Synthesis,Structures,Magnetic And Fluorescent Properties Of 3d-4f/3d-Schiff Base Complexes

Coordination compounds are widely used in magnetic materials,optical materials,superconducting materials and catalysis due to their diverse structures and properties.There are many kinds of ligands used to synthesize complexes.Among them,the Schiff bases ligand is formed by condensation of an amine and an active carbonyl group.In the process of synthesis,different amines can be selected to form by condensation with carbonyl compounds.In addition,it can form stable complexes with metal ions.Therefore,Schiff base ligand is an important ligand in organic synthesis.In this paper,we synthesized three Schiff bases ligands,and seven 3d-4f and 3d polynuclear metal clusters.Their structures and properties are characterized and discussed.The specific research contents are as follows:1.The ligand H₂ L was obtained by condensation of o-vanillin and 2-amino-4-tert-butyl phenol.By reacting the ligand H₂ L with the transition metal zinc salt and rare earth metal dysprosium salt,two cases of 3d-4f tetranuclear heterometal complexes with the same topological structure were obtained by changing the coordination anions,[Zn₂Dy₂?L?₄?NO₃?₂?CH₃OH?₂]·2CH₃COCH₃?1?and [Zn₂Dy₂?L?₄?CH₃COO?₂?CH₃CH₂OH?₂]·4CH₃COCH₃?2?.Their crystal structures and magnetism were tested.Combined with ab initio calculation,the effective energy barrier value of 1 is greater than that of 2.Finally,we elucidated the influence of different coordination anions on magnetic anisotropy.2.On the basis of the above work,H₂ L was reacted with transition metal zinc salt-rare earth metal dysprosium salt,and two complexes with similar structure were obtained by changing alcohol solvent,[Zn₂Dy₂?L?₄?CH₃COO?₂?CH₃CH₂OH?₂]·2CH₂Cl₂·0.5H₂O?3?and [Zn₂Dy₂?L?₄?CH₃COO?₂?CH₃OH?₂]·4CH₂Cl₂·2CH₃OH·0.1H₂O?4?.The structural difference of 3 and 4 is the the coordination mode modification of the acetate anion.Two cases of complexes of zinc???ions are distorted octahedral configurations,the configuration of Dy???is closest to the biaugmented trigonal prism?C₂v?in 3 and triangular dodecahedron?D₂d?in 4.By means of magnetic characterization and ab initio calculation,the effects of coordination of acetate anion ligand in bidentate chelating mode and in 2.11 bridging mode on the magnetism of dysprosium complexes were investigated.3.An asymmetric Schiff base organic ligand H₂L₁,was generated from a condensation treatment of 2-amino-4,6-di-tert-butylphenol with o-vanillin in an equivalent stoichiometric amount in methanol.Complex 5?[Zn₃?L₁?2?CH₃COO?₂?H₂O?₂]?was prepared by the reaction of the ligand and transition metal zinc salt.The crystal structure of it was examined using X-ray single crystal diffraction.And the properties were characterized by UV-vis and fluorescence spectra.In addition,to study the interaction between cations and 5,once Ag⁺ and the solution of 5 were mixed,the maximum peak at 576 nm disappeared gradually and a substitute maximum at 446 nm.During the reaction,phenolate of H₂L1 transfers electrons to Ag?I?and the reduction to Ag?0?accompanied by the formation of the benzoxazole ring?HL₂ ligand?occurs.And HL2 ligand coordinates with free Zn2+ in solution to form complex 6.[Zn₃?L₂?₄?CH₃COO?₂]·2CH₃CH₂OH·H₂O?6?.Furthermore,as Ag⁺ is added to the ethanol solution of complex 5 in the reaction process,the color of the solution changes from orange to colorless.So complex 5 can be detected with Ag⁺ naked-eye.Further metal ion response detection of 6 shows that Cu²⁺ will quench the fluorescence signal of complex 6 at 448 nm,so complex 6 shows high selectivity and sensitivity to Cu²⁺.