Rapid Crystallization and Versatile Metalation of Acetylhydrazone-Linked Covalent Organic Frameworks for Heterogenous Catalysis

Covalent organic frameworks (COFs) hold promise in heterogeneous metal catalysis benefiting from their robust, crystalline, and porous structures. However, synthetic challenges persist in prolonged crystallization times, limited metal loading, and uncertain coordination environments. Here, we present the rapid crystallization and versatile metalation of new acetylhydrazone-linked COFs (AH-COFs) by condensation of ketone and hydrazide components, featuring full conversion within 30 min under open-air and mild conditions. The obtained AH-COFs exhibit exceptional thermal and chemical stability, maintaining high crystallinity and microporosity even under harsh conditions. This method shows the versatility of in situ metalation through subcomponent assembly with a wide range of metal centers, and the delicate control of coordination geometry through isoreticular functionalization for fine-tuning of the pore environments and metal catalytic activity. The metalated AH-COFs demonstrate excellent catalytic performance: AH-COF-2-Zn achieves high efficiency in CO₂ cycloaddition, while AH-COF-1-Cu-PSM achieves near-quantitative conversion in copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions, with both catalysts retaining their activity over multiple cycles. This study offers an efficient and versatile method for the rapid crystallization of designable, stable, and functional COFs, heading to practical applications prioritized on efficiency, scalability, and sustainability.