A robust method for determining 1H–15N long‐range correlations: 15N optimized CIGAR‐HMBC experiments
A robust method for determining 1H–15N long‐range correlations: 15N optimized CIGAR‐HMBC experiments
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确定 1H–15N 长程相关性的稳健方法：15N 优化的 CIGAR-HMBC 实验
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
S. Cheatham
中科院分区：
文献类型：
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作者：
Mike Kline;S. Cheatham
对各种常见的含氮系统进行了检查，以优化观察 1H-15N 长程相关性的参数。由于 1H-15N 相关性遇到的耦合常数存在多样性，因此使用改进的基于手风琴的序列来提供最佳结果。手风琴延迟值的优化表明，3 到 10 Hz 之间的范围提供了弱相关性检测和 T2 过程信号丢失之间的最佳折衷。除苯胺外，每类化合物的多重键相关性都很容易检测到。杂环系统内的相关性揭示了一些一般模式。一般来说，与咪唑和吡唑的“吡啶型”氮相比，质子与“吡咯类”氮的相关性更强。在甲基和芳香杂环的氮之间经常观察到非常长程（四键和五键）的相关性。版权所有 © 2003 约翰·威利父子有限公司
An examination of a variety of common nitrogen‐containing systems was undertaken to optimize parameters for observation of 1H–15N long‐range correlations. Because of the diversity of coupling constants encountered with 1H–15N correlations, a modified accordion‐based sequence was used to provide the best results. Optimization of the values for the accordion delay revealed that a range between 3 and 10 Hz provided the best compromise between detection of weak correlations and loss of signal to T2 processes. Multiple bond correlations were readily detected for each class of compound with the exception of anilines. Correlations within heterocyclic systems revealed some general patterns. In general, stronger correlations were observed from protons to ‘pyrrole‐like’ nitrogens than to the ‘pyridine‐type’ nitrogens of imidazoles and pyrazoles. Very long‐range (four‐ and five‐bond) correlations were routinely observed between methyl groups and the nitrogens of aromatic heterocycles. Copyright © 2003 John Wiley & Sons, Ltd.