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Updated: Jun 29, 2025

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
溶剂和质子状态对[s]-Triazines中的旋转障碍物的影响
Liam E Claton1, Hongjun Pan2, Eric E Simanek1
1Department of Chemistry & Biochemistry, Texas Christian University, Fort Worth, Texas 76109, United States.
质子化增加了氨基替代三中三-N键周围的旋转屏障 (ΔG‡),在较低的介电溶剂中观察到更高的屏障. 这种阻碍旋转受到溶剂极性和质子状态的影响.
科学领域:
- 有机化学 有机化学
- 物理化学 物理化学
- 频谱学是一种光谱学.
背景情况:
- 氨基替代的三酸在三酸-N键周围的旋转受到限制,中性化合物的能量障碍 (ΔG‡) 报告为15.1至17.7kcal/mol.
- 溶剂极性和质子化状态对这种旋转屏障的影响在很大程度上仍未得到研究.
研究的目的:
- 为了研究溶剂和质子化状态对氨基替代三中三-N键周围的旋转屏障 (ΔG‡) 的影响.
- 阐明溶剂介电常数与观察到的旋转障碍之间的关系.
主要方法:
- 使用二甲基胺替代剂作为报告组,通过动态核磁共振 (DNMR) 光谱测量旋转屏障 (ΔG‡).
- 在一系列具有不同介电常数的化溶剂中进行了实验,包括D2O,DMSO-d6,MeCN-d3,MeOD-d4,THF-d8和TFE-d3.3.
- 研究了质子和竞争性质子对旋转屏障的影响.
主要成果:
- 在各种溶剂中,三的质子化显著增加了旋转屏障 (ΔG‡) 到17.519.3 kcal/mol.
- 在旋转屏障 (ΔG‡) 和溶剂介电常数 (p < 0.01) 之间观察到明显的反相关性.
- 中性三酸具有较低的旋转障碍 (ΔG‡) 为15.316.1 kcal/mol.
- 在氨酸中,质子化模型的旋转屏障与溶剂介电不相关,这归因于竞争性质子化.
结论:
- 溶剂极性在稳定三酸环在质子化时增加的电荷密度方面发挥着至关重要的作用,从而影响了旋转屏障.
- 质子化显著增强了围绕三-N键的阻碍旋转,其大小受溶剂性质的影响.
- 竞争性质子可以影响特定溶剂系统中观察到的旋转障碍.
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