Insights into the development of 2D covalent organic frameworks as photocatalysts in organic synthesis

Two-dimensional covalent organic frameworks (2D COFs) exhibit distinctive characteristics, including tunable topology, an extensive specific surface area, susceptibility to functionalization, and robust stability, making them frequently utilized in multiphase photocatalytic applications. This article begins with an overview of the synthesis methods for 2D COFs, covering solvothermal, ionothermal, mechanochemical, microwave-assisted, sonochemical, and interfacial synthesis techniques. It provides a concise introduction to various factors influencing photocatalytic performance, such as crystallinity and stability, band structure, charge transfer capability, pore size and specific surface area, and the nature of the light source. Subsequently, the discussion shifts to summarizing and analyzing advancements in the use of 2D COFs as photocatalysts for organic small molecule conversion reactions, particularly in photocatalytic oxidation, reduction, and coupling reactions. Finally, a summary and outlook are presented regarding the opportunities and challenges that 2D COFs face in photocatalytic organic transformations.