Hexaarylbenzenes (HABs) are valuable precursors for the bottom-up synthesis of (nano-)graphene structures. In this work the synthesis of several bis-pyrimidine substituted HABs furnished with tert-butyl groups at different sites of the four pendant phenyl rings is reported. The synthetic procedure is based on modular [4+2]-Diels-Alder cycloaddition reactions followed by decarbonylation. Analysis of the solid-state structures revealed that the newly synthesized HABs feature a propeller-like arrangement of the six arylic substituents around the benzene core. Here, the tilt of the aryl rings with respect to the central ring is strongly depending on the intermolecular interactions between the HABs as well as co-crystallized solvent molecules. Interestingly, by evading the closest proximity of the central ring using an alkyne spacer, the distant pyrimidine ring is oriented in coplanar geometry with regard to the benzene core, giving rise to a completely different UV-absorption profile.

中文翻译：

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嘧啶取代的六芳基苯作为N掺杂有机材料的多功能构建基块

六芳基苯（HAB）是自底向上合成（纳米）石墨烯结构的有价值的前体。在这项工作中，报道了几种在四个侧苯环的不同位置带有叔丁基的双嘧啶取代的HAB的合成。合成程序基于模块化的[4 + 2] -Diels-Alder环加成反应，然后进行脱羰基反应。固态结构的分析表明，新合成的HAB具有围绕苯核的六个芳基取代基的螺旋桨状排列。在此，芳基环相对于中心环的倾斜强烈地取决于HAB与共结晶的溶剂分子之间的分子间相互作用。有趣的是，通过使用炔烃间隔基避开中心环的最接近位置，