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

• Published in: Chemistry : a European journal Vol. 23; no. 44; pp. 10491 - 10495
• Main Authors: Iali, Wissam, Olaru, Alexandra M., Green, Gary G. R., Duckett, Simon B.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 04-08-2017; John Wiley and Sons Inc
• Subjects: Amplification; Catalysis; Catalysts; Chemistry; Communication; Communications; Contamination; Exchanging; Hyperpolarization; Iridium; Magnetic resonance imaging; Media; Nicotinamide; NMR; NMR spectroscopy; Nuclear magnetic resonance; para-hydrogen; Phase separation; Pyrazine; SABRE; Signal processing; Substrates; hyperpolarization; NMR spectroscopy; para-hydrogen; SABRE
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201702716

Signal amplification by reversible exchange (SABRE) is shown to allow access to strongly enhanced 1H 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 1H 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.
Show me the money: Catalyst separated hyperpolarization through signal amplification by reversible exchange or CASH‐SABRE allows access to strongly enhanced 1H, 13C and 15N NMR signals for a range of substrates in aqueous media through phase‐transfer catalysis. Very limited catalyst contamination is observed and hence a biocompatible bolus is readily achieved.