University of Oulu

B. J. Tickner, F. Ahwal, A. C. Whitwood, S. B. Duckett, ChemPhysChem 2021, 22, 13.

Reversible hyperpolarization of ketoisocaproate using sulfoxide‐containing polarization transfer catalysts

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Author: Tickner, Ben. J.1,2,3; Ahwal, Fadi1,2; Whitwood, Adrian C.2;
Organizations: 1Centre for Hyperpolarisation in Magnetic Resonance, University of York, Heslington, York, U.K., YO10 5NY
2Department of Chemistry, University of York, Heslington, York, U.K., YO10 5DD
3NMR Research Unit, Faculty of Science, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.7 MB)
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Language: English
Published: John Wiley & Sons, 2020
Publish Date: 2021-02-01


The substrate scope of sulfoxide‐containing magnetisation transfer catalysts is extended to hyperpolarize α‐ketoisocaproate and α‐ketoisocaproate‐1‐[¹³C]. This is achieved by forming [Ir(H)₂(κ²‐ketoisocaproate)(N‐heterocyclic carbene)(sulfoxide)] which transfers latent magnetism from p‐H₂ via the signal amplification by reversible exchange (SABRE) process. The effect of polarization transfer field on the formation of enhanced ¹³C magnetization is evaluated. Consequently, performing SABRE in a 0.5 μT field enabled most efficient magnetisation transfer. ¹³C NMR signals for α‐ketoisocaproate‐1‐[¹³C] in methanol‐d⁴ are up to 985‐fold more intense than their traditional Boltzmann derived signal intensity (0.8 % ¹³C polarisation). Single crystal X‐ray diffraction reveals the formation of the novel catalyst decomposition products [Ir(μ‐H)(H)₂(IMes)(SO(Ph)(Me)₂)]₂ and [(Ir(H)₂(IMes)(SO(Me)₂))₂(μ‐S)] when the sulfoxides methylphenylsulfoxide and dimethylsulfoxide are used respectively.

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Series: ChemPhysChem
ISSN: 1439-4235
ISSN-E: 1439-7641
ISSN-L: 1439-4235
Volume: 22
Issue: 1
Pages: 13 - 17
DOI: 10.1002/cphc.202000825
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Funding: The Wellcome Trust (Grants 092506 and 098335), the MRC (MR/M008991/1), the ESPRC (B.J.T. studentship) and the University of York are thanked for financial support.
Copyright information: © 2020 The Authors. ChemPhysChem published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.