Emodin as a novel organic photocatalyst for selective oxidation of sulfides under mild conditions.

Herein, we have developed naturally-occurring Emodin, which is commercially available at low-cost, as a novel organic photocatalyst for the first time. Emodin was successfully employed in the selective oxidation of sulfides promoted by visible-light, delivering valuable sulfoxides with high efficiency. Mechanistic investigations suggested both single-electron transfer (SET) and energy transfer (EnT) pathways might be involved in the oxidation reaction.