Volume 248, 2024

Singlet oxygen formation in non-aqueous oxygen redox chemistry: direct spectroscopic evidence for formation pathways and reliability of chemical probes

Abstract

Singlet oxygen (1O2) formation is now recognised as a key aspect of non-aqueous oxygen redox chemistry. For identifying 1O2, chemical trapping via 9,10-dimethylanthracene (DMA) to form the endoperoxide (DMA–O2) has become the main method due to its sensitivity, selectivity, and ease of use. While DMA has been shown to be selective for 1O2, rather than forming DMA–O2 with a wide variety of potentially reactive O-containing species, false positives might hypothetically be obtained in the presence of previously overlooked species. Here, we first provide unequivocal direct spectroscopic proof via the 1O2-specific near-infrared (NIR) emission at 1270 nm for the previously proposed 1O2 formation pathways, which centre around superoxide disproportionation. We then show that peroxocarbonates, common intermediates in metal–O2 and metal carbonate electrochemistry, do not produce false-positive DMA–O2. Moreover, we identify a previously unreported 1O2-forming pathway through the reaction of CO2 with superoxide. Overall, we provide unequivocal proof for 1O2 formation in non-aqueous oxygen redox chemistry and show that chemical trapping with DMA is a reliable method to assess 1O2 formation.

Graphical abstract: Singlet oxygen formation in non-aqueous oxygen redox chemistry: direct spectroscopic evidence for formation pathways and reliability of chemical probes

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
03 5 2023
Accepted
16 5 2023
First published
17 5 2023
This article is Open Access
Creative Commons BY-NC license

Faraday Discuss., 2024,248, 175-189

Singlet oxygen formation in non-aqueous oxygen redox chemistry: direct spectroscopic evidence for formation pathways and reliability of chemical probes

S. Mondal, R. B. Jethwa, B. Pant, R. Hauschild and S. A. Freunberger, Faraday Discuss., 2024, 248, 175 DOI: 10.1039/D3FD00088E

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