Synthesis And Properties Of Chiral-magnetic-luminescent 3d-4f Metal Complexes

Molecular magnets with transition metal ions and rare earth ions have attracted great interest.The system has the advantages of strong magnetic anisotropy of rare earth ions and high ground state spin of transition metal clusters,thus improving the effective energy barrier of monomolecular magnets.Because of its unique magnetic properties,there are potential applications in information storage and quantum computers.Multi-functional molecular materials with both magnetic and optical properties can be obtained by introducing chirality into this kind of molecular magnetic compounds.The aim of this paper is to design and synthesize new multi-functional complexes with chiral and magnetic properties.The main results are as follows:Chiral amine was synthesized by the reaction of cyclohexanediamine and o-vanillin,and the chiral cyclohexanol ligand H₂L was obtained after reduction.Using Zn?ClO₄?₂?6H₂O and Zn?NO₃?₂?6H₂O as transition metal ion source,six pairs of 3d-4f complex enantiomers?1-12?were successfully constructed by solvent evaporation using different rare earth ion salts,and their crystal structures were investigated.The properties of monomolecular magnets,such as fluorescence,near infrared?NIR?and so on,were systematically characterized.The results of single crystal diffraction show that,due to the different ion sources and reaction conditions,complexes 1-5 crystallized in the chiral C222₁ space group in the orthogonal crystal system.On the other hand,5-6 crystallized in the chiral P1 space group of the triclinic system.In magnetic measurement,the imaginary and real ac susceptibility peaks of complexes 1and 2 in 400 Oe and 2000 Oe dc fields have shifted with the change of frequency,indicating that there is a field-induced slow magnetic relaxation in the system.Under the condition of zero dc flow field,the ac magnetic susceptibility of complex 6 has been measured.There are frequency and temperature dependent signals in the curves of the real part and imaginary part of complex 6,and the maximum peak value appears,which indicates that complex 6 has a single molecular magnet behavior.This phenomenon is rare in Zn-Ln complexes.Through Fluorescence spectroscopic analysis showed that complexes 1-2 and 5-6 showed the characteristic luminescence of rare earth Dy???and Tb???ions,and then we also tested the lifetime of these complexes.For complex 3,the near infrared region characteristic luminescence of rare earth Yb???ion was observed.Four pairs of enantiomers?13-20?of Ni-Ln complexes were synthesized based on chiral aminophenol ligand H₂L and characterized by single crystal diffraction,infrared spectroscopy,circular dichroism and magnetic characterization.Single crystal tests show that complex belongs to isomorphous crystallization of orthogonal chiral C222₁ space group and 15-16isomorphous crystal group of monoclinic chiral P1 space group.Magnetic studies show that there is a ferromagnetic coupling between metal ions 13 and 15,and the field-induced slow magnetic relaxation behavior is observed when the field is added to complexes.