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Reversible Hyperpolarization of Ketoisocaproate Using Sulfoxide‐containing Polarization Transfer Catalysts
Author(s) -
Tickner Ben. J.,
Ahwal Fadi,
Whitwood Adrian C.,
Duckett Simon B.
Publication year - 2021
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000825
Subject(s) - chemistry , imes , hyperpolarization (physics) , dimethyl sulfoxide , catalysis , sulfoxide , magnetization transfer , magnetization , photochemistry , crystallography , carbene , stereochemistry , nuclear magnetic resonance spectroscopy , organic chemistry , magnetic field , medicine , physics , quantum mechanics , magnetic resonance imaging , radiology
The substrate scope of sulfoxide‐containing magnetisation transfer catalysts is extended to hyperpolarize α ‐ketoisocaproate and α ‐ketoisocaproate‐1‐[ 13 C]. This is achieved by forming [Ir(H) 2 ( κ 2 ‐ketoisocaproate)( N ‐heterocyclic carbene)(sulfoxide)] which transfers latent magnetism from p ‐H 2 via the signal amplification by reversible exchange (SABRE) process. The effect of polarization transfer field on the formation of enhanced 13 C magnetization is evaluated. Consequently, performing SABRE in a 0.5 μT field enabled most efficient magnetisation transfer. 13 C NMR signals for α ‐ketoisocaproate‐1‐[ 13 C] in methanol‐ d 4 are up to 985‐fold more intense than their traditional Boltzmann derived signal intensity (0.8 % 13 C 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.