One-pot mechanochemical access to quinoline-linked covalent organic frameworks

Abstract

Quinoline-linked COFs are formed by transforming reversible imine bonds into irreversible, π-extended quinoline linkages, thereby enhancing framework robustness and structural stability. Most reported syntheses, however, still rely on solvothermal methods that require high temperatures, multi-day reactions, and hazardous solvents. While mechanochemical synthesis has emerged as a solid-state and scalable alternative for COF construction, existing studies have predominantly focused on reversible linkages, such as imine and β-ketoenamine bonds, leaving the direct formation of irreversible quinoline-linked frameworks largely unexplored. Herein, we report a one-pot mechanochemical Povarov cascade that enables the in situ formation of imine-linked intermediates followed by their conversion into quinoline-linked COFs within a single vessel under open-air, room-temperature conditions. The reaction is completed within ∼3.5 h, affording eleven structurally diverse quinoline-linked COFs with high crystallinity and well-defined porosity, while requiring only trace amounts of liquid additives and supporting gram-scale synthesis. Comprehensive structural characterization confirms that the mechanochemically synthesized quinoline-linked COFs exhibit structural features comparable to those of solvothermal analogues. This work demonstrates an efficient solid-state route to irreversible linkage construction in COFs and broadens the scope of mechanochemical strategies for the synthesis of robust porous frameworks.