Mechanistic Insights into the Interface-Directed Transformation of Thiols into Disulfides and Molecular Hydrogen by Visible-Light Irradiation of Quantum Dots

Quantum dots (QDs) offer new and versatile ways to harvest light energy. However, there are few examples involving the utilization of QDs in organic synthesis. Visible‐light irradiation of CdSe QDs was found to result in virtually quantitative coupling of a variety of thiols to give disulfides and H...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2014-02, Vol.53 (8), p.2085-2089
Main Authors: Li, Xu-Bing, Li, Zhi-Jun, Gao, Yu-Ji, Meng, Qing-Yuan, Yu, Shan, Weiss, Richard G., Tung, Chen-Ho, Wu, Li-Zhu
Format: Article
Language:English
Subjects:
Cadmium selenides
Catalysts
Disulfide bonds
Disulfides
Energy harvesting
Formations
Hydrogen atoms
Irradiation
Light irradiation
Nickel
Oxidants
Oxidizing agents
photocatalysis
Quantum dots
Radiation
radical reactions
Reagents
Thiols
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Summary:Quantum dots (QDs) offer new and versatile ways to harvest light energy. However, there are few examples involving the utilization of QDs in organic synthesis. Visible‐light irradiation of CdSe QDs was found to result in virtually quantitative coupling of a variety of thiols to give disulfides and H2 without the need for sacrificial reagents or external oxidants. The addition of small amounts of nickel(II) salts dramatically improved the efficiency and conversion through facilitating the formation of hydrogen atoms, thereby leading to faster regeneration of the ground‐state QDs. Mechanistic studies reveal that the coupling reaction occurs on the QD surfaces rather than in solution and offer a blueprint for how these QDs may be used in other photocatalytic applications. Because no sacrificial agent or oxidant is necessary and the catalyst is reusable, this method may be useful for the formation of disulfide bonds in proteins as well as in other systems sensitive to the presence of oxidants. On the dot: A clean and efficient catalytic method for the preparation of disulfides from a variety of thiols in the absence of sacrificial reagents or external oxidants is described. Irradiation of CdSe quantum dots (QDs) with visible light results in good to excellent yields of the disulfides and equivalent amounts of H2. Mechanistic studies provide evidence for the formation of QD‐bound RS. and H. radicals as reaction intermediates.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201310249