Reversal in solvatochromism in some novel styrylpyridinium dyes having a hydrophobic cleft
- 作者：Mallika Panigrahi ; Sukalyan Dash ; Sabita Patel ; P.K. Behera ; B.K. Mishra
- 关键词：Styrylpyridinium dyes ; Solvatochromism ; ET(30) switch ; Dipolar aprotic solvents ; Nonpolar solvents ; Hydroxylic solvents
- 刊名：Spectrochimica Acta Part A ; Molecular and Biomolecular Spectroscopy
- 出版年：2007
- 期刊代码：99_13861425
- 类别：ch
- 出版时间：November 2007
- 卷：68
- 期：3
- 页码：757-762
- 文件大小：304 K
摘要
The influence of solvent polarity on the electronic transition of four different N-hexadecyl styrylpyridinium dyes has been investigated in 15 solvents. The ET(30) scale has been used to propose a quantitative approach towards the relative stability of the electronic ground and excited state species. The extents of contribution of dipolar aprotic solvents towards the solvation of the excited species have been determined to be 42–48%for some of the dyes. Instead of a steady solvatochromism, all the dyes suffer a reversal in solvatochromism. The transitions of the solvatochromism, referred to as solvatochromic switches, are found to be at ET(30) values of 
50 for methyl and N,N-dimethylamino substituted dyes while at 37.6 for hydroxyl substituted dye and 45 for 4-(1-methyl-2-phenylethenyl) pyridinium dye. A reversal in the trend of solvent effect in the later dye corresponding to 4-(4-methyl styryl)pyridinium dye has been attributed to an analogy of series and parallel electron flow.
50 for methyl and N,N-dimethylamino substituted dyes while at 37.6 for hydroxyl substituted dye and 45 for 4-(1-methyl-2-phenylethenyl) pyridinium dye. A reversal in the trend of solvent effect in the later dye corresponding to 4-(4-methyl styryl)pyridinium dye has been attributed to an analogy of series and parallel electron flow.