Unexpected multiplet patterns induced by the Haupt-effect

Icker, Maik; Berger, Stefan

doi:10.1016/j.jmr.2012.03.021

Cited by 39 publications

(55 citation statements)

References 16 publications

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“…[19][20] QRIP has been observed for compounds such as γ-picoline (4-methylpyridine) for which the methyl rotation encounters an unusually low rotational barrier, leading to a significant tunnelling splitting of ~ 6 K between the A and E manifolds in the cryogenic solid state. For such special cases, a significant AEI may be established simply by equilibrating the sample at a temperature below 10 K, without any paramagnetic agents or microwaves.…”

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confidence: 99%

Dynamic Nuclear Polarization of Long-Lived Nuclear Spin States in Methyl Groups

Dumez

Vuichoud

Mammoli

et al. 2017

J. Phys. Chem. Lett.

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We have induced hyperpolarized long-lived states in compounds containing 13C-bearing methyl groups by dynamic nuclear polarization (DNP) at cryogenic temperatures, followed by dissolution with a warm solvent. The hyperpolarized methyl long-lived states give rise to enhanced antiphase 13C NMR signals in solution, which often persist for times much longer than the 13C and 1H spin–lattice relaxation times under the same conditions. The DNP-induced effects are similar to quantum-rotor-induced polarization (QRIP) but are observed in a wider range of compounds because they do not depend critically on the height of the rotational barrier. We interpret our observations with a model in which nuclear Zeeman and methyl tunnelling reservoirs adopt an approximately uniform temperature, under DNP conditions. The generation of hyperpolarized NMR signals that persist for relatively long times in a range of methyl-bearing substances may be important for applications such as investigations of metabolism, enzymatic reactions, protein–ligand binding, drug screening, and molecular imaging.

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confidence: 99%

Dynamic Nuclear Polarization of Long-Lived Nuclear Spin States in Methyl Groups

Dumez

Vuichoud

Mammoli

et al. 2017

J. Phys. Chem. Lett.

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“…Only if this was possible, the observation could be made worthwhile for the NMR community, since then not only specific methyl groups which act as quantum rotors could be observed in hyperpolarization, but also other spins of interest in the inner part of the molecules investigated. Here we report our results with the model compound 4-picoline 1 which already served as the first example of the Haupt effect both in solid state [2] and in high resolution NMR [1].…”

Section: Introductionmentioning

confidence: 90%

“…Very recently we have observed hyperpolarized up and down multiplets of methyl groups both for 13 C and 1 H in high resolution NMR spectra after first cooling in liquid helium and then rapid dissolution in deuterated solvents at room temperature [1]. The phenomenon is related to the Haupt effect which was discovered in 1972 [2] and has since then very often been debated in the literature [3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 97%

Transfer of the Haupt-hyperpolarization to neighbor spins

Icker

Fricke

Berger

2012

Journal of Magnetic Resonance

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“…One can extend this idea to three identical spins, where the eight eigenstates are categorized into three groups labeled A, E + and E − where the last two are degenerate subspaces. Under cyclic permutation of the spins, the four eigenstates in group A remain invariant, and so, totally symmetric states, whereas the two eigenstates in each of degenerate subspaces, E ± , acquire a phase ε = e ± 2π 3 , and so, non-symmetric states [12,17,20,21]. In a similar manner to the two-spin case, one can polarize three identical spins with respect to their symmetry by creating an imbalance of population between the A states and the E ± states.…”

Section: Introductionmentioning

confidence: 99%

Dipolar relaxation mechanism of long-lived states of methyl groups

Annabestani

Cory

2017

Quantum Inf Process

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We analyze the symmetry properties of the dipolar Hamiltonian as the main relaxation mechanism responsible for the observed NMR spectra of long-lived states of methyl groups. Long-lived states exhibit relaxation times that are considerably longer than the spin-lattice relaxation time, T 1 . The analysis is complementary to previous studies and provides insight into the relaxation mechanism of long-lived states by focusing exclusively on the symmetry of the spin Hamiltonian. Our study shows that the dipole-dipole coupling between protons of a methyl group and between the protons and an external spin are both symmetry breaking interactions that can lead to relaxation pathways that transform the polarization from symmetry order to Zeeman order. The net contribution of the internal dipolar interaction to the NMR observation of long-lived states is zero. Our calculation is in good agreement with the reported features of the observed spectra and previous theoretical studies.

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Unexpected multiplet patterns induced by the Haupt-effect

Cited by 39 publications

References 16 publications

Dynamic Nuclear Polarization of Long-Lived Nuclear Spin States in Methyl Groups

Dynamic Nuclear Polarization of Long-Lived Nuclear Spin States in Methyl Groups

Transfer of the Haupt-hyperpolarization to neighbor spins

Dipolar relaxation mechanism of long-lived states of methyl groups

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