Influence of Structural Isomerism in Multicomponent Covalent Organic Frameworks on Their Photocatalytic H2O2 Production
Constitutional isomerism in covalent organic frameworks (COFs) has emerged as a powerful strategy to tailor material properties for photocatalytic applications. Here, we report the design and synthesis of two isomeric multicomponent COFs (MC-COFs) via Schiff-base condensation followed by Povarov reaction, converting imine linkages into quinoline structures. These isomeric MC-COFs exhibit opposing C=N bond orientations and distinct phenyl group alignments within the COF pores, leading to different torsion angles in the COF layers. Structural analyses reveal that enhanced planarity promotes π-π stacking and electron delocalization, resulting in favorable band structures and reduced exciton binding energies. Consequently, the optimized COF achieves a superior hydrogen peroxide (H2O2) production rate of 3128 μmol g−1 h−1 under visible light irradiation. This work underscores the critical influence of structural isomerism on the photocatalytic efficiency of MC-COFs and provides insights for rational design of high-performance COF-based photocatalysts.