title: Strongly hyperpolarized gas from parahydrogen by rational design of ligand-capped nanoparticles.
abstract: The production of hyperpolarized fluids in continuous mode would broaden substantially the range of applications in chemistry, materials science, and biomedicine. Here we show that the rational design of a heterogeneous catalyst based on a judicious choice of metal type, nanoparticle size and surface decoration with appropriate ligands leads to highly efficient pairwise addition of dihydrogen across an unsaturated bond. This is demonstrated in a parahydrogen-induced polarization (PHIP) experiment by a 508-fold enhancement (±78) of a CH(3) proton signal and a corresponding 1219-fold enhancement (±187) of a CH(2) proton signal using nuclear magnetic resonance (1H-NMR). In contrast, bulk metal catalyst does not show this effect due to randomization of reacting dihydrogen. Our approach results in the largest gas-phase NMR signal enhancement by PHIP known to date. Sensitivity-enhanced NMR with this technique could be used to image microfluidic reactions in-situ, to probe nonequilibrium thermodynamics or for the study of metabolic reactions.
authors.affiliation: Department of Chemistry and Biochemistry, University of California Los Angeles , 607 Charles E Young Dr East, CA 90095,  USA.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Sharma
authors.forename: Louis-S
authors.initials: LS
authors.lastname: Bouchard