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Published on: September 18, 2019
Acid-Catalyzed Rearrangement Reaction for Single-Molecule Junction Formation
Yihao Zhang1, Yunlong Li2, Zhenpin Lu2
1Department of Physics, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|June 6, 2026
Summary
Acid catalysis enables robust single-molecule junction formation for hydrazobenzenes. This breakthrough utilizes a rearrangement reaction to create stable metal-molecule-metal devices, paving the way for new molecular electronics.
Area of Science:
- Materials Science
- Nanotechnology
- Physical Chemistry
Background:
- Single-molecule junction formation is crucial for molecular electronics but challenging for molecules lacking anchoring groups.
- Hydrazobenzenes typically do not form stable junctions with gold electrodes due to the absence of suitable anchoring functionalities.
- Existing methods for creating metal-molecule-metal junctions often require specific functional groups or harsh conditions.
Purpose of the Study:
- To investigate a novel method for forming single-molecule junctions using hydrazobenzene derivatives.
- To explore the role of acid catalysis in promoting junction formation and stability.
- To elucidate the mechanism of acid-catalyzed rearrangement and subsequent dative bonding in single-molecule junctions.
Main Methods:
- Utilized scanning tunneling microscope-based break junction (STM-BJ) technique for real-time monitoring of junction formation.
- Employed acid catalysis to induce rearrangement of hydrazobenzene.
- Performed ex situ synthesis and characterization of benzidine and analyzed reaction products using high-performance liquid chromatography (HPLC).
Main Results:
- Addition of acid rapidly and robustly facilitated single-molecule junction formation for hydrazobenzenes.
- A characteristic conductance peak at 1.3×10-3 G0 indicated stable junction formation, attributed to benzidine via NH2→Au dative interactions.
- Observed deprotonation of reaction products in nonpolar solvents under applied voltage, and conversion of -NH3+ to -NH2 during junction formation.
Conclusions:
- A new, efficient acid-catalyzed method for forming single-molecule devices has been demonstrated.
- The study reveals an acid-induced rearrangement mechanism leading to robust metal-molecule-metal junctions.
- This approach offers a versatile strategy for fabricating molecular electronic devices from molecules previously unsuitable for junction formation.
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