Forming Chemisorbed Single-Molecule Junctions through Loss of Stable Carbocations.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40526061.
- Also identified by DOI 10.1021/acs.nanolett.5c01893 and PMC identifier 12232389.
- Licence recorded as CC BY-NC-ND.
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Abstract
Recent studies have found that "chemically inert" gold surfaces may drive S-C(<i>sp</i><sup>3</sup>) bond cleavage reactions in thioether (-SR) linker groups, providing access to single-molecule junctions with chemisorbed Au-S contacts following the elimination of R<sup>+</sup>. Here, we demonstrate that such transformations occur more readily at elevated temperatures, rough surfaces, and in <i>nonpolar</i> solvents. We further show that a greater proportion of chemisorbed bonds are formed when R = -CPh<sub>3</sub> or -C<sub>7</sub>H<sub>7</sub> than when R = -<i><sup>t</sup></i>Bu, consistent with the relative stability of [<i><sup>t</sup></i>Bu]<sup>+</sup> < [CPh<sub>3</sub>]<sup>+</sup> ∼ [C<sub>7</sub>H<sub>7</sub>]<sup>+</sup> carbocations. Our contact chemistry assignments are supported by first-principles transmission calculations, and we apply potential energy calculations to expose the relatively small influence of applied external electric fields on this bond breaking process. Together, this work provides a deeper understanding of reactivity at metal surfaces, of broad relevance to heterogeneous catalysis and critical to the stability and function of molecular junctions and monolayers.