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Updated: Jul 12, 2025

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
Published on: February 23, 2016
Non-classical disproportionation revealed by photo-chemically induced dynamic nuclear polarization NMR
Jakob Wörner1, Jing Chen1, Adelbert Bacher2
1Institute of Physical Chemistry, Albert-Ludwigs-Universität Freiburg, Freiburg, 79104, Germany.
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, (H(6)) and (H(8)), 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.
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