Forcing a Molecule to Switch: Quantifying Mechanical Control at the Atomic Scale.
basic_science · Level V
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- Record sourced from PubMed, PMID 42378372.
- Also identified by DOI 10.1021/acs.nanolett.6c01515.
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Abstract
Mechanically induced conformational switching at the single-molecule level represents a fundamental mechanism for molecular functionality, yet quantitative characterization of the underlying force and energy landscape remains limited. Here, we study individual TBrPP-Co(II) molecules on Au(111) using qPlus atomic force microscopy. By reconstructing interaction potentials from 3D Δ<i>f</i>(<i>x</i>,<i>y</i>,<i>z</i>) data, we determine a threshold force of ∼96 ± 8 pN and a tip-induced switching interaction energy of ∼38 ± 4 meV associate with the conformational transition. The isolated tip-molecule force follows a power law (exponent ∼6), indicating dominance of long-range van der Waals interactions. At closer distances, deviations reveal force-induced deformation preceding the transition. Validation via the inflection point test confirms measurement reliability. These findings show that long-range dispersive interactions can mechanically deform a molecule and facilitate conformational switching through a deformation-assisted pathway, providing a quantitative framework for controlling mechanically driven functionality at the single-molecule scale.