Photochemistry and photophysics of azo dyes

The photodegradation of azo dyes in solution and on cotton has been investigated. This is a major problem, because of the widespread use of this class of dyes to dye cotton. The photochemical pathways leading to photo degradation and the properties of the excited states and photophysical deactivation processes were studied. Many of the commercially used azo dyes are 1-aryl-2-naphthols with one or more azo groups which undergo azo-hydrazone tautomerism. [Continues.]