Acceleration of Diels-Alder reactions by mechanical distortion
Acceleration of Diels-Alder reactions by mechanical distortion
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DOI：
10.1126/science.adf5273
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发表时间：
2023-06-08
期刊：
影响因子：
56.9
通讯作者：
Braunschweig，Adam B.
中科院分区：
文献类型：
--
作者：
Zholdassov，Yerzhan S.;Yuan，Li;Braunschweig，Adam B.
量化力如何影响键形成的挑战阻碍了机械化学的广泛采用。我们使用基于平行尖端的方法来确定力加速的[4+2]狄尔斯-阿尔德环加成反应的反应速率，活化能和活化体积，表面固定的蒽和四种亲二烯体之间的电子和空间需求不同。速率对压力的依赖性出乎意料地强，并且在亲二烯体之间观察到实质性差异。多尺度建模表明，在接近表面，机械化学轨迹随之而来的是不同于所观察到的solvothermal或静水压力下。这些结果提供了一个框架，预计如何实验几何，分子限制，定向力有助于机械化学动力学。
Challenges in quantifying how force affects bond formation have hindered the widespread adoption of mechanochemistry. We used parallel tip-based methods to determine reaction rates, activation energies, and activation volumes of force-accelerated [4+2] Diels-Alder cycloadditions between surface-immobilized anthracene and four dienophiles that differ in electronic and steric demand. The rate dependences on pressure were unexpectedly strong, and substantial differences were observed between the dienophiles. Multiscale modeling demonstrated that in proximity to a surface, mechanochemical trajectories ensued that were distinct from those observed solvothermally or under hydrostatic pressure. These results provide a framework for anticipating how experimental geometry, molecular confinement, and directed force contribute to mechanochemical kinetics.