title: Separation of Anti-Phase Signals Due to Parahydrogen Induced Polarization via 2D Nutation NMR Spectroscopy.
abstract: The present work introduces a novel method for the selective detection of1H NMR anti-phase signals caused by the pairwise incorporation of parahydrogen into olefins on noble-metal-containing catalysts. Via a two-dimensional (2D) nutation NMR experiment, the anti-phase signals of hyperpolarized1H nuclei are separated due to their double nutation frequency compared to that of thermally polarized1H nuclei. For demonstrating this approach, parahydrogen induced polarization (PHIP) was achieved via the hydrogenation of propene with parahydrogen on platinum-containing silica and investigated by in situ1H MAS NMR spectroscopy under continuous-flow conditions, that is, the hydrogenation reaction was performed inside the magnet of the NMR spectrometer. The 2D nutation NMR experiment described in the present work is useful for the separation of overlapping anti-phase and in-phase signals due to hyperpolarized and thermally polarized1H nuclei, respectively, which is important for research in the field of heterogeneous catalysis.
authors.affiliation: Institute of Chemical Technology, University of Stuttgart, 70550, Stuttgart, Germany.
authors.forename: Utz
authors.initials: U
authors.lastname: Obenaus
authors.affiliation: Solid-State NMR Application, Bruker BioSpin GmbH, Silberstreifen 4, 76287, Rheinstetten, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Althoff-Ospelt
authors.affiliation: Institute of Chemical Technology, University of Stuttgart, 70550, Stuttgart, Germany.
authors.forename: Swen
authors.initials: S
authors.lastname: Lang
authors.affiliation: Institute of Chemical Technology, University of Stuttgart, 70550, Stuttgart, Germany.
authors.forename: Robin
authors.initials: R
authors.lastname: Himmelmann
authors.affiliation: Institute of Chemical Technology, University of Stuttgart, 70550, Stuttgart, Germany.
authors.forename: Michael
authors.identifier: http://orcid.org/0000-0002-1870-2743
authors.initials: M
authors.lastname: Hunger
keywords: NMR spectroscopy; heterogeneous catalysis; hydrogenation; parahydrogen induced polarization; propene