Synthesis of C−C Bonded Two‐Dimensional Conjugated Covalent Organic Framework Films by Suzuki Polymerization on a Liquid–Liquid Interface

Synthesis of free‐standing two‐dimensional (2D) conjugated covalent organic framework (COF) films linked by C−C bonds is highly desirable. Now a very simple and mild strategy has been developed to synthesize them by Suzuki polymerization on a water–toluene interface in a refrigerator. The versatility of this strategy was confirmed by the successful synthesis of two different 2D‐COF films: a porous graphene and a porphyrin‐contained 2D‐COF. Both 2D‐COF films have large lateral size and their crystalline domains were visualized by high resolution TEM. Based on the wide compatibility of Suzuki reaction, our breakthrough work opened a door for the synthesis of various 2D conjugated COF films. For application studies, the porous graphene exhibits a good carrier mobility, which is much higher than −C=N− linked 2D COF films and a good catalytic activity for hydrogen evolution reaction, which is comparable with nitrogen‐ or phosphorus‐doped graphene. COFs at the interface: A very simple and mild strategy to synthesize 2D conjugated COF films was developed. The method uses Suzuki polymerization on a liquid–liquid interface at low temperature (2 °C).