Chiral Zn<sub>3</sub>Ln<sub>3</sub> Hexanuclear Clusters of an Achiral Flexible Ligand
Lin Miao, Mei-Jiao Liu, Min Zeng, Hui‐Zhong Kou
Abstract
Multifunctional single-molecule magnets (SMMs) have sparked great interest, but chiral SMMs obtained via spontaneous resolution are rarely reported. We synthesized a series of chiral trinuclear hepta-coordinate lanthanide complexes [Zn II 3 Ln III 3 ] ( 1 for Dy, 2 for Tb, 3 for Gd, and 4 for Dy 0.07 Y 0.93 ) using the achiral flexible ligand H 2 L (2,2′-[1,2-ethanediylbis[(ethylimino)methylene]]bis[3,5-dimethylphenol]). The complexes crystallize in the chiral P 6 3 group space, and two enantiomers of different chirality are spontaneously resolved. Three [Zn(L)Cl] − anions utilize the two phenoxy oxygen atoms of each L 2– to coordinate with three lanthanide ions, respectively, and the three hepta-coordinate D 5h lanthanide ions are arranged in a triangle. The chirality comes from the propeller arrangement of the peripheral three bidentate chelate L 2– ligands like octahedral [M(AA) 3 ] n +/– (M = transition metal ions; AA = bidentate chelate ligands, e.g., 2,2′-bipyridine, 1,10-phenathroline, ethylenediamine, acac – or oxalate). Complex 1 exhibits an AC susceptibility signal and is frequency-dependent, which is typical of SMMs. Complex 4, doped with a large amount of diamagnetic Y(III) in Dy(III), exhibits U eff = 48.3 K and τ 0 = 4.4 × 10 –8 s in experiments. Complex 2 shows circularly polarized luminescence and apparent photoluminescence, typical of the f–f transitions of Tb(III).