Amplified Overhauser DNP with Selective Deuteration: Attenuation of Double-Quantum Cross-Relaxation
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nihms-1868137.pdf
Description
Accepted version
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1.02 MB
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Author(s)
Palani, Ravi Shankar
Mardini, Michael
Delage-Laurin, Leo
Banks, Daniel
Ouyang, Yifu
Bryerton, Eric
Kempf, James G
Swager, Timothy M
Griffin, Robert G
Date Issued
December 27, 2022
Journal
The Journal of Physical Chemistry Letters
Publisher
American Chemical Society
Citation
Amplified Overhauser DNP with Selective Deuteration: Attenuation of Double-Quantum Cross-Relaxation. Ravi Shankar Palani, Michael Mardini, Leo Delage-Laurin, Daniel Banks, Yifu Ouyang, Eric Bryerton, James G. Kempf, Timothy M. Swager, and Robert G. Griffin. The Journal of Physical Chemistry Letters 2023 14 (1), 95-100.
Version
Author's final manuscript
Abstract
We recently used selective 2H labeling of BDPA to investigate the Overhauser Effect (OE) dynamic nuclear polarization (DNP) mechanism in insulating solids doped with 1,3-bis(diphenylene)-2-phenylallyl (BDPA), and established that the α and γ 1H spins on the fluorene rings are responsible for generating a zero quantum (ZQ) mediated positive bulk polarization. Here, we establish that the phenyl 1H spins relax via double-quantum (DQ) processes and therefore contribute negative enhancements which attenuate the OE-DNP. With measurements at different magnetic field strengths, we show that phenyl-d5-BDPA offers >50% improvement in OE-DNP enhancement compared to h21-BDPA attaining a maximum of ∼90 at 14.1 T and 5 kHz MAS, the highest observed OE-DNP enhancement to date under these conditions. The approach may be utilized to optimize other polarizing agents exhibiting an OE, an important DNP mechanism with a favorable field and spinning frequency dependence.
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DOI of Published Version
https://doi.org/10.1021/acs.jpclett.2c03087
