Articles | Volume 2, issue 1
© Author(s) 2021. This work is distributed underthe Creative Commons Attribution 4.0 License.
Non-classical disproportionation revealed by photo-chemically induced dynamic nuclear polarization NMR
- Final revised paper (published on 07 May 2021)
- Supplement to the final revised paper
- Preprint (discussion started on 24 Feb 2021)
- Supplement to the preprint
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor |
: Report abuse
- RC1: 'Comment on mr-2021-22', Anonymous Referee #1, 03 Mar 2021
- RC2: 'Comment on mr-2021-22', Anonymous Referee #2, 25 Mar 2021
- AC1: 'Author Comment on mr-2021-22', Stefan Weber, 31 Mar 2021
Peer review completion
AR: Author's response | RR: Referee report | ED: Editor decision
AR by Stefan Weber on behalf of the Authors (03 Apr 2021)  Author's response Author's tracked changes Manuscript
ED: Publish as is (07 Apr 2021) by Rolf Boelens
Research on photolyases and cryptochromes is presently a hot field. Cryptochromes are even considered to be involved in “animal detected magnetic resonance”. Therefore, an update on flavin-related compounds, their capacity to form radical pairs and to build up hyperpolarization is highly desirable. The manuscript revealed the existence of a transient high redox state of 6,7,8-trimethyllumazine by means of photo-CIDNP NMR. The compound is able to form upon illumination radical pairs with its two different protonation states. The experimental isotropic hyperfine coupling constants are obtained and correlate well with DFT data. Combining DFT and CIDNP, the careful analysis of the data on the basis of Kaptein’s sign rule is convincing and allows a remarkable reconstruction of a reaction dynamics involving photochemistry, spin-chemistry as well as proton transfer.
As for the title, I feel that the authors are unnecessarily opening a discussion that is not really helpful. Why should a disproportionation (2A = A+ + A-) not also be able to be triggered photochemically (A* + A = A+ + A-)? In the textbook by Klessinger and Michel, photochemically triggered disproportionations are indeed discussed (for example, as a result of Norrish I). One could also ask whether a system A + AH really “disproportionates”, since A and AH are different species. Nevertheless, it seems to me that a very special CIDNP-capable donor-acceptor system is present here, perhaps deserving the term “non-classical”.