Miao Lin, Liu Mei-Jiao, Zeng Min, Kou Hui-Zhong
Department of Chemistry, Tsinghua University, Beijing 100084, P.R. China.
Inorg Chem. 2023 Aug 14;62(32):12814-12821. doi: 10.1021/acs.inorgchem.3c01449. Epub 2023 Aug 3.
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 [ZnLn] ( for Dy, for Tb, for Gd, and for DyY) using the achiral flexible ligand HL (2,2'-[1,2-ethanediylbis[(ethylimino)methylene]]bis[3,5-dimethylphenol]). The complexes crystallize in the chiral 6 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 to coordinate with three lanthanide ions, respectively, and the three hepta-coordinate lanthanide ions are arranged in a triangle. The chirality comes from the propeller arrangement of the peripheral three bidentate chelate L ligands like octahedral [M(AA)] (M = transition metal ions; AA = bidentate chelate ligands, e.g., 2,2'-bipyridine, 1,10-phenathroline, ethylenediamine, acac or oxalate). Complex exhibits an AC susceptibility signal and is frequency-dependent, which is typical of SMMs. Complex , doped with a large amount of diamagnetic Y(III) in Dy(III), exhibits = 48.3 K and τ = 4.4 × 10 s in experiments. Complex shows circularly polarized luminescence and apparent photoluminescence, typical of the f-f transitions of Tb(III).
多功能单分子磁体（SMMs）引发了极大的兴趣，但通过自发拆分获得的手性SMMs却鲜有报道。我们使用非手性柔性配体HL（2,2'-[1,2-乙二基双[(乙基亚氨基)亚甲基]]双[3,5-二甲基苯酚]）合成了一系列手性三核七配位镧系配合物[ZnLn]（Dy的为 ，Tb的为 ，Gd的为 ，DyY的为 ）。这些配合物在手性6群空间中结晶，不同手性的两种对映体被自发拆分。三个[Zn(L)Cl]阴离子分别利用每个L的两个苯氧基氧原子与三个镧系离子配位，三个七配位的镧系离子呈三角形排列。手性来自于外围三个双齿螯合L配体的螺旋桨状排列，类似于八面体[M(AA)]（M = 过渡金属离子；AA = 双齿螯合配体，例如2,2'-联吡啶、1,10-菲咯啉、乙二胺、乙酰丙酮或草酸盐）。配合物 表现出交流磁化率信号且与频率有关，这是SMMs的典型特征。在Dy(III)中掺杂大量抗磁性Y(III)的配合物 ，在实验中表现出 = 48.3 K和τ = 4.4 × 10 s。配合物 表现出圆偏振发光和明显的光致发光，这是Tb(III)的f-f跃迁的典型特征。
