Synthesis,Structure And Magnetic Research Of Low-nuclear Rare Earth Complexes Assembled By Schiff Base Ligands

Since the discovery of the first rare earth single-molecule magnets,rare earth metal ions have greater magnetic anisotropy than transition metal ions and exhibit excellent magnetic properties.Therefore,rare earth single-molecule magnets have become high-performance representative of molecular magnets.With the in-depth study of single-molecule magnets,researchers have discovered that the structure of the ligand also contributes greatly to the magnetic properties of the complex,especially the multidentate ligand Schiff base,due to its coordination modes with rare earths and transition metals,it is easy to get more interesting magnetic structure relationships.Based on this,this paper studies the synthesis,structure and magnetic properties of low-nuclear Ln-Schiff complexes prepared by coordination of Schiff base ligands with rare earth metals.At the same time,it also uses elemental analysis and infrared spectroscopy to obtain the results.The crystals were characterized.These include:1.Using Schiff base ligands（E）-2,4-dibromo-6-（（quinoline-8-imino）methyl）phenol（HL₁）and（E）-1-(（（quine Phospholine-8-imino）methyl）naphthalene-2-ol（HL₂）reacts with the lanthanide metal salt Dy（NO₃）·6H₂O to synthesize a mononuclear complex[Dy（L₁）₂（NO₃）（H₂O）]（1）and two binuclear complexes[Dy₂（L₂）₃（NO₃）₃]（2）and[Dy₂（μ₂-O₂）（L₂）₄（NO₃）₂]（3）.The structure study shows that complex 1 has C_4vsymmetry,and its structure is spherical capped square antiprism.Complex 2 has D_3h and Cs symmetry,and its structureis spherical tricapped trigonal prism and muffin.Complex3 has Cs symmetry,and its structure is muffin.Magnetic studies show that complex 1has single-molecule magnet behavior.2.Using Schiff base ligand 6,6’-(（（1E,1’E）-（ethane-1,2-diylbis（azaalkylene）））-bis（methyleneidene）Bis（2,4-dibromo-phenol）（H₂L₃）reacted with lanthanide metal salt Ln（NO₃）·6H₂O,and a series of new binuclear Ln₂-Salen complexes were prepared by using room temperature volatilization method[Ln（L₁）₂][Ln=Tb（4）,Dy（5）,Ho（6）].The structural study shows that complexes 4-6 have D_2d symmetry and also have a triangular dodecahedron structure.Magnetic studies show that none of the complexes4-6 exhibited single-molecule magnet behavior.