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1. Radical Reactivity of Thioimidates for Diversified Polymeric Amidines with Tunable Properties

   https://doi.org/10.1002/anie.202509727  

   Kinali‐Demirci, Selin; Demirci, Serkan; Byerly‐Duke, Jacob; VanVeller, Brett (July 2025, Angewandte Chemie International Edition)

   Abstract The first reactions of thioimidates under radical‐mediated conditions are described along with the delineation of structural factors that impact radical reactivity and possible side reactions. Thioimidate‐containing copolymers with methylmethacrylate (MMA) are synthesized through radical‐mediated, chain‐growth polymerization. These materials serve as a synthetic branch point for facile conversion into amidines by treatment with a weak acid and an external amine. Our approach allows for more diverse amidine structures than have been previously reported in polymers. This chemistry also enables crosslinking to form novel hydrogels with finely tuned acid–base behavior. Subsequent examination of the acid–base properties revealed that these features are preserved across linear, soluble amidine polymers to cross‐linked amidine gel polymer architectures. 

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2. Radical surface chemistry: Augmentation of reactivity by radicals at aqueous interfaces

   https://doi.org/10.1016/j.surfrep.2025.100668  

   Kolasinski, Kurt W (November 2025, Surface Science Reports)

   Cooperativity and non-additive interactions play central roles in the unusual and surprising behavior of water. A host of reactive oxygen species (ROS) including the hydroxyl radical •OH, superoxide radical anion (O2–•), hydroperoxide radical (HO2•), singlet oxygen (1O2), and also the more recently discussed water radical cation/anion pair (H2O+•/H2O–•) all add to the more familiar acid/base chemical pathways tread by hydronium (H3O+) and hydroxide (OH–). This is amplified in surface science because interfacial water – whether found at the gas/liquid, gas/solid, or liquid/solid interface – poses yet more unique behavior. This review explores the unexpected chemistry associated with ambient temperature aqueous interfaces much of which is mediated not only by ions and neutrals as expected, but also radical species. Water microdroplets catalyze numerous reactions and can also support simultaneous oxidation and reduction reactions through the production of reactive intermediates that owe their existence to the unique influence of the air/water or oil/water interface. Interfacial water influences and is influenced by the ubiquitous phenomenon of contact electrification, a manifestation of spontaneous symmetry breaking. The mechanisms of chemistry not only on and in microdroplets but also at the gas/solid and liquid/solid interfaces rely on a broad set of chemical transformations mediated by radicals. Furthermore, because aqueous macro- and micro-interfaces are ubiquitous on Earth, we find that water radical-mediated chemistry has applications to atmospheric chemistry, geochemistry, mineral weathering, pre-biotic chemistry, enhanced enzyme performance, wastewater remediation, public health, mechanochemistry, and potentially novel routes to pharmaceuticals. 

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3. Deciphering mechanism of excited state reactivity by spectroscopic methods

   https://doi.org/10.1016/j.jpap.2023.100207  

   Rakhimov, Sarvar Aminovich; Forbes, Malcolm D.E.; Sivaguru, Jayaraman (December 2023, Journal of Photochemistry and Photobiology)
4. Reactivity and statefulness: Action-based sensors, plans, and necessary state

   https://doi.org/10.1177/02783649221078874  

   McFassel, Grace; Shell, Dylan A. (May 2022, The International Journal of Robotics Research)

   Typically to a roboticist, a plan is the outcome of other work, a synthesized object that realizes ends defined by some problem; plans qua plans are seldom treated as first-class objects of study. Plans designate functionality: a plan can be viewed as defining a robot’s behavior throughout its execution. This informs and reveals many other aspects of the robot’s design, including: necessary sensors and action choices, history, state, task structure, and how to define progress. Interrogating sets of plans helps in comprehending the ways in which differing executions influence the interrelationships between these various aspects. Revisiting Erdmann’s theory of action-based sensors, a classical approach for characterizing fundamental information requirements, we show how plans (in their role of designating behavior) influence sensing requirements. Using an algorithm for enumerating plans, we examine how some plans for which no action-based sensor exists can be transformed into sets of sensors through the identification and handling of features that preclude the existence of action-based sensors. We are not aware of those obstructing features having been previously identified. Action-based sensors may be treated as standalone reactive plans; we relate them to the set of all possible plans through a lattice structure. This lattice reveals a boundary between plans with action-based sensors and those without. Some plans, specifically those that are not reactive plans and require some notion of internal state, can never have associated action-based sensors. Even so, action-based sensors can serve as a framework to explore and interpret how such plans make use of state. 

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5. Mechanochemical Reactivity of a Multimodal 2H-Bis-Naphthopyran Mechanophore

   https://doi.org/10.1039/d3py00344b  

   Osler, Skylar K.; McFadden, Molly E.; Zeng, Tian; Robb, Maxwell J. (June 2023, Polymer Chemistry)

   Multimodal mechanophores that react under mechanical force to produce discrete product states with uniquely coupled absorption properties are interesting targets for the design of force-sensing polymers. Herein, we investigate the reactivity of a 2H-bis-naphthopyran mechanophore that generates thermally persistent mono-merocyanine and bis-merocyanine products upon mechanical activation in solution using ultrasonication, distinct from the thermally reversible products generated photochemically. We demonstrate that a force-mediated ester C(O)–O bond scission reaction following ring opening establishes an intramolecular hydrogen bond, locking one merocyanine subunit in the open form. Model compound studies suggest that this locked subunit confers remarkable thermal stability to bis-merocyanine isomers possessing a trans exocyclic alkene on the other subunit, implicating the formation of an unusual trans merocyanine isomer as the product of mechanochemical activation. Density functional theory calculations unexpectedly predict a thermally reversible retro-cyclization reaction of the bis-merocyanine species that could explain the mechanochemical generation of the unusual trans merocyanine isomer. 

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