The Experts below are selected from a list of 576 Experts worldwide ranked by ideXlab platform
Lyndon Emsley - One of the best experts on this subject based on the ideXlab platform.
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fast remote correlation experiments for 1h Homonuclear Decoupling in solids
2020Co-Authors: Pinelopi Moutzouri, Bruno Simoes De Almeida, Lyndon EmsleyAbstract:Abstract In 1H MAS spectra, the residual homogeneous broadening under MAS is due to a combination of higher-order shifts and splittings. We have recently shown how the two-dimensional anti-z-COSY experiment can be used for the removal of the splittings. However, this requires spectra with high resolution in the indirect dimension (t1), leading to experiment times of hours. Here, we show how anti-z-COSY can be adapted to be combined with the two-dimensional one pulse (TOP) transformation which leads to significantly reduced experimental time while retaining the line narrowing effect. The experiment is demonstrated on a powdered sample of L-histidine monohydrochloride monohydrate, where the new TAZ-COSY sequence at 100 kHz MAS, yields between a factor 1.6 and 2.3 increase in resolution compared with the equivalent one-pulse experiment, in just 20 min. The same methodology is also adapted for the acquisition of liquid state 1H homodecoupled data, and an example is given for testosterone.
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Homonuclear Decoupling in 1 h nmr of solids by remote correlation
2020Co-Authors: Pinelopi Moutzouri, Bruno Simoes De Almeida, Federico M Paruzzo, Gabriele Stevanato, Lyndon EmsleyAbstract:The typical linewidths of 1 H NMR spectra of powdered organic solids at 111 kHz magic-angle spinning (MAS) are of the order of a few hundred Hz. While this is remarkable in comparison to the tens of kHz observed in spectra of static samples, it is still the key limit to the use of 1 H in solid-state NMR, especially for complex systems. Here, we demonstrate a novel strategy to further improve the spectral resolution. We show that the anti-z-COSY experiment can be used to reduce the residual line broadening of 1 H NMR spectra of powdered organic solids. Results obtained with the anti-z-COSY sequence at 100 kHz MAS on thymol, β-AspAla, and strychnine show an improvement in resolution of up to a factor of two compared to conventional spectra acquired at the same spinning rate.
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High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy
2015Co-Authors: Aaron J. Rossini, Judith Schlagnitweit, Anne Lesage, Lyndon EmsleyAbstract:We demonstrate that high field (9.4T) dynamic nuclear polarization (DNP) at cryogenic (similar to 100 K) sample temperatures enables the rapid acquisition of natural abundance H-1-H-2 cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance H-2 CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2 h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the H-2 solid-state NMR spectra is comparable to that of H-1 spectra obtained with state of the art Homonuclear Decoupling techniques.
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Homonuclear Decoupling of h 1 dipolar interactions in solids by means of heteronuclear recoupling
2014Co-Authors: Gregory L Olsen, Lyndon Emsley, Adonis Lupulescu, Jeannicolas Dumez, Lucio FrydmanAbstract:Line narrowing has been traditionally achieved in solid-state H-1 NMR spectroscopy by applying pulse sequences that combine multiple-pulse operations with magic-angle spinning (MAS), to effectively average out the dipoledipole Homonuclear Hamiltonian. The present study explores a new alternative that departs from the usual concept of directly acting on the strongly coupled spins with radiofrequency pulses; instead, we seek to achieve a net Homonuclear dipolar Decoupling in solids by exploring the reintroduction of MAS-averaged heteronuclear dipolar couplings between the H-1 nuclei and directly bonded C-13 or N-15 nuclei. This recouplinganti-recoupling (RaR) scheme thus relies on the recoupling of the dipolar interaction with heteronuclear spins, which, under fast MAS, will exceed the strength and will not commute with the Homonuclear (HH)-H-1-H-1 coupling one is intending to average out. Subsequent removal (antiRecoupling) of these heteronuclear interactions can lead to narrowed H-1 resonances, without ever pulsing on the aforementioned channel. The line-narrowing properties of RaR are illustrated with numerical simulations and with experiments on model organic solids.
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A common theory for phase-modulated Homonuclear Decoupling in solid-state NMR
2012Co-Authors: Meghan E. Halse, Lyndon EmsleyAbstract:We propose a new framework for Homonuclear dipolar Decoupling in solid-state NMR that provides a theoretical link between the FSLG, PMLG and DUMBO families. We show that through the use of a Legendre polynomial basis, the phase modulation of these Decoupling schemes can be described by the same set of parameters, permitting for the first time a direct theoretical comparison between these methods. Use of this common basis reveals that the central Decoupling mechanism is the same for DUMBO and FSLG/PMLG and that a similar vector picture can be used to describe both methods. In addition to the common root of Decoupling efficiency, this new analysis highlights two major points of difference between the methods. First, the DUMBO phase modulation consists not only of a linear change in phase with time a la PMLG but also smaller high-order oscillations, which act to improve line-narrowing performance. Second, we show how the DUMBO phase waveforms are generated from a four-step permutation of a single asymmetric unit, in contrast to the two-step permutation of PMLG. Numerical simulations and experimental results suggest that this latter point of difference is responsible for the superior performance of DUMBO in the presence of significant RF inhomogeneity.
