The effects of fluorescent substances on the photofading of colours. Part 4-photochemical interaction between fluorescent brightening agent of a pyrazoline type and 1,4-diaminoanthraquinone

Abstract

The catalytic fading of 1,4-diaminoanthraquinone by a fluorescent agent of a pyrazoline type was demonstrated on irradiation with 366 nm light in aerobic acetonitrile solution. The quenching study with a singlet oxygen quencher and the chromatographic analysis of the photoproducts revealed a singlet oxygen intermediate. The fluorescent agent generated singlet oxygen in cellulose acetate films as well, causing a small amount of enhanced fading of the dye. No acceleration of the fading was observed either in ethanol or in nylon films. On 253 nm light irradiation the dye and the fluorescent agent suppressed each other's fading.