美国伊利诺伊大学厄本那香槟分校Jeffrey S. Moore团队报道了外力作用下的化学动力学产生“飞越反应轨迹”。相关研究成果于2021年7月9日发表在《科学》。

动力学效应是化学反应性和选择性的一个重要决定因素，但在化学转化过程中对原子运动的有意操纵并非易事。

该文中，研究人员证明了通过拉伸悬垂聚合物链施加在环丁烷上的外力，通过对逐步开环反应施加非统计动力学效应来影响产物选择性。高产物立体选择性通过碳-13标记进行量化，并显示出依赖于外力、反应物立体化学和中间稳定性。

计算模型和模拟表明，除了改变能量势垒外，机械力还随机地激活分子内的反应性运动，建立了直接进入产物的“飞越轨迹”，而没有异构化偏移。一个包含非统计动态效应的机械模型解释了异构体依赖的机械化学立体选择性。

附：英文原文

Title: Flyby reaction trajectories: Chemical dynamics under extrinsic force

Author: Yun Liu, Soren Holm, Jan Meisner, Yuan Jia, Qiong Wu, Toby J. Woods, Todd J. Martinez, Jeffrey S. Moore

Issue&Volume: 2021/07/09

Abstract: Dynamic effects are an important determinant of chemical reactivity and selectivity, but the deliberate manipulation of atomic motions during a chemical transformation is not straightforward. Here, we demonstrate that extrinsic force exerted upon cyclobutanes by stretching pendant polymer chains influences product selectivity through force-imparted nonstatistical dynamic effects on the stepwise ring-opening reaction. The high product stereoselectivity is quantified by carbon-13 labeling and shown to depend on external force, reactant stereochemistry, and intermediate stability. Computational modeling and simulations show that, besides altering energy barriers, the mechanical force activates reactive intramolecular motions nonstatistically, setting up “flyby trajectories” that advance directly to product without isomerization excursions. A mechanistic model incorporating nonstatistical dynamic effects accounts for isomer-dependent mechanochemical stereoselectivity.

DOI: 10.1126/science.abi7609

Source: https://science.sciencemag.org/content/373/6551/208