Covalent organic frameworks catalyzed by organic Lewis acid

We report the synthesis of covalent organic framework (COF) crystals with organic Lewis acid instead of the conventional use of Brønsted acid or inorganic Lewis acid. Specifically, tris(pentafluorophenyl)borane was applied for the growth of seven imine COFs: TAPB-PDA-, TAPB-2,5-DMTA-, TAPB-2,3-DMTA-, TAPT-PDA-, TAPT-2,5-DMTA-, TAPT-2,3-DMTA-COF with hcb topology and varied in functional groups, as well as a new one, COF-820, with sql topology. All these COFs were obtained at room temperature. Their high crystallinity and porosity demonstrate the versatility of the organic Lewis acid as a catalyst. Bulky organic Lewis acid was found critical for the production of COF-820, while its absence resulted in the formation of a different COF, 4PE-1P-COF, with kgm topology using the same building blocks. Such steric effect, typical for organic catalysts, provides a new way to regulate the topology of COFs and their future design.