Geoffrey Bodenhausen - One of the best experts on this subject based on the ideXlab platform.
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Homonuclear Decoupling for spectral simplification of carbon 13 enriched molecules in solution state nmr enhanced by dissolution dnp
2016Co-Authors: Srinivas Chinthalapalli, Aurelien Bornet, Diego Carnevale, Sami Jannin, Geoffrey BodenhausenAbstract:Complex overlapping multiplets due to scalar couplings (n)J((13)C, (13)C) in fully (13)C-enriched molecules can be simplified by polychromatic irradiation of selected spins. The signal intensities of the remaining non-irradiated signals are proportional to the concentrations, as shown in this work for the anomeric (13)C signals of the α- and β-conformers of glucose. Homonuclear Decoupling can therefore be useful for quantitative NMR studies. The resulting decoupled lineshapes show residual fine structures that have been investigated by means of numerical simulations. Simulations also show that Homonuclear Decoupling schemes remain effective despite inhomogeneous static fields that tend to hamper in cellulo and in vivo studies. Homonuclear Decoupling schemes can be combined with dissolution DNP to obtain signal enhancements of more than four orders of magnitude. Polychromatic irradiation of selected spins does not cause significant losses of hyperpolarization of the remaining non-irradiated spins.
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polychromatic Decoupling of a manifold of Homonuclear scalar interactions in solution state nmr
2012Co-Authors: Diego Carnevale, Geoffrey Bodenhausen, Takuya F SegawaAbstract:Keywords: Fourier transform spectroscopy ; Homonuclear Decoupling ; J-coupling ; NMR spectroscopy Reference EPFL-ARTICLE-181116doi:10.1002/chem.201200481View record in Web of Science Record created on 2012-09-03, modified on 2017-05-12
Benedicte Elena - One of the best experts on this subject based on the ideXlab platform.
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enhanced sensitivity in high resolution 1h solid state nmr spectroscopy with dumbo dipolar Decoupling under ultra fast mas
2009Co-Authors: Elodie Salager, Anne Lesage, Robin S Stein, Stefan Steuernagel, Benedicte Elena, Lyndon EmsleyAbstract:The solid-state NMR H-1 Homonuclear Decoupling sequences in the DUMBO family are shown to be effective at ultra-fast MAS rates of up to 65 kHz. The sequences are applied to model compounds glycine and [2-C-13]-L-alanine as well as the dipeptide beta-L-Asp-L-Ala in windowed and continuous phase-modulated versions. They are shown to achieve especially impressive resolution when implemented in a 2D constant-time experiment. At 65 kHz MAS, H-1 resolution using Homonuclear Decoupling is similar to that obtained at lower MAS rates, but peak intensity, and therefore spectral sensitivity, is improved by a factor of 5 over Homonuclear-decoupled spectra at 10 kHz MAS. (C) 2008 Elsevier B. V. All rights reserved.
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direct spectral optimisation of proton proton Homonuclear dipolar Decoupling in solid state nmr
2004Co-Authors: Lyndon Emsley, Benedicte Elena, Gael De PaepeAbstract:Abstract We show how direct spectral optimisation can be used to provide significantly improved resolution for proton NMR spectroscopy in the solid state. We describe the design of new continuous phase modulated schemes for proton–proton Homonuclear dipolar Decoupling, exploiting an experimental optimisation procedure through observation of carbon-13 lineshapes. The performance of the resulting eDUMBO Homonuclear Decoupling sequences is demonstrated with a variety of high resolution proton NMR experiments at 500 and 700 MHz, and at different magic angle spinning speeds.
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experimental aspects of proton nmr spectroscopy in solids using phase modulated Homonuclear dipolar Decoupling
2003Co-Authors: Anne Lesage, Stefan Steuernagel, Benedicte Elena, Dimitris Sakellariou, Sabine Hediger, Patrick Charmont, Lyndon EmsleyAbstract:In this paper we demonstrate experimentally that the continuously phase-modulated Homonuclear Decoupling sequence DUMBO-1 is suitable for high-resolution proton NMR spectroscopy of rigid solids. Over a wide range of experimental conditions, we show on the model sample L-alanine as well as on small peptides that proton linewidths of less than 0.5 ppm can be obtained under DUMBO-1 Decoupling. In particular the DUMBO-1 sequence yields well resolved proton spectra both at slow and fast MAS. The DUMBO-1 Decoupling scheme can in principle be inserted in any multi-nuclear or multi-dimensional solid-state NMR experiment which requires a high-resolution 1H dimension. An example is provided with the 13C-1H MAS-J-HMQC experiment.
Anne Lesage - One of the best experts on this subject based on the ideXlab platform.
