Non-classical disproportionation revealed by photo-chemically induced dynamic nuclear polarization NMR

Abstract: Photo-chemically induced dynamic nuclear polarization (photo-CIDNP) was used to observe the light-induced disproportionation reaction of 6,7,8-trimethyllumazine starting out from its triplet state to generate a pair of radicals comprising a one-electron reduced and a one-electron oxidized species. Our evidence is based on the measurement of two marker proton hyperfine couplings, Aiso(H(6α)) and Aiso(H(8α)), which we correlated to predictions from density functional theory. The ratio of these two hyperfine couplings is reversed in the oxidized and the reduced radical species. Observation of the dismutation reaction is facilitated by the exceptional C–H acidity of the methyl group at position 7 of 6,7,8-trimethyllumazine and the slow proton exchange associated with it, which leads to NMR-distinguishable anionic (TML−) and neutral (TMLH) protonation forms

Location
Deutsche Nationalbibliothek Frankfurt am Main
Extent
Online-Ressource
Language
Englisch
Notes
Magnetic resonance. - 2, 1 (2021) , 281-290, ISSN: 2699-0016

Event
Veröffentlichung
(where)
Freiburg
(who)
Universität
(when)
2021
Creator

DOI
10.5194/mr-2-281-2021
URN
urn:nbn:de:bsz:25-freidok-2179673
Rights
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Last update
14.08.2025, 10:54 AM CEST

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Time of origin

  • 2021

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