通过固态NMR光谱学探测异质核 (15) N - 17 O 和 (13) C - 17 O 的连接性和近距离
Ivan Hung1, Anne-Christine Uldry, Johanna Becker-Baldus
1Department of Physics, University of Warwick, Coventry, UK.
Journal of the American Chemical Society
|January 14, 2009
概括
这项研究展示了新的固态NMR方法,以精确测量-氧 (15N-17O) 二极和J合在甘氨酸和 uracil. 这些技术为这些重要的分子提供了准确的结构和结合见解.
科学领域:
- 固态核磁共振 (NMR) 光谱学 固态核磁共振 (NMR) 光谱学
- 量子化学和计算建模 量子化学和计算建模
- 材料科学和结构分析
背景情况:
- 准确确定核间合对于理解固态材料中的分子结构和结合至关重要.
- 异核双极和J合器分别提供了关于穿越空间和穿越键相互作用的独特信息.
- 测量固体中15N-(17) O合的先前方法在准确性和适用性方面存在局限性.
研究的目的:
- 开发和验证先进的固态NMR实验,用于测量 (15) N-(17) O双极和J合.
- 将这些方法应用于同位素标记的甘氨酸和 uracil,以评估它们的结构和电子特性.
- 将实验结果与理论计算进行比较,以验证NMR方法.
主要方法:
- 实施异质核固态魔力角旋转 (MAS) 的NMR实验,包括R(3)-HMQC,REDOR和REAPDOR.
- 使用的同位素丰富样本:[ 2H ] NH 3 ] ,1 - 13 C ,15 N ,17 O 2]甘氨酸2HCl 和[ 15 N 2 ] ,17 O 2 ] uracil.
- 通过对异质核和同核旋回回声实验的分析量化J合 (S(Q) ((tau) = S(HET) ((tau) /S(HOM) ((tau)).
- 使用CASTEP代码与几何优化的晶体结构进行计算的J合计算.
主要成果:
- 成功获得了2D (15) N-(17) O相关性光谱,峰值强度反映了 (15) N-(17) O二极合的大小.
- 对甘氨酸2HCl的实验双极合显示出与来自晶体结构的值有很好的一致性 (在+/-20%范围内).
- 测量了甘氨2HCl (24.7-25.3 Hz) 的单键J合物 ((1) J ((CO)) 和 uracil (5.1 +/- 0.6 Hz) 的键介导的J合物.
- 确定的双键分子内J合: (2) J(OO) = 8.8 +/- 0.9 Hz对于甘氨酸.2HCl和 (2) J(N1,N3) = 2.7 +/- 0.1 Hz对于乌拉.
- 在实验和CASTEP计算的J合之间观察到的优异一致性,对于甘氨酸和 uracil.
结论:
- 本文所介绍的固态核磁共振技术对于表征 (15) N - 17 O 双极和 J 合是有效的.
- 结果验证了这些NMR方法的准确性,并为甘氨酸和 uracil 提供了详细的结构和结合信息.
- 这项研究强调了将实验性NMR与用于固态结构阐明的计算方法相结合的力量.
相关概念视频
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