Advances and Mechanistic Insights into Covalent Organic Framework-Mediated Photocatalysis for Organic Transformations

Photocatalysis offers a mild and energy-efficient strategy for organic synthesis, yet developing systems that integrate high activity, selectivity, and recyclability remain a major challenge. Covalent organic frameworks (COFs) have emerged as a distinctive class of crystalline porous polymers with promise in visible-light-driven organic photocatalysis. Their tunable architecture, high stability, and designable optoelectronic properties endow COFs with distinctive advantages as heterogeneous photocatalysts. This review comprehensively summarizes recent advances in COF-mediated photocatalytic organic transformations, with a particular focus on the underlying reaction mechanisms. We highlight representative reaction categories, including oxidation, addition, C–H functionalization, cross-coupling, and more, and examine how the structural features of COFs influence reactivity and selectivity. Methodologies employed to elucidate reaction mechanisms are critically discussed, offering insights into the fundamental principles governing photocatalytic behavior. Moreover, we outline recent developments in hybrid systems integrating COFs with transition metals to enhance catalytic activity and broaden reaction scopes. Despite notable progress, challenges remain in expanding the diversity of COF-photocatalyzed reactions and unraveling complex structure–activity relationships. Looking forward, we propose future directions involving tailored COFs design, advanced mechanistic investigations, and the development of multifunctional, synergistic catalytic systems. This review aims to offer a mechanistic foundation and design blueprint for advancing COF-based platforms in organic synthesis.