Energy transfer-mediated multiphoton synergistic excitation for selective C(sp³)-H functionalization with coordination polymer.

Abstract

Activation and selective oxidation of inert C(sp³)-H bonds remain one of the most challenging tasks in current synthetic chemistry due to the inherent inertness of C(sp³)-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 Fe^IIIFe^II species and chlorine radicals (Cl^•) are generated via ligand-to-metal charge transfer (LMCT) between Fe^III and chlorine ions. These Cl^• radicals abstract a hydrogen atom from the inert C(sp³)-H bond of alkanes via hydrogen atom transfer (HAT). In addition, NDI converts oxygen to ¹O₂ via energy transfer (EnT), which then coordinates to Fe^II, forming an Fe^IV = O intermediate for the selective oxidation of C(sp³)-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(sp³)-H oxidation under mild conditions and a blueprint for designing coordination polymer-based photocatalysts for C(sp³)-H bond oxidation.