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Switch chemistry at cryogenic conditions: quantum tunnelling under electric fields
Chemical Science ( IF 7.6 ) Pub Date : 2020-12-15 , DOI: 10.1039/d0sc06295b
Omer Kirshenboim 1 , Alexander Frenklah 1 , Sebastian Kozuch 1
Affiliation  

While the influence of intramolecular electric fields is a known feature in enzymes, the use of oriented external electric fields (EEF) to enhance or inhibit molecular reactivity is a promising topic still in its infancy. Herein we will explore computationally the effects that EEF can provoke in simple molecules close to the absolute zero, where quantum tunnelling (QT) is the sole mechanistic option. We studied three exemplary systems, each one with different reactivity features and known QT kinetics: π bond-shifting in pentalene, Cope rearrangement in semibullvalene, and cycloreversion of diazabicyclohexadiene. The kinetics of these cases depend both on the field strength and its direction, usually giving subtle but remarkable changes. However, for the cycloreversion, which suffers large changes on the dipole through the reaction, we also observed striking results. Between the effects caused by the EEF on the QT we observed an inversion of the Arrhenius equation, deactivation of the molecular fluxionality, and stabilization or instantaneous decomposition of the system. All these effects may well be achieved, literally, at the flick of a switch.

中文翻译:


低温条件下的开关化学:电场下的量子隧道



虽然分子内电场的影响是酶的一个已知特征,但使用定向外部电场 (EEF) 来增强或抑制分子反应性是一个仍处于起步阶段的有前途的课题。在这里,我们将通过计算探索 EEF 在接近绝对零的简单分子中引起的效应,其中量子隧道 (QT) 是唯一的机械选择。我们研究了三个示例性系统,每个系统都具有不同的反应特征和已知的 QT 动力学:戊烯中的 π 键转移、半牛瓦烯中的 Cope 重排以及二氮杂双环己二烯的环化回复。这些情况的动力学取决于场强及其方向,通常会产生微妙但显着的变化。然而,对于通过反应使偶极子发生巨大变化的环化回复,我们也观察到了惊人的结果。在 EEF 对 QT 造成的影响之间,我们观察到阿累尼乌斯方程的反转、分子流动性的失活以及系统的稳定或瞬时分解。从字面上看,所有这些效果都可以通过轻按开关来实现。
更新日期:2021-01-20
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