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Jean-paul Amoureux - One of the best experts on this subject based on the ideXlab platform.

  • improving the resolution in proton detected through space heteronuclear multiple quantum correlation nmr spectroscopy
    Journal of Magnetic Resonance, 2014
    Co-Authors: Bingwen Hu, Jean-paul Amoureux, Olivier Lafon, Frédérique Pourpoint, Julien Trebosc, Qun Chen, Ming Shen
    Abstract:

    Abstract Connectivities and proximities between protons and low-gamma nuclei can be probed in solid-state NMR spectroscopy using two-dimensional (2D) proton-detected heteronuclear correlation, through Heteronuclear Multiple Quantum Correlation (HMQC) pulse sequence. The indirect detection via protons dramatically enhances the sensitivity. However, the spectra are often broadened along the indirect F 1 dimension by the decay of heteronuclear multiple-quantum coherences under the strong 1 H– 1 H dipolar couplings. This work presents a systematic comparison of the performances of various decoupling schemes during the indirect t 1 Evolution Period of dipolar-mediated HMQC ( D -HMQC) experiment. We demonstrate that 1 H– 1 H dipolar decoupling sequences during t 1 , such as symmetry-based schemes, phase-modulated Lee–Goldburg (PMLG) and Decoupling Using Mind-Boggling Optimization (DUMBO), provide better resolution than continuous wave 1 H irradiation. We also report that high resolution requires the preservation of 1 H isotropic chemical shifts during the decoupling sequences. When observing indirectly broad spectra presenting numerous spinning sidebands, the D -HMQC sequence must be fully rotor-synchronized owing to the rotor-synchronized indirect sampling and dipolar recoupling sequence employed. In this case, we propose a solution to reduce artefact sidebands caused by the modulation of window delays before and after the decoupling application during the t 1 Period. Moreover, we show that 1 H– 1 H dipolar decoupling sequence using Smooth Amplitude Modulation (SAM) minimizes the t 1 -noise. The performances of the various decoupling schemes are assessed via numerical simulations and compared to 2D 1 H–{ 13 C} D -HMQC experiments on [U– 13 C]– L -histidine⋅HCl⋅H 2 O at various magnetic fields and Magic Angle spinning (MAS) frequencies. Great resolution and sensitivity enhancements resulting from decoupling during t 1 Period enable the detection of heteronuclear correlation between aliphatic protons and ammonium 14 N sites in L -histidine⋅HCl⋅H 2 O.

  • indirect high resolution detection for quadrupolar spin 3 2 nuclei in dipolar hmqc solid state nmr experiments
    Chemical Physics Letters, 2010
    Co-Authors: Julien Trebosc, Bingwen Hu, Olivier Lafon, Jean-paul Amoureux
    Abstract:

    Abstract We present a new kind of NMR pulse sequences to observe heteronuclear correlation (HETCOR) specifically between spin-1/2 and spin-3/2 nuclei with isotropic resolution on the quadrupolar channel. These methods, called HMQC-ST, feature a STMAS filter during the Evolution Period of the HMQC scheme. Compared to existing HETCOR techniques involving quadrupolar nuclei, the HMQC-ST combines high-resolution and high efficiency and allows indirect detection of spin-3/2 nuclei via sensitive nuclei. We study analytically and using simulations how through-bond and through-space HMQC-ST perform compared to regular HMQC sequence. HMQC-ST potential is demonstrated experimentally by recording through-space HETCOR 2D spectra of Na 2 HPO 4 and NaH 2 PO 4 .

Bikash Baishya - One of the best experts on this subject based on the ideXlab platform.

