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Transferred Overhauser DNP: A Fast, Efficient Approach for Room Temperature 13C ODNP at Moderately Low Fields and Natural Abundance
Abhishek Banerjee,
Published in American Chemical Society
2017
PMID: 28658577
Volume: 121
   
Issue: 29
Pages: 7156 - 7162
Abstract
Overhauser dynamic nuclear polarization (ODNP) is investigated at a moderately low field (1.2 T) for natural abundance 13C NMR of small molecules in solution state at room temperature. It is shown that ODNP transferred from 1H to 13C by NMR coherence transfer is in general significantly more efficient than direct ODNP of 13C. Compared to direct 13C ODNP, we demonstrate over 4-fold higher 13C sensitivity (signal-to-noise ratio, SNR), achieved in one-eighth of the measurement time by transferred ODNP (t-ODNP). Compared to the 13C signal arising from Boltzmann equilibrium in a fixed measurement time, this is equivalent to about 1500-fold enhancement of 13C signal by t-ODNP, as against a direct 13C ODNP signal enhancement of about 45-fold, both at a moderate ESR saturation factor of about 0.25. This owes in part to the short polarization times characteristic of 1H. Typically, t-ODNP reflects the essentially uniform ODNP enhancements of all protons in a molecule. Although the purpose of this work is to establish the superiority of t-ODNP vis-à-vis direct 13C ODNP, a comparison is also made of the SNR in t-ODNP experiments with standard high resolution NMR as well. Finally, the potential of t-ODNP experiments for 2D heteronuclear correlation spectroscopy of small molecules is demonstrated in 2D 1H-13C HETCOR experiments at natural abundance, with decoupling in both dimensions. © 2017 American Chemical Society.
About the journal
JournalData powered by TypesetJournal of Physical Chemistry B
PublisherData powered by TypesetAmerican Chemical Society
ISSN15206106
Open AccessNo
Concepts (12)
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    Molecules
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    Nuclear magnetic resonance
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    Polarization
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    BOLTZMANN EQUILIBRIUM
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    COHERENCE TRANSFER
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    Dynamic nuclear polarization
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    HETERONUCLEAR CORRELATION
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    MEASUREMENT TIME
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    NATURAL ABUNDANCE
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    SATURATION FACTORS
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    SIGNAL ENHANCEMENT
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    Signal to noise ratio