Untersuchungen zum UV/Vis-Spektralverhalten von Azofarbstoffen. IV. Zum Einfluß von Lösungsmitteln auf die Farbbande von Azobenzenen

✍ Scribed by Dipl.-chem. H. Mustroph; Dr. sc. J. Epperlein

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 415 KB
• Volume: 322
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/prac.19803220217

✦ Synopsis

Studies on UV/VIS Absorption Spectra of Azo Dyes. IV. Solvent Effects on the Visible Absorption Band of Azobenzenes

Solvent effects on \documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} \sim \ {\nu _{\max } } \ \end{array} $\end{document} values of substituted azobenzenes are studied and correlated with solvent polarity parameters. Poor correlations of \documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} \sim \ {\nu _{\max } } \ \end{array} $\end{document} values with functions of ϵ and n of solvents are found. A comparison of spectral data with the E~T~ scale shows a much poorer correlation. The correlation with the E~T~ values are significantly better if the protic solvents are excluded. The best of the tested relationships was found with the empirical solvent parameters π^*^. Values of S in the equation \documentclass{article}\pagestyle{empty}\begin{document}$\begin{array}{*{20}c} \sim \ {\nu _{\max } } \\end{array} = {\rm S}\pi ^{\rm *} {\rm + }\begin{array}{*{20}c} \sim \ {\nu 0} \\end{array}, $\end{document} depend on the dye structure. It is found a relationship between S and the difference of quantum chemical calculated dipol moments in the first exited singlet (μ(S~1~)) and in the ground state (μ(S~0~)) of the dyes.