  • pure shift hmqc resolution and sensitivity enhancement by bilinear rotation decoupling in the indirect and direct dimensions
    Journal of Magnetic Resonance, 2020
    Co-Authors: Upendra Singh, Subrato Bhattacharya, Bikash Baishya
    Abstract:

    Abstract The heteronuclear multiple-quantum coherence in the indirect dimension of the two-dimensional HMQC experiment evolves under the passive 1H-1H J-couplings leading to multiplet structures in the F1 dimension. Besides, 1H-1H J-multiplets appear in the direct dimension as well. Thus, multiplets along both dimensions lower the resolution and sensitivity of this technique, when high resolution is required along both dimensions. An efficient broadband homodecoupling scheme along the F1 dimension of the HMQC experiment has not been realized to date. We have implemented broadband homonuclear decoupling using bilinear rotation decoupling (BIRD) by adding a 1H SQ Evolution Period followed by BIRD before the 1H-13C multiple-quantum Evolution Period in the HMQC. In the direct time domain, BIRD is implemented using a real-time or single-scan scheme, which further improves resolution and sensitivity of this technique. The resulting pure shift HMQC provides singlet peak per chemical site along F1 as well as F2 axes and, hence, better resolution and sensitivity than conventional HMQC spectrum for all peaks except diastereotopic methylene protons. Due to the incorporation of the BIRD, the indirect time domain becomes double in length compared to the conventional HMQC. However, slow relaxation of small molecules favors better sensitivity for ps-HMQC relative to conventional HMQC under all conditions. We also found that the sensitivity of ps-HMQC is only slightly less than ps-HSQC for small molecules.

  • perfect echo hmqc sensitivity and resolution enhancement by broadband homonuclear decoupling
    Journal of Magnetic Resonance, 2013
    Co-Authors: Bikash Baishya, C L Khetrapal, Krishna Kishor Dey
    Abstract:

    Abstract Homonuclear 1 H– 1 H J -modulation leads to J -multiplets in F 1 dimension of 2D 1 H– 13 C HMQC spectra. This hampers unambiguous signal assignment for overcrowded 13 C spectra. Broadband homonuclear decoupling has been achieved in the indirect t 1 Evolution Period by incorporating blocks of perfect echo. This method of perfect echo HMQC demonstrates better resolution and sensitivity than conventional HMQC spectra. The results on Cyclosporine demonstrate that the method is very efficient for refocusing geminal couplings in weakly coupled – 13 CH 2 groups. Partial refocusing of vicinal couplings is also observed for – 13 CH and – 13 CH 3 groups. Interpretation of the result based on product operator formalism is also given. Comparison of pe-HMQC, HMQC and HSQC reveals that the F 1 linewidth of pe-HMQC is much narrower than HMQC and very close to that of HSQC for CH 2 groups.

Bingwen Hu - One of the best experts on this subject based on the ideXlab platform.

  • improving the resolution in proton detected through space heteronuclear multiple quantum correlation nmr spectroscopy
    Journal of Magnetic Resonance, 2014
    Co-Authors: Bingwen Hu, Jean-paul Amoureux, Olivier Lafon, Frédérique Pourpoint, Julien Trebosc, Qun Chen, Ming Shen
    Abstract:

    Abstract Connectivities and proximities between protons and low-gamma nuclei can be probed in solid-state NMR spectroscopy using two-dimensional (2D) proton-detected heteronuclear correlation, through Heteronuclear Multiple Quantum Correlation (HMQC) pulse sequence. The indirect detection via protons dramatically enhances the sensitivity. However, the spectra are often broadened along the indirect F 1 dimension by the decay of heteronuclear multiple-quantum coherences under the strong 1 H– 1 H dipolar couplings. This work presents a systematic comparison of the performances of various decoupling schemes during the indirect t 1 Evolution Period of dipolar-mediated HMQC ( D -HMQC) experiment. We demonstrate that 1 H– 1 H dipolar decoupling sequences during t 1 , such as symmetry-based schemes, phase-modulated Lee–Goldburg (PMLG) and Decoupling Using Mind-Boggling Optimization (DUMBO), provide better resolution than continuous wave 1 H irradiation. We also report that high resolution requires the preservation of 1 H isotropic chemical shifts during the decoupling sequences. When observing indirectly broad spectra presenting numerous spinning sidebands, the D -HMQC sequence must be fully rotor-synchronized owing to the rotor-synchronized indirect sampling and dipolar recoupling sequence employed. In this case, we propose a solution to reduce artefact sidebands caused by the modulation of window delays before and after the decoupling application during the t 1 Period. Moreover, we show that 1 H– 1 H dipolar decoupling sequence using Smooth Amplitude Modulation (SAM) minimizes the t 1 -noise. The performances of the various decoupling schemes are assessed via numerical simulations and compared to 2D 1 H–{ 13 C} D -HMQC experiments on [U– 13 C]– L -histidine⋅HCl⋅H 2 O at various magnetic fields and Magic Angle spinning (MAS) frequencies. Great resolution and sensitivity enhancements resulting from decoupling during t 1 Period enable the detection of heteronuclear correlation between aliphatic protons and ammonium 14 N sites in L -histidine⋅HCl⋅H 2 O.

