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Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs
In the majority of hydrogenative parahydrogen-induced polarization (PHIP) experiments, the hydrogen molecule undergoes pairwise cis addition to an unsaturated precursor to occupy vicinal positions on the product molecule. However, some ruthenium-based hydrogenation catalysts induce geminal hydrogena...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Copernicus GmbH
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10500696/ https://www.ncbi.nlm.nih.gov/pubmed/37904826 http://dx.doi.org/10.5194/mr-1-175-2020 |
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author | Dagys, Laurynas Ripka, Barbara Leutzsch, Markus Moustafa, Gamal A. I. Eills, James Colell, Johannes F. P. Levitt, Malcolm H. |
author_facet | Dagys, Laurynas Ripka, Barbara Leutzsch, Markus Moustafa, Gamal A. I. Eills, James Colell, Johannes F. P. Levitt, Malcolm H. |
author_sort | Dagys, Laurynas |
collection | PubMed |
description | In the majority of hydrogenative parahydrogen-induced polarization (PHIP) experiments, the hydrogen molecule undergoes pairwise cis addition to an unsaturated precursor to occupy vicinal positions on the product molecule. However, some ruthenium-based hydrogenation catalysts induce geminal hydrogenation, leading to a reaction product in which the two hydrogen atoms are transferred to the same carbon centre, forming a methylene ( [Formula: see text] ) group. The singlet order of parahydrogen is substantially retained over the geminal hydrogenation reaction, giving rise to a singlet-hyperpolarized [Formula: see text] group. Although the [Formula: see text] relaxation times of the methylene protons are often short, the singlet order has a long lifetime, provided that singlet–triplet mixing is suppressed, either by chemical equivalence of the protons or by applying a resonant radiofrequency field. The long lifetime of the singlet order enables the accumulation of hyperpolarization during the slow hydrogenation reaction. We introduce a kinetic model for the behaviour of the observed hyperpolarized signals, including both the chemical kinetics and the spin dynamics of the reacting molecules. Our work demonstrates the feasibility of producing singlet-hyperpolarized methylene moieties by parahydrogen-induced polarization. This potentially extends the range of molecular agents which may be generated in a hyperpolarized state by chemical reactions of parahydrogen. |
format | Online Article Text |
id | pubmed-10500696 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | Copernicus GmbH |
record_format | MEDLINE/PubMed |
spelling | pubmed-105006962023-10-30 Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs Dagys, Laurynas Ripka, Barbara Leutzsch, Markus Moustafa, Gamal A. I. Eills, James Colell, Johannes F. P. Levitt, Malcolm H. Magn Reson (Gott) Research Article In the majority of hydrogenative parahydrogen-induced polarization (PHIP) experiments, the hydrogen molecule undergoes pairwise cis addition to an unsaturated precursor to occupy vicinal positions on the product molecule. However, some ruthenium-based hydrogenation catalysts induce geminal hydrogenation, leading to a reaction product in which the two hydrogen atoms are transferred to the same carbon centre, forming a methylene ( [Formula: see text] ) group. The singlet order of parahydrogen is substantially retained over the geminal hydrogenation reaction, giving rise to a singlet-hyperpolarized [Formula: see text] group. Although the [Formula: see text] relaxation times of the methylene protons are often short, the singlet order has a long lifetime, provided that singlet–triplet mixing is suppressed, either by chemical equivalence of the protons or by applying a resonant radiofrequency field. The long lifetime of the singlet order enables the accumulation of hyperpolarization during the slow hydrogenation reaction. We introduce a kinetic model for the behaviour of the observed hyperpolarized signals, including both the chemical kinetics and the spin dynamics of the reacting molecules. Our work demonstrates the feasibility of producing singlet-hyperpolarized methylene moieties by parahydrogen-induced polarization. This potentially extends the range of molecular agents which may be generated in a hyperpolarized state by chemical reactions of parahydrogen. Copernicus GmbH 2020-08-07 /pmc/articles/PMC10500696/ /pubmed/37904826 http://dx.doi.org/10.5194/mr-1-175-2020 Text en Copyright: © 2020 Laurynas Dagys et al. https://creativecommons.org/licenses/by/4.0/This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ |
spellingShingle | Research Article Dagys, Laurynas Ripka, Barbara Leutzsch, Markus Moustafa, Gamal A. I. Eills, James Colell, Johannes F. P. Levitt, Malcolm H. Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs |
title |
Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs |
title_full |
Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs |
title_fullStr |
Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs |
title_full_unstemmed |
Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs |
title_short |
Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs |
title_sort | geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10500696/ https://www.ncbi.nlm.nih.gov/pubmed/37904826 http://dx.doi.org/10.5194/mr-1-175-2020 |
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