Synthesis,Structures And Magnetic Properties Of Lanthanide Complexes Based On 8-hydroxyquinoline Acylhydrazone Derivatives

Single-Molecule Magnets(SMMs)have attracted increasing attention because of the prospect and potential applications in high-density information storage,quantum computing and molecular spintronics at a molecular level.The magnetic relaxation in Ln systems is more difficult to elucidate beeause of its association with several factors.Herein,with the aim of investigating the relationship between structure and magnetic properties,we have designed and synthesized five acylhydrazone ligands and two schiff base ligands,and obtained a series of lanthanide complexes.These compunds have been determined by single-crystal X-ray diffraction analysis,elemental analysis,IR spectra and thermal analysis.Furthermore,their magnetic properties have been studied by magnetic properties measurement system.The main work is summarized as follows:1,We have designed and synthesized five acylhydrazone ligands(L,-L5)based on 8-hydroxyquinoline derivative with the change of substituent.As a result,we have successfully synthesized five mononuclear dysprosium complexes(1-5),five mononuclear terbium complexes(6-10),and five mononuclear erbium complexes(11-15)by solvothermal method.The single-crystal X-ray diffraction data show that complexes 1-15 are mononuclear complexes;each eight-coordinated center Ln(Ⅲ)(Ln=Dy,Tb,Er)is in a slightly distorted dodecahedral geometry with two 8-hydroxyquinoline acylhydrazone derivative ligands.Variable-temperature dc magnetic susceptibility measurements of 1-15 suggest that the presence of an antiferromagnetic interaction in complexes(1-3,6-8,11-15),while a ferromagnetic interaction in complexes(4-5,9-10).Unfortunately,the ac susceptibility of complexes 1-15 do not exhibit any out-of-phase ac-susceptibility signal.2.The Schiff-base ligand L6 and L7 were synthesized in a simple aldimine condensation reaction of 3-amino-1,2-propanediol with 2-pyridinecarboxaldehyde and 2-aldehyde-8-hydroxyquinoline respectively.The solvothermal reaction of the Schiff-base ligand L6 with Dy(NO3)3·6H2O affords a binuclear dysprosium complex[DyZ(CgH10NZOZ)2(NO3)4](16).Meanwhile,we also have achieved the[Dy3(C13H12N2O3)3(μ3-OH)(H2O)(CH3OH)2]·(NO3)2·CH3OH·CH3CN(17)through the reaction of L7 with Dy(NO3)3·6H2O,which is a typical Dy3 triangle complex.The dc magnetic susceptibility studies of 16-17 indicate that both complexes exhibit anti ferromagnetic interaction between the Dy(Ⅲ)ions.The complex 16 do not exhibit any out-of-phase ac-susceptibility signal.And complex 17 exhibits merely frequency-dependent behavior under zero dc field.However,the ac susceptibilities of 17 were further measured in a static dc field of 1 kOe to weaken the possible quantum tunneling effect.The in-phase and out-of-phase signals display frequency dependence and clear out-of-phase peaks appear in the low temperature,indicating the presence of field-induced SMMs behavior.