Tchoń Daniel, Makal Anna
Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089 Warszawa, Poland.
Acta Crystallogr B Struct Sci Cryst Eng Mater. 2019 Jun 1;75(Pt 3):343-353. doi: 10.1107/S2052520619003354. Epub 2019 May 17.
The crystal structure of pyrene-1-carbaldehyde (PA), a model polyaromatic hydrocarbon, highly luminescent in the solid state and crystallizing in the triclinic system, has been re-determined at several pressures ranging from atmospheric up to 3 GPa using a diamond anvil cell. A `multi-crystal' approach was used in crystal structure determination, significantly improving completeness of X-ray diffraction data attainable for such a low-symmetry system. The crystal structure consists of infinite π-stacks of PA molecules with discernible dimers, which resemble aggregates formed by pyrene derivatives in solution as well as in the solid state. A series of measurements showed that the average inter-planar distance between individual molecules within π-stacks decreases with pressure in the investigated range. This results in piezochromic properties of PA: a significant sample color change as well as a red-shift of fluorescence with pressure, as studied with UV-vis spectroscopy. Periodic DFT calculations allowed us to relate the variations in the crystal structure with pressure to the changes in the electronic structure of this material.
芘-1-甲醛（PA）是一种典型的多环芳烃，在固态下具有高发光性，属于三斜晶系晶体。利用金刚石对顶砧池，在从常压到3 GPa的几个压力下对其晶体结构进行了重新测定。在晶体结构测定中采用了“多晶体”方法，显著提高了这种低对称系统可获得的X射线衍射数据的完整性。晶体结构由PA分子的无限π堆积组成，其中有可分辨的二聚体，这类似于芘衍生物在溶液和固态中形成的聚集体。一系列测量表明，在所研究的压力范围内，π堆积中单个分子之间的平均面间距随压力减小。这导致了PA的压致变色特性：如通过紫外-可见光谱研究发现，随着压力增加，样品颜色发生显著变化，荧光发生红移。周期性密度泛函理论计算使我们能够将晶体结构随压力的变化与该材料电子结构的变化联系起来。
