A redox-active C3-symmetric triindole-based triazacyclophane
A redox-active C3-symmetric triindole-based triazacyclophane
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DOI：
10.1002/anie.200600526
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发表时间：
2006-01-01
影响因子：
16.6
通讯作者：
Echavarren, Antonio M.
中科院分区：
文献类型：
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作者：
Gomez-Lor, Berta;Hennrich, Gunther;Echavarren, Antonio M.
咔唑基化合物由于其光电导特性和传输正电荷（空穴）的能力，在过去几年中引起了人们的兴趣。许多含咔唑的聚合物和低聚物已被合成用于电子应用。[1]在非线性光学、静电复印、光折变和有机发光二极管等领域中，咔唑基的光电导或空穴传输性质被广泛利用。[2]此外，已经制备了新的咔唑相关分子，如吲哚并[3，2-B]咔唑（1）[3]和6，11-二氢-5H-二吲哚并[2，3-a; 2 '，3'-c]咔唑（2）[4]，其显示出扩展的π系统，其中两个或三个咔唑单元分别共享一个芳环（方案1）。这些结构在有机电子学领域中被广泛研究。与吲哚氧化三聚容易得到的化合物2相反，对称类似物10，15-二氢-5H-5，10，15-三氮杂二茚并[1，2-a; 1 ′，2 ′-c]芴（3）的研究很少，可能是由于其合成困难。[5]由于其扩展的π系统和其平面的盘状结构，这种C3对称分子提供了作为用于构建一维传导的柱状液晶的中心核的巨大潜力。[6]我们最近报道了从已知的对称六溴三吲哚[8]通过钯催化的用三乙基甲酸铵还原脱溴方便地合成3 [7]。3在多克规模上的现成可用性促使我们研究该平台的给电子性质，本文报道了基于该三吲哚平台的新的三氮杂环蕃的高产率合成，其晶体结构和氧化还原行为，以及相应的自由基阳离子的X-射线衍射表征。三吲哚平台3被N-烷基化以避免NH3-N偶联，NH3-N偶联是不期望的化学副反应之一，其可以在氧化时引起咔唑衍生物的不可逆循环伏安行为。3与三（苄基溴）苯4的烷基化进行的目的是得到一个环蕃，因为它们独特的几何形状迫使芳环成为共面排列，使它们成为电荷传输过程的完美模型。[9]以几乎定量的产率获得白色粉末状三氮杂环蕃5（方案2）。[10个国家]
Interest in carbazole-based compounds has grown over the last few years due to their photoconductive properties and ability to transport positive charges (holes). Many carbazolecontaining polymers and oligomers have been synthesized for electronic applications.[1] In fields like nonlinear optics, xerography, photorefractives, and organic light-emitting diodes, the photoconductivity or hole-transport properties of the carbazolyl groups are being extensively utilized.[2] In addition, new carbazole-related molecules such as indolo [3, 2-b] carbazole (1)[3] and 6, 11-dihydro-5H-diindolo [2, 3-a; 2’, 3’-c] carbazole (2)[4] have been prepared which show extended π systems in which two or three carbazole units, respectively, share an aromatic ring (Scheme 1). These structures are being widely investigated in the field of organic electronics. In contrast to compound 2, which is easily obtained by oxidative trimerization of indole, the symmetrical analogue 10, 15-dihydro-5H-5, 10, 15-triazadiindeno [1, 2-a; 1’, 2’-c] fluorene (3) has been very rarely studied, probably due to difficulties in its synthesis.[5] Owing to its extended π system and its planar, disk-like structure, this C3-symmetric molecule offers great potential as a central core for the construction of columnar liquid crystals for one-dimensional conduction.[6] We have recently reported the convenient synthesis of 3 [7] from a known symmetrical hexabromotriindole [8] by palladium-catalyzed reductive debromination with triethylammonium formate. The ready availability of 3 on the multigram scale prompted us to investigate the electron-donating nature of this platform.Herein we report on the high-yielding synthesis of a new triazacyclophane based on this triindole platform, its crystal structure and redox behavior, and the characterization by X-ray diffraction of the corresponding radical cation. Triindole platform 3 is N-alkylated in order to avoid NÀN coupling, which is one of the undesired chemical side reactions that can cause irreversible cyclic voltammetry behavior of carbazole derivatives upon oxidation. The alkylation of 3 with tris (benzylbromide) benzene 4 was performed with the aim to get a cyclophane as their unique geometry forces the aromatic rings into a cofacial arrangement that makes them perfect models for charge-transport processes.[9] Triazacyclophane 5 was obtained as a white powder in almost quantitative yield (Scheme 2).[10]