Putting pressure on aromaticity along with in situ experimental electron density of a molecular crystal.
Putting pressure on aromaticity along with in situ experimental electron density of a molecular crystal.
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对分子晶体的芳香性以及原位实验电子密度施加压力。
DOI：
10.1038/ncomms10901
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发表时间：
2016-03-16
影响因子：
16.6
通讯作者：
Macchi P
中科院分区：
文献类型：
--
作者：
Casati N;Kleppe A;Jephcoat AP;Macchi P
当施加压力时，晶体内的分子的立体电子特性会发生显着变化。最有趣的是那些增强系统反应性的方法，否则这些系统在环境条件下将相当惰性。然而，在反应发生之前，分子必须被激活，这意味着分子不稳定。在芳香族化合物中，分子稳定性源于两个电子构型之间的共振。在这里，我们展示了如何在施加压力时降低分子晶体中的共振能量。重点是 syn-1,6:8,13-双羰基[14]轮烯，这是一种芳香族化合物，在环境条件下逐渐定位压缩时的一种共振构型。从在几个压力下测量的分子几何形状以及通过实验确定的 7.7GPa 下的电子密度分布来看，这种现象是显而易见的；这项工作中提出的观察结果通过定期 DFT 计算得到验证。 由于离域 π 键，芳香族化合物表现出增强的稳定性。在这里，作者利用 X 射线衍射和计算研究了压力下的芳香族分子晶体，并观察到压力增加时 π 键离域的减少。
When pressure is applied, the molecules inside a crystal undergo significant changes of their stereoelectronic properties. The most interesting are those enhancing the reactivity of systems that would be otherwise rather inert at ambient conditions. Before a reaction can occur, however, a molecule must be activated, which means destabilized. In aromatic compounds, molecular stability originates from the resonance between two electronic configurations. Here we show how the resonance energy can be decreased in molecular crystals on application of pressure. The focus is on syn-1,6:8,13-Biscarbonyl[14]annulene, an aromatic compound at ambient conditions that gradually localizes one of the resonant configurations on compression. This phenomenon is evident from the molecular geometries measured at several pressures and from the experimentally determined electron density distribution at 7.7 GPa; the observations presented in this work are validated by periodic DFT calculations. Aromatic compounds display enhanced stability due to delocalized π-bonding. Here, the authors study an aromatic, molecular crystal under pressure using x-ray diffraction and calculations, and observe a reduction in π-bond delocalization under increasing pressure.