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Hot Electron-Driven Amide Bond Formation in Plasmonic Nanogaps without Chemical Activation
Balaji Sanap1, Abhinav Sharma1, Takuo Tanaka1,2
1Institute of Post-LED Photonics, Tokushima University, 2-1 minami-Josanjima, Tokushima 770-8506, Japan.
The Journal of Physical Chemistry Letters
|June 6, 2026
Summary
Plasmonic nanogaps use light energy to create amide bonds, a reaction typically requiring harsh conditions. This novel method drives challenging chemical transformations using hot electrons and nanoscale confinement.
Area of Science:
- Nanotechnology
- Photochemistry
- Organic Chemistry
Background:
- Plasmonic nanostructures facilitate light-induced chemical reactions via localized fields and hot carriers.
- Amide bond formation is thermodynamically challenging under ambient conditions and usually requires coupling agents or heat.
Purpose of the Study:
- To demonstrate direct amide bond formation in plasmonic nanogaps without coupling agents or thermal activation.
- To investigate the mechanism of light-driven amide synthesis using plasmonic nanostructures.
Main Methods:
- Utilizing plasmonic nanogaps for direct amide bond formation under resonant light excitation.
- Employing in situ surface-enhanced Raman spectroscopy (SERS) to detect amide vibrational modes.
- Performing density functional theory (DFT) calculations to support experimental observations.
- Investigating the reaction's dependence on excitation power and frequency, and thermal effects.
Main Results:
- Successful direct amide bond formation between carboxylic acids and amines within plasmonic nanogaps.
- Observation of characteristic amide vibrational modes via SERS, consistent with DFT calculations.
- Demonstration of a nonthermal reaction mechanism with a clear excitation power threshold and off-resonant suppression.
- Evidence of covalent bond formation through plasmon-induced nanoparticle aggregation.
Conclusions:
- Plasmonic nanogaps serve as effective reaction environments for driving thermodynamically unfavorable reactions.
- Localized electronic excitation and nanoscale confinement in plasmonic systems can overcome reaction barriers without conventional reagents.
- This work opens new avenues for photocatalytic synthesis and light-driven chemistry at the nanoscale.
