在水中抵消pi-pi堆叠相互作用的意想不到的替代物效应
Mark J Rashkin1, Marcey L Waters
1Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
Journal of the American Chemical Society
|February 28, 2002
概括
这项研究使用动态NMR测量替代化中旋转障碍物. 电子负元替代剂显著增加了旋转障碍,表明蛋白质中更强的偏移堆叠相互作用.
科学领域:
- 有机化学 有机化学
- 生物物理化学 生物物理化学
- 化学物理 化学物理
背景情况:
- 抵消堆叠相互作用对蛋白质结构和功能至关重要.
- 了解这些非共价相互作用需要强大的模型系统.
- 盐为研究芳香相互作用提供了一个可调的平台.
研究的目的:
- 量化元替代剂和副替代剂对N--2--2-二基化物中旋转障碍物的影响.
- 模拟和理解溶液相系统中芳香环之间的偏移堆叠相互作用.
- 为了将替代物效应与这些堆叠相互作用的强度相关联.
主要方法:
- 动态核磁共振 (NMR) 谱学被用来测量旋转障碍.
- 合成甲基和副替代的N-基-2-(2-化) 二化物.
- 分析光谱变化以确定基态和过渡态之间的能量差异.
主要成果:
- 观察到一个小的变化 (0.1 kcal/mol) 在旋转屏障被观察到的para-substituted化合物.
- 电子负元替代剂,如三甲基 (CF3),导致旋转屏障显著增加 (高达0.66 kcal/mol).
- 观察到的效应表明堆叠和静电相互作用的结合.
结论:
- 这个模型系统中的旋转屏障有效地反映了偏移堆叠相互作用的强度.
- 电子阴性元替代剂大大增强了这些相互作用,可能是通过静电贡献.
- 这项研究提供了关于生物系统中,特别是蛋白质中调节芳香相互作用的力量的宝贵见解.
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