Perspectives for Uranyl Photoredox Catalysis

The application of uranyl salts as powerful photoredox catalysts in chemical transformations lags behind the advances achieved in thermocatalysis and structural chemistry. In fact, uranyl cations (UO ₂²⁺) have proven to be ideal photoredox catalysts in visible-light-driven chemical reactions. The excited state of uranyl cations (^*UO ₂²⁺) that is generated by visible-light irradiation has a long-lived fluorescence lifetime up to microseconds and high oxidizing ability [ E ^o= +2.6 V vs. standard hydrogen electrode (SHE)]. After ligand-to-metal charge transfer (LMCT), quenching occurs with organic substrates via hydrogen-atom transfer (HAT) or single-electron transfer (SET). Interestingly, the ground state and excited state of uranyl cations (UO ₂²⁺) are chemically inert toward oxygen molecules, preventing undesired transformations from active oxygen species. This review summarizes recent advances in photoredox transformations enabled by uranyl salts. 1 Introduction 2 The Application of Uranyl Photoredox Catalysis in HAT Mode 3 The Application of Uranyl Photoredox Catalysis in SET Mode 4 Conclusion and Outlook.