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首页> 外文期刊>Spectrochimica acta, Part A. Molecular and biomolecular spectroscopy >Fluorescence characteristics and photostability of benzoxazole derived donor-acceptor dyes in constrained media
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Fluorescence characteristics and photostability of benzoxazole derived donor-acceptor dyes in constrained media

机译：受限介质中苯并恶唑衍生的供体-受体染料的荧光特性和光稳定性

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摘要

The spectroscopic properties and photoreactivity of 2-(4-dimethylaminostryl)benzoxazole and its butadienyl analogue (abbreviated as DMASBO and BODB, respectively) were investigated in thin films of PS, PMMA and PVA polymer matrices as well as immobilized on silica surface. The experimental results showed that the investigated benzoxazole derivatives are sensitive to the polarity of its microenvironment even in the glassy matrices and in the solid state. The micropolarity of PVA and silica surface is greater than that of PMMA and PS. The combined results of fluorescence quantum yield and photoisomerization indicated that the size of the free volume within the polymer matrix influence strongly the photochemical reactivity of the used dyes. In PVA, which offers the smaller free volume, the photoreaction is totally blocked while the fluorescence yield is extremely enhanced relative to those in solutions and other polymer matrices. This is associated with an emission of green laser from DMASBO-PVA doped film when pumped by nitrogen laser (337 nm). The results showed that the present dyes are excellent probes for nonfluorescent systems presenting constrained geometry. The spectra of amorphous solid thin films of both dyes were also measured and show large red shifts relative to those in solutions indicating symmetric aggregation of molecules in the solid crystals. (c) 2005 Elsevier B.V. All rights reserved.
机译：在PS，PMMA和PVA聚合物基质的薄膜中以及固定在二氧化硅表面上，研究了2-（4-二甲基氨基苯乙烯基）苯并恶唑及其丁二烯类似物（分别简称为DMASBO和BODB）的光谱性质和光反应性。实验结果表明，所研究的苯并恶唑衍生物即使在玻璃基质和固态中也对其微环境的极性敏感。 PVA和二氧化硅表面的微极性大于PMMA和PS。荧光量子产率和光致异构化的组合结果表明，聚合物基质中自由体积的大小强烈影响所用染料的光化学反应性。在提供较小自由体积的PVA中，与溶液和其他聚合物基质中的荧光相比，光反应被完全阻断，而荧光产量却大大提高。当用氮气激光（337 nm）泵浦时，这与DMASBO-PVA掺杂薄膜发出的绿色激光有关。结果表明，本发明的染料是用于几何形状受限的非荧光体系的优良探针。还测量了两种染料的非晶态固体薄膜的光谱，并且相对于溶液中的那些显示出大的红移，表明在固体晶体中分子对称聚集。 （c）2005 Elsevier B.V.保留所有权利。

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