Chiral Zn3Ln3 Hexanuclear Clusters of an Achiral Flexible Ligand

• Published in: Inorganic chemistry Vol. 62; no. 32; pp. 12814 - 12821
• Main Authors: Miao, Lin, Liu, Mei-Jiao, Zeng, Min, Kou, Hui-Zhong
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14.08.2023
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.3c01449

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 [ZnII 3LnIII 3] (1 for Dy, 2 for Tb, 3 for Gd, and 4 for Dy0.07Y0.93) using the achiral flexible ligand H2L (2,2′-[1,2-ethanediylbis­[(ethylimino)­methylene]]­bis­[3,5-dimethylphenol]). The complexes crystallize in the chiral P63 group space, and two enantiomers of different chirality are spontaneously resolved. Three [Zn­(L)­Cl]− anions utilize the two phenoxy oxygen atoms of each L2– 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 L2– 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 τ0 = 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).