Using the[1+1]condensation approach for the preparation of new macrocyclic scaffolds(L^(N6)_(phen)and L^(N4O2)_(phen))with the rigid phenanthroline-based‘head’unit produces the air-stable mononuclear compounds[Dy(L^...Using the[1+1]condensation approach for the preparation of new macrocyclic scaffolds(L^(N6)_(phen)and L^(N4O2)_(phen))with the rigid phenanthroline-based‘head’unit produces the air-stable mononuclear compounds[Dy(L^(N6)_(phen))(Ph_(3)SiO)_(2)](PF_(6))(1-L^(N6)_(phen))and[Dy(L^(N4O2)_(phen))(Ph_(3)SiO)_(2)](PF_(6))(1-L^(N4O2)_(phen))through a stepwise metal-ion templated synthesis.Both compounds exhibit pseudo-D_(6h)symmetry with different degrees of distortion from the ideal hexagonal bipyramidal geometry,depending on the planarity of the equatorial macrocycles and the intramolecularπ-πstacking interactions between the phenyl groups of the apical siloxide ligand and the equatorial macrocycle.Both compounds are single-molecule magnets(SMMs)with large energy barriers for the magnetization reversal,exhibiting out-of-phase AC susceptibility signals up to 75 K or 90 K.The closer-to-ideal D_(6h)complex 1-L^(N4O2)_(phen)possesses a U_(eff)of 1360 K,which is the highest reported barrier among all mononuclear Dy^(Ⅲ)SMMs synthesized using the[1+1]Schiff-base macrocycle approach.The experimental results are supported by ab initio calculations,which indicate relaxation of the magnetization via the first-or second-excited state for 1-L^(N6)_(phen)and 1-L^(N4O2)_(phen),respectively.The results demonstrate the ability of Schiff-base macrocycles to facilitate the synthesis of high-performance and air-stable SMMs through a chemical modulation of the individual carbonyl‘head’and amine subunits,deciphering the factors which affect the magnetic dynamics of SMMs.展开更多
基金the UK EPSRC(grants EP/V003089/1,EP/X036626/1)for financial supportthe National Natural Science Foundation of China(grant 92261103).
文摘Using the[1+1]condensation approach for the preparation of new macrocyclic scaffolds(L^(N6)_(phen)and L^(N4O2)_(phen))with the rigid phenanthroline-based‘head’unit produces the air-stable mononuclear compounds[Dy(L^(N6)_(phen))(Ph_(3)SiO)_(2)](PF_(6))(1-L^(N6)_(phen))and[Dy(L^(N4O2)_(phen))(Ph_(3)SiO)_(2)](PF_(6))(1-L^(N4O2)_(phen))through a stepwise metal-ion templated synthesis.Both compounds exhibit pseudo-D_(6h)symmetry with different degrees of distortion from the ideal hexagonal bipyramidal geometry,depending on the planarity of the equatorial macrocycles and the intramolecularπ-πstacking interactions between the phenyl groups of the apical siloxide ligand and the equatorial macrocycle.Both compounds are single-molecule magnets(SMMs)with large energy barriers for the magnetization reversal,exhibiting out-of-phase AC susceptibility signals up to 75 K or 90 K.The closer-to-ideal D_(6h)complex 1-L^(N4O2)_(phen)possesses a U_(eff)of 1360 K,which is the highest reported barrier among all mononuclear Dy^(Ⅲ)SMMs synthesized using the[1+1]Schiff-base macrocycle approach.The experimental results are supported by ab initio calculations,which indicate relaxation of the magnetization via the first-or second-excited state for 1-L^(N6)_(phen)and 1-L^(N4O2)_(phen),respectively.The results demonstrate the ability of Schiff-base macrocycles to facilitate the synthesis of high-performance and air-stable SMMs through a chemical modulation of the individual carbonyl‘head’and amine subunits,deciphering the factors which affect the magnetic dynamics of SMMs.
