Using signal amplification by reversible exchange (SABRE) to hyperpolarise 119Sn and 29Si NMR nuclei

• Published in: Chemical communications (Cambridge, England) Vol. 52; no. 100; pp. 14482 - 14485
• Main Authors: Olaru, Alexandra M, Burt, Alister, Rayner, Peter J, Hart, Sam J, Whitwood, Adrian C, Green, Gary G R, Duckett, Simon B
• Format: Journal Article
• Language: English
• Published: 13.12.2016
• Subjects: Amplification; Exchange; Field strength; Nuclear magnetic resonance; Nuclei; Nuclei (nuclear physics); Reaction time; Sensitivity analysis
• ISSN: 1359-7345; 1364-548X
• DOI: 10.1039/c6cc07109k

The hyperpolarisation of the 119Sn and 29Si nuclei in 5-(tributylstannyl)pyrimidine (ASn) and 5-(trimethylsilyl)pyrimidine (BSi) is achieved through their reaction with [IrCl(COD)(IMes)] (1a) or [IrCl(COD)(SIMes)] (1b) and parahydrogen via the SABRE process. 1a exhibits superior activity in both cases. The two inequivalent pyrimidine proton environments of ASn readily yielded signal enhancements totalling ∼2300-fold in its 1H NMR spectrum at a field strength of 9.4 T, with the corresponding 119Sn signal being 700 times stronger than normal. In contrast, BSi produced analogous 1H signal gains of ∼2400-fold and a 29Si signal that could be detected with a signal to noise ratio of 200 in a single scan. These sensitivity improvements allow NMR detection within seconds using micromole amounts of substrate and illustrate the analytical potential of this approach for high-sensitivity screening. Furthermore, after extended reaction times, a series of novel iridium trimers of general form [Ir(H)2Cl(NHC)(μ-pyrimidine-κN:κN')]3 precipitate from these solutions whose identity was confirmed crystallographically for BSi.