Intramolecular London Dispersion Interactions in Single-Molecule Junctions

23 January 2024, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


This manuscript shows the first example of using intramolecular London dispersion interactions to control molecular geometry and quantum transport in single-molecule junctions. Flexible σ-bonded molecular junctions typically occupy straight-chain geometries due to steric effects. Here we synthesize a series of thiomethyl-terminated oligo(dimethylsilmethylene)s that bear [CH2-Si(CH3)2]n repeat units, where all backbone dihedral states are sterically equivalent. Scanning tunneling microscopy break-junction (STM-BJ) measurements and theoretical calculations indicate that in the absence of a strong steric bias, concerted intramolecular London dispersion interactions staple the carbosilane backbone into coiled conformations that remain intact even as the junction is stretched to its breakpoint. As these kinked conformations are highly resistive to electronic transport, we observe record-high conductance decay values on an experimental junction length basis (β = 1.86 ± 0.12 Å-1). These studies reveal the potential in using intramolecular London dispersion interactions to design single-molecule electronics.


London dispersion
non-covalent interactions
molecular electronics
single-molecule junction

Supplementary materials

Supporting Information
Supporting figures, tables, notes, NMR spectra, and general synthesis and characterization information.


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