在溶液中确定沿碳-碳单键的旋转异构率
Seongchul Park1,2, Hojeong Yoon2, Juhyang Shin2
1Korea Institute for Future Earth, Pusan National University, Busan 46241, Korea.
Physical chemistry chemical physics : PCCP
|January 31, 2025
概括
五秒红外光谱测量了CF2BrCF2基的旋转异构化时间常数. 使用 ωB97XD/aug-cc-pVTZ 方法的密度函数理论计算可靠地估计了类似基的这个常数.
科学领域:
- 物理化学 物理化学
- 化学动力学 化学动力学
- 频谱学是一种光谱学.
背景情况:
- 了解分子旋转对于反应动态至关重要.
- 旋转异构化时间常数 (τ_rot) 是化学动力学中的关键参数.
- CF2BrCF2基因作为研究溶液中键旋转的模型系统.
研究的目的:
- 测量CF2BrCF2基的取决于温度和粘度的旋转异构化时间常数 (τ_rot).
- 为了验证使用克莱默斯的理论结合DFT计算来预测 τ_rot.
- 建立一种可靠的计算方法,用于在类似系统中估计 τ_rot.
主要方法:
- 采用5秒红外光谱,探测光解离后的C-Ċ键动态.
- 使用 aug-cc-pVTZ 基础集的 ωB97XD,APFD 和 B3LYP 函数进行密度函数理论 (DFT) 计算.
- 克拉默斯的反应速率理论被用来从DFT衍生参数计算t_rot.
主要成果:
- 在溶液中测量CF2BrCF2基的试验式t_rot与DFT计算有很好的一致性.
- 使用 ωB97XD/aug-cc-pVTZ 计算的振动频率和旋转障碍与实验结果相关性良好.
- 克莱默斯的理论预测进一步通过CF3CF2CF2的实验数据得到了验证.
结论:
- 克拉默斯的理论,加上使用 ωB97XD/aug-cc-pVTZ 组合的 DFT 计算,为估计旋转异构化时间常数提供了一种可靠的方法.
- 这种方法适用于溶液中的乙烯基基和乙衍生物的C-C( ̇) 键.
- 这项研究促进了对凝结相中的分子旋转动态的理解.
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