Li Guangwu, Matsuno Taisuke, Han Yi, Wu Shaofei, Zou Ya, Jiang Qing, Isobe Hiroyuki, Wu Jishan
Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore.
Department of Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Angew Chem Int Ed Engl. 2021 Apr 26;60(18):10326-10333. doi: 10.1002/anie.202100606. Epub 2021 Mar 17.
A series of fused quinoidal dithiophene-based double and triple helicenes (1-M, 2-M, 2-M-Cl, 3-M, 3-M-Cl) were synthesized by intramolecular radical-radical coupling followed by oxidative dehydrogenation reaction. These helical molecules show dynamic interconversion of enantiomers in solution as revealed by variable-temperature NMR measurements, and the energy barriers are correlated to the substituents and topological structures. Notably, dynamic high performance liquid chromatography was used to quantitatively investigate the room-temperature racemization process between the (P,P,M)- and (P,M,M)- enantiomers of the triple helical 3-M-Cl, which gave an interconversion energy barrier in consistent with density functional theory calculations. Their optical and electrochemical properties are dependent on the fusion mode. Our studies provide both new synthetic strategy and new dynamic analytical method for helicenes with unique electronic structure.
通过分子内自由基-自由基偶联反应，随后进行氧化脱氢反应，合成了一系列稠合喹啉二噻吩基双螺旋和三螺旋分子（1-M、2-M、2-M-Cl、3-M、3-M-Cl）。可变温度核磁共振测量表明，这些螺旋分子在溶液中表现出对映体的动态相互转化，并且能垒与取代基和拓扑结构相关。值得注意的是，采用动态高效液相色谱法定量研究了三螺旋3-M-Cl的（P,P,M）-和（P,M,M）-对映体之间的室温外消旋过程，得到的相互转化能垒与密度泛函理论计算结果一致。它们的光学和电化学性质取决于稠合模式。我们的研究为具有独特电子结构的螺旋分子提供了新的合成策略和新的动态分析方法。
