Hydrogen-bond-assisted self-assembly of donor-acceptor structures for metal-free oxygen activation

Molecular oxygen (O 2 ) is a potential green oxidant. It is not only widely used for the selective oxidation of organic compounds, but also can synthesize hydrogen peroxide (H 2 O 2 ) through the oxygen reduction reaction (ORR) process in water. However, the spin prohibition of O 2 limits its application, and it requires an activation process to improve its reactivity. Among various catalysts for photocatalytic oxygen activation, covalent organic frameworks (COFs) with donor-acceptor (D-A) structures have shown promising potential. However, the construction of D-A structures through covalent bonds poses challenges in catalyst synthesis and expansion. In this work, we propose a hydrogen bond-assisted self-assembly method for COFs catalysts. The results show that after the self-assembly modification of K-TPBP with 9-anthracenemethanol, it exhibits better O 2 activation performance, and its H 2 O 2 production performance is doubled compared with the original catalyst. At the same time, the modified catalyst showed better reactivity in the selective aerobic oxidation of sulfides. Further insight into the mechanism revealed that the D-A structure analogs achieved via self-assembly modification effectively strengthen the built-in electric field on the catalyst surface and facilitate charge transfer and dispersion within the catalyst, highlighting its beneficial effect on the reaction.