Structure And Magneto-Optical Properties (UV-Vis/NIR) Of Rare Earth-Transition Metal Clusters By Chiral Schiff Base Ligands

The interaction among chirality,light and magnetism leads to the cross of many fields and gives birth to a new magneto-optical phenomena(MChD),namely magnetic-chiral effect.With the development of magneto-optical devices and the emergence of new asymmetric synthesis methods,MChD,as an explanation of the origin of life homology,has attracted extensive attention in recent years.According to current reports,the largest MChD effect should exist in the f-f transition of rare earth.The chiral 3d-4f metal clusters also have rigid chiral structures,multiple magnetic centers and abundant adjustable magnetic interactions,so they are ideal research objects.In addition,the rare earth f-f transitions in the near infrared region are not easily masked by the strong absorption bands of ligands.Therefore,it is of great significance to study the magneto-optic effects of chiral 3d-4f metal clusters involving near infrared region by combining CD and MCD.Based on the above research background,a variety of chiral rare earth transition metal clusters were synthesized using Schiff base ligands,and their structures and magneto-optical properties(UV-Vis/NIR)were studied in combination with CD and MCD.Specific research contents are as follows:1.The synthesis of chiral metal clusters R/S-Mn4ⅡMn8ⅢLn12,R/S-Mn4Ln3,R/S-[Mn10Ln6][Mn6Ln2],R/S-Co2ⅡCo2ⅢLn3.The chiral Schiff base ligand(R/S-H3LⅠ)was prepared by the condensation reaction of o-vanillin and(R/S)-3-amino-1,2-propanediol,and synthesized square ring series chiral clusters R/S-Mn4ⅡMn8ⅢLn12(Ln=Dy/Y)and hepta-nuclear linear chiral clusters R/S-Mn4Dy3 by reaction with rare earth and manganese salt.The main ligand(R/S-H2LⅡ)was prepared by the condensation reaction of 2-hydroxy-4-methoxybenzaldehyde and(R/S)-2-amino-1-butanol,and synthesized a chiral eutectic cluster R/S[Mn10Ln6][Mn6Ln2](Ln=Dy/Y)with Mn10Ln6 and Mn6Ln2 units by reaction with rare earth and metal manganese salt.Using(R/S)-3-amino-1,2-propanediol as ligand(R/S-H2LⅢ),the chiral clusters R/S-Co2ⅡCo2ⅢLn3(Ln=Dy/Gd/Y)were synthesized by reaction with rare earth and cobalt salts.2.The study of the basic characterization and magneto-optical properties of R/S-Mn4ⅡMn8ⅢLn12,R/S-Mn4Ln3,R/S-[Mn10Ln6][Mn6Ln2],R/S-Co2ⅡCo2ⅢLn3.The UV-Vis or NIR absorption spectra,CD and MCD spectra of the above systems confirmed the chirality and metal transfer between the ligands of each system,studied the magneto-optic effect of the clusters,and calculated the maximum gCD and gMCD.In addition,the magneto-optical properties of some ligands and clusters were also compared.3.The preliminary study of the magnetic hand dichroism(MChD)of the chiral metal cluster R/S-Ln5Ni6.Based on the above prediction,the MChD of R/S-LnsNi6(Ln=Dy)in the near infrared region was measured at room temperature and DC magnetic field with the help of the magnetic chiral dichroism spectrometer built by our group and the center of the strong magnetic field in France.In the near-infrared region,the MChD signal associated with the f-f(6H15/2→6F9/2)transition of rare earth ions in chiral rare earth transition metal clusters is found,which reached 0.1 T-1 in the research group and about 0.3cm-1 in foreign countries.