Parahydrogen induced hyperpolarization of molecules can significantly enhance their nuclear magnetic resonance (NMR) signal intensity, thereby reducing needed sample quantities and instrument cost. These benefits have rendered parahydrogen induced hyperpolarization a promising research direction for magnetic resonance image (MRI) as well as other NMR-based structure/dynamics characterization techniques. We have discovered that intermetallic PtSn, an ordered alloy formed by 1:1 stoichiometry of Pt to Sn, can selectively catalyze the symmetry-breaking pairwise addition of a parahydrogen molecule to a C=C bond in propene, inducing the hyperpolarized proton signal in propane. Pairwise selective addition can be achieved if hydrogen molecules do not undergo dissociative adsorption on the catalyst surface. Pt alone is not a good catalyst for pairwise addition because H<sub>2</sub> readily dissociates to produce H ad-atoms that freely diffuse on its surface. On the other hand, PtSn can effectively prevent the dissociation of the hydrogen molecules and lead to high pairwise addition selectivity. Moreover, we have discovered that Pt<sub>3</sub>Sn, another member of Pt-Sn intermetallic family, can hyperpolarize water using parahydrogen in a remarkable process that we refer to as SWAMP (Surface Waters Are Magnetized by Parahydrogen).

Parahydrogen-induced hyperpolarization on ordered surface of intermetallic nanoparticles

2019 Fall National Meeting

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