„Direct“ 13 C Hyperpolarization of 13 C-Acetate by MicroTesla NMR Signal Amplification by Reversible Exchange (SABRE)

Journal Article (Journal Article)

Herein, we demonstrate „direct“ 13C hyperpolarization of 13C-acetate via signal amplification by reversible exchange (SABRE). The standard SABRE homogeneous catalyst [Ir-IMes; [IrCl(COD)(IMes)], (IMes=1,3-bis(2,4,6- trimethylphenyl), imidazole-2-ylidene; COD=cyclooctadiene)] was first activated in the presence of an auxiliary substrate (pyridine) in alcohol. Following addition of sodium 1-13C-acetate, parahydrogen bubbling within a microtesla magnetic field (i.e. under conditions of SABRE in shield enables alignment transfer to heteronuclei, SABRESHEATH) resulted in positive enhancements of up to ≈ 100- fold in the 13C NMR signal compared to thermal equilibrium at 9.4 T. The present results are consistent with a mechanism of „direct“ transfer of spin order from parahydrogen to 13C spins of acetate weakly bound to the catalyst, under conditions of fast exchange with respect to the 13C acetate resonance, but we find that relaxation dynamics at microtesla fields alter the optimal matching from the traditional SABRE-SHEATH picture. Further development of this approach could lead to new ways to rapidly, cheaply, and simply hyperpolarize a broad range of substrates (e.g. metabolites with carboxyl groups) for various applications, including biomedical NMR and MRI of cellular and in vivo metabolism.

Full Text

Duke Authors

Cited Authors

  • Gemeinhardt, ME; Limbach, MN; Gebhardt, TR; Eriksson, CW; Eriksson, SL; Lindale, JR; Goodson, EA; Warren, WS; Chekmenev, EY; Goodson, BM

Published Date

  • January 1, 2020

Published In

Volume / Issue

  • 59 / 1

Start / End Page

  • 426 - 431

Electronic International Standard Serial Number (EISSN)

  • 1521-4095

International Standard Serial Number (ISSN)

  • 0935-9648

Digital Object Identifier (DOI)

  • 10.1002/ANGE.201910506

Citation Source

  • Scopus