Metal-free G-C3N4 Nanosheets As A Highly Visible-light-active ...

Metal-free g-C3N4 nanosheets as a highly visible-light-active photocatalyst for thiol–ene reactions†

Shouren Zhang, ‡a Wenjing Yi,‡a Yanzhen Guo,a Ruoqi Ai,b Zhichao Yuan,a Baocheng Yang*a and Jianfang Wang *b Author affiliations

* Corresponding authors

a Henan Key Laboratory of Nanocomposites and Applications, Institute of Nanostructured Functional Materials, Huanghe Science and Technology College, Zhengzhou 450006, China E-mail: [email protected]

b Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China E-mail: [email protected]

Abstract

Thiol–ene click reactions are important for the construction of carbon–sulfur bonds. The use of visible-light photoredox catalysis for the formation of C–S bonds has attracted much attention. In this work, two-dimensional metal-free graphitic carbon nitride (g-C3N4) nanosheets are prepared through a simple thermal polymerization method and used to catalyze the thiol–ene click reaction under visible light-illumination. This green, atom-economic, and inexpensive approach for the hydrothiolation of alkenes is applicable for structurally different substrates and exhibits superior yields. In air or nitrogen atmosphere, the reaction yield decreases when a hole scavenging agent, CH3OH, is introduced, which indicates that photogenerated holes in the g-C3N4 nanosheets play an important role in the formation of thiyl radicals. The g-C3N4 nanosheets still show a good stability and favorable photocatalytic activity after five cycles of the reaction. Moreover, this approach can be scaled up to the gram-scale synthesis of benzyl(phenethyl)sulfane with a yield up to 93%. Our study suggests a good potential of semiconducting g-C3N4 nanosheets as a metal-free, efficient photocatalyst for various thiol–ene click reactions and even for other organic reactions.

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