Affiliation:
1. Institute of Physical Chemistry PAS: Polska Akademia Nauk Instytut Chemii Fizycznej NMR Kasprzaka 44/52 01-224 Warsaw POLAND
2. Institute of Physical Chemistry PAS: Polska Akademia Nauk Instytut Chemii Fizycznej NMR Kasprzaka 44/52 01-224 Wrsaw POLAND
3. University of Warsaw: Uniwersytet Warszawski Chemistry Pasteura 1 02-093 Warsaw POLAND
4. TU Darmstadt: Technische Universitat Darmstadt Chemistry GERMANY
5. TU Darmstadt: Technische Universitat Darmstadt Chemistry Alarich-Weiss-Straße 8 64287 Darmstadt GERMANY
6. Institute of Physical Chemistry Polish Academy of Sciences: Polska Akademia Nauk Instytut Chemii Fizycznej NMR Kasprzaka 44/52 01-224 Warsaw POLAND
Abstract
The hydrogen molecule, which exists in two spin isomers (ortho‐ and parahydrogen), is a highly studied system due to its fundamental properties and practical applications. Parahydrogen is used for Nuclear Magnetic Resonance signal enhancement, which is hyperpolarization of other molecules, including biorelevant ones. Hyperpolarization can be achieved by using Signal Amplification by Reversible Exchange (SABRE). SABRE can also convert parahydrogen into orthohydrogen, and surprisingly, in some cases, it has been discovered that orthohydrogen’s resonance has the Partially Negative Line (PNL) pattern. Here, an approach for obtaining orthohydrogen with a PNL signal is presented for two catalysts: Ir‐IMes, and Ir‐IMesBn. The type of solvent in which SABRE is conducted is crucial for the observation of PNL. Specifically, a PNL signal can be easily generated in benzene using both catalysts, but it is more intense for Ir‐IMesBn. In acetone, PNL is observed only for Ir‐IMesBn. In methanol, no PNL is detected. The PNL effect is only detectable during the initial steps of pre‐catalyst activation, and disappears as the activation process progresses. We have proposed a working hypothesis that explains our results. The presented data may facilitate the further investigation of PNL and its applications in material science and catalysis.
Subject
General Chemistry,Catalysis
Cited by
1 articles.
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