Detection of Pyridine Derivatives by SABRE Hyperpolarization at Zero Field



Zero-field nuclear magnetic resonance (NMR) recently emerged as an interesting new analytical modality. While zero-field NMR provides new capabilities, it also suffers from some limitations associated, to a great degree, with low signal amplitude. In this context, parahydrogen-induced polarization naturally complements zero-field NMR, as this hyperpolarization is active even at zero magnetic field. In turn, the efficient production of large non-equilibrium polarization is possible in zero field, boosting the signal amplitude and enabling realization of the concept of "NMR without magnets''. In this work, we present zero-field NMR studies of various hyperpolarized pyridine derivatives where the 15N isotope is present at a natural abundance (0.36%). By comparing the signals of these pyridine derivatives, which include vitamin B3, as a function of their substituents, we demonstrate unique zero-field NMR spectra, consequently establishing how chemical analysis is possible even in zero field. We also study the effect of the parahydrogen-polarization-transfer catalyst activation on the resulting hyperpolarization dynamics. All of these measurements were made using apparatus designed to allow repeated in situ hyperpolarization of these samples without affecting their composition.


Supplementary material

Supplementary information (experimental, secondary results)
Bubbling system and experimental sequence; SABRE spectrum of 15N-pyridine during catalyst activation; J-coupling Constants of Pyridine Derivatives