A series of indole-based helicenes, namely, 15-hexyl-15H-tetraphenyl[1,2-e]indole (HTPI), 14-hexyl-14H-benzo[4',5']thieno [2',3':7,8]naphtha[1,2-e]indole (HBTNI), 7-hexyl-7H-indolo[5,4-k] phenanthridine (HIPD) and 3-hexyl-3H-phenanthro[4,3-e]indole (HPI) were successfully synthesized by three- or four-step reactions. They exhibited good solubility and high thermal stability of Td =247, 388, 294 and 251 °C, respectively. These compounds emit violet-blue light with maximum emission peaks at 415, 397, 397 and 391 nm in hexane. Among them, HBTNI had excellent thermal stability, narrow and sharp emission peaks, and highest photoluminescence quantum yield (0.32). Thus, HBTNI was an ideal candidate for the violet-blue emitters of OLEDs. Furthermore, the four compounds had two-photon absorption and two-photon excited fluorescence. HTPI showed the maximum TPA with the TPA cross-section (δ) of 171.5 GM at 770 nm. They were rare examples of helicenes with both violet-blue emission and TPA.

中文翻译：

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带有紫蓝荧光和双光子吸收（TPA）的基于吲哚的氮杂[n]螺旋烯（n = 5，6）。

一系列基于吲哚的螺旋烯，即15-己基-15H-四苯基[1,2-e]吲哚（HTPI），14-己基-14H-苯并[4'，5']噻吩[2'，3' ：7,8]石脑油[1,2-e]吲哚（HBTNI），7-己基-7H-吲哚[5,4-k]菲啶（HIPD）和3-己基-3H-菲咯[4,3-e通过三步或四步反应成功合成了吲哚（HPI）。它们分别显示出良好的溶解度和Td = 247、388、294和251°C的高热稳定性。这些化合物发出的蓝紫色光在己烷中的415、397、397和391 nm处具有最大发射峰。其中，HBTNI具有出色的热稳定性，窄而尖锐的发射峰以及最高的光致发光量子产率（0.32）。因此，HBTNI是OLED的紫蓝色发射器的理想选择。此外，这四种化合物具有两个光子吸收和两个光子激发的荧光。HTPI显示最大TPA，在770 nm处的TPA横截面（δ）为171.5 GM。它们是具有紫兰色发射和TPA的螺旋烯的罕见例子。