Journal ArticleDOI
Heteronuclear decoupling in rotating solids
Andrew E. Bennett,Chad M. Rienstra,Michèle Auger,Michèle Auger,K. V. Lakshmi,K. V. Lakshmi,Robert G. Griffin +6 more
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TLDR
In this article, a simple two pulse phase modulation (TPPM) scheme was proposed to reduce the residual linewidths arising from insufficient proton decoupling power in double resonance magic angle spinning (MAS) experiments.Abstract:
A simple two pulse phase modulation (TPPM) scheme greatly reduces the residual linewidths arising from insufficient proton decoupling power in double resonance magic angle spinning (MAS) experiments. Optimization of pulse lengths and phases in the sequence produces substantial improvements in both the resolution and sensitivity of dilute spins (e.g., 13C) over a broad range of spinning speeds at high magnetic field. The theoretical complications introduced by large homo‐ and heteronuclear interactions among the spins, as well as the amplitude modulation imposed by MAS, are explored analytically and numerically. To our knowledge, this method is the first phase‐switched sequence to exhibit improvement over continuous‐wave (cw) decoupling in a strongly coupled homogeneous spin system undergoing sample spinning.read more
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Journal ArticleDOI
Interaction of epicatechin gallate with phospholipid membranes as revealed by solid-state NMR spectroscopy
Yoshinori Uekusa,Miya Kamihira-Ishijima,Osamu Sugimoto,Takeshi Ishii,Shigenori Kumazawa,Kozo Nakamura,Ken Ichi Tanji,Akira Naito,Tsutomu Nakayama +8 more
TL;DR: The Galloyl moiety contributes to increasing the hydrophobicity of catechin molecules, and consequently to high affinity of galloyl-type catechins for phospholipid membranes, as well as to stabilization of cATEchin molecules in the phospholIPid membranes by cation-π interaction between the galloyL ring and quaternary amine of the phospholiipid head-group.
Journal ArticleDOI
Investigation of Polymorphism in Aspartame and Neotame Using Solid-State NMR Spectroscopy
Mark T. Zell,Brian E. Padden,David J. W. Grant,Stephen A. Schroeder,Wachholder Kurt L,Indra Prakash,Eric J. Munson +6 more
TL;DR: In this paper, the artificial sweeteners aspartame ( l -aspartyl- l -phenylalanine methyl ester) and neotame (N-(3,3-dimethylbutyl)- l -Aspartyl l -L-phenyl-l -phenyi methyl esters) have been studied for their polymorphism.
Journal ArticleDOI
Repeat Domains of Melanosome Matrix Protein Pmel17 Orthologs Form Amyloid Fibrils at the Acidic Melanosomal pH
TL;DR: It is reported that the RPT domains of mouse and zebrafish, as well as a small splice variant of human Pmel17, all form amyloid specifically at mildly acid pH (pH ∼5.0), and protease digestion, mass per unit length measurements, and solid-state NMR experiments suggest thatAmyloid of the mouse RPT has an in-register parallel β-sheet architecture with two RPT molecules per layer, similar to amyloids
Journal ArticleDOI
35Cl solid-state NMR of HCl salts of active pharmaceutical ingredients: structural prediction, spectral fingerprinting and polymorph recognition
Marcel P. Hildebrand,Hiyam Hamaed,Andrew M. Namespetra,John M. Donohue,Riqiang Fu,Ivan Hung,Zhehong Gan,Robert W. Schurko +7 more
TL;DR: In this paper, a series of HCl salts of active pharmaceutical ingredients (APIs) have been characterized via 35Cl solid-state NMR (SSNMR) spectroscopy and first-principles plane-wave density functional theory (DFT) calculations of 35Cl NMR interaction tensors.
Journal ArticleDOI
Spectral editing in solid-state NMR using scalar multiple quantum filters.
TL;DR: The use of heteronuclear scalar couplings in solid-state NMR in order to generate multiple-quantum filtering (MQF) pulse sequences that can be used to edit CP/MAS spectra according to carbon multiplicity is described.
References
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Journal ArticleDOI
Proton‐enhanced NMR of dilute spins in solids
TL;DR: In this article, the NMR signals of isotopically or chemically dilute nuclear spins S in solids can be enhanced by repeatedly transferring polarization from a more abundant species I of high abundance (usually protons) to which they are coupled.
