Pulse sequence and sample formulation optimization for dipolar order mediated <SUP>1</SUP>H→<SUP>13</SUP>C cross-polarization
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Published version
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Author(s)
Type
Journal Article
Abstract
We have recently demonstrated the use of contactless radiofrequency pulse sequences under dissolution-dynamic nuclear polarization conditions as an attractive way of transferring polarization from sensitive 1H spins to insensitive 13C spins with low peak radiofrequency pulse powers and energies via a reservoir of dipolar order. However, many factors remain to be investigated and optimized to enable the full potential of this polarization transfer process. We demonstrate herein the optimization of several key factors by: (i) implementing more efficient shaped radiofrequency pulses; (ii) adapting 13C spin labelling; and (iii) avoiding methyl group relaxation sinks. Experimental demonstrations are presented for the case of [1-13C]sodium acetate and other relevant molecular candidates. By employing the range of approaches set out above, polarization transfer using the dipolar order mediated cross-polarization radiofrequency pulse sequence is improved by factors approaching ∼1.65 compared with previous results. Dipolar order mediated 1H→13C polarization transfer efficiencies reaching ∼76% were achieved using significantly reduced peak radiofrequency pulse powers relative to the performance of highly sophisticated state-of-the-art cross-polarization methods, indicating 13C nuclear spin polarization levels on the order of ∼32.1% after 10 minutes of 1H DNP. The approach does not require extensive pulse sequence optimization procedures and can easily accommodate high concentrations of 13C-labelled molecules.
Date Issued
2021-04-21
Date Acceptance
2021-03-31
Citation
Physical Chemistry Chemical Physics, 2021, 23 (15), pp.9457-9465
ISSN
1463-9076
Publisher
Royal Society of Chemistry
Start Page
9457
End Page
9465
Journal / Book Title
Physical Chemistry Chemical Physics
Volume
23
Issue
15
Copyright Statement
This journal is © the Owner Societies 2021. This article is licensed under aCreative Commons Attribution-NonCommercial 3.0 Unported Licence (https://creativecommons.org/licenses/by-nc/3.0/)
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/33885108
Subjects
Chemistry
Chemistry, Physical
Physical Sciences
Physics
Physics, Atomic, Molecular & Chemical
Science & Technology
Publication Status
Published
Coverage Spatial
England
Date Publish Online
2021-04-01