Photochromic and fluorescence switching properties of oxidized triangle terarylenes in solution and in amorphous solid states
作者:Maki Taguchi、Tetsuya Nakagawa、Takuya Nakashima、Tsuyoshi Kawai
DOI:10.1039/c1jm12993g
日期:——
Three hexatriene-type photochromic compounds 4,5-bis(2,4-dimethyl-5-phenylthiophene-S,S-dioxide-3-yl)-2-phenylthiazole, 1, 4,5-bis(2-methylbenzo[b]thiophene-S,S-dioxide-3-yl)-2-phenylthiazole, 2, and 1,2-bis(2,4-dimethyl-5-phenylthiophene-S,S-dioxide-3-yl)-3,3,4,4,5,5-hexafluorocyclopentene, 3, are synthesized and their photochromic and fluorescence properties are studied, which are analogous to photochromic molecules of triangle terarylene and diarylethene with oxidized aryl units containing S,S-dioxide moieties. These compounds showed photochromic coloration reaction to form a ring-closed form isomer having a cyclohexadiene backbone. Compound 2 showed backward cycloreversion reaction with about 2.4% of photochemical quantum yield, whereas compounds 1 and 3 showed markedly low cycloreversion quantum yields less than 0.1%. Their colored isomers exhibited green or orange fluorescence with relatively high fluorescence quantum yields. Compound 1 also showed similar fluorescence switching nature and fluorescence pattern formation in a stable amorphous film. Intramolecular hydrogen bonding between S,S-dioxide units and methyl groups at photo-reactive carbon atoms is discussed on the basis of molecular structure determined by X-ray single analysis and quantum chemical calculation in the DFT method, which is regarded to contribute to the enhanced emission nature and suppressed cycloreversion photoreactivity of the ring-closed form isomers.
合成了三种六三烯类光致变色化合物 4,5-双(2,4-二甲基-5-苯基噻吩-S,S-二氧 化-3-基)-2-苯基噻唑 1、4,5-双(2-甲基苯并[b]噻吩-S,S-二氧 化-3-基)-2-苯基噻唑 2 和 1,2-双(2,4-二甲基-5-苯基噻吩-S,S-二氧 化-3-基)-3、合成了 3,4,4,5,5-六氟环戊烯 3,并研究了它们的光致变色和荧光特性。这些化合物发生了光致变色反应,形成了以环己二烯为骨架的闭环异构体。化合物 2 发生了后向环化反应,光化量子产率约为 2.4%,而化合物 1 和 3 的环化量子产率明显偏低,不足 0.1%。它们的有色异构体呈现绿色或橙色荧光,荧光量子产率相对较高。化合物 1 也显示出类似的荧光切换性质,并在稳定的无定形薄膜中形成荧光图案。根据 X 射线单分析法确定的分子结构和 DFT 方法进行的量子化学计算,讨论了 S,S-二氧化物单元与光反应碳原子上的甲基之间的分子内氢键,认为这有助于增强环闭形式异构体的发射性质和抑制环化光活性。