Fully Conjugated Covalent Organic Framework Nanosheets for Visible–Light–Driven Organic Synthesis in Water

Covalent organic framework (COF) nanosheets have recently garnered great attention as a new class of functional materials. As one of the sustainable processes, however, the photocatalytic organic synthesis in water has not been investigated using COF nanosheets as a photocatalyst to date. Herein, we reported the synthesis of a fully conjugated COF nanosheets with carboxyl functional group through a cooperative strategy of chemical exfoliation and group transformation. The new COF nanosheets was found to be an efficient heterogeneous photocatalyst for a wide range of organic synthesis including selective oxidation of sulfides and oxidative coupling of benzylamines in water under visible–light illumination. This work contributes a new roadmap for the design and synthesis of functional COF–based nanosheets, but also further extends the application boundary of the ultrathin COF nanosheets.