Remote Control Over Covalent Assemblies With Photoswitch-Modulated Dynamic C-N Bonds

Dynamic covalent assemblies offer ample structural and functional diversity, and dynamic bonding systems with tunable stability and controlled bond transformation are challenging to achieve due to the inherent conflict between the stability and the reversibility. Herein we report a photoswitching-mediated C-N bond strategy based on a novel molecular design that overcomes this limitation, enabling remote and multiple regulation of dynamic covalent macrocycles and polymers. The integration of dithienylethene (DTE) with sultam-derived hemiaminal provided photocontrolled switching of reactivity, where the closed-ring form undergoes facile C-N bond making/breaking while the open-ring form remains kinetically locked. This photoswitchable platform allowed the construction of intramolecular/intermolecular macrocycles by incorporating multiple reactive sites via modular synthesis. On-demand reversible topological transformation between an intramolecular macrocycle and its linear scaffold was realized with light and acid/base stimuli. Moreover, the change of irradiation wavelength achieved reversal of kinetic selectivity and photoprogrammed self-sorting in competing intermolecular macrocycle systems, further locking non-equilibrium states and temporal component distribution with light. Finally, the strategy was employed for photocontrolled polymer degradation and polymer-to-macrocycle conversion. This work showcases the capability of sulfonamide-based photoaddressed dynamic C-N bonds for constructing diverse architectures and should set the stage for adaptive materials and responsive systems.