对富勒烯反应的影响
Michael Frunzi1, R James Cross, Martin Saunders
1Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, USA.
Journal of the American Chemical Society
|October 11, 2007
概括
与 (He@C60) 相比, (Xe@C60) 在富勒烯中的 (Xe@C60) 的存在显著改变了化学反应平衡. 这种效应取决于温度,影响反应和.
科学领域:
- 富勒烯的化学结构
- 核磁共振 (NMR) 光谱学是指核磁共振 (NMR) 的光谱学.
- 超分子化学 超分子化学
背景情况:
- 富勒 (C60) 可以封装原子或分子.
- 内分层富勒伦,如He@C60和Xe@C60,具有独特的特性.
- 内分体富勒伦与外部分子的反应性具有显著的兴趣.
研究的目的:
- 研究封装-3 (3He) 和-129 (129Xe) 对涉及C60.0的反应平衡的影响.
- 确定封装原子如何影响反应的热力学参数 (DeltaH和DeltaS).
- 为了比较3He@C60和129Xe@C60与9,10-二甲基 (DMA) 的反应性和NMR光谱特性.
主要方法:
- 制备含有3He@C60,129Xe@C60和不同度的9,10-二甲基甲烯 (DMA) 的溶液.
- 允许溶液在受控温度下达到化学平衡.
- 获取和分析3He和129Xe核磁共振 (NMR) 频谱,以确定反应产物比率.
主要成果:
- 核磁共振光谱显示了He@C60和Xe@C60系统中未发生反应的X@C60和单添加物的存在.
- 与DMA反应的平衡常数因封装的原子的存在而显著改变.
- 封装的原子对平衡常数的影响取决于温度,表明和的变化.
- 9,10-二甲基甲烯表现出差异性的反应性,在较低的温度下偏爱He@C60,在较高的温度下偏爱Xe@C60.
- 单添加物和未反应的X@C60之间的化学转移差异对于X@C60比He@C60更大,并且在相反的方向上.
- 计算分析表明,与空C60相比,Xe@C60子外部的电子密度增加了.
结论:
- 封装的原子大大改变了涉及C60衍生物的反应平衡.
- 这些反应的热力学驱动力 (DeltaH和DeltaS) 被封装的改变.
- 与He@C60.0相比,Xe@C60的电子特性,包括增加的外部电子密度,可能有助于其明显的反应性.
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