Directing isomerization reactions of cumulenes with electric fields
Directing isomerization reactions of cumulenes with electric fields
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DOI：
10.1038/s41467-019-12487-w
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发表时间：
2019-10-02
影响因子：
16.6
通讯作者：
Venkataraman, Latha
中科院分区：
文献类型：
--
作者：
Zang, Yaping;Zou, Qi;Venkataraman, Latha
电场被认为具有通过稳定极性或离子中间过渡态来催化化学反应的独特能力。虽然场辅助催化正在研究中，但利用电场催化溶液中的反应的能力仍然难以捉摸，对这种催化的机理的了解也很少。在扫描隧道显微镜下，我们证明了电场可以催化溶液中[3]异丙苯衍生物的顺反异构化。我们进一步证明，外加电场可以改变抑制反式为顺式反应的热力学，赋予反式异构体选择性。基于密度泛函理论的计算发现，外加电场促进了两性离子共振态的形成，从而保证了异构化反应处于较低的能量过渡态。相对于顺式，磁场也稳定了反式，决定了顺式/反式热力学，驱使平衡产物完全朝向反式。
Electric fields have been proposed as having a distinct ability to catalyze chemical reactions through the stabilization of polar or ionic intermediate transition states. Although field-assisted catalysis is being researched, the ability to catalyze reactions in solution using electric fields remains elusive and the understanding of mechanisms of such catalysis is sparse. Here we show that an electric field can catalyze the cis-to-trans isomerization of [3] cumulene derivatives in solution, in a scanning tunneling microscope. We further show that the external electric field can alter the thermodynamics inhibiting the trans-to-cis reverse reaction, endowing the selectivity toward trans isomer. Using density functional theory-based calculations, we find that the applied electric field promotes a zwitterionic resonance form, which ensures a lower energy transition state for the isomerization reaction. The field also stabilizes the trans form, relative to the cis, dictating the cis/trans thermodynamics, driving the equilibrium product exclusively toward the trans.