Heterogeneous Microtesla SABRE Enhancement of 15N NMR Signals. Issue 35 (28th July 2017)

• Record Type: Journal Article
• Authors: Kovtunov, Kirill V.; Kovtunova, Larisa M.; Gemeinhardt, Max E.; Bukhtiyarov, Andrey V.; Gesiorski, Jonathan; Bukhtiyarov, Valerii I.; Chekmenev, Eduard Y.; Koptyug, Igor V.; Goodson, Boyd M.
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 35(2017)
• Page Start: 10433
• Page End: 10437
• Publication Date: 2017-07-28
• Subjects: heterogeneous catalysis -- heteronuclei -- het-SABRE -- hyperpolarization -- parahydrogen; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201705014
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The hyperpolarization of heteronuclei via signal amplification by reversible exchange (SABRE) was investigated under conditions of heterogeneous catalysis and microtesla magnetic fields. Immobilization of [IrCl(COD)(IMes)], [IMes=1, 3‐bis(2, 4, 6‐trimethylphenyl), imidazole‐2‐ylidene; COD=cyclooctadiene] catalyst onto silica particles modified with amine linkers engenders an effective heterogeneous SABRE (HET‐SABRE) catalyst that was used to demonstrate a circa 100‐fold enhancement of 15 N NMR signals in 15 N‐pyridine at 9.4 T following parahydrogen bubbling within a magnetic shield. No 15 N NMR enhancement was observed from the supernatant liquid following catalyst separation, which along with XPS characterization supports the fact that the effects result from SABRE under heterogeneous catalytic conditions. The technique can be developed further for producing catalyst‐free agents via SABRE with hyperpolarized heteronuclear spins, and thus is promising for biomedical NMR and MRI applications. Abstract : Making the insensitive sensitive : A heterogeneous catalyst for NMR enhancement was prepared by immobilizing an iridium‐based catalyst on silica microparticles. Addition of parahydrogen as a source of nuclear spin order within a magnetic shield led to enhancement of 15 N NMR signals by about 100. The catalyst particles are easy to separate, which should allow substrates with hyperpolarized heteronuclei to be prepared free of catalyst contamination.