Parahydrogen-Induced Polarization Relayed via Proton Exchange

The hyperpolarization of nuclear spins is a game-changing technology that enables hitherto inaccessible applications for magnetic resonance in chemistry and biomedicine. Despite significant advances and discoveries in the past, however, the quest to establish efficient and effective hyperpolarization methods continues. Here, we describe a new method that combines the advantages of direct parahydrogenation, high polarization (P), fast reaction, and low cost with the broad applicability of polarization transfer via proton exchange. We identified the system propargyl alcohol + pH(2) -> allyl alcohol to yield H-1 polarization in excess of P approximate to 13% by using only 50% enriched pH(2) at a pressure of approximate to 1 bar. The polarization was then successfully relayed via proton exchange from ally! alcohol to various target molecules. The polarizations of water and alcohols (as target molecules) approached P approximate to 1% even at high molar concentrations of 100 mM. Lactate, glucose, and pyruvic acid were also polarized, but to a lesser extent. Several potential improvements of the methodology are discussed. Thus, the parahydrogen-induced hyperpolarization relayed via proton exchange (PHIP-X) is a promising approach to polarize numerous molecules which participate in proton exchange and support new applications for magnetic resonance.

Automated summary

The method described combines direct parahydrogenation with polarization transfer, achieving high polarization of H-1 that can be relayed to various target molecules via proton exchange. Water and alcohols also reached high levels of polarization even at high concentrations.