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Forming Chemisorbed Single-Molecule Junctions through Loss of Stable Carbocations
Jazmine Prana1, Luana Zagami1, Kelly Yan1
1Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
Nano Letters
|June 17, 2025
Summary
Chemically inert gold surfaces facilitate S-C bond cleavage in thioether linkers, forming stable single-molecule junctions. This reaction is enhanced by higher temperatures, rougher surfaces, and nonpolar solvents, with carbocation stability influencing bond formation.
Area of Science:
- Surface Chemistry
- Materials Science
- Nanotechnology
Background:
- Gold surfaces, traditionally considered inert, can mediate chemical reactions.
- Thioether linker groups (-SR) are crucial in forming contacts for molecular junctions.
- Understanding surface reactivity is key for developing stable molecular devices.
Purpose of the Study:
- To investigate the conditions favoring S-C(sp3) bond cleavage on gold surfaces.
- To determine the influence of carbocation stability on chemisorbed bond formation.
- To explore the role of surface properties and solvent polarity in these reactions.
Main Methods:
- Experimental studies on thioether-gold interactions under varying conditions (temperature, surface roughness, solvent polarity).
- Analysis of carbocation stability correlating with R group identity (e.g., -CPh3, -C7H7, -tBu).
- First-principles transmission and potential energy calculations to support contact chemistry and field effects.
Main Results:
- Elevated temperatures, rougher gold surfaces, and nonpolar solvents accelerate S-C bond cleavage.
- Carbocation stability, dictated by the R group, directly impacts the proportion of chemisorbed Au-S bonds formed.
- External electric fields have a minimal effect on the bond-breaking process.
Conclusions:
- Gold surfaces are more reactive than previously assumed, particularly for thioether functionalized molecules.
- Reaction conditions significantly influence the formation of stable single-molecule junctions.
- This research provides fundamental insights into metal-surface reactivity, relevant for catalysis and molecular electronics.
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