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High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy
2015Co-Authors: Aaron J. Rossini, Judith Schlagnitweit, Anne Lesage, Lyndon EmsleyAbstract:We demonstrate that high field (9.4T) dynamic nuclear polarization (DNP) at cryogenic (similar to 100 K) sample temperatures enables the rapid acquisition of natural abundance H-1-H-2 cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance H-2 CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2 h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the H-2 solid-state NMR spectra is comparable to that of H-1 spectra obtained with state of the art Homonuclear Decoupling techniques.
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enhanced sensitivity in high resolution 1h solid state nmr spectroscopy with dumbo dipolar Decoupling under ultra fast mas
2009Co-Authors: Elodie Salager, Anne Lesage, Robin S Stein, Stefan Steuernagel, Benedicte Elena, Lyndon EmsleyAbstract:The solid-state NMR H-1 Homonuclear Decoupling sequences in the DUMBO family are shown to be effective at ultra-fast MAS rates of up to 65 kHz. The sequences are applied to model compounds glycine and [2-C-13]-L-alanine as well as the dipeptide beta-L-Asp-L-Ala in windowed and continuous phase-modulated versions. They are shown to achieve especially impressive resolution when implemented in a 2D constant-time experiment. At 65 kHz MAS, H-1 resolution using Homonuclear Decoupling is similar to that obtained at lower MAS rates, but peak intensity, and therefore spectral sensitivity, is improved by a factor of 5 over Homonuclear-decoupled spectra at 10 kHz MAS. (C) 2008 Elsevier B. V. All rights reserved.
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experimental aspects of proton nmr spectroscopy in solids using phase modulated Homonuclear dipolar Decoupling
2003Co-Authors: Anne Lesage, Stefan Steuernagel, Benedicte Elena, Dimitris Sakellariou, Sabine Hediger, Patrick Charmont, Lyndon EmsleyAbstract:In this paper we demonstrate experimentally that the continuously phase-modulated Homonuclear Decoupling sequence DUMBO-1 is suitable for high-resolution proton NMR spectroscopy of rigid solids. Over a wide range of experimental conditions, we show on the model sample L-alanine as well as on small peptides that proton linewidths of less than 0.5 ppm can be obtained under DUMBO-1 Decoupling. In particular the DUMBO-1 sequence yields well resolved proton spectra both at slow and fast MAS. The DUMBO-1 Decoupling scheme can in principle be inserted in any multi-nuclear or multi-dimensional solid-state NMR experiment which requires a high-resolution 1H dimension. An example is provided with the 13C-1H MAS-J-HMQC experiment.
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Homonuclear dipolar Decoupling in solid state nmr using continuous phase modulation
2000Co-Authors: Dimitris Sakellariou, Anne Lesage, Paul Hodgkinson, Lyndon EmsleyAbstract:Abstract We present a theoretical framework for the use of continuously phase modulated radio-frequency pulses for Homonuclear Decoupling in solid-state NMR. Within this framework, we have derived new families of Decoupling sequences using numerical optimization. One of these sequences is tested experimentally on an ordinary organic solid, and its performance is compared with standard multiple-pulse sequences.
Marek Pruski - One of the best experts on this subject based on the ideXlab platform.
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enhanced 1h x d hmqc performance through improved 1h Homonuclear Decoupling
2019Co-Authors: Frederic A Perras, Tian Wei Goh, Linlin Wang, Wenyu Huang, Marek PruskiAbstract:The sensitivity of solid-state NMR experiments that utilize 1H zero-quantum heteronuclear dipolar recoupling, such as D-HMQC, is compromised by poor Homonuclear Decoupling. This leads to a rapid decay of recoupled magnetization and an inefficient recoupling of long-range dipolar interactions, especially for nuclides with low gyromagnetic ratios. We investigated the use, in symmetry-based 1H heteronuclear recoupling sequences, of a basic R element that was principally designed for efficient Homonuclear Decoupling. By shortening the time required to suppress the effects of Homonuclear dipolar interactions to the duration of a single inversion pulse, spin diffusion was effectively quenched and long-lived recoupled coherence lifetimes could be obtained. We show, both theoretically and experimentally, that these modified sequences can yield considerable sensitivity improvements over the current state-of-the-art methods and applied them to the indirect detection of 89Y in a metal-organic framework.
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directly and indirectly detected through bond heteronuclear correlation solid state nmr spectroscopy under fast mas
2009Co-Authors: Kanmi Mao, Marek PruskiAbstract:Two-dimensional through-bond (1)H{(13)C} solid-state NMR experiments utilizing fast magic angle spinning (MAS) and Homonuclear multipulse (1)H Decoupling are presented. Remarkable efficiency of polarization transfer can be achieved at MAS rates exceeding 40 kHz, which is instrumental in these measurements. Schemes utilizing direct and indirect detection of heteronuclei are compared in terms of resolution and sensitivity. A simple procedure for optimization of (1)H Homonuclear Decoupling sequences under these conditions is proposed. The capabilities of these techniques were confirmed on two naturally abundant solids, tripeptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (f-MLF-OH) and brown coal.