Halogenated polymers pose a persistent waste challenge with significant environmental impact. This perspective highlights emerging strategies—including photo-, electro-, and mechanochemistry—that facilitate depolymerization via halogen abstraction and polymer bond scission. These approaches open pathways to simultaneous carbon and halogen circularity by recovering halogens while converting polymer backbones into hydrocarbons and oxygenated chemicals.

Multi-site photoswitching is realized in a tetra-oxindole–resorcinarene that undergoes efficient all-E ↔ all-Z isomerization via thermodynamically favored pathways. Intramolecular hydrogen bonds and mechanochemically induced deprotonation cooperatively invert isomer stability. Density functional theory (DFT) and gas-phase ion mobility mass spectrometry (IM-MS) reveal charge-dependent switching direction. ABSTRACT Integration of multiple photoswitches into a single multi-responsive system is a promising strategy toward achieving high information density, complex logic operations, and large-amplitude motion. However, such systems typically suffer from poor efficiency. In this study, we present a strategy for efficient multi-site photoswitching that is based on realizing forward and reverse transformations along thermodynamically favorable pathways. We show that tetra-E-oxindole-resorcinarene undergoes effective multi-site photoswitching to form a tetra-Z-isomer, which is more stable due to the intramolecular hydrogen-bonding network. To achieve a reverse transformation, modulation of the relative stability of the isomers is required. Here, deprotonation under mechanochemical conditions effectively swaps stability, enabling effective back transformation to the tetra-E-isomer. Mechanochemistry is indispensable for this transformation, as swapping the stability of isomers is ineffective in solutions. By DFT calculations, we demonstrate that a network of hydrogen bonds is crucial for the modulation of isomers’ stability and multiplication of energetic effects. Finally, gas-phase ion mobility mass spectrometry provided a complementary picture, confirming the all-E ↔ all-Z interconversions and their charge-dependent direction.

Akitsu et al. show that clonotype-specific αβ T cell receptor-ligand geometry and force transmission bias cytotoxic T cell memory differentiation within a shared influenza A viral epitope response. Distinct receptor load polarities associate with effector-memory, central-memory, and bipolar outcomes, linking receptor mechanochemistry to memory fate.

Vukotic and coworkers introduce a modular, semi-automated platform integrating solution crystallization, mechanochemistry, thermal treatment, and in situ X-ray diffraction for high-throughput pharmaceutical solid form discovery. Applied to carbamazepine, it produced multicomponent phases in 122 of 144 reactions, yielding 33 solid forms while enabling rapid screening of polymorphs, solvates, and hydrates.

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Source: https://doi.org/10.1021/jacs.6c11635 At a glance Breaking carbon–fluorine bonds is only one part of PFAS treatment. The chemical form in which fluorine leaves the organic material matters a...

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