Book
Principles of high-resolution NMR in solids
Abstract: 1 Introduction.- 2 Nuclear Spin Interactions in Solids.- 2.1 Basic Nuclear Spin Interactions in Solids.- 2.2 Spin Interactions in High Magnetic Fields.- 2.3 Transformation Properties of Spin Interactions in Real Space.- 2.4 Powder Spectrum Line Shape.- 2.5 The NMR Spectrum. Lineshapes and Moments.- 2.6 Magic Angle Spinning (MAS).- 2.7 Rapid Anisotropic Molecular Rotation.- 2.8 Line Shapes in the Presence of Molecular Reorientation.- 3 Multiple-Pulse NMR Experiments.- 3.1 Idealized Multiple-Pulse Sequences.- 3.2 The Four-Pulse Sequence (WHH-4).- 3.3 Coherent Averaging Theory.- 3.4 Application of Coherent Averaging Theory to Multiple-Pulse Sequences.- 3.5 Arbitrary Rotations and Finite Pulse Width in Multiple-Pulse Experiments.- 3.6 Second Averaging.- 3.7 The Influence of Pulse Imperfections on Multiple-Pulse Experiments.- 3.8 Resolution of Multiple-Pulse Experiments.- 3.9 Magic Angle Rotating Frame Line Narrowing Experiments.- 3.10 Modulation Induced Line Narrowing.- 3.11 Applications of Multiple-Pulse Experiments.- 4 Double Resonance Experiments.- 4.1 Basic Principles of Double Resonance Experiments.- 4.2 Cross-Polarization of Dilute Spins.- 4.3 Cross-Polarization Dynamics.- 4.4 Spin-Decoupling Dynamics.- 4.5 Application of Cross-Polarization Experiments.- 5 Two-Dimensional NMR Spectroscopy.- 5.1 Basic Principles of 2 D-Spectroscopy.- 5.2 2D-Spectroscopy of 13C-1H Interactions in Solids.- 5.3 Applications of 2D-Spectroscopy.- 6 Multiple-Quantum NMR Spectroscopy.- 6.1 Double-Quantum Decoupling.- 6.2 The Three-Level System Double Quantum Coherence.- 6.3 Multiple-Quantum Coherence.- 6.4 Selective Multiple-Quantum Coherence.- 6.5 Double-Quantum Cross-Polarization.- 7 Magnetic Shielding Tensor.- 7.1 Ramsey's Formula.- 7.2 Approximate Calculations of the Shielding Tensor.- 7.3 Proton Shielding Tensors.- 7.4 19F Shielding Tensors.- 7.5 13C Shielding Tensors.- 7.6 Other Shielding Tensors.- 8 Spin-Lattice Relaxation.- 8.1 Spin-Lattice Relaxation in the Weak Collision Limit.- 8.2 Spin-Lattice Relaxation in Multiple-Pulse Experiments.- 8.3 Application of Multiple-Pulse Experiments to the Investigation of Spin-Lattice Relaxation.- 8.4 Spin-Lattice Relaxation in Dilute Spin Systems.- 8.5 Selective Excitation and Spectral Diffusion.- 9 Appendix.- A Irreducible Tensor Representation of Spin Interactions.- B Rotations.- C General Line Shape Theory.- D Homogeneous, Inhomogeneous and Heterogeneous Lineshapes.- E Lineshape and Relaxation due to Fluctuating Chemical Shift Tensors.- F Time Evolution and Magnus Expansion.- G Coherent Versus Secular Averaging Theory.- H Applications of Average Hamiltonian Theory.- I Relaxation Theory.- 10 References.- 11 Subject Index.
Journal ArticleDOI
Nuclear Magnetic Resonance Spectra from a Crystal rotated at High Speed
TL;DR: In this article, it was shown that when these weak side-spectra are included the second moment does indeed remain invariant even though the second moments of the central portion, which is all that is observed experimentally, becomes smaller.
Journal ArticleDOI
Carbon-13 nuclear magnetic resonance of polymers spinning at the magic angle
Journal ArticleDOI
An improved sequence for broadband decoupling: WALTZ-16
TL;DR: In this paper, the effects of the proton irradiation sequence by means of a train of spin rotation operators, the overall effect at the end of the cycle being calculated by explicit matrix multiplication, the offset dependence of this proton response determined the residual splitting of the carbon-13 resonance and hence the effectiveness of the decoupling.