Flyby reaction trajectories: Chemical dynamics under extrinsic force
Flyby reaction trajectories: Chemical dynamics under extrinsic force
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DOI：
10.1126/science.abi7609
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发表时间：
2021-07-09
期刊：
影响因子：
56.9
通讯作者：
Moore, Jeffrey S.
中科院分区：
文献类型：
--
作者：
Liu, Yun;Holm, Soren;Moore, Jeffrey S.
动态效应是化学反应性和选择性的重要决定因素，但在化学转化过程中故意操纵原子运动并非直截了当。在这里，我们证明了外力施加在环丁烷上，通过力传递的非统计动态效应影响逐步开环反应的产物选择性。高产物立体选择性通过碳-13标记量化，并表明取决于外力、反应物立体化学和中间稳定性。计算模型和模拟表明，除了改变能垒之外，机械力激活了非统计的反应性分子内运动，建立了“飞掠轨迹”，直接推进到产物而没有异构化偏移。结合非统计动态效应的机制模型解释了依赖于异构体的机械化学立体选择性。
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.