Spin Relaxation Effects in Photochemically Induced Dynamic Nuclear Polarization Spectroscopy of Nuclei with Strongly Anisotropic Hyperfine Couplings

2007 ◽  
Vol 129 (29) ◽  
pp. 9004-9013 ◽  
Author(s):  
Ilya Kuprov ◽  
Timothy D. Craggs ◽  
Sophie E. Jackson ◽  
P. J. Hore
Keyword(s):  
Spin Relaxation ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Polarization Spectroscopy ◽  
Relaxation Effects ◽  
Anisotropic Hyperfine ◽  
Hyperfine Couplings

scholarly journals Maximizing NMR signal per unit time by facilitating the e–e–n cross effect DNP rate

2018 ◽  
Vol 20 (43) ◽  
pp. 27646-27657 ◽  
Author(s):  
Alisa Leavesley ◽  
Sheetal Jain ◽  
Ilia Kamniker ◽  
Hui Zhang ◽  
Suchada Rajca ◽  
...  
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Spin ◽  
Nuclear Polarization ◽  
Nuclear Spin Relaxation ◽  
Cross Effect ◽  
Spin Clusters

Dynamic nuclear polarization (DNP) efficiency is critically dependent on the properties of the radical, solvent, and solute, where electron spin clusters will shorten nuclear spin relaxation and enhance CE-DNP.

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

2021 ◽  
Vol 2 (1) ◽  
pp. 281-290
Author(s):  
Jakob Wörner ◽  
Jing Chen ◽  
Adelbert Bacher ◽  
Stefan Weber
Keyword(s):  
Density Functional Theory ◽  
Dynamic Nuclear Polarization ◽  
Density Functional ◽  
Nuclear Polarization ◽  
Proton Exchange ◽  
Radical Species ◽  
Functional Theory ◽  
Methyl Group ◽  
Chemically Induced ◽  
Hyperfine Couplings

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.

scholarly journals Non-classical disproportionation revealed by photo-CIDNP NMR

2021 ◽  
Author(s):  
Jakob Wörner ◽  
Jing Chen ◽  
Adelbert Bacher ◽  
Stefan Weber
Keyword(s):  
Density Functional Theory ◽  
Dynamic Nuclear Polarization ◽  
Density Functional ◽  
Nuclear Polarization ◽  
Proton Exchange ◽  
Radical Species ◽  
Functional Theory ◽  
Methyl Group ◽  
Chemically Induced ◽  
Hyperfine Couplings

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.

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