Oxidative regulation of the mechanical strength of a C–S bond

Lin, Yangju; Craig, Stephen L.

doi:10.1039/d0sc04381h

Cited by 9 publications

(4 citation statements)

References 52 publications

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“…For example, the C-S(VI) bond in PSU has rupture force F act[T = 298.15 K, t = 654 s],calc of 1790 pN, which is lower than that of C-S(II) bond in PPS (F act[T = 298.15 K, t = 654 s],calc = 1990 pN). It is consistent to what Craig and co-workers found experimentally 31. It was also found that the C-C bonds in polyethylene (PE) are the most force-resistant among all the polyalkenes.…”

supporting

confidence: 90%

Computational Exploration of Polymer Mechanochemistry: Quantitation of Activation Force and Systematic Discovery of Reaction Sites Utilizing Two Forces

Jiang

Koyama

Jin

et al. 2022

Preprint

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A series of mechanophores were studied computationally by employing the AFIR (Artificial Force Induced Reaction) method, which applies an artificial force on the molecule to trigger reactions, and meanwhile with a tensile force to simulate a mechanochemical reaction. The calculation results were both qualitatively and quantitatively consistent to those reported experimentally, indicating that the AFIR is a reliable approach to studying mechanochemical reactions. It was then applied to the study of retro-Diels-Alder reactions for the theoretical predictions of activation force levels which are currently unavailable. Moreover, it also helped to reveal the favored geometry for the enhancement of force effect. Later, the AFIR method was employed to study the mechanodegradation of generic polymers. The substituents effect and the polymer tacticity in strengthening the mechanical responsiveness, were highlighted by our study. Given the importance of cross-linker molecules in the double-network (DN) hydrogels, a fully automatic search of mechanochemical transformation pathways of a commonly used cross-linker molecule, N,N'-methylenebisacrylamide (MBAA), was also performed by the AFIR method. Through the work described in this article, we demonstrated that, in the field of polymer mechanochemistry, the AFIR method utilizing two forces is a simple but effective tool to give accurate predictions of activation force levels at any given timescale. In the meantime, the mechanistic study of mechanochemical reactions shown in this article is believed to provide insightful suggestions for the further design and application of mechanophores.

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confidence: 90%

Computational Exploration of Polymer Mechanochemistry: Quantitation of Activation Force and Systematic Discovery of Reaction Sites Utilizing Two Forces

Jiang

Koyama

Jin

et al. 2022

Preprint

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“…gDCC is an extensively studied mechanophore that undergoes ring opening reaction to yield 2,3‐dichloroalkene [32] . Because the rate and extent of mechanophore activation depend on the chain length of the mechanophore‐containing polymers [33] and it is difficult to control molecular weight in polycondensation, we chose gDCC as an internal standard to also be incorporated into polymers as reported in other studies in order to compare the degree of activation for the three regioisomers [10,34–36] . Thus, the ratio of mechanoactivation for cyclobutane relative to gDCC can be used to compare the reactivity difference among the three isomers embedded in polymers with different lengths.…”

Section: Resultsmentioning

confidence: 99%

Force Transduction Through Distant Force‐Bearing Regioisomeric Linkages Affects the Mechanochemical Reactivity of Cyclobutane

Flear,

Horst,

Yang

et al. 2024

Angewandte Chemie

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Fundamental understanding of mechanochemical reactivity is important for designing new mechanophores. Besides the core structure of mechanophores, substituents on a mechanophore can affect its mechanochemical reactivity through electronic stabilization of the intermediate or effectiveness of force transduction from the polymer backbone to the mechanophore. The latter factor represents a unique mechanical effect in considering polymer mechanochemistry. Here, we show that regioisomeric linkage that is not directly adjacent to the first cleaving bond in cyclobutane can still significantly affect the mechanochemical reactivity of the mechanophore. We synthesized three non‐scissile 1,2‐diphenyl cyclobutanes, varying their linkage to the polymer backbone via the o, m, or p‐position of the diphenyl substituents. Even though the regioisomers share the same substituted cyclobutane core structure and similar electronic stabilization of the diradical intermediate from cleaving the first C‐C bond, the p isomer exhibited significantly higher mechanochemical reactivity than the o and m isomers. The observed difference in reactivity can be rationalized as the much more effective force transduction to the scissile bond through the p‐position than the other two substitution positions. These findings point to the importance of considering force‐bearing linkages that are more distant from the bond to be cleaved when incorporating mechanophores into polymer backbones.

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“…1,2 Since the emergence of the mechanophore concept, 3 chemists have been able to explore and control reactivity under tension with clever molecular designs. 4 Several factors affecting the reactivity under tension have been uncovered such as: the polymer architecture, [5][6][7] the nature of the linker, [8][9][10][11][12] substituents, [13][14][15][16] or dependence on their stereo-, [16][17][18][19][20][21][22] regio-, 18,[23][24][25][26][27] or topochemistry. [28][29][30] These factors usually affect the rate of activation or, more rarely, the outcome of the reaction itself.…”

mentioning

confidence: 99%

“…The reactivity of molecules under tension can significantly deviate from their force-free reactivity. , Since the emergence of the mechanophore concept, chemists have been able to explore and control reactivity under tension with clever molecular designs . Several factors affecting the reactivity under tension have been uncovered such as the polymer architecture, − the nature of the linker, − substituents, − or dependence on their stereo-, − regio-, ,− or topochemistry. − These factors usually affect the rate of activation or, more rarely, the outcome of the reaction itself. ,,, The latter case is often the result of a post-transition-state bifurcation on the force-modified potential energy surface (PES). ,, …”

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Isotope Effect in the Activation of a Mechanophore

Nixon

2020

J. Am. Chem. Soc.

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In mechanochemistry, molecules under tension can react in unexpected ways. The reactivity of mechanophores (mechanosensitive molecules) can be controlled using various geometric or electronic factors. Often these factors affect the rate of mechanical activation but sometimes give rise to alternative reaction pathways. Here we show that a simple isotope substitution (H to D) leads to a reversal of selectivity in the activation of a mechanophore. Remarkably this isotope effect is not kinetic in nature but emerges from dynamic effects in which deuteration reduces the ability of the reactant to follow a post-transition-state concerted trajectory on the bifurcated force-modified potential energy surface. These results give a new insight into the reactivity of molecules under tension.

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Oxidative regulation of the mechanical strength of a C–S bond

Abstract: The mechanical strength of individual polymer chains is believed to underlie a number of performance metrics in bulk materials, including adhesion and fracture toughness. Methods by which the intrinsic molecular...

Cited by 9 publications

References 52 publications

Computational Exploration of Polymer Mechanochemistry: Quantitation of Activation Force and Systematic Discovery of Reaction Sites Utilizing Two Forces

Computational Exploration of Polymer Mechanochemistry: Quantitation of Activation Force and Systematic Discovery of Reaction Sites Utilizing Two Forces

Force Transduction Through Distant Force‐Bearing Regioisomeric Linkages Affects the Mechanochemical Reactivity of Cyclobutane

Isotope Effect in the Activation of a Mechanophore

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