Pyridinium N-phenoxide betaine dyes and their application to the determination of solvent polarities part 29 -: Polarity of ionic liquids determined empirically by means of solvatochromic pyridinium N-phenolate betaine dyes
Pyridinium N-phenoxide betaine dyes and their application to the determination of solvent polarities part 29 -: Polarity of ionic liquids determined empirically by means of solvatochromic pyridinium N-phenolate betaine dyes
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DOI：
10.1039/b500106b
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发表时间：
2005-01-01
期刊：
影响因子：
9.8
通讯作者：
Reichardt, C
中科院分区：
文献类型：
--
作者：
Reichardt, C
两性离子甜菜碱染料2，6-二苯基-4-（2，4，6-三苯基吡啶鎓-1-基）苯酚盐的溶液是溶剂化变色的、热致变色的、压致变色的和卤致变色的。也就是说，最长波长分子内CT吸收带的位置取决于溶剂极性、溶液温度、外部压力以及添加盐的性质和浓度。该标准甜菜碱染料的突出的大负溶剂化显色性已被用于在光谱学上引入溶剂极性的经验标度，称为ET（30）或E-T（N）标度，其同时包括大量的分子溶剂和溶剂混合物。在这篇综述中，努力确定经验的极性室温离子液体的甜菜碱染料的手段进行了总结和讨论，因为离子液体已经获得了重要性，作为环境更良性的新的反应介质的框架内的绿色化学。
Solutions of the zwitterionic betaine dye 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate are solvatochromic, thermochromic, piezochromic, and halochromic. That is, the position of the longest-wavelength intramolecular CT absorption band depends on the solvent polarity, solution temperature, external pressure, and the nature and concentration of added salts. The outstanding large negative solvatochromism of this standard betaine dye has been used to introduce spectroscopically an empirical scale of solvent polarity, called the ET(30) or E-T(N) scale, which includes meanwhile a large number of molecular solvents and solvent mixtures. In this review, efforts to determine empirically the polarity of room-temperature ionic liquids by means of this betaine dye are summarized and discussed, because ionic liquids have gained importance as environmentally more benign new reaction media in the framework of Green Chemistry.