Mangel Shai, Skripnik Maxim, Polyudov Katharina, Dette Christian, Wollandt Tobias, Punke Paul, Li Dongzhe, Urcuyo Roberto, Pauly Fabian, Jung Soon Jung, Kern Klaus
Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany.
Phys Chem Chem Phys. 2020 Mar 21;22(11):6370-6375. doi: 10.1039/c9cp06868f. Epub 2020 Mar 6.
The electric field is an important parameter to vary in a single-molecule experiment, because it can directly affect the charge distribution around the molecule. Yet, performing such an experiment with a well-defined electric field for a model chemical reaction at an interface has proven to be extremely difficult. Here, by combining a graphene field-effect transistor and a gate-tunable scanning tunneling microscope (STM), we reveal how this strategy enables the intramolecular H atom transfer of a metal-free macrocycle to be controlled with an external field. Experiments and theory both elucidate how the energetic barrier to tautomerization decreases with increasing electric field. The consistency between the two results demonstrates the potential in using electric fields to engineer molecular switching mechanisms that are ubiquitous in nanoscale electronic devices.
电场是单分子实验中一个重要的可变参数，因为它可以直接影响分子周围的电荷分布。然而，事实证明，在界面处对模型化学反应使用定义明确的电场进行这样的实验极其困难。在这里，通过将石墨烯场效应晶体管和栅极可调谐扫描隧道显微镜（STM）相结合，我们揭示了这种策略如何能够利用外部电场控制无金属大环分子的分子内氢原子转移。实验和理论都阐明了互变异构的能垒如何随电场增加而降低。这两个结果之间的一致性证明了利用电场设计纳米级电子设备中普遍存在的分子开关机制的潜力。
