A Metal-Organic Framework as a Multiphoton Excitation Regulator for the Activation of Inert C(sp3)-H Bonds and Oxygen.

The activation and oxidization of inert C(sp3)-H bonds into value-added chemicals affords attractively economic and ecological benefits as well as central challenge in modern chemistry. Inspired by the natural enzymatic transformation, herein, we report a new multiphoton excitation approach to activate the inert C(sp3)-H bonds and oxygen by integrating the photoinduced electron transfer (PET), ligand-to-metal charge transfer (LMCT) and hydrogen atom transfer (HAT) events together into one metal-organic framework. The well-modified nicotinamide adenine dinucleotide (NAD+) mimics oxidized CeIII-OEt moieties to generate CeIV-OEt chromophore and its reduced state mimics NAD• via PET. The in situ formed CeIV-OEt moiety triggers a LMCT excitation to form the alkoxy radical EtO•, abstracts a hydrogen atom from the C(sp3)-H bond, accompanying the recovery of CeIII-OEt and the formation of alkyl radicals. The formed NAD• activates oxygen to regenerate the NAD+ for next recycle, wherein, the activated oxygen species interacts with the intermediates for the oxidization functionalization, paving a catalytic avenue for developing scalable and sustainable synthetic strategy.