University of Oulu

Kristina Sorochkina, Vladimir V. Zhivonitko, Konstantin Chernichenko, Ville-Veikko Telkki, Timo Repo, and Igor V. Koptyug. Spontaneous 15N Nuclear Spin Hyperpolarization in Metal-Free Activation of Parahydrogen by Molecular Tweezers. The Journal of Physical Chemistry Letters 2018 9 (4), 903-907 DOI: 10.1021/acs.jpclett.7b03433.

Spontaneous ¹⁵N nuclear spin hyperpolarization in metal-free activation of parahydrogen by molecular tweezers

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Author: Sorochkina, Kristina1; Zhivonitko, Vladimir V.2,3,4; Chernichenko, Konstantin1;
Organizations: 1Department of Chemistry, University of Helsinki, A. I. Virtasen aukio 1, 00014 Helsinki, Finland
2NMR Research Unit, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
3Laboratory of Magnetic Resonance Microimaging, International Tomography Center SB RAS, Institutskaya Street 3A, 630090 Novosibirsk, Russia
4Department of Natural Sciences, Novosibirsk State University, Pirogova Street 2, 630090 Novosibirsk, Russia
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.9 MB)
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Language: English
Published: American Chemical Society, 2018
Publish Date: 2018-04-13


The ability of frustrated Lewis pairs (FLPs) to activate H₂ is of significant interest for metal-free catalysis. The activation of H₂ is also the key element of parahydrogen-induced polarization (PHIP), one of the nuclear spin hyperpolarization techniques. It is demonstrated that o-phenylene-based ansa-aminoboranes (AABs) can produce ¹H 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 ¹⁵N 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 ¹⁵N 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 ¹⁵N, was also observed for ¹¹B nuclei.

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Series: Journal of physical chemistry letters
ISSN: 1948-7185
ISSN-E: 1948-7185
ISSN-L: 1948-7185
Volume: 9
Pages: 903 - 907
DOI: 10.1021/acs.jpclett.7b03433
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
114 Physical sciences
Funding: V.V.Z. thanks the University of Oulu (Kvantum Institute) for financial support. I.V.K. and V.V.Z. acknowledge RFBR (Grant # 16-03-00407-a) and basic funding from FASO Russia (Project # 0333-2017-0002). V.V.T. and V.V.Z. acknowledge the European Research Council (ERC) under Horizon 2020 (H2020/2018-2022/ERC Grant Agreement No. 772110) and the Academy of Finland for financial support (Grants # 289649, 294027, and 311604). K.S., K.C., and T.R. acknowledge the Academy of Finland for financial support (Grant # 276586).
EU Grant Number: (772110) UFLNMR - Ultrafast Laplace NMR
Academy of Finland Grant Number: 289649
Detailed Information: 289649 (Academy of Finland Funding decision)
294027 (Academy of Finland Funding decision)
311604 (Academy of Finland Funding decision)
Dataset Reference: The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpclett.7b03433.
Copyright information: © 2018 American Chemical Society. ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.