Research on Electric Field-Induced Catalysis Using Single-Molecule Electrical Measurement

Abstract

The role of catalysis in controlling chemical reactions is crucial. As an important external stimulus regulatory tool, electric field (EF) catalysis enables further possibilities for chemical reaction regulation. To date, the regulation mechanism of electric fields and electrons on chemical reactions has been modeled. The electric field at the single-molecule electronic scale provides a powerful theoretical weapon to explore the dynamics of individual chemical reactions. The combination of electric fields and single-molecule electronic techniques not only uncovers new principles but also results in the regulation of chemical reactions at the single-molecule scale. This perspective focuses on the recent electric field-catalyzed, single-molecule chemical reactions and assembly, and highlights promising outlooks for future work in single-molecule catalysis.

Keywords: chemical reactions; electric field catalysis; single-molecule electronic techniques.

Figure 1

(A) Schematic representation of the MCBJ technology and scanning electron microscopy images of wires. Reproduced with permission from [26]. Copyrights, 2018 American Chemical Society. (B) Schematic of graphene–diarylethene–graphene junction. Reproduced with permission from [34]. Copyrights, 2016 American Association for the Advancement of Science. (C) Schematic illustration of junctions of the EGaIn technology and the mechanism of charge transport across them. Reproduced with permission from [38]. Copyrights, 2013 Nature Publishing Group.

Figure 2

(A) The schematic of the DA reaction in STM-BJ conductance measurements. (B) The two diastereoisomers of the exo-syn product of this reaction. Different positions of the substituent of the furan are shown. (C) The predicted effects of the strength and direction of the external electric field (EEF) on the reaction–barrier height (ΔE^‡) for molecules in B. (D) The frequency of blinks (junctions) as a function of the applied bias. Reproduced with permission from [17]. Copyright, 2016 Macmillan Publishers Limited. All rights reserved.

Figure 3

(A) Bias voltage-dependent experiments. The left side is the statistical histogram of the zwitterionic intermediate (ZI). The right side is the zoom-in picture of the concerted reaction process. (B) Statistical histograms and the corresponding attribution of the six conductance states obtained from Gaussian fittings of I-t measurements. (C) The schematic of the single-molecule electrical monitoring platform. Reproduced with permission from [55]. Copyright, 2021 the authors, some rights reserved; exclusive licensee is the American Association for the Advancement of Science. No claim to original U.S. Government works. Distributed under a Creative Commons Attribution Non-Commercial License 4.0 (CC BY-NC).

Figure 4

(A) The thermal-reversible DA reactions between AnAm and C₆₀. (B) The schematic of DA process using STM-BJ technology. (C) The single-molecule conductance of each compound was characterized through conductance histograms. The inset shows typical traces of both molecule junctions. Reproduced with permission from [44]. Copyright, 2022 Elsevier B.V. All rights reserved.

Figure 5

(A) The schematic of the MCBJ technique for in situ single-molecule conductance measurement. (B) The left column shows the reaction between 3,6-di(4-pyridyl)-1,2,4,5-tetrazine (a) and 2,3-dihydrofuran to form compound b, which goes through an aromatization process to form compound c. The 1D conductance histogram results constructed for the single-molecule conductance of each compound are shown in the right column. The inset shows the typical traces of the compounds. Figure reproduced from reference [45]. Copyright, 2019 the authors, some rights reserved; exclusive licensee is the American Association for the Advancement of Science. No claim made to original U.S. Government works. Distributed under a Creative Commons Attribution Non-Commercial License 4.0 (CC BY-NC).

Figure 6

(A) The schematic of C-O bond cleavage catalysis by an EEF. (B) Molecular conductance changed during electrostatic catalysis in the homolysis of alkoxyamines. (C,D) A schematic depiction of the STM-BJ setup for a single-molecule junction experiment used to investigate the effect of an external electrical field on the breaking of a C-ON bond. Reproduced with permission from [41]. Copyright, 2017 American Chemical Society.

Figure 7

(A) The schematic of the homolysis of 4-(methylthio)benzoic peroxyanhydride 1 used to obtain 4-(methylthio)benzoic acid 2. (B) The 1D conductance histogram traces measured at different reaction times. Reproduced with permission from [42]. Copyright, 2023 the author. Published by the Royal Society of Chemistry. (C) A schematic illustration of the STM-BJ environment. (D) Logarithmically binned 1D conductance histograms stemming from traces collected for the coupling reaction of the kinetically inert transition metal complex. Reproduced with permission from [43]. Copyright, 2022 The Royal Society of Chemistry.

Figure 8

(A) The schematic of the electron-catalyzed dehydrogenation at an STM junction. (B) A plausible mechanism for the electron-catalyzed DPA²⁺-to-DPE²⁺ dehydrogenation. (C) The schematic of the electron-catalyzed dehydrogenation of cyclophanes. (D) Conductance comparisons between molecular pairs bearing either a DPA²⁺ (blue) or a DPE²⁺ (red) backbone. Reproduced with permission from [46]. Copyright, 2021 American Chemical Society.

Figure 9

(A) The schematic of the EEF-induced single-stacking junctions of terphenyl. (B) The 1D conductance histograms under 0.10 (blue) and 0.35 V (red). The inset shows traces of the typical conductance displacement. (C) The structures of the molecules used in the formation of single-stacking junctions. The red arrow shows the increase in the formation probability of single-stacking junctions. (D) A scatter plot of the ratio of traces with twist and stacking features with the four molecules in C. Reproduced with permission from [47]. Copyright, 2020 American Chemical Society.