Bond cleavage

Catalysis

Network covalent bonding

Supramolecular chemistry

Reactivity (psychology)

Dynamic covalent chemistry

Photochemistry

Molecule

Polymer

Alternative medicine

Combinatorial chemistry

Organic chemistry

Chemical stability

Computational chemistry

Tautomer

Molecular switch

Medicine

Chemistry

Covalent bond

Pathology

Journal of the American Chemical Society

The manipulation of covalent bonds could be directed toward degradable, recyclable, and sustainable materials. However, there is an intrinsic conflict between properties of stability and degradability. Here we report light-controlled formation/scission of three types of covalent bonds (C-N, C-O, and C-S) through photoswitching between equilibrium and nonequilibrium states of dynamic covalent systems, achieving dual benefits of photoaddressable stability and cleavability. The photocyclization of dithienylethene fused aldehyde ring-chain tautomers turns on the reactivity, incorporating/releasing amines, alcohols, and thiols reversibly with high efficiency, respectively. Upon photocycloreversion the system is shifted to kinetically locked out-of-equilibrium form, enabling remarkable robustness of covalent assemblies. Reaction coupling allows remote and directional control of a diverse range of equilibria and further broadens the scope. Through locking and unlocking covalent linkages with light when needed, the utility is demonstrated with capture/release of bioactive molecules, modification of surfaces, and creation of polymers exhibiting tailored stability and degradability/recyclability. The versatile toolbox for photoswitchable dynamic covalent reactions to toggle matters on and off should be appealing to many endeavors.

Light-Induced Formation/Scission of C–N, C–O, and C–S Bonds Enables Switchable Stability/Degradability in Covalent Systems