Linkage orientation in covalent organic frameworks directs peroxymonosulfate activation toward selective singlet oxygen generation for antibiotic degradation

The catalytic activation of peroxymonosulfate (PMS) by covalent organic frameworks (COF) presents a promising advanced oxidation process (AOP) for water remediation. However, the influence of atomic-level linkage engineering on the PMS activation mechanism remains poorly understood. Here, we demonstrate that subtle manipulation of imine linkage orientation in two isomeric COF dictates their catalytic activity towards selectively generating singlet oxygen ( 1 O 2 ), a long-lived reactive oxygen species. We reveal that the spatial arrangement of the polar C N bond governs electronic structure and electron transfer behaviors by modulating intralayer coplanarity and the degree of electron delocalization across the COF skeleton. This structural control directly impacts the PMS adsorption and consequent 1 O 2 catalytic generation pathway, resulting in a 9.6-fold difference in the degradation rate constant for sulfamethoxazole (SMX, a cytotoxic antibiotic pollutant). The optimal COF catalyst achieves complete removal of SMX within 2 min, outperforming most state-of-the-art catalysts. This work elucidates the critical role of linkage orientation in COF-catalyzed PMS activation and providing new insights into the water remediation by 1 O 2 -mediated AOPs.