Analysis of Cross-Polarization Dynamics between Two Abundant Nuclei, 19F and 1H, Based on Spin Thermodynamics Theory

Ando, Shinji; Harris, Robin K.; Reinsberg, Stefan A.

doi:10.1006/jmre.1999.1866

Cited by 34 publications

(20 citation statements)

References 16 publications

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“…3A 0 ), the significant drop of the signal intensity of about 60% was observed in the region belonging to the response from carbons 5, 10 and 20 ($100 ppm), the only ones that have directly attached protons, while the signals originating from the quaternary carbons are not influenced by 1 H spin lock. This observation is consistent with direct LGCP experiments under MAS, where the carbon signal intensity shows an oscillatory behavior as a function of contact time, with maximum signal intensity usually obtained under 100 ls contact time for CH moiety, depending on the strength of the heteronuclear dipolar coupling [60]. Since CP is a coherent process, similar behavior happens for 13 C ?…”

Section: C ? 1 H Hyperpolarization Transfer and Carbon Acquisitionsupporting

confidence: 88%

“…The possible 13 C ? 1 H transfer of hyperpolarization can be studied either by detecting the residual 13 C polarization after CP transfer similar to CP-drain experiments [60] or by detecting the buildup of 1 H polarization directly. In the first set of experiments, we used sequences 1 and 2 and expected to observe the decay of 13 C hyperpolarization presumably due to 13 C ?…”

Section: C ? 1 H Hyperpolarization Transfer and Carbon Acquisitionmentioning

confidence: 99%

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13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

Bielytskyi

Gräsing

Mote

et al. 2018

Journal of Magnetic Resonance

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In the present study, we exploit the light-induced hyperpolarization occurring on C nuclei due to the solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) effect to boost the NMR signal intensity of selected protons via inverse cross-polarization. Such hyperpolarization transfer is implemented intoH-detected two-dimensional C-H correlation magic-angle-spinning (MAS) NMR experiment to study protons in frozen photosynthetic reaction centers (RCs). As a first trial, the performance of such an experiment is tested on selectively C labeled RCs from the purple bacteria of Rhodobacter sphaeroides. We observed response from the protons belonging to the photochemically active cofactors in their native protein environment. Such an approach is a potential heteronuclear spin-torch experiment which could be complementary to the classical heteronuclear correlation (HETCOR) experiments for mapping proton chemical shifts of photosynthetic cofactors and tounderstand the role of the proton pool around the electron donors in the electron transfer process occurring during photosynthesis.

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Section: C ? 1 H Hyperpolarization Transfer and Carbon Acquisitionsupporting

confidence: 88%

Section: C ? 1 H Hyperpolarization Transfer and Carbon Acquisitionmentioning

confidence: 99%

13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

Bielytskyi

Gräsing

Mote

et al. 2018

Journal of Magnetic Resonance

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“…Hence, eq can be simplified as where T 2 is the time constant of Gauss decay (eq ). This equation is perhaps the most often used for the processing of experimental CP kinetic data in the cases where it was deduced that the nonclassical I–I*–S model , was to be more appropriate, compared to the classical one (I–S model), , see, for example, refs , , , and . The time constant T 2 characterizes the dipolar 31 P– 1 H coupling.…”

Section: Resultsmentioning

confidence: 99%

Subnanoscale Order and Spin Diffusion in Complex Solids through the Processing of Cross-Polarization Kinetics

2016

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The advanced strategy of processing of NMR crosspolarization (CP) data has been developed separating the short-range order-and the bulk effects in the manifold of spin interactions. The effectiveness of such treatment have been demonstrated on 1 H− 31 P CP kinetics in the nanostructured calcium hydroxyapatite (nano-CaHA) and that containing amorphous phosphate phase (amorph-CaHA). This allowed to describe the oscillatory manner of CP kinetics, oscillation blurring phenomenon, and to determine the spin distribution at the short-and moderate internuclear distances. The contribution of the dipolar coupling with remote spins has been removed modeling their spatial distribution using a set of radial profiles. The short 31 P− 1 H contact peak at 0.24−0.27 nm has been well resolved in the spatial distribution profile of the nano-CaHA sample and it is hardly noticeable in the case of amorph-CaHA. It reflects the differences in surface organization in nanostructured and amorphous materials. The spin diffusion processes in both systems are practically unaffected upon MAS. The MAS decimates 31 P interactions with the protons on the surface layers and with the remote protons (>0.5 nm) that are plausibly involved in the H-bond network.

