Photoswitchable dynamic conjugate addition-elimination reactions as a tool for light-mediated click and clip chemistry

Phototriggered click and clip reactions can endow chemical processes with high spatiotemporal resolution and sustainability, but are challenging with a limited scope. Herein we report photoswitchable reversible covalent conjugate addition-elimination reactions toward light-addressed modular covalent connection and disconnection. By coupling between photochromic dithienylethene switch and Michael acceptors, the reactivity of Michael reactions was tuned through closed-ring and open-ring forms of dithienylethene, allowing switching on and off dynamic exchange of a wide scope of thiol and amine nucleophiles. The breaking of antiaromaticity in transition states and enol intermediates of addition-elimination reactions provides the driving force for photoinduced change in kinetic barriers. To showcase the versatile application, light-mediated modification of solid surfaces, regulation of amphiphilic assemblies, and creation/degradation of covalent polymers on demand were achieved. The manipulation of dynamic click/clip reactions with light should set the stage for future endeavors, including responsive assemblies, biological delivery, and intelligent materials. Photoinduced dynamic covalent bonds have the advantage of light-mediated bond making and breaking. Here, the authors report photoswitchable dynamic conjugate addition-elimination reactions with a broad scope and demonstrate diverse applications.

Automated summary

Phototriggered click and clip reactions can achieve high spatiotemporal resolution and sustainability in chemical processes, and this study reports a photoswitchable reversible covalent conjugate addition-elimination reaction with a broad scope. By coupling a photochromic dithienylethene switch with Michael acceptors, the reactivity of Michael reactions can be controlled, allowing the dynamic exchange of various nucleophiles. The authors demonstrate the versatile applications of this reaction, including light-mediated surface modification, regulation of amphiphilic assemblies, and creation/degradation of covalent polymers on demand.