Phenolic Resin with an Optimized Donor–Acceptor Architecture for Photocatalytic Aerobic Oxidation

A promising strategy to enhance exciton dissociation and charge separation in phenolic-polymer-based photocatalysts is the generation and utilization of benzenoid–quinoid donor–acceptor (D–A) couples inside the phenolic resin frameworks. However, there are often more donors than acceptors in phenolic resin due to the sluggish kinetics of in situ oxidation of phenols to quinoid methides, leading to a mismatched D/A ratio. Herein, we report a well-cross-linked phenolic resin with a unity D/A ratio synthesized by using phloroglucinol as a building block for condensation with formaldehyde. The higher electron density on the aromatic ring not only facilitates the in situ oxidation of phloroglucinols to quinoid methides, forming equivalent D–A couples, but also lowers the energy barrier for the condensation reaction, resulting in a highly cross-linked framework with a well-developed π-conjugated electronic structure. The phloroglucinol-formaldehyde resin product demonstrates significantly improved photocatalytic performance in the selective oxidation of methyl phenyl sulfide and the oxidative coupling of benzylamine. Our approach shows the potential of photocatalytic phenolic resins for solar-induced chemical conversion.