Magnetic Coupling Strategy For Regulating Slow Magnetic Relaxation Behavior In Multinuclear Lanthanide Single-Molecule Magnets

Single-molecule magnets(SMMs),exhibiting magnetic bistability at the molecular level,demonstrate significant potential for applications in high-density information storage,quantum computing,and molecular spintronics.Despite numerous breakthrough advancements,the field still faces challenges such as low blocking temperatures and severe quantum tunneling of magnetization phenomena.Introducing magnetic interactions combined with the adjustment of the local coordination environment of rare earth ions presents an effective strategy for constructing high-performance molecular magnets.For this purpose,this paper selected four organic bridging ligands: Salen-type Schiff bases,polydentate oxygen-containing ligands,polydentate nitrogen-containing ligands,combined with paramagnetic transition metals and rare earth metals,to construct 34 multinuclear rare earth SMMs.The precise structures of all complexes were obtained through X-ray single crystal diffraction,infrared spectroscopy,powder XRD,and elemental analysis.The molecular magnetic properties of all complexes were tested using a SQUID magnetometer.Combined with ab initio calculations,the study investigated the relationship between spin-spin magnetic coupling,local coordination environment and molecular magnetism,designing and synthesizing a series of high-performance rare earth SMMs.1.The [M-Dy-M] type SMMs were constructed with hexadentate Salen Schiff base,and a series of multinuclear rare earth complexes were constructed by introducing paramagnetic 3d transition metal to magnetic interaction with 4f rare earth ions.The effects of different rare earth ions and coordination anions,Schiff base ligands substituted by different diamine scaffolders and transition metals,and the introduction of cyanogen ions to construct multi-dimensional systems on molecular structure were investigated,and the key factors affecting molecular magnetic behavior based on this model were explored.2.Using 2,6-dimethoxyphenol as ligand,a series of multinuclear rare earth complexes were synthesized by introducing organic coligand to regulate the magnetic interaction and the direction of local magnetic axis.The effect of phenoxy ligand and solvent on the arrangement of magnetic axis was studied.The effects of the remote coordination environment of rare earth ions on the slow magnetic relaxation behavior were systematically studied using salicylaldehyde and its derivatives and sulfonic acid and its derivatives ligands,respectively.3.Multinuclear rare earth complexes were constructed with polydentate nitrogen-containing organic ligands as bridges.The important effect of novel polynitrogen bridge ligand transfer magnetic coupling on the magnetic properties of the molecule was investigated by binding β-diketone rare earth salt with dihydrogen-substituted tetrazine ligand.The phenomenon of asymmetric in situ ring opening with the assistance of metal was found by using pyrimidine substituted tetrazine ligands.