Organisch-Chemisches Institut, Ruprecht-Karls-Universität, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
Angew Chem Int Ed Engl. 2016 Dec 12;55(50):15594-15598. doi: 10.1002/anie.201607740. Epub 2016 Sep 21.
Contorted two-dimensional aromatic molecules are fascinating synthetic targets because they are molecular "cutouts" of nonplanar graphene structures, fullerenes, or carbon nanotubes. In most cases, the curvature is introduced by the implementation of either five-, seven-, or eight-membered rings into the fused aromatic plane. Curvature can also be generated for two-dimensional systems consisting of six-membered rings exclusively, by the introduction of cove or fjord regions. The synthesis of a polycyclic aromatic hydrocarbon (PAH) that contains two peripheral triptycene units and six tert-butyl substituents is described. As a result of steric repulsion, the structure is highly contorted with two phenylene blades of the peripheral triptycene units oriented almost coplanar with respect to each other at a distance of 16 Å, as has been verified by single crystal X-ray diffraction. The conformation is stable in solution even at a temperature of 150 °C. Additionally, internal tert-butyl groups could be selectively removed, allowing a UV/Vis-spectroscopic comparison of two structures with the same π-system, but different degrees of contortion.
扭曲的二维芳香分子是非常有趣的合成目标，因为它们是平面石墨烯结构、富勒烯或碳纳米管的分子“镂空”结构。在大多数情况下，通过在稠合芳环平面中引入五、七或八个环来实现曲率。也可以通过引入穹顶或峡湾区域，为仅由六个元环组成的二维系统产生曲率。描述了一种含有两个外围三并苯单元和六个叔丁基取代基的多环芳烃（PAH）的合成。由于空间位阻的影响，该结构高度扭曲，两个外围三并苯单元的苯环叶片彼此几乎共面，彼此之间的距离为 16 Å，这已通过单晶 X 射线衍射得到证实。该构象在溶液中甚至在 150°C 的温度下也是稳定的。此外，内部的叔丁基可以被选择性地去除，允许对具有相同π-体系但扭曲程度不同的两种结构进行紫外/可见光谱比较。
