Generation and Confinement of Long-Lived N-Oxyl Radical and Its Photocatalysis

Generation of controllable carbon radical under the assistance of N-oxyl radical is an efficient method for the activation of C-H bonds in hydrocarbons. We herein report that irradiation of α-Fe₂O₃ and N-hydroxyphthalimide (NHPI) under 455 nm light generates phthalimide-N-oxyl radical (PINO*), which after being formed by oxidation with holes, is confined on α-Fe₂O₃ surface. The half-life time of the confined radical reaches 22 s as measured by in situ electron paramagnetic resonance (EPR) after the light being turned off. This allows the long-lived N-oxyl radical to abstract the H from C-H bond to form a carbon radical that reacts with molecular oxygen to form R₃C-OO· species, decomposition of which leads to oxygenated products.