Synthesis, structure, and UV–VIS absorption spectra of azo dyes derived from (dialkylamino)thiazole dimers †

Abstract

(Dialkylamino)thiazole dimers act as very strong electron-donating coupling components in azo dyes, the first and second UV–VIS absorption bands of which were observed at λ = 568–737 (ε = 24000–88000) and 404–475 (ε = 9200–52000) nm in dichloromethane, respectively. The azo compounds derived from the (dialkylamino)thiazole dimers having very strong electron-withdrawing moieties such as 4-(perfluoroalkylsulfonyl)phenyls, 2,4-dinitrophenyl, and thiazol-2-yls exhibited a negative solvatochromism. This is the first example of a negative solvatochromism in neutral azo dyes.