Energy transfer-mediated multiphoton synergistic excitation for selective C(sp 3)–H functionalization with coordination polymer

Abstract

Abstract Activation and selective oxidation of inert C(sp 3)–H bonds remain one of the most challenging tasks in current synthetic chemistry due to the inherent inertness of C(sp 3)–H bonds. In this study, inspired by natural monooxygenases, we developed a coordination polymer with naphthalenediimide (NDI)-based ligands and binuclear iron nodes. The mixed-valence FeIIIFeII species and chlorine radicals (Cl•) are generated via ligand-to-metal charge transfer (LMCT) between FeIII and chlorine ions. These Cl• radicals abstract a hydrogen atom from the inert C(sp 3)–H bond of alkanes via hydrogen atom transfer (HAT). In addition, NDI converts oxygen to 1O2 via energy transfer (EnT), which then coordinates to FeII, forming an FeIV = O intermediate for the selective oxidation of C(sp 3)–H bonds. This synthetic platform, which combines photoinduced EnT, LMCT and HAT, provides a EnT-mediated parallel multiphoton excitation strategy with kinetic synergy effect for selective C(sp 3)–H oxidation under mild conditions and a blueprint for designing coordination polymer-based photocatalysts for C(sp 3)–H bond oxidation.