Enhanced Visible-Light Photoredox Catalysis with Rubicene-Embedded Polycyclic Aromatic Hydrocarbons (PAHs)

Abstract

Visible-light-absorbing, metal-free photoredox catalysts are attractive because they are inexpensive and offer tunable redox potentials. However, the use of organic photocatalysts is often limited by their incompatibility with strongly acidic or basic media and by short excited-state lifetimes. Here we report a series of rubicene-based organic photoredox catalysts that operate under visible-light irradiation and promote substitution, addition and chemical-doping reactions. Mechanistic studies, including radical-trapping experiments and Stern-Volmer fluorescence-quenching analyses, support a singleelectron-transfer (SET) pathway. Notably, the rubicene-based catalysts exhibit excellent operational stability and higher reactivity than commercial metal-free photocatalysts, indicating a broad scope and high tolerance in metal-free photoredox transformations.