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“…Two spin coupling models are met in the literature that are most often applied for the processing of CP kinetic data: the “classical” model, denoted as I–S (in the present work the spins I and S are 1 H and 13 C, respectively) and the “nonclassical” one, I–I*–S, where the asterisk denotes spins I being in close neighborhood to S spins . In the first case (I–S model) it is assumed that spin-diffusion is fast enough to establish communication between the protons and to force them to behave as a system with a uniform spin temperature. , If S nuclei are highly diluted among I nuclei, i.e., N S ≪ N I , and the CP process is fast enough compared with the spin–lattice relaxation of spin S in the rotating frame the dependence of the CP signal intensity I ( t ) on the contact time t can be described by where 1/ T IS is the CP rate constant and 1/ T 1ρ is the spin–lattice relaxation rate of spin I in the rotating frame.…”

Section: Theoretical Modelsmentioning

confidence: 99%

“…6 In the first case (I−S model) it is assumed that spin-diffusion is fast enough to establish communication between the protons and to force them to behave as a system with a uniform spin temperature. 6,34 If S nuclei are highly diluted among I nuclei, i.e., N S ≪ N I , and the CP process is fast enough compared with the spin−lattice relaxation of spin S in the rotating frame the dependence of the CP signal intensity I(t) on the contact time t can be described by…”

Section: Theoretical Modelsmentioning

confidence: 99%

Quasi-Equilibria and Polarization Transfer Between Adjacent and Remote Spins: ¹H–¹³C CP MAS Kinetics in Glycine

et al. 2018

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The 1H–13C CP MAS kinetic curves were measured in glycine powder sample at the MAS rates of 7, 10, and 12 kHz. Each experimental curve contained up to 1000 equidistant points over the whole contact time range of 10 μs - 10 ms. The CP kinetic data for CH2 group, i.e., for the system containing adjacent 1H–13C spin pairs with a definite dominant dipolar coupling can be described in the frame of the isotropic spin-diffusion approach. The local order parameter ⟨S⟩ ≈ 1.0, determined as the ratio of the measured dipolar 1H–13C coupling constant and the calculated static dipolar coupling constant, is very close to the values deduced in series of other amino acids. The strong narrow peaks observed in the spin coupling spectrum at multiples of the MAS frequency can be considered as the confirmation that the periodic quasi-equilibrium state can appear also in the powder samples. The anisotropic spin-diffusion approach improved by the introducing of the thermal equilibration in the proton bath is the most proper model to describe the CP kinetics in the system containing remote spins. Very realistic values of the spin-cluster size (N) have been obtained without any constraint on the flow of the nonlinear curve fitting. The finite values of N ≤ 4 means that CP transfer is located within one glycine molecule.

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Analysis of Cross-Polarization Dynamics between Two Abundant Nuclei, 19F and 1H, Based on Spin Thermodynamics Theory

Cited by 34 publications

References 16 publications

13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

Subnanoscale Order and Spin Diffusion in Complex Solids through the Processing of Cross-Polarization Kinetics

Quasi-Equilibria and Polarization Transfer Between Adjacent and Remote Spins: ¹H–¹³C CP MAS Kinetics in Glycine

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Analysis of Cross-Polarization Dynamics between Two Abundant Nuclei, 19F and 1H, Based on Spin Thermodynamics Theory

Cited by 34 publications

References 16 publications

13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

Subnanoscale Order and Spin Diffusion in Complex Solids through the Processing of Cross-Polarization Kinetics

Quasi-Equilibria and Polarization Transfer Between Adjacent and Remote Spins: 1H–13C CP MAS Kinetics in Glycine

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Product

Resources

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13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

Quasi-Equilibria and Polarization Transfer Between Adjacent and Remote Spins: ¹H–¹³C CP MAS Kinetics in Glycine