Seven anthraquinone-based photosensitizers were synthesized via structural modification at the α- and β-positions of the anthraquinone core. These compounds exhibited excellent photocatalytic performance in the photooxidation of methyl groups. Specifically, 2-trifluoromethylanthraquinone (PC6) was identified as the most active and selective catalyst, with a photocatalytic rate nearly 30-fold higher than that of unmodified anthraquinone. Moreover, PC6 showed good substrate generality, affording favorable to excellent yields for most electron-deficient and electron-rich heteroaromatic methyl derivatives. Systematic characterizations, including UV-Vis absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and density functional theory (DFT) calculations, were conducted to elucidate the catalytic mechanism. The results revealed that the enhanced catalytic performance of PC6 is primarily attributed to its higher fluorescence quantum yield, which is 2.5 times that of anthraquinone. This photocatalytic system features simplicity, high efficiency, mild reaction conditions, and excellent functional group tolerance. Thus, it provides an efficient catalyst and a practical strategy for C(sp³)—H activation reactions.

Key words: photocatalysis, anthraquinone photosensitizer, C(sp³)—H oxidation