Photo-, Solvent-, and Ion-Controlled Multichromism of Imidazolium-Substituted Diarylethenes
Photo-, Solvent-, and Ion-Controlled Multichromism of Imidazolium-Substituted Diarylethenes
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DOI：
10.1002/chem.200801192
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发表时间：
2009-01-01
影响因子：
4.3
通讯作者：
Kawai, Tsuyoshi
中科院分区：
文献类型：
--
作者：
Nakashima, Takuya;Miyamura, Kentaro;Kawai, Tsuyoshi
首次合成了含咪唑环的阳离子二芳基乙烯。咪唑鎓阳离子部分直接连接到乙烯单元，作为参与光诱导的周环化反应的芳基单元之一。咪唑鎓取代的二芳基乙烯在包括离子液体在内的多种有机介质中发生可逆的光致变色反应，即使它们在五元芳环之一中具有离域阳离子电荷。闭环异构体显示溶剂化显色性取决于溶剂供体数目。在二芳基乙烯的有色有机溶液中加入一些四烷基铵盐，如硝酸四丁基铵，也会引起颜色变化，表明其具有离子致色性。这些溶剂化和离子致变色性能被认为是与闭环异构体之间的化学平衡的移动，一个扩展的π共轭系统和一个有限的π共轭，由于与溶剂分子和阴离子的强相互作用与高供体数。
Cationic diarylethenes with an imidazolium ring are synthesized for the first time. The imidazolium cationic moiety is connected directly to the ethene unit as one of the aryl units that take part in the photoinduced pericyclization reaction. The imidazolium-substituted diarylethenes undergo reversible photochromic reactions in a variety of organic media, including ionic liquids, even though they have a delocalized cationic charge in one of the five-membered aromatic rings. The closed-ring isomer shows solvatochromism depending on the solvent donor numbers. Addition of some tetraalkylammonium salts, such as tetrabutyl ammonium nitrate, into the colored organic solution of diarylethene also causes a color change, indicating its ionochromic property. These solvato- and ionochromic properties are considered in connection with the shift of chemical equilibrium between the closed-ring isomers, one with an extended pi-conjugation system and one with limited pi-conjugation due to the strong interaction with solvent molecules and anions with high donor number.