Research Gallery
![Polymers that release small molecules in response to mechanical force are promising candidates as next-generation on-demand delivery systems. Despite advancements in the development of mechanophores for releasing diverse payloads through careful molecular design, the availability of scaffolds capable of discharging biomedically significant cargos in substantial quantities remains scarce. In this report, we detail a nonscissile mechanophore built from an 8-thiabicyclo[3.2.1]octane 8,8-dioxide (TBO) motif that releases one equivalent of sulfur dioxide (SO2) from each repeat unit. The TBO mechanophore exhibits high thermal stability but is activated mechanochemically using solution ultrasonication in either organic solvent or aqueous media with up to 63% efficiency, equating to 206 molecules of SO2 released per 143.3 kDa chain. We quantified the mechanochemical reactivity of TBO by single-molecule force spectroscopy and resolved its single-event activation. The force-coupled rate constant for TBO opening reaches ∼9.0 s–1 at ∼1520 pN, and each reaction of a single TBO domain releases a stored length of ∼0.68 nm. We investigated the mechanism of TBO activation using ab initio steered molecular dynamic simulations and rationalized the observed stereoselectivity. These comprehensive studies of the TBO mechanophore provide a mechanically coupled mechanism of multi-SO2 release from one polymer chain, facilitating the translation of polymer mechanochemistry to potential biomedical applications.](https://static.wixstatic.com/media/13c469_dcd60e0427e441068c6ec43dee0a4098~mv2.jpeg/v1/fit/w_723,h_707,q_90/13c469_dcd60e0427e441068c6ec43dee0a4098~mv2.webp)
![Macrocyclic dimeric lactones have pharmacological activities that make them attractive synthetic targets, but typical synthetic strategies employ an iterative approach to construct the macrocycle. Herein, we report a visible-light-mediated approach that enables facile access to 1- and 2-azetine-based dimeric lactones of up to 30-membered ring macrocycles. These products form via four consecutive triplet energy transfers for 1-azetine dimeric products and two consecutive triplet energy transfers for 2-azetine dimeric products. Computational investigations provide insights into the mechanism of this reaction, consistent with an unexpected initial intermolecular [2 + 2]-cycloaddition being preferred under nonstandard Curtin–Hammett conditions over the corresponding intramolecular reaction, which ultimately enables an efficient reaction pathway for macrocyclic dimerization.](https://static.wixstatic.com/media/13c469_570ab6406196469da2ac8a5ea386f19c~mv2.jpeg/v1/fit/w_791,h_514,q_90/13c469_570ab6406196469da2ac8a5ea386f19c~mv2.webp)
Follow Our Center's Research:
Research that drives:
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Fundamental chemical advances in molecule-material relationships by recasting a major field of study as a fully chemistry-centered sub-discipline and extending our understanding and application of fundamental chemical principles.
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Technological advances that rewrite existing performance and end-of-life rules for polymer network materials via efficient chemical resetting and recycling to improve performance, extend lifetime, and minimize waste stream.
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Conceptual advances, by demonstrating that new forms of embedded covalent response, such as reactive strand extension, improve the limits to which polymer gels and elastomers can be stretched and the energy they can absorb.
Our accomplishments continue to evolve.
Please see our collection of publications that describe some of the achievements of our team.