Synthesis,Crystal Structures And Magnetic Properties Of 3d-4f Metal Complexes With Mixed Mutidentate Ligands

Magnetic materials have been developed rapidly with the coming of theinformation age;however,the classical magnetic materials including metallic oxide,metalhydroxide and metal alloy have some shortcomings on dimensions of storage materials because of the presence of magnetic domain within the materials.Therefore,it is need to find new materials to replace classical magnetic materials.Single molecule magnets?SMMs?,in which the magnet is derived from each molecule,have become popular in the field of magnetic materials due to their superiority on size,solubility and dispersibility,and easy processing.SMM is a molecule,showingmagnetic hysteresis loop below the blocking temperature?T_B?;it possesses many potential applications at magnetic information data storage,quantum computing,spintronics,and low temperature magnetic refrigerant.For the past many years,the studies on 3d SMMs have shown that it is inefficient to improve the energy barrier?U?just by increasing the ground state?S?of coordination compounds.Consequently,the lanthanides with large magnetic anisotropy were introduced into 3d SMMs to obtain 3d–4f mixed compounds.Fortunately,large number of studieshave manifested that 3d–4f mixed compounds have an advantage over the 3d compounds at structures and magnetic properties,and the energy barriers and blocking temperatures were also improved to some extent.Therefore,it provides a new research ideal to synthesize and research single molecule magnets and promotes many researchers to exploit 3d–4f SMMs with novel structures.In this text,we primitively introduce about single molecule magnets and summarize the research progress of SMMs of 3d,3d-4f,4f and single ion magnets?SIM?reported in recent years;meanwhile,we have prepared some 3d-4f clusters.In addition,some3d complexeswere synthesized when preparing 3d-4f complexes,which are helpful for synthesizing 3d-4f compounds.The major contents are shown as follows.The first chapter is the introduction part,and it primarily states the background of molecular magnetic materials and single molecule magnets,including synthetic strategies and studying methods.Then we put emphasis on the research progress in different kind of SMMs reported in recent years and finally present our highlights of innovation and research thoughts.In the second chapter,the structures and magnetic properties of prepared 3d-4f compounds are illustrated.The compounds 1[Mn₈Dy₂]and 2[Mn₈Dy₂]were obtained by using di-2-pyridyl ketone and triethanolamine in the presence of Mn salts and Dy or Tb salts in MeCN.The ac magnetic susceptibility measurements showed the frequency dependence of the out-of-phase signals for these compounds,indicating that compounds 1 and 2 exhibit single molecule magnet behavior.The high frequency ac susceptibilitieswere also measured for compound 2 to further investigate the relaxation dynamics,estimating the energy barrier E_a=18.97 K,and?₀=1.71×10^-9 s.BythereactionofapplyingsynthesizedligandL1?N1,N5-bis?3-methoxysalicylidene?-di-imino-3-azapentane?and triethanolamine in the presence of Ni and dysprosiumsalt,two different structures of 3d-4f compounds tetranuclear[Ni₂Dy₂]?3?and dodenuclear[Ni₆Dy₆]?4?wereobtained.If using the Fe replacing Ni in the same reaction,tetranuclear[Fe₂Dy₂]?5?is obtained.And one[Mn4Dy]?6?with the Dy ions separately locatedbetween two[Mn2]units was prepared.In addition,a trinuclear of 4f compound[Dy₃]?7?is also prepared and studied.In the third chapter,some 3d compounds are introduced?8-10?.These 3d compounds were prepared although the existence of lanthanides.The compounds are one[Ni₄]?8?,one[Co₄]?9?,one[Cu₂]?10?.