and ?-diketone as ligands have been used;the aim is to explore the synthesis of complexes with near infrared luminescent properties and superior single molecule magnets.The main research results are as follows:1.With 8-hydroxyquinoline and dibenzoylmethane as ligands,six dinuclear lanthanide complexes[Ln2(dbm)4(OQ)2(CH3OH)2](Ln = Nd(1),Eu(2),Tb(3),Dy(4),Ho(5))[Er2(dbm)4(OQ)2(CH3OH)]·CH3COCH3(6)have been synthesized.Complex 1 in the solid-state displays typical emissions of the Ndm ions in the NIR region.Dynamic magnetic studies reveal single-molecule magnet behavior for complex 4.Fitting the dynamic magnetic data to the Arrhenius law gives an energy barrier ?E/kB = 109.8 K and pre-exponential factor ?0 = 4.07×10-9 s under 1500 Oe de field.2.With 8-hydroxyquinoline,acetylacetone and dibenzoylmethane as ligands,three tetranuclear complexes[Ln4(acac)4(OQ)6(?3-OH)2](Ln = Tb(7),Dy(8)),[Dy4(dbm)4(OQ)6(?3-OH)2]·2CH3CN(9)have been synthesized.Complexes 8 and 9 have slow magnetic relaxation behavior,their magnetic relaxation is 115 K and 72 K,respectively.The analysis shows that different ?-diketone(acetylacetone and dibenzoylmethane)will have different degree of space steric hindrance and density of electron cloud,which will affect the geometric configurations of center Dy? ion and intensity of ligand field,and generate the influence of magnetic relaxation.3.With 8-hydroxyquinoline derivative(HLi)as ligand and dibenzoylmethane,acetylacetone as coligands,four tetranuclear complexes[Dy4(L1)6(dbm)4(?3-OH)2](10),[Ho4(L1)6(dbm)4(?3-OH)2](11),[Gd4(L1)6(acac)4(?3-OH)2]·1.124CH3CN(12),[Er4(L1)6(acac)4(?3-OH)2]·CH3CN·H2O(13)have been synthesized.Among them,complex 10 has double relaxation processes,and their magnetic relaxation energy barriers are 48 K and 121 K,respectively.Comparing complexes 10 and 9 with similar structures,we find that difference of magnetic relaxation is mainly caused by field strength of center ion ligand and the change of coordination environment.4.With 2-(2'-benzothiazole)-8-hydroxyquinoline(HL2)with N,N,O chelating unit for metal binding and hexaluorine acetylacetone of strong electron-withdrawing ability,seven lanthanide complexes[Ln2(hfac)4(L2)2](Ln = Eu(14),Gd(15),Tb(16),Dy(17),Ho(18),Er(19),Lu(20))have been synthesized.The characteristics of the Er? emission peak of complex 19 can be observed.Dynamic magnetic studies reveal single-molecule magnet(SMM)behavior for complex 17.Fitting the dynamic magnetic data to the Arrhenius law gives an energy barrier ?E/kB = 50.33 K and pre-exponential factor ?0= 1.05×10-8 s.5.With acylhydrazone schifffbase(H2L3)and ?-diketone or benzoic acid as ligand,five dinuclear dysprosium complexes[Dy2(bfa)2(L3)2(H2O)2]·4CH3OH(21),[Dy2(dbm)2(L3)2(CH3OH)2]·2CH3OH(22),[DY2(TTA)2(L3)2(H2O)2]·4CH3OH(23),[Dy2(acac)2(L3)2(H20)2]·2H20(24),[Dy2(PhC00)2(L3)2(H20)2](25)have been synthesized.Results show that,the magnetic coupling interaction of center ion,as well as the symmetry and strength of ligand field can largely influence the nature of single molecule magnet.6.With(2-[(2-(hydroxyimino)propanehydrazide)methyl]-8-hydroxyquinoline)(H2L4)and dibenzoylmethane as ligands,new lanthanide complexes of different structures can be synthesized in different solvents.Two dinuclear complexes,[Nd2(dbm)2(L4)2(CH3OH)2]·4CH3OH(26)and[Dy2(dbm)2(L4)2(CH3OH)2]·4CH3OH(27)were synthesized by using methanol and dichloromethane as solvent.Three chain tetra-nuclear complexes[Dy4(dbm)8(L4)2(C3H7OH)2]·C3H2OH·2CH3CN(28),[Er4(dbm)8(L4)2(C3H7OH)2]·6CH3CN(29)and[Yb4(dbm)8(L4)2(C3H7OH)2]·8CH3CN(30)were obtained by using propanol and acetonitrile.[Y4(dbm)6(L4)2(?3-OH)2]·2CH3CN(31)and[Dy4(dbm)6(L4)2(?3-OH)2]·0.368CH2Cl2 1.632CH3CN(32)were coplanar Ln4 clusters by using acetonitrile and dichloromethane as solvent.Complex 26 in the solid-state displays typical emissions of the Ndu ions in the NIR region under 570 nm excitation.Complexes 29 and 30 in the solid-state display typical emissions of the corresponding lanthanide ions(Er?,Yb?)in the NIR region under 610 nm.The excitation wavelengths of three complexes are all in the visible light region.In addition,complexes 27,28 and 32 all show frequency dependence in ac magnetic field.Through the above research,5 complexes were obtained with near infrared luminescent properties,including 3 cases of excitation wavelength in the visible light region,which has potential application value.In addition 9 complexes with slow magnetic relaxation behavior of single molecule magnets have been successfully obtained.The magnetic study reveals that the local coordination environment of rare earth ions and ligands field strength can be adjusted by 8-hydroxyquinoline and its derivatives and ?-diketone.The purpose of regulating the magnetic relaxation behavior of single-molecule magnets can be achieved,which provides a meaningful exploration for the design and synthesis of new single-molecule magnets with good performance.