Layered Double Hydroxide-Stabilized AgI Photocatalyst for Efficient Arene Arylation and Alkylation.

Developing clean and efficient methods for carbon-carbon bond formation remains a central challenge in sustainable chemistry. Here, we report a unified photocatalytic strategy for direct arene arylation and alkylation under visible light. By integrating silver iodide (AgI) nanoparticles with magnesium-aluminum-layered double hydroxide (Mg2Al1-LDH), we achieve efficient cross-coupling of arenes with both aryl and unactivated alkyl iodides under mild conditions and natural sunlight. This system operates without external bases or photoredox cocatalysts and tolerates base-sensitive functional groups, producing only water and iodine as byproducts. Mechanistic studies reveal a synergistic process in which photogenerated electrons reduce halides via an inner-sphere transfer mechanism, while photogenerated holes oxidize surface hydroxyl groups to generate ·OH radicals. These radicals enable hydrogen abstraction and C-H bond activation, completing the coupling process. The availability of surface hydroxyls and oxygen vacancies, along with favorable band alignment between AgI and Mg2Al1-LDH, is critical to catalyst performance. This work demonstrates the first example of a single catalyst system enabling both arylation and alkylation through a unified radical mechanism, offering a sustainable platform for light-driven C-H functionalization and expanding the frontiers of green synthetic chemistry.