In Situ Preparation of Highly Fluorescent Dyes upon Photoirradiation
In Situ Preparation of Highly Fluorescent Dyes upon Photoirradiation
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DOI：
10.1021/ja204583e
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发表时间：
2011-08-31
影响因子：
15
通讯作者：
Irie, Masahiro
中科院分区：
文献类型：
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作者：
Uno, Kakishi;Niikura, Hiroyuki;Irie, Masahiro
当染料具有高荧光性和大吸收系数时，光开关或光活化荧光染料可能适用于超高密度光学、存储介质以及超分辨率荧光成像。在这里，我们报道了高荧光的光致变色染料，这种染料在可见光照射下最初在溶液中不发光，但在紫外线照射下被激活发出绿色或红色荧光。染料Sa-9a是1,2-二（2-乙基-6-苯基（或噻吩基）-1-苯并噻吩-3-基）全氟环戊烯的砜衍生物。研究发现，在苯并噻吩-1,1-二氧化基团的6′和6′位置取代苯基或噻吩环可以有效地使闭环异构体的荧光量子产率提高到0.7以上，吸收系数提高到4 × 10(4) M-1 cm（-1）以上。苯基取代衍生物5a-7a经过光环反应生成黄色闭环异构体5b-7b，在488 nm光照射下发出550 nm左右的亮绿色荧光（Phi(F) = 0.87-0.88）。闭环异构体在80℃下黑暗保存100 h后，吸收强度也没有变化，在可见光（λ > 480 nm）照射下，闭环异构体慢慢恢复到初始的开环异构体。开环量子产率（Phi(C ->)）为（1.6-4.0）× 10（-4）。当苯基取代基被噻吩环取代时，如化合物8a和9a，闭环异构体的吸收带位移到500 nm以上。闭环异构体在532 nm光的照射下，在620 nm附近（Phi(F) = 0.61-0.78）表现出明亮的红色荧光。开环反应非常缓慢(φ （C ->) < 1 × 10(-5)）。这些砜衍生物的荧光寿命约为2-3 ns，比1,2-二（2-甲基-1-苯并噻吩-3-基）全氟环戊烯的闭环异构体（tau(F) = 4和22 ps）的荧光寿命长得多。1,4-二氧六环中的闭环异构体8b在可见光（λ > 440 nm）照射下表现出优异的抗疲劳性能，优于罗丹明101在乙醇中的稳定性
Photoswitchable or photoactivatable fluorescent dyes are potentially applicable to ultrahigh density optical, memory media as well as super-resolution fluorescence imaging when the dyes are highly fluorescent and have large absorption coefficients. Here, we report on highly fluorescent photochromic dyes, which are initially nonluminous in solution under irradiation with visible light but activated to emit green or red fluorescence upon irradiation with ultraviolet (UV) light. The dyes Sa-9a are sulfone derivatives of 1,2-bis(2-ethyl-6-phenyl(or thienyl)-1-benzothiophen-3-yl)perfluorocyclopentene. It was found that substitution of phenyl or thiophene rings at 6 and 6' positions of the benzothiophene-1,1-dioxide groups is effective to increase the fluorescence quantum yields of the closed-ring isomers over 0.7 and absorption coefficients over 4 x 10(4) M-1 cm(-1). The phenyl-substituted derivatives 5a-7a undergo photocyclization reactions to produce yellow closed-ring isomers 5b-7b, which emit brilliant green fluorescence at around 550 nm (Phi(F) = 0.87-0.88) under irradiation with 488 nm light. Any absorption intensity change of the closed-ring isomers was not observed even after 100 h storage in the dark at 80 degrees C. The closed-ring isomers slowly returned to the initial open-ring isomers upon irradiation with visible (lambda > 480 nm) light. The ring-opening quantum yields (Phi(C -> O)) were measured to be (1.6-4.0) x 10(-4). When the phenyl substituents are replaced with thiophene rings, such as compounds 8a and 9a, the absorption bands of the closed-ring isomers shift to longer than 500 nm. The closed-ring isomers exhibit brilliant red fluorescences at around 620 nm (Phi(F) = 0.61-0.78) under irradiation with 532 nm light. The ring-opening reactions are very slow (Phi(C -> O) < 1 x 10(-5)). The fluorescence lifetimes of these sulfone derivatives were measured to be around 2-3 ns, which is much longer than the value of the closed-ring isomer of 1,2-bis (2-methyl-1-benzothiophen-3-yl)perfluorocyclopentene (tau(F) = 4 and 22 ps). The closed-ring isomer 8b in 1,4-dioxane exhibits excellent fatigue resistant property under irradiation with visible light (lambda > 440 nm) superior to the stability of Rhodamine 101 in ethanol