A Single-Site Cu(II)-Anchored Covalent-Organic Framework for SO 2 Catalytic Conversion

Sulfur dioxide (SO 2 ) is a major atmospheric pollutant as well as an indispensable chemical raw material for the synthesis of sulfuric acid and fine chemicals. From the perspectives of efficiency, ecology, and economy, the catalytic SO 2 conversion into high value-added chemicals is particularly fascinating, while developing robust catalysts capable of efficiently activating and converting SO 2 remains extremely challenging. Herein, we report the rational construction of a single-site Cu(II)-anchored covalent-organic framework (COF), COF bpy -CuBr 2, for the highly efficient catalytic conversion of SO 2 . The COF bpy -CuBr 2 showed multiple favorable SO 2 adsorption sites within the framework, including OSO···Cu, O 2 S···π, and OSO···N contacts, thus exhibiting remarkable SO 2 selectivity and excellent SO 2 adsorption capacity of 10.98 mmol/g at 298 K and 1 bar. The strong Cu-SO 2 interactions promoted the enrichment of SO 2 at the catalytic center, further facilitating the SO 2 insertion in the coupling with aryl diazoniums and alcohols, thus enabling the highly efficient conversion into sulfonate esters. Moreover, COF bpy -CuBr 2 could be applied to the late-stage functionalization for the gram-scale synthesis of a biologically active coumarin derivative. Mechanism investigations revealed a Cu(II)-catalyzed radical pathway for this catalytic process. This work provides a novel paradigm for the rational construction of next-generation COFs to achieve highly efficient and selective SO 2 catalytic conversion.