Chiral six-coordinate Dy(III) and Tb(III) complexes of an achiral ligand: structure, fluorescence, and magnetism

摘要

Two new chiral six-coordinate lanthanide complexes (1 for Dy and 2 for Tb) have been synthesized using the achiral flexible ligand H2L (2,2'-[1,2-ethanediylbis[(methylimino) methylene]] bis[4,5-dimethylphenol]). Both complexes crystallize in the chiral P1 group space, and the enantiomers [Zn(L)Cl](3)Dy center dot MeOH center dot 0.5H(2)O (Lambda-1), [Zn(L) Cl](3)Dy center dot 1.5H(2)O (triangle-1), [Zn(L)Cl](3)Tb center dot 1.5H(2)O (Lambda-2) and [Zn(L)Cl](3)Tb center dot H2O (triangle-2) are isolated in the reaction. Three [Zn(L) Cl](-) anions coordinate to the central lanthanide ion using two phenoxo oxygen atoms of L2-, and the lanthanide ion has the coordination geometry of D-3. Complex 1 exhibits a field-induced slow magnetization relaxation, which is typical of a single-ion magnet (SIM). Ab initio calculations on complex 1 and studies on magneto-structural correlationship of six-coordinate Dy(III) SIMs indicate that the small energy barrier of complex 1 might be related to the absence of a unique anisotropic axis for the regular octahedral coordination configuration of Dy(III) and the high quantum tunneling gap between the ground states (m(J) = +/- 15/2). Complex 2 displays green photofluorescence and triboluminescence.