The many faces of organosulfur compounds: photocatalysis, hydrogen-atom transfer, and electron donation in photochemical organic synthesis.

Organosulfur compounds, including thiols, thiobenzoic acids, and arene thiolates, have emerged as versatile and sustainable catalysts in visible-light photochemistry. Their ability to serve as photocatalysts, hydrogen-atom transfer (HAT) reagents, and electron donors enables direct photoexcitation to generate S-centered radicals that participate in single-electron transfer (SET) and HAT processes under mild, metal-free conditions. This review highlights recent advances (2013-2026) in the multifunctional roles of organosulfur compounds, with a focus on three distinct behaviors: (1) as photocatalysts enabling redox-neutral cross-couplings; (2) HAT catalysts for selective C-H and X-H bond functionalization; and (3) electron donors via EDA complex formation. Mechanistic insights and synthetic applications are discussed, with an emphasis on green chemistry principles such as catalyst-free conditions, low toxicity, and the use of visible light. The review concludes with an outlook on current limitations and future opportunities for sulfur-based photochemistry in sustainable synthesis.