  • indirect high resolution detection for quadrupolar spin 3 2 nuclei in dipolar hmqc solid state nmr experiments
    Chemical Physics Letters, 2010
    Co-Authors: Julien Trebosc, Bingwen Hu, Olivier Lafon, Jean-paul Amoureux
    Abstract:

    Abstract We present a new kind of NMR pulse sequences to observe heteronuclear correlation (HETCOR) specifically between spin-1/2 and spin-3/2 nuclei with isotropic resolution on the quadrupolar channel. These methods, called HMQC-ST, feature a STMAS filter during the Evolution Period of the HMQC scheme. Compared to existing HETCOR techniques involving quadrupolar nuclei, the HMQC-ST combines high-resolution and high efficiency and allows indirect detection of spin-3/2 nuclei via sensitive nuclei. We study analytically and using simulations how through-bond and through-space HMQC-ST perform compared to regular HMQC sequence. HMQC-ST potential is demonstrated experimentally by recording through-space HETCOR 2D spectra of Na 2 HPO 4 and NaH 2 PO 4 .

Ming Shen - One of the best experts on this subject based on the ideXlab platform.

  • improving the resolution in proton detected through space heteronuclear multiple quantum correlation nmr spectroscopy
    Journal of Magnetic Resonance, 2014
    Co-Authors: Bingwen Hu, Jean-paul Amoureux, Olivier Lafon, Frédérique Pourpoint, Julien Trebosc, Qun Chen, Ming Shen
    Abstract:

    Abstract Connectivities and proximities between protons and low-gamma nuclei can be probed in solid-state NMR spectroscopy using two-dimensional (2D) proton-detected heteronuclear correlation, through Heteronuclear Multiple Quantum Correlation (HMQC) pulse sequence. The indirect detection via protons dramatically enhances the sensitivity. However, the spectra are often broadened along the indirect F 1 dimension by the decay of heteronuclear multiple-quantum coherences under the strong 1 H– 1 H dipolar couplings. This work presents a systematic comparison of the performances of various decoupling schemes during the indirect t 1 Evolution Period of dipolar-mediated HMQC ( D -HMQC) experiment. We demonstrate that 1 H– 1 H dipolar decoupling sequences during t 1 , such as symmetry-based schemes, phase-modulated Lee–Goldburg (PMLG) and Decoupling Using Mind-Boggling Optimization (DUMBO), provide better resolution than continuous wave 1 H irradiation. We also report that high resolution requires the preservation of 1 H isotropic chemical shifts during the decoupling sequences. When observing indirectly broad spectra presenting numerous spinning sidebands, the D -HMQC sequence must be fully rotor-synchronized owing to the rotor-synchronized indirect sampling and dipolar recoupling sequence employed. In this case, we propose a solution to reduce artefact sidebands caused by the modulation of window delays before and after the decoupling application during the t 1 Period. Moreover, we show that 1 H– 1 H dipolar decoupling sequence using Smooth Amplitude Modulation (SAM) minimizes the t 1 -noise. The performances of the various decoupling schemes are assessed via numerical simulations and compared to 2D 1 H–{ 13 C} D -HMQC experiments on [U– 13 C]– L -histidine⋅HCl⋅H 2 O at various magnetic fields and Magic Angle spinning (MAS) frequencies. Great resolution and sensitivity enhancements resulting from decoupling during t 1 Period enable the detection of heteronuclear correlation between aliphatic protons and ammonium 14 N sites in L -histidine⋅HCl⋅H 2 O.

