Yang Chen, Liu Zitong, Li Yanwei, Zhou Shuyao, Lu Chenxi, Guo Yilin, Ramirez Melissa, Zhang Qingzhu, Li Yu, Liu Zhirong, Houk K N, Zhang Deqing, Guo Xuefeng
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
Sci Adv. 2021 Jan 20;7(4). doi: 10.1126/sciadv.abf0689. Print 2021 Jan.
Precise time trajectories and detailed reaction pathways of the Diels-Alder reaction were directly observed using accurate single-molecule detection on an in situ label-free single-molecule electrical detection platform. This study demonstrates the well-accepted concerted mechanism and clarifies the role of charge transfer complexes with or configurations on the reaction path. An unprecedented stepwise pathway was verified at high temperatures in a high-voltage electric field. Experiments and theoretical results revealed an electric field-catalyzed mechanism that shows the presence of a zwitterionic intermediate with one bond formation and variation of concerted and stepwise reactions by the strength of the electric field, thus establishing a previously unidentified approach for mechanistic control by electric field catalysis.
在原位无标记单分子电学检测平台上，通过精确的单分子检测直接观察到了狄尔斯-阿尔德反应的精确时间轨迹和详细反应途径。本研究证实了被广泛接受的协同机理，并阐明了电荷转移复合物在反应路径上顺式或反式构型的作用。在高温高压电场中验证了前所未有的分步途径。实验和理论结果揭示了一种电场催化机理，该机理表明存在一种两性离子中间体，有一个键形成，且协同反应和分步反应会因电场强度而变化，从而建立了一种以前未被识别的通过电场催化进行机理控制的方法。
