s-Indacene Revisited: Modular Synthesis and Modulation of Structures and Molecular Orbitals of Hexaaryl Derivatives
s-Indacene Revisited: Modular Synthesis and Modulation of Structures and Molecular Orbitals of Hexaaryl Derivatives
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DOI：
10.1021/jacs.2c13159
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发表时间：
2023-02-16
影响因子：
15
通讯作者：
Tobe, Yoshito
中科院分区：
文献类型：
--
作者：
Jhang, Shun-Jie;Pandidurai, Jayabalan;Tobe, Yoshito
尽管 s-indacene 是一种有趣的 12 个 pi 电子反芳香烃，但由于缺乏有效且通用的方法来制备稳定的衍生物，因此它的代表性不足。在此，我们报告了一种简明、模块化的合成方法，用于在特定位置带有电子供体/受电子基团的六芳基-s-二茚衍生物，以提供 C2h-、D2h- 和 C2v-对称取代模式。我们还报告了取代基对其分子结构、前沿分子轨道（MO）水平和磁感应环电流趋向性的影响。理论计算和X射线结构分析均表明，C2h取代模式的衍生物采用不同的C2h结构，并且根据取代基的电子性质，键长变化显着。由于前沿MO的分布不均匀，它们的能级受到供电子取代基的选择性调节。这导致 HOMO 和 HOMO-1 序列相对于本征 s-indacene 的序列反转，正如理论预测和通过可见光和近红外区域的吸收光谱实验证明的那样。 s-indacene衍生物的NICS值和1H NMR化学位移表明它们具有弱的反芳香性。不同的取向性可以通过 HOMO 和 HOMO-1 能级的调节来解释。此外，对于己二酰衍生物，由于S1和S2态之间的能隙较大，检测到来自S2激发态的微弱荧光。值得注意的是，使用六二苯衍生物制造的有机场效应晶体管（OFET）表现出中等的空穴载流子迁移率，这一结果为s-indacene衍生物的光电应用打开了大门。
Though s-indacene is an intriguing antiaromatic hydrocarbon of 12 pi-electrons, it has been underrepresented due to the lack of efficient and versatile methods to prepare stable derivatives. Herein we report a concise and modular synthetic method for hexaaryl-s-indacene derivatives bearing electron donating/-accepting groups at specific positions to furnish C2h-, D2h-, and C2v-symmetric substitution patterns. We also report the effects of substituents on their molecular structures, frontier molecular orbital (MO) levels, and magnetically induced ring current tropicities. Both theoretical calculations and X-ray structure analyses indicate that the derivatives of the C2h- substitution pattern adopt different C2h structures with significant bond length alternation depending on the electronic property of the substituents. Due to the nonuniform distribution of the frontier MOs, their energy levels are selectively modulated by the electron-donating substituents. This leads to the inversion of the HOMO and HOMO-1 sequences with respect to those of the intrinsic s-indacene as theoretically predicted and experimentally proven by the absorption spectra at visible and near-infrared regions. The NICS values and the 1H NMR chemical shifts of the s-indacene derivatives indicate their weak antiaromaticity. The different tropicities are explained by the modulation of the HOMO and HOMO-1 levels. In addition, for the hexaxylyl derivative, weak fluorescence from the S2 excited state was detected due to the large energy gap between the S1 and S2 states. Notably, an organic field-effect transistor (OFET) fabricated using the hexaxylyl derivative exhibited moderate hole carrier mobility, a result which opens the door for optoelectronic applications of s-indacene derivatives.