Triazole-Extended Anthracenes as Optical Force Probes

Baumann, Christoph; Göstl, Robert

doi:10.1055/s-0040-1720924

Cited by 5 publications

(1 citation statement)

References 42 publications

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“…The rate of ultrasound-induced polymer chain scission, which indirectly reports on the activity of a scissile mechanophore located near the chain midpoint, is routinely characterized using a linearization function applied to time-dependent changes in average molecular weight. ,,− The theoretical eq , which was originally developed to describe random polymer degradation processes, , was applied by Sato and Nalepa to the ultrasonic degradation of cellulose derivatives as early as 1978 where M n, t and M n,0 are the number-average molecular weight at time t and t = 0, respectively, and k ′ is the apparent rate constant for polymer chain scission. While values of k ′ with units of mol kg –1 min –1 are often reported in the literature, ,,− ,, the actual rate constant from this linearization analysis is provided by eq where k L has units of min –1 after adjusting for the molecular weight of the polymer repeat unit, m 0 .…”

Section: Introductionmentioning

confidence: 99%

Quantifying Activation Rates of Scissile Mechanophores and the Influence of Dispersity

2021

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The ability to accurately and quantitatively characterize structure−mechanochemical activity relationships is important for informing the fundamental understanding of mechanochemical reactivity and, in turn, the successful advancement of the rapidly growing field of polymer mechanochemistry. Ultrasound-induced mechanical activation of polymers remains one of the most general methods for studying mechanophore reactivity; however, the activation rates of scissile mechanophores are still routinely deduced from changes in polymer size using gel permeation chromatography (GPC) that indirectly report on mechanophore activation with questionable accuracy. Here, the rates of ultrasound-induced mechanochemical activation of two distinct scissile and fluorogenic mechanophores are measured using photoluminescence spectroscopy and compared directly to rates determined using various methods for analyzing chain scission kinetics from GPC measurements. This systematic study confirms that the conventional method for analyzing chain scission kinetics is inaccurate and that it provides a misleading picture of mechanophore activity. Instead, time-dependent changes in the GPC refractive index response closely reproduce the rates of mechanophore activation determined spectroscopically. These results expand on prior work by providing a systematic evaluation of the methods used to characterize mechanophore activation kinetics and emphasize the need for a unified approach to kinetic analysis in the field of polymer mechanochemistry. Moreover, analysis of mechanophore activation efficiency reveals an important insight into the consequences of molecular weight dispersity on the characterization of mechanophore reactivity.

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Section: Introductionmentioning

confidence: 99%

Quantifying Activation Rates of Scissile Mechanophores and the Influence of Dispersity

2021

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Diverse reactivity of maleimides in polymer science and beyond

Kirkpatrick,

Anseth,

Hebner

2024

Polymer International

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Maleimides are remarkably versatile functional groups, capable of participating in homo‐ and copolymerizations, Diels–Alder and (photo)cycloadditions, Michael additions, and other reactions. Their reactivity has afforded materials ranging from polyimides with high upper service temperatures to hydrogels for regenerative medicine applications. Moreover, maleimides have proven to be an enabling chemistry for pharmaceutical development and bioconjugation via straightforward modification of cysteine residues. To exert spatiotemporal control over reactions with maleimides, multiple approaches have been developed to photocage nucleophiles, dienes, and dipoles. Additionally, further substitution of the maleimide alkene (e.g. monohalo‐, dihalo‐, thio‐, amino‐ and methyl‐maleimides, among other substituents) confers tunable reactivity and dynamicity, as well as responsive mechanical and optical properties. In this mini‐review, we highlight the diverse functionality of maleimides, underscoring their notable impact in polymer science. This moiety and related heterocycles will play an important role in future innovations in chemistry, biomedical, and materials research. © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Regiochemical effects for the mechanochemical activation of 9‐π‐extended anthracene‐maleimide Diels–Alder adducts

Baumann

Willis‐Fox

Campagna

et al. 2022

Journal of Polymer Science

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The attachment point of the polymer chain to a force-responsive molecular unit (mechanophore) is a decisive parameter determining bond scission rate and ultimately the mechanochemical reaction outcome. However, such regiochemical polymer substituent effects have not yet been investigated for 9-πextended anthracene-maleimide Diels-Alder adducts. Here we combine three methods, namely ultrasonication, CoGEF computation, and flow activation, to understand the influence of the pulling point location on the mechanochemical reactivity of this mechanophore class. We find minor mechanochemical reactivity differences between the investigated constitutional mechanophore isomers. Concomitantly, our results highlight the capabilities and limitations of the employed experimental techniques for such delicate variances and raise the question whether these are relevant for mechanochemical applications in a material context.

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Triazole-Extended Anthracenes as Optical Force Probes

Cited by 5 publications

References 42 publications

Quantifying Activation Rates of Scissile Mechanophores and the Influence of Dispersity

Quantifying Activation Rates of Scissile Mechanophores and the Influence of Dispersity

Diverse reactivity of maleimides in polymer science and beyond

Regiochemical effects for the mechanochemical activation of 9‐π‐extended anthracene‐maleimide Diels–Alder adducts

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