Photoswitchable fluorescent diarylethene derivatives with short alkyl chain substituents
Photoswitchable fluorescent diarylethene derivatives with short alkyl chain substituents
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DOI：
10.1039/c2pp25078k
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发表时间：
2012-01-01
影响因子：
3.1
通讯作者：
Irie, Masahiro
中科院分区：
文献类型：
--
作者：
Takagi, Yuta;Kunishi, Tomohiro;Irie, Masahiro
合成了1，2-双（2-烷基-6-苯基-1-苯并噻吩-3-基）全氟环戊烯的砜衍生物，研究了活性碳上不同短链烷基取代对闭环异构体荧光性质的影响。在用紫外（UV）光照射时，衍生物在用可见光（> 400 nm）照射时显示出明亮的绿色荧光，而在单独用可见光（> 400 nm）照射时荧光消失。当溶剂由正己烷变为乙腈时，甲基取代的衍生物（1b）的荧光量子产率从0.84急剧下降到0.15，而乙基、正丙基和正丁基取代的衍生物（2b）~（4 b）的荧光量子产率变化不大。即使在极性乙腈中，（2b）-（4 b）的量子产率也保持在接近0.7的值。荧光寿命的测量表明，在极性溶剂中，（1b）发生了有效的非辐射衰减过程，而在（2b）-（4 b）中，它们对失活的贡献并不大。在连接碳上相邻的短烷基链被认为是保护砜单元免受极性溶剂分子的攻击，削弱溶剂极性效应。
The sulfone derivatives of 1,2-bis(2-alkyl-6-phenyl-1-benzothiophen-3-yl)perfluorocyclopentene having various short alkyl chain substituents at reactive carbons were prepared and the effect of alkyl substitution on the fluorescence property of the closed-ring isomers was studied. Upon irradiation with ultraviolet (UV) light the derivatives exhibit a brilliant green fluorescence under irradiation with visible (> 400 nm) light, while the fluorescence disappears upon irradiation with visible (> 400 nm) light alone. The fluorescence quantum yield of the methyl substituted derivative (1b) dramatically decreases from 0.84 to 0.15 when the solvent is changed from hexane to acetonitrile, while the changes of ethyl, n-propyl and n-butyl substituted derivatives (2b)-(4b) are moderate. The quantum yields of (2b)-(4b) are kept to values close to 0.7 even in polar acetonitrile. The fluorescence lifetime measurement revealed that efficient non-radiative decay processes took place in (1b) in polar solvent, while their contribution to the deactivation was not so large in (2b)-(4b). The neighboring short alkyl chains at the connecting carbons are considered to defend the sulfone units against the attack of polar solvent molecules and weaken the solvent polarity effect.