Harnessing the Conformer/Atropisomer-Dependent Photochromism of Diarylethene Photoswitches and Forcing a Diarylethene Atropisomer to Its Configurational Diastereomers with Polymer Mechanochemistry

Diarylethenes are an important class of photoswitches that usually exist in interconvertible parallel (photoinert) and antiparallel (photochromic) conformational states. Recent research afforded sterically congested diarylethenes that exist as stable and separable configurational atropisomers. Rational manipulation of stereochemistry is a robust strategy for regulating diarylethene photochemistry. Here, we present a brief account of the conformer/atropisomer-dependent photochromism of diarylethene photoswitches, and we discuss a recent advance at the interface of diarylethene photochemistry and polymer mechanochemistry: our group recently introduced a mechanical approach for converting a parallel diarylbenzothiadiazole into its antiparallel configurational diastereomers, thereby turning on its photochromic reactivity. After mechanical activation, UV light changes the converted diarylethene molecule into a colored ring-closed form by a 6?-electrocyclization reaction that permits the visualization of the mechanical activation event. Besides the fundamentally new mechanism of converting a molecule into its configurational diastereomers through force stereochemistry coupling, the conversion of atropisomer stereochemistry is a noncovalent process and features high mechanical reactivity in comparison to conventional mechanophores, which require covalent bond scission. This new type of configurational mechanophore holds promise for various applications, such as high-sensitivity stress sensing, lithography, and information storage. 1 Diarylethene Conformers and Atropisomers 2 Polymer Mechanochemistry and Configurational Mechanophores 3 Regulating the Stereochemistry and Reactivity of a Diarylethene Atropisomer with Mechanical Force 4 Summary and Future Outlook.