Synthesis of Imine-Based Covalent Organic Frameworks Catalyzed by Metal Halides and in Situ Growth of Perovskite@COF Composites

The development of economical and versatile catalysts is of both technological and fundamental interest in the synthesis of COFs. Imine COFs are a widely investigated class of COFs commonly synthesized via the Schiff base reaction that requires the use of acetic acid, elevated temperatures, reduced pressure, and long reaction periods. Here, we present group 14-15 metal halides as general and low-cost catalysts for the synthesis of imine COFs. The catalytic activity of lead, antimony, and bismuth halides is proved by the successful synthesis of a series of imine COFs with varying pore sizes and structural stability. Synthesis of highly crystalline COFs with surface areas up to 2522 m(2)/g is achieved. Mechanistic studies reveal that the dynamic imine exchange triggered by metal halides promotes the crystallization of COFs. The COF matrices formed under metal halide catalysis were used for in situ perovskite synthesis. The perovskite@COF composites maintain the integrity of COFs while enhancing the stability of perovskites by being embedded in COFs. This work expands the catalyst choice for imine-based COFs and provides a design paradigm for the synthesis of perovskite@COF composites for future applications.