Julien Trebosc - One of the best experts on this subject based on the ideXlab platform.

  • improving the resolution in proton detected through space heteronuclear multiple quantum correlation nmr spectroscopy
    Journal of Magnetic Resonance, 2014
    Co-Authors: Bingwen Hu, Jean-paul Amoureux, Olivier Lafon, Frédérique Pourpoint, Julien Trebosc, Qun Chen, Ming Shen
    Abstract:

    Abstract Connectivities and proximities between protons and low-gamma nuclei can be probed in solid-state NMR spectroscopy using two-dimensional (2D) proton-detected heteronuclear correlation, through Heteronuclear Multiple Quantum Correlation (HMQC) pulse sequence. The indirect detection via protons dramatically enhances the sensitivity. However, the spectra are often broadened along the indirect F 1 dimension by the decay of heteronuclear multiple-quantum coherences under the strong 1 H– 1 H dipolar couplings. This work presents a systematic comparison of the performances of various decoupling schemes during the indirect t 1 Evolution Period of dipolar-mediated HMQC ( D -HMQC) experiment. We demonstrate that 1 H– 1 H dipolar decoupling sequences during t 1 , such as symmetry-based schemes, phase-modulated Lee–Goldburg (PMLG) and Decoupling Using Mind-Boggling Optimization (DUMBO), provide better resolution than continuous wave 1 H irradiation. We also report that high resolution requires the preservation of 1 H isotropic chemical shifts during the decoupling sequences. When observing indirectly broad spectra presenting numerous spinning sidebands, the D -HMQC sequence must be fully rotor-synchronized owing to the rotor-synchronized indirect sampling and dipolar recoupling sequence employed. In this case, we propose a solution to reduce artefact sidebands caused by the modulation of window delays before and after the decoupling application during the t 1 Period. Moreover, we show that 1 H– 1 H dipolar decoupling sequence using Smooth Amplitude Modulation (SAM) minimizes the t 1 -noise. The performances of the various decoupling schemes are assessed via numerical simulations and compared to 2D 1 H–{ 13 C} D -HMQC experiments on [U– 13 C]– L -histidine⋅HCl⋅H 2 O at various magnetic fields and Magic Angle spinning (MAS) frequencies. Great resolution and sensitivity enhancements resulting from decoupling during t 1 Period enable the detection of heteronuclear correlation between aliphatic protons and ammonium 14 N sites in L -histidine⋅HCl⋅H 2 O.

  • indirect high resolution detection for quadrupolar spin 3 2 nuclei in dipolar hmqc solid state nmr experiments
    Chemical Physics Letters, 2010
    Co-Authors: Julien Trebosc, Bingwen Hu, Olivier Lafon, Jean-paul Amoureux
    Abstract:

    Abstract We present a new kind of NMR pulse sequences to observe heteronuclear correlation (HETCOR) specifically between spin-1/2 and spin-3/2 nuclei with isotropic resolution on the quadrupolar channel. These methods, called HMQC-ST, feature a STMAS filter during the Evolution Period of the HMQC scheme. Compared to existing HETCOR techniques involving quadrupolar nuclei, the HMQC-ST combines high-resolution and high efficiency and allows indirect detection of spin-3/2 nuclei via sensitive nuclei. We study analytically and using simulations how through-bond and through-space HMQC-ST perform compared to regular HMQC sequence. HMQC-ST potential is demonstrated experimentally by recording through-space HETCOR 2D spectra of Na 2 HPO 4 and NaH 2 PO 4 .