Ambient Nucleation and Growth of Highly Crystalline Imine-Connected Covalent Organic Frameworks for Scalable Synthesis

The exploration of facile polymerization strategies is critical for circumventing frustrating issues in the preparation of conventional covalent organic frameworks (COFs) and promoting their promising applications. Here, we report an ambient nucleation and growth strategy for synthesizing highly crystalline imine-connected COFs. The tetrahydrofuran/toluene cosolvent ensures the optimal dissolution of both monomers and oligomers, while aliphatic amine further enhances the solubility of aldehyde monomers and modulates the molecular assembly dynamically. Ordered COF nanosheets are observed in the early stage of polymerization, indicating the different nucleation mechanism from the predominant error-correction concept. This strategy demonstrates great versatility and robustness for 12 COFs with various functional groups and programmable topologies are successfully prepared, and near-theoretical surface areas in COF-TBDM and COF-TATA are achieved even in the large-scale (5 g) production batch. The effective integration of palladium nanoparticles (Pd NPs) on COF-TBDM is realized, resulting in a Pd@COF-TBDM catalyst with exceptional catalytic performance and stability during the nitro-hydrogenation reaction.