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- Title
基于 NOAH 技术的二维核磁共振应用.
- Authors
闫 丽; 熊嫣; 赵伟; 彭绍春
- Abstract
[Objective] Nuclear magnetic resonance (NMR) technology has emerged as a pivotal analytical tool for characterizing organic small molecules and drug molecular structures. Its applications span various fields, including chemistry, biomedicine, materials science, and food analysis. By providing detailed information about molecular structure, dynamics, and interactions, NMR helps researchers make informed decisions in drug development, quality control, and material characterization. In this respect, two-dimensional (2D) NMR plays a crucial role when it is necessary to clearly elucidate an unknown molecular structure, relying mainly on a series of 2D NMR experiments: correlation spectroscopy, total correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum coherence, and heteronuclear multiple-bond correlation. By analyzing the distance and coupling between atoms in chemical bonds or space, 2D NMR links the correlation between one-dimensional spectral peaks and further defines the attribution of one-dimensional spectral peaks, thereby resolving complex molecular structures. However, to obtain high-resolution 2D NMR spectra, the time domain must be sampled at equidistant time intervals, which consequently increases the time cost of data collection. For example, unstable compounds that are easily decomposed may undergo structural changes during long-term 2D NMR data collection, potentially leading to signal loss. Thus, the accuracy and reliability of structural analyses are compromised. In cases where the sample concentration is low or the natural abundance of nuclei is insufficient, it is often necessary to extend the acquisition time to ensure high-quality spectrograms, which consequently reduces the efficiency of the spectrometer. [Methods] In this paper, a fast 2D NMR acquisition method based on NOAH (NMR by ordered acquisition using ¹H-detection) is proposed. Different from the traditional 2D NMR acquisition approach, the NOAH method employs a set of nested NMR super sequences founded upon ¹H detection, which facilitate the orderly acquisition of NMR spectra with high sensitivity. By optimizing the sequence of data collection and sharing a recovery time (d1), several 2D NMR experiments related to both multiple homonuclear and heteronuclear processes can be completed in a relatively short time. Finally, a complete set of relevant data can be obtained in a single scan through the spatial coding of the NMR response. Data can be automatically collected and processed directly from within to generate individual 2D NMR experiment data. [Results] The 2D NMR data of Rifamycin-S was collected by NOAH-3_BSC pulse sequence combined with a high-field NMR spectrometer (700 MHz). The experimental results showed that the NOAH method can rapidly collect multiple homonuclear- and heteronuclear-related 2D NMR experiments in a short time. This not only reduces the time required for the experiment by 60% but also enhances the sensitivity and resolution of data compared with conventional 2D NMR and nonuniform sampling methods. [Conclusions] The NOAH method can effectively solve the structural changes and signal loss caused by long-term data acquisition of unstable and easily decomposed compounds. It provides a useful reference and a practical scheme for the rapid identification of compound structures, thereby improving the open sharing of future spectrometers.
- Subjects
OVERHAUSER effect (Nuclear physics); NUCLEAR magnetic resonance; MATERIALS science; NMR spectrometers; MOLECULAR structure
- Publication
Experimental Technology & Management, 2024, Vol 41, Issue 12, p7
- ISSN
1002-4956
- Publication type
Academic Journal
- DOI
10.16791/j.cnki.sjg.2024.12.002