Achieving High Levels of NMR-Hyperpolarization in Aqueous Media With Minimal Catalyst Contamination Using SABRE

Wissam Iali; Alexandra M Olaru; Gary G R Green; Simon B Duckett

doi:10.1002/chem.201702716

Achieving High Levels of NMR-Hyperpolarization in Aqueous Media With Minimal Catalyst Contamination Using SABRE

Chemistry. 2017 Aug 4;23(44):10491-10495. doi: 10.1002/chem.201702716. Epub 2017 Jul 19.

Authors

Wissam Iali¹, Alexandra M Olaru¹, Gary G R Green², Simon B Duckett¹

Affiliations

¹ Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
² York Neuroimaging Centre, The Biocentre, York Science Park Innovation Way, Heslington, York, YO10 5DD, UK.

Abstract

Signal amplification by reversible exchange (SABRE) is shown to allow access to strongly enhanced ¹ H NMR signals in a range of substrates in aqueous media. To achieve this outcome, phase-transfer catalysis is exploited, which leads to less than 1.5×10^-6 mol dm^-3 of the iridium catalyst in the aqueous phase. These observations reflect a compelling route to produce a saline-based hyperpolarized bolus in just a few seconds for subsequent in vivo MRI monitoring. The new process has been called catalyst separated hyperpolarization through signal amplification by reversible exchange or CASH-SABRE. We illustrate this method for the substrates pyrazine, 5-methylpyrimidine, 4,6-d₂ -methyl nicotinate, 4,6-d₂ -nicotinamide and pyridazine achieving ¹ H signal gains of approximately 790-, 340-, 3000-, 260- and 380-fold per proton at 9.4 T at the time point at which phase separation is complete.

Keywords: NMR spectroscopy; SABRE; hyperpolarization; para-hydrogen.

Abstract

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