有机共轭聚炔的 NMR 光谱中屏蔽和去屏蔽效应的起源。
Origin of Shielding and Deshielding Effects in NMR Spectra of Organic Conjugated Polyynes.
机构信息
Department of Chemistry , Texas A&M University , P.O. Box 30012, College Station , Texas 77843-3012 , United States.
出版信息
Org Lett. 2019 Feb 1;21(3):753-757. doi: 10.1021/acs.orglett.8b03990. Epub 2019 Jan 18.
Nucleus independent chemical shifts (NICS) for conjugated polyynes H(C≡C) H are reported ( n = 2-10). There is marked shielding within the carbon chain, gradually decreasing with radial distance and transitioning to a weakly deshielding region at 2.5-3.0 Å, as well as other trends. Interestingly, the magnitude of the shielding is only very weakly dependent upon the chain length or distance from the termini. H and C NMR chemical shifts are also computed and the trends analyzed.
报道了共轭多炔 H(C≡C) H 的核独立化学位移 (NICS)（n = 2-10）。在碳链中存在显著的屏蔽效应，随着径向距离逐渐减小，并在 2.5-3.0 Å 处过渡到弱去屏蔽区域，以及其他趋势。有趣的是，屏蔽的大小仅与链长或与末端的距离有非常微弱的依赖关系。还计算了 1 H 和 13 C NMR 化学位移，并分析了这些趋势。
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