Ionic liquid as a green solvent for ionothermal synthesis of 2D keto-enamine-linked covalent organic frameworks

Covalent organic frameworks (COFs) are usually synthesized under solvothermal conditions in a mixture of high-boiling organic solvents in a sealed system. By using a room temperature ionic liquid (IL) as a solvent, we presented the preparation of two-dimensional (2D) keto-enamine-linked COFs in an open container at ambient pressure. The as-synthesized 2D keto-enamine-linked COFs have ordered open channels and so the IL can be completely removed from the pores to provide the sole formation of crystalline 2D COFs. Not only the imidazolium-based IL acted as both solvent and catalyst, it was also recycled for further use without activity loss.