Urea/Thiourea Imine Linkages Provide Accessible Holes in Flexible Covalent Organic Frameworks and Dominates Self-Adaptivity and Exciton Dissociation

Unraveling the robust self-adaptivity and minimal energy-dissipation of soft reticular materials for environmental catalysis presents a compelling yet unexplored avenue. Herein, a top-down strategy, tailoring from the unique linkage basis, flexibility degree, skeleton electronics to trace-guest adaptability, is proposed to fill the understanding gap between micro-soft covalent organic frameworks (COFs) and photocatalytic performance. The thio(urea)-basis-dominated linkage within benzotrithiophene-based COFs induce the framework contraction/swelling (intralayer micro-flexibility) in response to tetrahydrofuran or water. Adaptability of micro-flexible thiourea-COF with pore hydrophilicity not only contributes to the favorable mass transfer, but also enhances the accessible redox active sites, culminating in nearly 100% removal of micropollutant with low-energy dissipation in wastewater. The incorporating urea/thiourea into imine linkage facilitates polarization reduction and exciton dissociation within skeleton wall, inducing strong localization for holes. This transformation facilitates interchain charge transport and unbalanced distribution conducive to oxidative holes-mediated micropollutant decomposition.