We report a novel 1D J-edited pure shift NMR experiment (J-PSHIFT) that was constructed from a pseudo 2D experiment for the direct measurement of proton-proton scalar couplings. The experiment gives homonuclear broad-band (1)H-decoupled (1)H NMR spectra, which provide a single peak for chemically distinct protons, and only retain the homonuclear-scalar-coupled doublet pattern at the chemical-shift positions of the protons in the coupled network of a specific proton. This permits the direct and unambiguous measurement of the magnitudes of the couplings. The incorporation of a 1D selective correlation spectroscopy (COSY)/ total correlation spectroscopy (TOCSY) block in lieu of the initial selective pulse, results in the exclusive detection of the correlated spectrum of a specific proton.
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http://dx.doi.org/10.1002/cphc.201402792 | DOI Listing |
Anal Chim Acta
October 2023
Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China. Electronic address:
Scalar (J) couplings constitute one of vital features observed in NMR spectroscopy and show valuable information for molecular structure elucidation and conformation analysis. However, existing J coupling measurement techniques are generally confined by the concerns of resolution, SNR, and experimental efficiency. Herein, we exploit an efficient 2D NMR protocol to deal with the above concerns by enabling rapid, sensitive, and high-resolution J coupling extraction.
View Article and Find Full Text PDFAnal Chim Acta
November 2021
Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, China. Electronic address:
J coupling constitutes an important NMR parameter for molecular-level composition analysis and conformation elucidation. Dozens of J-based approaches have been exploited for J coupling measurement and coupling network determination, however, they are generally imposed to insufficient spectral resolution to resolve crowded NMR resonances and low measurement efficiency that a single experiment records one J coupling network. Herein, we propose a general NMR method to collect high-resolution 2D J-edited NMR spectra, which are characterized with advantages of pure absorptive lineshapes, decoupled chemical shift dimension, as well as eliminated axial peaks, thus facilitating J coupling partner assignments and J coupling constant measurements.
View Article and Find Full Text PDFJ Magn Reson
June 2018
Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China.
Nuclear magnetic resonance (NMR) spectra are often utilized for gathering accurate information relevant to molecular structures and composition assignments. In this study, we develop a homonuclear encoding approach based on imparting a discrete phase modulation of the targeted cross peaks, and combine it with a pure shift experiments (PSYCHE) based J-modulated scheme, providing simple 2D J-edited spectra for accurate measurement of scalar coupling networks. Chemical shifts and J coupling constants of protons coupled to the specific protons are demonstrated along the F and F dimensions, respectively.
View Article and Find Full Text PDFMagn Reson Chem
October 2018
Equipe de RMN en milieu orienté, ICMMO, UMR 8182 (CNRS-UPS), Université Paris-Sud, Université Paris-Saclay, 91405, Orsay Cedex, France.
We report the application of pure shift and J-edited nuclear magnetic resonance spectroscopies to the structural analysis of a protected maltotrioside synthetic intermediate whose crowded H spectrum displays highly crowded regions. The analytical strategy is based on the implementation of J-edited and TOCSY experiments whose resolution is optimized by the use of broadband homonuclear decoupling and selective refocusing techniques, to assign and measure chemical shifts and homonuclear scalar couplings with high accuracy. The resulting data show a high level of complementarity, providing a detailed insight into each subunit of this oligomeric saccharide, even for proton sites whose nuclear magnetic resonance signals strongly overlap.
View Article and Find Full Text PDFPhys Chem Chem Phys
August 2016
Equipe de RMN en milieu orienté, ICMMO, UMR 8182 (CNRS-UPS), Université Paris-Saclay, 91405 Orsay cedex, France.
A detailed analysis of NMR spectra acquired based on spatial frequency encoding is presented. A theoretical model to simulate gradient encoded pulses is developed in order to describe the spatial properties of the NMR signals that are locally created throughout the sample. The key features that affect the efficiency of the slice selection process during excitation as well as refocusing pulses are investigated on a model ABX spin system, both theoretically and experimentally.
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