The Application of MAS Recoupling Methods in the Intermediate Motional Regime

Saalwächter, Kay; Fischbach, Ingrid

doi:10.1006/jmre.2002.2552

Cited by 47 publications

(62 citation statements)

References 45 publications

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“…Thus, for a smaller interaction strength the interaction is averaged up to longer time scales. Experimental approaches to characterizing this intermediate regime have been discussed [150,151].…”

Section: Measurements Of Anisotropic Interactions Under Mas Can Be Domentioning

confidence: 99%

Studying dynamics by magic-angle spinning solid-state NMR spectroscopy: Principles and applications to biomolecules

Schanda

Ernst

2016

Progress in Nuclear Magnetic Resonance Spectroscopy

198

295

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Magic-angle spinning solid-state NMR spectroscopy is an important technique to study molecular structure, dynamics and interactions, and is rapidly gaining importance in biomolecular sciences. Here we provide an overview of experimental approaches to study molecular dynamics by MAS solid-state NMR, with an emphasis on the underlying theoretical concepts and differences of MAS solid-state NMR compared to solution-state NMR. The theoretical foundations of nuclear spin relaxation are revisited, focusing on the particularities of spin relaxation in solid samples under magic-angle spinning. We discuss the range of validity of Redfield theory, as well as the inherent multi-exponential behavior of relaxation in solids. Experimental challenges for measuring relaxation parameters in MAS solid-state NMR and a few recently proposed relaxation approaches are discussed, which provide information about time scales and amplitudes of motions ranging from picoseconds to milliseconds. We also discuss the theoretical basis and experimental measurements of anisotropic interactions (chemical-shift anisotropies, dipolar and quadrupolar couplings), which give direct information about the amplitude of motions. The potential of combining relaxation data with such measurements of dynamically-averaged anisotropic interactions is discussed. Although the focus of this review is on the theoretical foundations of dynamics studies rather than their application, we close by discussing a small number of recent dynamics studies, where the dynamic properties of proteins in crystals are compared to those in solution.

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Section: Measurements Of Anisotropic Interactions Under Mas Can Be Domentioning

confidence: 99%

Studying dynamics by magic-angle spinning solid-state NMR spectroscopy: Principles and applications to biomolecules

Schanda

Ernst

2016

Progress in Nuclear Magnetic Resonance Spectroscopy

198

295

View full text Add to dashboard Cite

show abstract

“…This includes the Floquet theory, 15,21 extended exchange theory, 22,23 approximate theories based on the Anderson-Weiss theory, [18][19][20] and stepwise numerical propagation 24,25 using the solution of the stochastic Liouville-von-Neumann equation. Among these approaches, full spin dynamics simulations based on density matrix propagation were chosen to be employed here for the method validation.…”

Section: Spin Dynamics Simulationsmentioning

confidence: 99%

“…Specifically, a spin dynamics simulation program described by Saalwachter and Fischbach in Ref. 25 was used. Since there is a comprehensive description of this approach in Ref.…”

Section: Spin Dynamics Simulationsmentioning

confidence: 99%

“…16 Successful approaches to calculate spectra include the application of the AndersonWeiss theory, [17][18][19][20] Floquet theory, 15,21 extended exchange theory, 22,23 or stepwise numerical propagation in the framework of partial analytical solutions or of explicit density matrix simulations. 24,25 In addition, in most of the cases for natural isotopic abundance nuclei in organic solids, dipolar decoupling has to be applied in concert with MAS to achieve appreciable spectral resolution. The 1 H irradiation adds another coherent perturbation that interferes with the incoherent molecular exchange process and results in another source of line broadening.…”

Section: Introductionmentioning

confidence: 99%

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Intermediate motions as studied by solid-state separated local field NMR experiments

deAzevedo

Saalwächter

Pascui

et al. 2008

The Journal of Chemical Physics

126

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Second-order dipolar order in magic-angle spinning nuclear magnetic resonance J. Chem. Phys. 135, 154507 (2011) Single crystal nuclear magnetic resonance in spinning powders J. Chem. Phys. 135, 144201 (2011) Resistive detection of optically pumped nuclear polarization with spin phase transition peak at Landau level filling factor 2/3 Appl. Phys. Lett. 99, 112106 (2011) High-resolution 13C nuclear magnetic resonance evidence of phase transition of Rb,Cs-intercalated singlewalled nanotubes J. Appl. Phys. 110, 054306 (2011) Introduction of the Floquet-Magnus expansion in solid-state nuclear magnetic resonance spectroscopy J. Chem. Phys. 135, 044109 (2011) Additional information on J. Chem. Phys. In this report, the application of a class of separated local field NMR experiments named dipolar chemical shift correlation ͑DIPSHIFT͒ for probing motions in the intermediate regime is discussed. Simple analytical procedures based on the Anderson-Weiss ͑AW͒ approximation are presented. In order to establish limits of validity of the AW based formulas, a comparison with spin dynamics simulations based on the solution of the stochastic Liouville-von-Neumann equation is presented. It is shown that at short evolution times ͑less than 30% of the rotor period͒, the AW based formulas are suitable for fitting the DIPSHIFT curves and extracting kinetic parameters even in the case of jumplike motions. However, full spin dynamics simulations provide a more reliable treatment and extend the frequency range of the molecular motions accessible by DIPSHIFT experiments. As an experimental test, molecular jumps of imidazol methyl sulfonate and trimethylsulfoxonium iodide, as well as the side-chain motions in the photoluminescent polymer poly͓2-methoxy-5-͑2Ј-ethylhexyloxy͒-1,4-phenylenevinylene͔, were characterized. Possible extensions are also discussed.

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“…Motions with rates between 10 3 and 10 7 Hz average the 13 C-1 H coupling, changing the shape of the DIPSHIFT curves and making possible to distinguish rigid from mobile groups [10]. Although, motions with rates of about 1 kHz can be already detected by DIPSHIFT, the analysis of DIPSHIFT curves when motions with rates between 10 3 and 10 6 Hz (intermediate regime) take place involves more elaborated approaches [11], which includes dynamic spins dynamics simulations to describe the motion effect in the quantum evolution of the 13 C nuclear spins under homonuclear decoupling of the 1 H nuclei [12]. In contrast, for motions in the so called fast limit (motional rates higher than 10 6 Hz) the analysis is much simpler since the DIPSHIFT curves become dependent of only geometrical aspects of the motion, for example, reorientation angles or if the motion is isotropic or anisotropic [10].…”

Section: Resultsmentioning

confidence: 99%