Equbal, Asif, Kan Tagami, and Songi Han. “Balancing Dipolar and Exchange Coupling in Biradicals to Maximize Cross Effect Dynamic Nuclear Polarization.” Physical Chemistry Chemical Physics 22, no. 24 (2020): 13569–79.
Dynamic nuclear polarization (DNP) by the Cross Eect (CE) has become a game changer for solid-state nuclear magnetic resonance (NMR) spectroscopy. The eciency of CE-DNP depends on the strength of the electron-electron coupling in biradical polarizing agents. Hence, the focus lately has been on designing biradicals with a large net exchange (J) and dipolar (D) coupling. In this study, we reveal that the crucial factor for CE-DNP is not the sum, J+D, but rather the relative magnitude of J and D, expressed as the J/D ratio. We show that the mechanistic basis of this interference lies in the isotropic v.s. the anisotropic nature of the J and D couplings, respectively. This interference can lead to a small (eective) electron-electron coupling for many orientations even when J+D is large, resulting in non-adiabatic rotor-events. We find that when 0< jJ/Dj < 1 the CE-DNP eciency is attenuated for the majority of orientations, with greater attenuation observed at higher magnetic elds and faster Magic-Angle Spinning (MAS) frequency. The interference eect of J and D coupling introduced in this study can explain why many biradicals with high or comparable J + D still show signicantly divergent DNP performances. We debut J/D as a consequential criteria for designing ecient biradicals to robustly perform across a large range of B0 elds and MAS frequencies.
Dipolar Order Mediated 1H -> 13C Cross-Polarization for Dissolution-Dynamic Nuclear Polarization #DNPNMR
From The DNP-NMR Blog:
Dipolar Order Mediated 1H -> 13C Cross-Polarization for Dissolution-Dynamic Nuclear Polarization #DNPNMR
Elliott, Stuart J., Samuel F. Cousin, Quentin Chappuis, Olivier Cala, Morgan Ceillier, Aurélien Bornet, and Sami Jannin. “Dipolar Order Mediated 1H -> 13C Cross-Polarization for Dissolution-Dynamic Nuclear Polarization.” Preprint. Hyperpolarization/Pulse-sequence development, February 20, 2020.
https://doi.org/10.5194/mr-2020-4
nmrlearner
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04-29-2020 04:16 PM
De novo prediction of cross-effect efficiency for magic angle spinning dynamic nuclear polarization #DNPNMR
From The DNP-NMR Blog:
De novo prediction of cross-effect efficiency for magic angle spinning dynamic nuclear polarization #DNPNMR
Mentink-Vigier, Frédéric, Anne-Laure Barra, Johan van Tol, Sabine Hediger, Daniel Lee, and Gaël De Paëpe. “De Novo Prediction of Cross-Effect Efficiency for Magic Angle Spinning Dynamic Nuclear Polarization.” Physical Chemistry Chemical Physics 21, no. 4 (2019): 2166–76.
https://doi.org/10.1039/C8CP06819D.
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05-06-2019 04:47 PM
Bis-Gadolinium Complexes for Solid Effect and Cross Effect Dynamic Nuclear Polarization #DNPNMR
From The DNP-NMR Blog:
Bis-Gadolinium Complexes for Solid Effect and Cross Effect Dynamic Nuclear Polarization #DNPNMR
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Kaushik, M., et al., Bis-Gadolinium Complexes for Solid Effect and Cross Effect Dynamic Nuclear Polarization. Angew Chem Int Ed Engl, 2017. 56(15): p. 4295-4299.
https://www.ncbi.nlm.nih.gov/pubmed/28319293
nmrlearner
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07-15-2017 05:05 PM
Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization #DNPNMR
From The DNP-NMR Blog:
Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization #DNPNMR
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Kubicki, D.J., et al., Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization. Chem. Sci., 2016. 7(1): p. 550-558.
http://dx.doi.org/10.1039/C5SC02921J
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01-06-2017 07:43 PM
Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization #DNPNMR
From The DNP-NMR Blog:
Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization #DNPNMR
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Kubicki, D.J., et al., Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization. Chem. Sci., 2016. 7(1): p. 550-558.
http://dx.doi.org/10.1039/C5SC02921J
nmrlearner
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12-19-2016 03:37 AM
Correction: Theory of solid effect and cross effect dynamic nuclear polarization with half-integer high-spin metal polarizing agents in rotating solids #DNPNMR
From The DNP-NMR Blog:
Correction: Theory of solid effect and cross effect dynamic nuclear polarization with half-integer high-spin metal polarizing agents in rotating solids #DNPNMR
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Corzilius, B., Correction: Theory of solid effect and cross effect dynamic nuclear polarization with half-integer high-spin metal polarizing agents in rotating solids. Phys. Chem. Chem. Phys., 2016. 18(42): p. 29643-29643.
http://dx.doi.org/10.1039/C6CP90249A
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12-17-2016 07:18 AM
Theory of solid effect and cross effect dynamic nuclear polarization with half-integer high-spin metal polarizing agents in rotating solids #DNPNMR
From The DNP-NMR Blog:
Theory of solid effect and cross effect dynamic nuclear polarization with half-integer high-spin metal polarizing agents in rotating solids #DNPNMR
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Corzilius, B., Theory of solid effect and cross effect dynamic nuclear polarization with half-integer high-spin metal polarizing agents in rotating solids. Phys. Chem. Chem. Phys., 2016. 18(39): p. 27190-27204.
http://dx.doi.org/10.1039/C6CP04621E
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11-21-2016 11:02 PM
Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization
From The DNP-NMR Blog:
Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization
Kubicki, D.J., et al., Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization. Chem. Sci., 2015.
http://dx.doi.org/10.1039/C5SC02921J
Balancing dipolar and exchange coupling in biradicals to maximize cross effect dynamic nuclear polarization #DNPNMR
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