Direct activation of C(sp3)−H bonds by carbon dots photoredox catalysts

Photoredox catalysis driven by precious metal complexes has unlocked significant opportunities in organic synthesis. However, their extreme scarcity and high environmental footprint necessitate the development of more sustainable alternatives. While other photocatalysts such as organic dyes and polyoxometalate anions have been explored, they often suffer from limited tunability of their photophysical properties. Carbon dots (CDs), low-cost and easily synthesized materials with highly tunable photo- and electro-physical characteristics, offer a promising yet underexplored option for photocatalysis. Here, we present the first example of CDs-catalyzed photoredox C(sp³)–H bond functionalization. Remarkably, minor variations in CDs composition significantly alter reactivity, switching between Giese radical addition and dehydrogenative annulation. These results establish CDs as versatile, metal-free photoredox catalysts, offering unique selectivity and mechanistic diversity for sustainable organic synthesis.