Visible light-driven photocatalytic thiol–ene/yne reactions using anisotropic 1D Bi2S3 nanorods: a green synthetic approach

Abstract

Thiol–ene/yne click reactions play a significant role in creating carbon–sulfur (C–S) bonds, and there has been a growing interest in using visible-light photoredox catalysis for their formation. In this study, anisotropic 1D Bi₂S₃ nanorods were prepared using a simple polyol-assisted reflux method, and they were used as catalysts for the thiol–ene/yne click reactions under visible light irradiation. The developed protocol is highly compatible and tolerant to various substrates with excellent product yields. Also, thiol–ene and –yne reactions achieved maximum TONs of 93 and 95, respectively. Detailed mechanistic studies were conducted and supported by NMR studies, radical trapping utilizing TEMPO, and ESI-MS product analysis. The ability of Bi₂S₃ nanorods to catalyze thiol–ene/yne reactions is primarily due to the creation of photoexcited holes, which aid in the formation of thiyl radicals. This method can be scaled up to the gram-scale synthesis of benzyl styryl sulfide with an excellent chemical yield of 90%. The 1D Bi₂S₃ nanorods also demonstrated structural and morphological stability throughout five reaction cycles while maintaining a favorable photocatalytic activity. The developed methodology had the advantages of broad substrate scope, mild reaction conditions, scaled-up synthesis, and nonrequirement of free radical initiators.