北京大学郭雪峰团队报道了精确的单分子动力学同位素效应。相关研究成果于2022年1月17日发表在国际知名学术期刊《美国化学会杂志》。

通过利用石墨烯-分子-石墨烯单分子结，利用精确的单分子动力学同位素效应（sm-KIE）绕过了传统系综KIE的固有局限性。高时间分辨率的单分子反应轨迹实时原位监测能够表征KIE带来的更深层次的信息。在Claisen重排过程中，通过次级动力学同位素效应观察到C–O键断裂和过渡态（TS）C–C键的形成，表明该方法具有较高的检测灵敏度和准确性。

更有趣的是，该sm-KIE可用于确定不同电场下的TS结构，揭示TS的多维调节。TS的检测和操纵为理解和优化化学反应和仿生进展提供了广阔的前景。

附：英文原文

Title: Accurate Single-Molecule Kinetic Isotope Effects

Author: Yilin Guo, Chen Yang, Huiping Li, Lei Zhang, Shuyao Zhou, Xin Zhu, Huanyan Fu, Zhizhou Li, Zhirong Liu, Chuancheng Jia, Zitong Liu, Wenguang Zhu, Fanyang Mo, Deqing Zhang, Xuefeng Guo

Issue&Volume: January 17, 2022

Abstract: An accurate single-molecule kinetic isotope effect (sm-KIE) was applied to circumvent the inherent limitation of conventional ensemble KIE by using graphene–molecule–graphene single-molecule junctions. In situ monitoring of the single-molecule reaction trajectories in real time with high temporal resolution has the capability to characterize the deeper information brought by KIE. The C–O bond cleavage and the C–C bond formation of the transition state (TS) were observed in the Claisen rearrangement through the secondary kinetic isotope effect, demonstrating the high detection sensitivity and accuracy of this method. More interestingly, this sm-KIE can be used to determine TS structures under different electric fields, revealing the multidimensional regulation of the TS. The detection and manipulation of the TS provide a broad perspective to understand and optimize chemical reactions and biomimetic progress.

DOI: 10.1021/jacs.1c12490

Source: https://pubs.acs.org/doi/10.1021/jacs.1c12490