Spontaneous N-15 Nuclear Spin Hyperpolarization in Metal-Free Activation of Parahydrogen by Molecular Tweezers

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Sorochkina , K , Zhivonitko , V V , Chernichenko , K , Telkki , V-V , Repo , T & Koptyug , I V 2018 , ' Spontaneous N-15 Nuclear Spin Hyperpolarization in Metal-Free Activation of Parahydrogen by Molecular Tweezers ' , Journal of Physical Chemistry Letters , vol. 9 , no. 4 , pp. 903-907 . https://doi.org/10.1021/acs.jpclett.7b03433

Title: Spontaneous N-15 Nuclear Spin Hyperpolarization in Metal-Free Activation of Parahydrogen by Molecular Tweezers
Author: Sorochkina, Kristina; Zhivonitko, Vladimir V.; Chernichenko, Konstantin; Telkki, Ville-Veikko; Repo, Timo; Koptyug, Igor V.
Contributor: University of Helsinki, Department of Chemistry
University of Helsinki, Department of Chemistry
University of Helsinki, Department of Chemistry
Date: 2018-02-15
Language: eng
Number of pages: 5
Belongs to series: Journal of Physical Chemistry Letters
ISSN: 1948-7185
URI: http://hdl.handle.net/10138/301184
Abstract: The ability of frustrated Lewis pairs (FLPs) to activate H-2 is of significant interest for metal-free catalysis. The activation of H-2 is also the key element of parahydrogen-induced polarization (PHIP), one of the nuclear spin hyper polarization techniques. It is demonstrated that o-phenylene-based ansa-aminoboranes (AABs) can produce H-1 nuclear spin hyperpolarization through a reversible interaction with parahydrogen at ambient temperatures. Heteronuclei are useful in NMR and MRI as well because they have a broad chemical shift range and long relaxation times and may act as background-free labels. We report spontaneous formation of N-15 hyperpolarization of the N-H site for a family of AABs. The process is efficient at the high magnetic field of an NMR magnet (7 T), and it provides up to 350-fold N-15 signal enhancements. Different hyperpolarization effects are observed with various AAB structures and in a broad temperature range. Spontaneous hyperpolarization, albeit an order of magnitude weaker than that for N-15, was also observed for B-11 nuclei.
Subject: FRUSTRATED LEWIS PAIRS
PARA-HYDROGEN
INDUCED POLARIZATION
NMR
MRI
RELAXATION
ALIGNMENT
SABRE
ORDER
P-31
116 Chemical sciences
114 Physical sciences
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