Suspending ionic single-atom catalysts in porphyrinic frameworks for highly efficient aerobic oxidation at room temperature

Room temperature and atmosphere pressure are highly desired catalytic conditions for aerobic oxidation of inert sp3 CH bonds. To meet this challenge, we developed a simple strategy by suspending ionic single atoms (ISAs) inside the anionic pores of metal–organic frameworks (MOFs). CZJ-22-Cu, consisting of suspended ISA copper(II) inside the anionic pores, exhibits exceptionally high catalytic efficiency in aerobic oxidation of ethers to esters at room temperature and atmosphere pressure, in which turnover number (TON) 77,100 and turnover frequency (TOF) 7710 h−1 have been realized for aerobic oxidation of isobenzofuran. The unmatched catalytic properties of CZJ-22-Cu are attributed to the unique features of suspended ISAs inside the anionic pores, which result in high surface free energy of redox-active centers, and the substrate-selective accumulation nature of the inside pores, which would significantly improve the reactivity and reaction rate.