Long-lived nuclear spin states in methyl groups and quantum-rotor-induced polarization

Benno Meier; Jean Nicolas Dumez; Gabriele Stevanato; Joseph T. Hill-Cousins; Soumya Singha Roy; Pär Haìškansson; Salvatore Mamone; Richard C D Brown; Giuseppe Pileio; Malcolm H. Levitt

doi:10.1021/ja410432f

Long-lived nuclear spin states in methyl groups and quantum-rotor-induced polarization

Benno Meier, Jean Nicolas Dumez, Gabriele Stevanato, Joseph T. Hill-Cousins, Soumya Singha Roy, Pär Haìškansson, Salvatore Mamone, Richard C D Brown, Giuseppe Pileio, Malcolm H. Levitt^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

Substances containing rapidly rotating methyl groups may exhibit long-lived states (LLSs) in solution, with relaxation times substantially longer than the conventional spin-lattice relaxation time T₁. The states become long-lived through rapid internal rotation of the CH₃ group, which imposes an approximate symmetry on the fluctuating nuclear spin interactions. In the case of very low CH₃ rotational barriers, a hyperpolarized LLS is populated by thermal equilibration at liquid helium temperature. Following dissolution, cross-relaxation of the hyperpolarized LLS, induced by heteronuclear dipolar couplings, generates strongly enhanced antiphase NMR signals. This mechanism explains the NMR signal enhancements observed for ¹³C-γ-picoline (Icker, M.; Berger, S. J. Magn. Reson. 2012, 219, 1-3).

Original language	English
Pages (from-to)	18746-18749
Number of pages	4
Journal	Journal of the American Chemical Society
Volume	135
Issue number	50
Early online date	20 Nov 2013
DOIs	https://doi.org/10.1021/ja410432f
Publication status	Published - 18 Dec 2013

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title = "Long-lived nuclear spin states in methyl groups and quantum-rotor-induced polarization",

abstract = "Substances containing rapidly rotating methyl groups may exhibit long-lived states (LLSs) in solution, with relaxation times substantially longer than the conventional spin-lattice relaxation time T1. The states become long-lived through rapid internal rotation of the CH3 group, which imposes an approximate symmetry on the fluctuating nuclear spin interactions. In the case of very low CH3 rotational barriers, a hyperpolarized LLS is populated by thermal equilibration at liquid helium temperature. Following dissolution, cross-relaxation of the hyperpolarized LLS, induced by heteronuclear dipolar couplings, generates strongly enhanced antiphase NMR signals. This mechanism explains the NMR signal enhancements observed for 13C-γ-picoline (Icker, M.; Berger, S. J. Magn. Reson. 2012, 219, 1-3).",

author = "Benno Meier and Dumez, {Jean Nicolas} and Gabriele Stevanato and Hill-Cousins, {Joseph T.} and Roy, {Soumya Singha} and P{\"a}r Ha{\`i}{\v s}kansson and Salvatore Mamone and Brown, {Richard C D} and Giuseppe Pileio and Levitt, {Malcolm H.}",

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month = dec,

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doi = "10.1021/ja410432f",

language = "English",

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T1 - Long-lived nuclear spin states in methyl groups and quantum-rotor-induced polarization

AU - Meier, Benno

AU - Dumez, Jean Nicolas

AU - Stevanato, Gabriele

AU - Hill-Cousins, Joseph T.

AU - Roy, Soumya Singha

AU - Haìškansson, Pär

AU - Mamone, Salvatore

AU - Brown, Richard C D

AU - Pileio, Giuseppe

AU - Levitt, Malcolm H.

PY - 2013/12/18

Y1 - 2013/12/18

N2 - Substances containing rapidly rotating methyl groups may exhibit long-lived states (LLSs) in solution, with relaxation times substantially longer than the conventional spin-lattice relaxation time T1. The states become long-lived through rapid internal rotation of the CH3 group, which imposes an approximate symmetry on the fluctuating nuclear spin interactions. In the case of very low CH3 rotational barriers, a hyperpolarized LLS is populated by thermal equilibration at liquid helium temperature. Following dissolution, cross-relaxation of the hyperpolarized LLS, induced by heteronuclear dipolar couplings, generates strongly enhanced antiphase NMR signals. This mechanism explains the NMR signal enhancements observed for 13C-γ-picoline (Icker, M.; Berger, S. J. Magn. Reson. 2012, 219, 1-3).

AB - Substances containing rapidly rotating methyl groups may exhibit long-lived states (LLSs) in solution, with relaxation times substantially longer than the conventional spin-lattice relaxation time T1. The states become long-lived through rapid internal rotation of the CH3 group, which imposes an approximate symmetry on the fluctuating nuclear spin interactions. In the case of very low CH3 rotational barriers, a hyperpolarized LLS is populated by thermal equilibration at liquid helium temperature. Following dissolution, cross-relaxation of the hyperpolarized LLS, induced by heteronuclear dipolar couplings, generates strongly enhanced antiphase NMR signals. This mechanism explains the NMR signal enhancements observed for 13C-γ-picoline (Icker, M.; Berger, S. J. Magn. Reson. 2012, 219, 1-3).

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JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

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ER -

Long-lived nuclear spin states in methyl groups and quantum-rotor-induced polarization

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