Communication: Dissolution DNP reveals a long-lived deuterium spin state imbalance in methyl groups

Jhajharia, Aditya; Weber, Emmanuelle M. M.; Kempf, James; Abergel, Daniel; Bodenhausen, Geoffrey; Kurzbach, Dennis

doi:10.1063/1.4974358

Cited by 17 publications

(23 citation statements)

References 23 publications

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“…In the absence of a rotational splitting, long-lived symmetry order can be established in a range of substances using DNP. [23,31,56] The longlived symmetry order in methyl groups can also be established or in fact enhanced using DNP in presence of a small tunneling splitting, as has been shown for protonated methyl groups. [30] This interesting observation implies that DNP can facilitate symmetry conversion and at least indirectly lower the temperature of the rotational reservoir.…”

Section: Methyl Groupsmentioning

confidence: 89%

“…[24] Symmetry order in methyl groups can also be established using DNP. [30,31] Here, I do not reiterate the details of the relaxation mechanisms of long-lived spin order in methyl or other quantum rotors-these have been described in detail by Dumez et al [29] -but focus on theoretical and experimental considerations for the establishment and observation of symmetry order in quantum rotors. To the best of my knowledge, methyl groups and fullerene-encapsulated, 17 O-labelled water are the only quantum rotors in which D-QRIP has been observed to date.…”

Section: Introductionmentioning

confidence: 99%

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Quantum‐rotor‐induced polarization

Meier

2018

Magnetic Reson in Chemistry

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Quantum-rotor-induced polarization is closely related to para-hydrogen-induced polarization. In both cases, the hyperpolarized spin order derives from rotational interaction and the Pauli principle by which the symmetry of the rotational ground state dictates the symmetry of the associated nuclear spin state. In quantum-rotor-induced polarization, there may be several spin states associated with the rotational ground state, and the hyperpolarization is typically generated by hetero-nuclear cross-relaxation. This review discusses preconditions for quantum-rotor-induced polarization for both the 1-dimensional methyl rotor and the asymmetric rotor H O@C , that is, a single water molecule encapsulated in fullerene C . Experimental results are presented for both rotors.

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Section: Methyl Groupsmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Quantum‐rotor‐induced polarization

Meier

2018

Magnetic Reson in Chemistry

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“…Molecules containing at least two magnetically equivalent deuterium nuclei that have spin S = 1 (in this paper, we shall use the symbol "D" rather than 2 H for simplicity) imbalances between populations of spin states of different symmetry can give rise to LLS, in the sense that their lifetime T LLS (D) can be longer than their Zeeman spin-lattice relaxation times T 1 (D), which are usually short because of rapid quadrupolar relaxation of deuterium nuclei. 15,16 In the extreme narrowing regime, deuterium spin-lattice relaxation rates R 1 (D) = 1/T 1 (D) are proportional to ω 2 Q τ C where ω Q is the quadrupolar coupling and τ C is the correlation time of molecular tumbling.…”

Section: Introductionmentioning

confidence: 99%

“…To create LLSs in deuterated 13 CD 2 and 13 CD 3 groups, we employed dissolution dynamic nuclear polarization (D-DNP), 15 which allows one to generate imbalances between the averaged populations of the A-states and E-states, thus giving rise to long-lived states.…”

Section: Introductionmentioning

confidence: 99%

“…A description of LLS in 13 CD 2 groups has been outlined elsewhere. 15 The nine energy states of the D 2 subsystem can be separated into six sextet states that are symmetric with respect to the permutation of the two deuterium nuclei, and three triplet states are anti-symmetric upon permutation. The LLS has been identified as a "sextet-triplet imbalance" (STI).…”

Section: Introductionmentioning

confidence: 99%

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Relaxation of long-lived modes in NMR of deuterated methyl groups

Ivanov

Kress

Baudin

et al. 2018

The Journal of Chemical Physics

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Long-lived imbalances of spin state populations can circumvent fast quadrupolar relaxation by reducing effective longitudinal relaxation rates by about an order of magnitude. This opens new avenues for the study of dynamic processes in deuterated molecules. Here we present an analysis of the relaxation properties of deuterated methyl groups CD. The number of coupled equations that describe cross-relaxation between the 27 symmetry-adapted spin states of a D system can be reduced to only 2 non-trivial "lumped modes" by (i) taking the sums of the populations of all states that equilibrate rapidly within each irreducible representation of the symmetry group, and (ii) by combining populations that have similar relaxation rates although they belong to different irreducible representations. The quadrupolar relaxation rates of the spin state imbalances in CD groups are determined not by the correlation time of overall tumbling of the molecule, but by the frequency of jumps of methyl groups about their three-fold symmetry axis. We access these states via dissolution dynamic nuclear polarization (D-DNP), a method that allows one to populate the desired long-lived states at cryogenic temperatures and their subsequent detection at ambient temperatures after rapid dissolution. Experimental examples of DMSO-d and ethanol-d demonstrate that long-lived deuterium spin states are indeed accessible and that their lifetimes can be determined. Our analysis of the system via "lumped" modes allows us to visualize different possible spin-state populations of symmetry A, B, or E. Thus, we identify a long-lived spin state involving all three deuterons in a CD group as an A/E imbalance that can be populated through DNP at low temperatures.

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Homonuclear ADAPT: A general preparation route to long-lived nuclear singlet order

Elliott

Stevanato

2019

Journal of Magnetic Resonance

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We introduce a simple strategy to access and readout nuclear singlet order based on the alternate repetition of hard pulses and delays. We demonstrate the general applicability of the method by accessing nuclear singlet order in spin systems characterized by diverse coupling regimes. We show that the method is highly efficient in the strong-coupling and chemical equivalence regimes, and can overcome some limitations of other well-established and more elaborated pulse sequences. A simulation package is provided which allows the determination of pulse sequence parameters.

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Communication: Dissolution DNP reveals a long-lived deuterium spin state imbalance in methyl groups

Abstract: Theory of long-lived nuclear spin states in methyl groups and quantum-rotor induced polarisation

Cited by 17 publications

References 23 publications

Quantum‐rotor‐induced polarization

Quantum‐rotor‐induced polarization

Relaxation of long-lived modes in NMR of deuterated methyl groups

Homonuclear ADAPT: A general preparation route to long-lived nuclear singlet order

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