Synthesis and spectral properties of azohydroxypyridone disperse dyes containing a fluorosulphonyl group

A series of azohydroxypyridone disperse dyes containing fluorosulphonyl groups have been synthesised and their spectral properties were investigated. Azohydroxypyridone dyes, containing a nitro group instead of a fluorosulphonyl group para to the azo group in the diazo component, were also synthesised in order to compare spectral properties. The fluorosulphonyl substituted derivatives absorb maximally at shorter wavelengths and are tinctorially weaker than the nitroarylazopyridone dyes, although the former dyes have higher molar extinction coefficients. Also, the synthesised dyes exhibit positive solvatochromism so that the absorption bands of the dyes move toward longer wavelengths as the polarity of the solvent increases. Molecular computational methods provided reasonable predictions in the direction of solvatochromism for the dyes prepared.