Design,Syntheses And Magnetic Investigations Of Low-Nuclearity Lanthanide And Mutil-Nuclear Heterometallic Complexes

Because of its unique magnetic properties,such as magnetic bistability and slow relaxation mechanism,single-molecular magnets(SMMs)have attracted widely attention by the reasearchers in the fields of physics,chemistry and materials due to the potential applications in ultrahigh-density information storage materials,spintronic devices and quantum computers.This dissertation will mainly focus on the synthesis of the low-nuclearity lanthanide and mutil-nuclear heterometallic complexes,and the investigation of their static and dynamic magnetic behaviors of these systems.We have explored the effects of the structure and coordination configuration of the complexes on their properties through the multi-relaxation mechanism and relaxation process of single-molecule magnets.The details are divided into the following three aspects1.A dinuclear complex[Dy(?-OH)(DBP)2(TMG)]2(1)was obtained by bridging two Dy?single ion units.We got another dinuclear complex[Dy(?-OEt)(DBP)(OEt)(TMG)]2(2)by changing the bridging ligand.The alter current magnetic susceptibility test showed that both complexes had excellent single-molecule magnet behavior under zero applied direct current field.The combined investigations into the crystal structures and magnetic properties revealed that the selection of bridging ligands had a great impact on the magnetic properties of the complexes.2.The reaction of a hydrazine ligand with different dysprosium metal salts under different experimental conditions,we obtained three Dy2 complexes with similar skeleton but different in coordination anions:?Dy2L12(NO3)4]2CH3CN(3),[Dy2L12(SCN)4(CH3O)2]·2CH3CN(4)and[Dy2L12(DMF)6]DMF(5).Magnetic measurements manifested that three complexes showed different magnetic properties respectively.Among which,more planar coordination geometry of complex 3 with nitrate coordination anions displayed the best magnetic properties within three complexes.In addition,we also synthesized the ligand L2 by replacing the 8-Hydroxyquinoline-2-carbaldehyde in ligand L1 with similar but small molecular weight and more flexible 6-(Hydroxymethyl)pyridime-2-carboxaldehyde.A Dy4L24(PhCOO)4(6)was obtained by diffusion method under reacting Dy benzoate with multiple bridges carried out by benzoic acid anions.3.The utilization of a new flexible long hydrazine ligand L3 resulted in the self-assembly of two novel heterometallic complexes Dy6Cu4L32(PhCOO)10(7)and Gd2Cu4L33(PhCOO)2(OCH3)4(8).Magnetic studies revealed that the Dy-based complex 7 showed slow magnetic relaxation behavior,and the Gd-based complex 8 exhibited significant cryogenic magnetocaloric effect.The relationship between magnetic properties and molecular structures were also explored.