Assembly Conditions And Regulation Of Ligand Reaction Of A Series Of Dy(Ⅲ)-bptm Complexes:Crystal Structure,Mass Spectrometry And Magnetic Properties

At present,single molecular magnets is the major research topic of molecule-based magnetic materials,and introducing the rare earth ions into the single molecular magnets system is an effective way to prepare molecular magnetism with high energy barriers.Moreover,magnetic materials have potential applications in molecular spintronics,quantum computing,high density data storage and information processing,microwave material and magnetic refrigerant materials.With the rapid development of science and technology,the original information storage materials have been difficult to satisfy the human needs,so it is great significance to study and prepare high-performance and multifunctional molecular-based magnetic materials.In this paper,we have designed and synthsised the bis（3-（pyridin-2-yl）-1,2,4-triazol-5-yl）methane（bptm or H₂L）ligand,reaction of the ligand with Dy（X）₃·6H₂O（X=NO₃^-,Ac^-,ClO₄^-）based on the solvent/anions/ligand reaction-induced effect,gave nineteen coordination compounds under solvothermal conditions and solution method,which structures have been characterized by IR spectra,single-crystal X-ray diffraction analysis,powder X-ray diffraction analysis.Morever,mass spectrometry analysis and magnetic properties of some complexes have been investigated.This paper includes four chapters:Chapter One:we introduce the concept and development of rare earth single molecule magnet and single ion magnet,introduced the method for regulating rare earth monomolecular magnet,and application of mass spectrometry in the research of complexes.Moreover,the general contents of this paper are briefly summarized.Chapter Two:based on the solvent-induced effect,reaction of the Dy（Ac）₃·6H₂O,rigid–flexible bis（3-（pyridin-2-yl）-1,2,4-triazol-5-yl）methane（H₂L）,and Na N₃,we have successfully synthesized four coordination compounds with Dy₆ structure under solvothermal conditions,[Dy₆（L）₄（Ac）₆（NO₃）₂（DMF）]·2Ac（1）,[Dy₆（L）₄（Ac）₆（NO₃）₂（DMA）]·2Ac（2）,[Dy₆（L）₄（μ₃-OH）₄（μ₂-OH）₂（Ac）₄（Et OH）₄]·2H₂O（3）,[Dy₆（L）₄（μ₃-OH）₄（μ₂-OH）₂（Ac）₄（H₂O）₄]·6H₂O（4）.X-ray Single-crystal diffraction structural analysis reveals that the six dysprosium ions in the complexes（1）and（2）are connected through the Ac^-and NO₃^-;the complexes（3）and（4）are bridged through[μ₃-OH]^-,which make the six dysprosium ions closer,moreover,in situ methylene oxidation reaction of ligand was occurred to construct the complex（4）.In addition,mass spectrometry and magnetic properties of complexes have been investigated.According to electrospray ionization mass spectrometry data,the complex（1）can be stabilized in the form of hexanuclear in DMF solution,but under the condition of electrospray,the breakage of the decomposer and the solution fragment with a lower nuclear will also occur.However,from the analysis of magnetic data,the measured complexes show an antiferromagnetic coupling interaction,and theχ’andχ’’curves are the frequency dependent behavior.Although bridging ligands and bridging modes of complexes between（1）and（3）Dy atoms are not identical,Dy atom the effect of the large quantum tunneling and intermetallic super exchange on the single molecule magnetic properties of the complex at low temperature is not very obvious in the zero field,the bridging pattern of the complexes is mainly reflected in the weak antiferromagnetic super exchange between the metals.Chapter Three:based on the ligand reaction-induced effect,reaction of the Dy（X）₃·6H₂O（X=NO₃^-,Ac^-）,rigid–flexible bis（3-（pyridin-2-yl）-1,2,4-triazol-5-yl）methane（H₂L）,and Na N₃,we have successfully synthesized eight coordination compounds with in situ reaction of ligands under solvothermal conditions,[Dy₄（L₂）₂（μ₃-OH）₂（Ac）₆（NO₃）₂]（5）,[Dy₄（L₃）₂（μ₃-OH）₂（Ac）₆（NO₃）₂]（6）,[Dy（HL₄）（NO₃）₃]（7）,[Dy（HL₄）（acac）（NO₃）₂]（8）,[Dy₂（L₅）（NO₃）₂（H₂O）₆]·2H₂O（9）,[Dy₂（L₅）（NO₃）₂（H₂O）₂]_n（10）,[Dy（L₆）（NO₃）₂（H₂O）]（11）,[Dy（L₁）（μ₂-OH）]_n（12）.X-ray Single-crystal diffraction structural analysis reveals that the in situ condensation reaction of ligand with solvent was occurred to construct the complexes（5）～（8）;the in situ C-C coupling reaction of ligand was occurred to construct the complexes（9）and（10）;the in situ nitrozation reaction of ligand was occurred to construct the complex（11）;the in situ methylene oxidation reaction of ligand was occurred to construct the complex（12）.At the same time,we also put forward a reasonable mechanism of in situ reaction of organic ligands.In addition,mass spectrometry and magnetic properties of complexes have been investigated.According to electrospray ionization mass spectrometry data,the complexes can maintain its own main frame under the measured solution conditions,but under the condition of electrospray,the breakage of the decomposer and the solution fragment with a lower nuclear will also occur.Meanwhile,we have identified the existence of new organic ligands.However,from the analysis of magnetic data,the measured complexes show an antiferromagnetic coupling interaction,and theχ’’curves are the frequency dependent behavior,and further tests show that complexes（9）and（11）may have single molecule magnets behavior.Chapter Four:based on the solvent/anions-induced effect,reaction of the Dy（X）₃·6H₂O（X=NO₃^-,Ac^-,ClO₄^-）,rigid–flexible bis（3-（pyridin-2-yl）-1,2,4-triazol-5-yl）methane（H₂L）,and Na N₃,we have successfully synthesized seven coordination compounds under solution method with Dy₂ and Dy₁ structure,[Dy₂（H₂L）₂（μ₂-OH）₂（Me CN）₂（H₂O）₂]·4ClO₄·2Me CN（13）,[Dy₂（H₂L）₂（μ₂-OH）₂（DMF）₂（H₂O）₂]·4ClO₄·2H₂O（14）,[Dy₂（H₂L）₂（μ₂-OH）₂（H₂O）₄]·4NO₃·2H₂O（15）,[Dy₂（L₁）（HL）（NO₃）₂（H₂O）₄]·NO₃·4H₂O（16）,[Dy（H₂L）（NO₃）（H₂O）₃]·2NO₃·H₂O（17）,[Dy（L₁）（Ac）（H₂O）₃]·5H₂O（18）,[Dy（H₂L）（Ac）₂（H₂O）]·ClO₄·Me OH·H₂O（19）.X-ray Single-crystal diffraction structural analysis reveals that complexes（13）～（16）exhibit binuclear structures,the two dysprosium ions in the complexes（13）and（15）are connected through the[μ₂-OH]^-,the complex（16）are bridged throughμ₃-NO₃;complexes（17）～（19）are mononuclear structures.In addition,magnetic properties of complexes have been investigated.From the analysis of magnetic data,the measured complexes show an antiferromagnetic coupling interaction,and theχ’’curves are the frequency dependent behavior.Although bridging ligands and bridging modes of complexes between（13）and（16）Dy atoms are not identical,Dy atom the effect of the large quantum tunneling and intermetallic super exchange on the single molecule magnetic properties of the complex at low temperature is not very obvious in the zero field,the bridging pattern of the complexes is mainly reflected in the weak antiferromagnetic super exchange between the metals.