The York Research Database

Signal Amplification by Reversible Exchange (SABRE) is used to switch on the latent singlet spin order of para-hydrogen (p-H₂) so that it can hyperpolarize a substrate (sub = nicotinamide, nicotinate, niacin, pyrimidine and pyrazine). The substrate then reacts reversibly with [Pt(OTf)₂(bis-diphenylphosphinopropane)] by displacing OTf- to form [Pt(OTf)(sub)(bis-diphenylphosphinopropane)]OTf. The ³¹P NMR signals of these metal complexes prove to be enhanced when the substrate possesses an accessible singlet state or long-lived Zeeman polarization. In the case of pyrazine, the corresponding ³¹P signal was 105 ± 8 times larger than expected, which equated to an 8-hour reduction in total scan time for an equivalent signal to noise ratio under normal acquisition conditions. Hence p-H₂ derived spin order is successfully relayed into a second metal complex via a suitable polarization carrier (sub). When fully developed we expect this route involving a second catalyst to successfully hyperpolarize many classes of substrate that are not amenable to normal SABRE.