"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" 13 C hyperpolarization of 13 C-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 1-13 C-acetate, parahydrogen bubbling within a microtesla magnetic field (i.e. under conditions of SABRE in shield enables alignment transfer to heteronuclei, SABRE-SHEATH) resulted in positive enhancements of up to ≈100-fold in the 13 C 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 13 C spins of acetate weakly bound to the catalyst, under conditions of fast exchange with respect to the 13 C 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 2020

Published In

Volume / Issue

  • 59 / 1

Start / End Page

  • 418 - 423

PubMed ID

  • 31661580

Electronic International Standard Serial Number (EISSN)

  • 1521-3773

International Standard Serial Number (ISSN)

  • 1433-7851

Digital Object Identifier (DOI)

  • 10.1002/anie.201910506

Language

  • eng