Rational Design and Advancement of Metal-Free Covalent Organic Frameworks for Photocatalytic Organic Transformation

Covalent organic frameworks (COFs) stand at the forefront of reticular chemistry, weaving crystalline porosity with unparalleled designability and functional tunability. Their expansive channels and modular architectures have driven rapid advances in photocatalytic organic transformations, providing a platform for sunlight-driven reactions with high selectivity and sustainability. This review spotlights the rational engineering of metal-free COFs—from pore-size orchestration to chromophore integration—as versatile platforms for selective C–H activation, cross-coupling, and beyond. We survey landmark advances since 2016, dissecting the structure–activity relationships that drive efficiency under visible light, while unveiling challenges such as charge recombination and scalability issues. By establishing in-depth correlations between the structure of metal-free COFs and their photocatalytic performance, this work offers new opportunities to forge ahead in synthetic chemistry.