通过在现场的X射线晶体分析来确定三重二甲的结构
Masaki Kawano1, Katsuyuki Hirai, Hideo Tomioka
1Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo 152-8551, Japan. mkawano@appchem.t.u-tokyo.ac.jp
Journal of the American Chemical Society
|February 1, 2007
概括
研究二二甲的结晶状态光反应表明,三二碳 (DPC) 采用了受结晶包装影响的结构,而不仅仅是热力学稳定性. 在DPC中,当周围的矩阵变软时,硬质拥堵会导致几何放松.
科学领域:
- 摄影化学的使用.
- 固态化学 固态化学
- 晶体学 晶体学是指结晶学.
- 有机化学 有机化学
背景情况:
- 双二甲是二碳素 (DPC) 的前体,是各种环境中研究的反应性中间体.
- 之前在玻璃矩阵上的研究提供了DPC结构的光谱数据.
- 了解固态对DPC几何学的影响对于控制光反应至关重要.
研究的目的:
- 为了研究一系列替代的二二甲的结晶状态光反应.
- 为了比较光诱导三重体DPC在晶体状态中的结构与溶液或玻璃矩阵中获得的结构.
- 阐明晶体包装和硬质效应对DPC几何和稳定性的作用.
主要方法:
- 在现场X射线晶体学以确定二二甲及其光诱导DPC的晶体结构.
- 光谱技术 (例如,ESR) 来探测分子性质.
- 理论计算 (例如,潜在能量表面分析) 以了解能量景观.
主要成果:
- 确定了由bis(2,4,6-trichlorophenyl) diazomethane,bis(2,4,6-tribromophenyl) diazomethane和bis(2,6-dibromo-4-tert-butylphenyl) diazomethane衍生出的三重 DPC 的晶体结构.
- 在晶态结构和之前在玻璃矩阵中报告的结构之间观察到显著的差异.
- 三重体DPC在晶体状态中表现出微妙的结构变化,除了C(:) -Ar键的长度,在固态阻碍的情况下显著更短.
- 晶体包装显著影响了DPC结构,一些化合物的包装相同,而另一些则有不同的图案.
- 在ESR研究中,与结合角度相比,在平际角度的灵活性更大.
结论:
- 晶体包装效应在决定三重DPC在固态中的几何方面发挥着至关重要的作用.
- 立体拥挤的三重体DPC被前体结构在刚性矩阵中构造性地捕获,但在矩阵软化时放松.
- 观察到的结构差异凸显了周围环境在稳定DPC等反应性中间体方面的重要性.
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