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Mechanical force drives distinct chemical reactions; yet, its vectoral nature results in complicated coupling with reaction trajectories. Here, we utilize a physical organic model inspired by the classical Morse potential and its differential forms to identify effective force constant (keff) and reaction energy (ΔE) as key molecular features that govern mechanochemical kinetics. Through a comprehensive experimental and computational investigation with four norborn-2-en-7-one (NEO) mechanophores, we establish the relationship between these features and the force-dependent energetic changes along the reaction pathways. We show that the complex kinetic behavior of the tensioned bonds is generally and quantitatively predicted by a simple multivariate linear regression based on the two easily computed features with a straightforward workflow. These results demonstrate a general mechanistic framework for mechanochemical reactions under tensile force and provide a highly accessible tool for the large-scale computational screening in the design of mechanophores.
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Advancing the Mechanosensitivity of Atropisomeric Diarylethene Mechanophores Through a Lever-Arm Effect
Understanding structure-mechanical activity relationships (SMARs) in polymer mechanochemistry is essential for the rational design of mechanophores with desired properties, yet SMARs in noncovalent mechanical transformations remain relatively underexplored. In this study, we designed a subset of diarylethene mechanophores based on a lever-arm hypothesis and systematically investigated their mechanical activity toward a noncovalent-yet-chemical conversion of atro-pisomer stereochemistry. Results from DFT calculations, single-molecule force spectroscopy (SMFS) measurements, and ultrasonication experiments collectively support the lever-arm hypothesis and confirm the exceptional sensitivity of chemo-mechanical coupling in these atropisomers. Notably, the transition force for the diarylethene M3 featuring extended 5-phenylbenzo[b]thiophene aryl groups is determined to be 131 pN ± 4 pN by SMFS. This value is lower than typically recorded for other mechanically induced chemical processes, highlighting its exceptional sensitivity to low-magnitude forces. This work contributes a fundamental understanding of chemo-mechanical coupling in atropisomeric configurational mechanophores and paves the way for designing highly sensitive mechanochemical processes that could facilitate the study of nanoscale mechanical behaviors across scientific disciplines.
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- Award ID(s):
- 1950802
- PAR ID:
- 10585314
- Publisher / Repository:
- Cambridge University Press
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Posted Content:
- https://doi.org/10.26434/chemrxiv-2024-smxcc-v2
