Synthesis,Structure And Optical,Electrical And Magnetic Properties Of Chiral Transition Lanthanide Complexes

Due to the important role of chiral compounds in asymmetric catalysis,life science,optical materials and other fields,their development has attracted more and more attention.The chirality of compounds is closely related to optics and magnetism.For example,the synergy between chirality and fluorescence can produce fascinating circularly polarized luminescence.The synergy between chirality and magnetism in chiral molecular magnets can produce magnetic circular dichroism and faraday effect.According to the hard soft acid base principle,lanthanide ions are hard acids that tend to be oxygenophilic,while transition metal ions are soft acids that tend to coordinate with nitrogen.Therefore,chiral ligands containing both N and O coordination atoms can be used to construct versatile 3d-4f multifunctional complexes with 3d transition metal ions and lanthanide 4f ions.In this paper,two chiral organic ligands with multiple coordination sites were selected to react with 3d and 4f metal salts,and four pairs of 3d-4f metal complex enantiomers were reasonably designed and successfully synthesized.Their structures and optical,electrical,and magnetic properties were investigated in detail.1.Two pairs of metal complexes enantiomers（Ln Cu₂[R,R/S,S-L]₂[H₂O]₃）·（NO₃）₃·（H₂O）[Ln=Tb（1/2）,Dy（3/4）]（H₄L=[R,R/S,S]-N,N’-bis[3-hydroxysalicylic]-1,2-cyclohexanediamine）were successfully synthesized using chiral Schiff base ligands,Cu（Ac）₂and Ln（NO₃）₃·6H₂O（Ln=Tb,Dy）by volatilization at room temperature（H₄L=[R,R/S,S]-N,N’-bis[3-hydroxysalicylic]-1,2-cyclohexanediamine）.The crystal structure test shows that the complexes 1-4 are isomorphic compounds,all of which are Ln Cu₂trinuclear structures and crystallized in the monoclinic chiral space group C2.Among them,complex 3 shows single-molecule magnet（SMM）behavior,effective energy barrier(U_eff)is 17.7 K.Moreover,complex 3 has an optimal proton conductivity at 50°C and 98%relative humidity(1.34×10^-4S cm^-1),which isdue to the 1D extended hydrogen bond chain formed by the coordination water molecule,nitrate and phenol groups of RR-L^2-ligand proving an effective proton migration path.In addition,3 and 4 are rare examples of chiral proton-conducting magnets that exhibit magneto-optic Faraday effect.2.Four complexes with trinuclear Ln Zn₂structure（Ln Cu₂[R,R/S,S-L]₂[H₂O]₃）·（NO₃）₃·（H₂O）[Ln=Tb（5/6）,Dy（7/8）]（H₄L=[R,R/S,S]-N,N’-bis[3-hydroxysalicylyl]-1,2-cyclohexanediamine）have been successfully prepared by the reaction of chiral aminophenol ligand,Zn Cl₂and Ln Cl₃·6H₂O(Ln=Tb（5/6）by room temperature evaporation.Complexes 5-8 are isomorphic compounds,which are crystallized in the orthogonal chiral space group P2₁2₁2₁.Studies have shown that they all have chiral optical characteristics.In addition,complex 5 shows obvious fluorescence emission of Tb.It is noteworthy that complexes 5 and 6 have significant CPL activity.In methanol solution,the g_lumvalues of enantiomers 5 and 6 at 515 nm are-9.36×10^-3and+8.22×10^-3,respectively.The complex 7 shows the behavior of single molecular magnet（SMM）,the effective energy barrier(U_eff)is 110.79K,and the relaxation time isτ₀=6.205×10^-7s.Surprisingly,complexes 7 and 8 show a strong magneto-optical faraday effect.Complexes 5-8 is an unprecedented multifunctional molecular-based material,providing a new method for developing multifunctional complexes.