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使用分子旋转器测量的n→π*相互作用的过渡状态稳定
Erik C Vik1, Ping Li1, Perry J Pellechia1
1Department of Chemistry and Biochemistry , University of South Carolina , Columbia , South Carolina 29208 , United States.
Journal of the American Chemical Society
|October 15, 2019
概括
分子旋转器表明,n→π*相互作用显著稳定了键旋转的过渡状态 (TS). 这种稳定性高达10 kcal/mol,通过计算研究和NBO分析得到证实.
科学领域:
- 有机化学
- 计算化学
- 超分子化学
背景情况:
- 了解旋转障碍在分子动力学中至关重要.
- 非共价相互作用在分子结构和反应性中起着关键作用.
- n→π* 相互作用是一种具有潜在稳定作用的非共价相互作用.
研究的目的:
- 研究n→π*相互作用对键旋转的过渡状态 (TSs) 的稳定作用.
- 量化n→π*相互作用所提供的稳定能量.
- 阐明特定功能组在促进这些相互作用中的作用.
主要方法:
- 16个分子旋转器的合成,具有不同的电子和硬质性质.
- 使用缺乏 n→π* 相互作用能力的控制旋转器隔离固体输入.
- 测量旋转速度的动力学研究.
- 计算建模 (例如,DFT) 来预测TS几何和稳定.
- 自然键轨道 (NBO) 分析以确认相互作用类型.
主要成果:
- 具有强受体 π* 轨道的旋转器 (基,化物) 的旋转率显著增加.
- 观察到的TS稳定达到大约10kcal/mol.
- 在平面TS中,imide碳基氧和正方形R组之间的 n→π* 相互作用被确定为主要稳定因素.
- 计算研究准确地预测了TS稳定性和几何.
结论:
- 在稳定键旋转的过渡状态时,n→π*相互作用是有效的.
- 稳定强度受接受器 π* 轨道的性质的影响.
- 包括NBO分析在内的计算方法是了解和量化分子旋转器中的这些非共价相互作用的有价值工具.
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