Geometrical and Electronic Structure of Cation Radical Species of Tetraarylanthraquinodimethane: An Intermediate for Unique Electrochromic Behavior
Geometrical and Electronic Structure of Cation Radical Species of Tetraarylanthraquinodimethane: An Intermediate for Unique Electrochromic Behavior
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四芳基蒽醌二甲烷阳离子自由基的几何和电子结构：独特电致变色行为的中间体
DOI：
10.1002/asia.202200914
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Suzuki Takanori
中科院分区：
文献类型：
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作者：
Ishigaki Yusuke;Fukagawa Reina;Sugawara Kazuma;Harimoto Takashi;Suzuki Takanori
通过二溴甲基化和Suzuki偶联反应，合成了两种具有不同芳基（氨基苯基和甲氧基苯基）的四芳基蒽醌二甲烷（Ar 4AQD）衍生物. X射线分析表明，它们在中性状态下采用折叠结构，而相应的双阳离子具有平面蒽环，二芳基甲基鎓单元垂直连接到平面蒽环上。与具有相同取代基的Ar 4AQD在与双阳离子态相互转化期间经历容易的双电子转移不同，中间阳离子自由基在新制备的不对称衍生物中变得长寿命。通过电化学和理论研究阐明了开壳层中间体的几何结构和电子结构，揭示了阳离子自由基采用扭曲的几何构型，如dications。在电解双阳离子时，扭曲阳离子自由基参与电致变色，而它们的稳态浓度在氧化过程中可忽略不计，从而实现了具有颜色变化滞后模式（无色->紫色->蓝色->无色）的独特三色电致变色行为。
Two tetraarylanthraquinodimethane (Ar4AQD) derivatives having two different aryl groups (aminophenyl and methoxyphenyl) were prepared by sequential dibromomethylation and Suzuki‐coupling reactions. X‐ray analyses showed that they adopt a folded structure in the neutral state whereas the corresponding dications have a planar anthracene ring, to which diarylmethylium units are perpendicularly attached. Different from Ar4AQD having the same substituents that undergoes facile two‐electron transfer during interconversion with the dicationic state, the intermediary cation radical becomes long‐lived in the newly prepared unsymmetric derivatives. The geometric and electronic structures of the open‐shell intermediates were elucidated through electrochemical and theoretical investigation, with revealing that the cation radicals adopt the twisted geometry like dications. Upon electrolyses of the dications, the twisted cation radicals were involved in the electrochromism whereas their steady‐state concentration is negligible in the oxidation process, thus realizing unique tricolor electrochromic behavior with a hysteretic pattern of color change (colorless ‐> purple ‐> blue ‐> colorless).