In order to further search efficient [8]circulene materials for OLED applications we have theoretically investigated the structure and electronic absorption spectra of functionalized tetrabenzo[8]circulenes with different substituents in the outer perimeter. These hydrocarbon materials complement the wide family of [8]circulenes which earlier have been demonstrated to possess promising emissive and exciplex-forming properties suitable for organic light emitting diodes. The hydrocarbon tetrabenzo[8]circulenes show saddle shape of the molecular skeleton which can exist in two different conformations with different curvatures of the macrocycle. The aromaticity, electronic structure and orbital pattern are found to be principally different for these two isomers, where the global minimum isomer is weakly antiaromatic and electronically less stable comparing with the non-aromatic local minimum structure. The absorption spectra are also very different: the global minimum structure is more active in the long-wavelength region while the local minimum isomer shows absorption only at short wavelengths. Our computational findings suggest a new concept for optical tuning of curved [8]circulenes through conformational isomerization and aromaticity control, thus through structural variations without changing the molecular composition. Based on this principle we have designed novel functionalized [8]circulenes with promising fluorescence activity.

为了进一步搜索用于OLED应用的高效[8]环戊烯材料，我们从理论上研究了在外围具有不同取代基的功能化四苯并[8]环烯的结构和电子吸收光谱。这些烃类材料补充了[8]环烷酮的广泛家族，早先已证明它们具有适用于有机发光二极管的有希望的发射和激基复合物形成特性。烃四苯并[8]环具有分子骨架的鞍形，可以以两种不同的构型存在，并具有不同的大环曲率。发现这两种异构体的芳香性，电子结构和轨道模式主要不同，与非芳族局部最小结构相比，全局最小异构体的抗芳香性较弱，电子稳定性较差。吸收光谱也有很大不同：整体最小结构在长波长区域更活跃，而局部最小异构体仅在短波长下显示吸收。我们的计算发现提出了通过构象异构化和芳香性控制，从而通过结构变化而不改变分子组成来对[8]环进行光学调谐的新概念。基于此原理，我们设计了具有前途荧光活性的新型功能化[8]环。整体最小结构在长波长区域更活跃，而局部最小异构体仅在短波长下显示吸收。我们的计算发现提出了通过构象异构化和芳香性控制，从而通过结构变化而不改变分子组成来对[8]环进行光学调谐的新概念。基于此原理，我们设计了具有前途荧光活性的新型功能化[8]环。整体最小结构在长波长区域更活跃，而局部最小异构体仅在短波长下显示吸收。我们的计算发现提出了通过构象异构化和芳香性控制，从而通过结构变化而不改变分子组成来对[8]环进行光学调谐的新概念。基于此原理，我们设计了具有前途荧光活性的新型功能化[8]环。