One-Pot Sequential Catalysis as a General Method for Pore-Wall Functionalization of Vinylene-Linked Covalent Organic...

Vinylene-linked covalent organic frameworks (COFs) are robust crystalline porous materials with high thermal stability and extended π-conjugation, but their pore-wall functionalization remains challenging because many functional groups are incompatible with the basic conditions required for Knoevenagel polymerization. Here, we report a one-pot acid-base sequential catalytic strategy that decouples pore-wall functionalization from framework growth. Acid-catalyzed Schiff-base condensation between functional monoaldehydes and benzylic diamine nodes first installs pore-facing functional units and activates benzylic methylene sites; subsequent in situ switching to basic conditions promotes Knoevenagel polymerization with multitopic aldehydes to afford vinylene-linked COFs. Using this strategy, we constructed a chemically diverse series of functionalized COFs bearing nitro, halogen, organic oxoacid, electron deficient heterocycle, and cyano groups across mesoporous and narrow microporous architectures. The modular combination of functional monoaldehydes, diamine nodes, and COF forming aldehyde monomers enables systematic variation of inward-facing pore chemistry and pore aperture. Paired COFs with similar pore wall motifs but distinct pore apertures reveal how pore confinement regulates cooperative water vapor uptake. This work establishes one-pot sequential catalysis as a versatile paradigm for functionalizing vinylene-linked COFs and regulating their properties through coordinated control of pore chemistry and size.