Johnstone Russell D L, Allan David, Lennie Alistair, Pidcock Elna, Valiente Rafael, Rodríguez Fernando, Gonzalez Jesús, Warren John, Parsons Simon
School of Chemistry, Centre for Science at Extreme Conditions, The University of Edinburgh, Scotland, UK.
Acta Crystallogr B. 2011 Jun;67(Pt 3):226-37. doi: 10.1107/S0108768111009657. Epub 2011 Apr 13.
Bianthrone [10(10-oxoanthracen-9-ylidene)anthracen-9-one] consists of two tricyclic anthraceneone units connected by a carbon-carbon double bond. Crystals of the form obtained under ambient conditions are yellow and contain folded centrosymmetric conformers in which the central ring of the anthraceneone unit is non-planar. When hydrostatic pressure is applied the crystals assume a red colouration which gradually deepens as pressures increases. The colour change is limited in extent to the surface of the crystals, the bulk remaining yellow. Comparison of high-pressure, single-crystal UV-vis spectra and powder diffraction data demonstrate that the colour change is associated with the formation of a polymorph containing a conformer in which the tricyclic fragments are planar and the molecule is twisted about the central C-C bond. Single-crystal diffraction data collected as a function of pressure up to 6.5 GPa reveal the effect of compression on the yellow form, which consists of layers of molecules which stack along the [010] direction. The structure remains in a compressed form of the ambient-pressure phase when subjected to hydrostatic pressure up to 6.5 GPa, and the most prominent effect of pressure is to push the layers closer together. PIXEL calculations show that considerable strain builds up in the crystal as pressure is increased with a number of intermolecular contacts being pushed into destabilizing regions of their potentials.
二蒽酮[10(10-氧代蒽-9-亚基)蒽-9-酮]由两个通过碳-碳双键连接的三环蒽酮单元组成。在环境条件下得到的晶体呈黄色，含有折叠的中心对称构象异构体，其中蒽酮单元的中心环是非平面的。当施加静水压力时，晶体呈现红色，且随着压力增加颜色逐渐加深。颜色变化仅限于晶体表面，内部仍为黄色。高压单晶紫外-可见光谱和粉末衍射数据的比较表明，颜色变化与一种多晶型体的形成有关，该多晶型体包含一种构象异构体，其中三环片段是平面的，分子围绕中心碳-碳键扭曲。在高达6.5 GPa的压力下收集的单晶衍射数据显示了压缩对黄色晶型的影响，黄色晶型由沿[010]方向堆叠的分子层组成。当施加高达6.5 GPa的静水压力时，结构保持在常压相的压缩形式，压力最显著的影响是使分子层靠得更近。PIXEL计算表明，随着压力增加，晶体中会积累相当大的应变，许多分子间接触被推到其势能的不稳定区域。
