The Effects of Fluorescent Substances on the Photofading of Colours. II – The Effects of Fluorescent Brightening Agents on the Photofading of Triphenylmethane Dyes

The addition of fluorescent brightening agents of the pyrazoline-type accelerates the photofading of triphenylmethane dyes, while the dyes quench the photoreactions of the fluorescent brightening agents. The accelerations were most marked when irradiation was carried out in the maximum fluorescence excitation region of the fluorescent brightening agents. Stern- Volmer quenching studies and chromatographic analyses of the photoproducts revealed that the accelerated photofading reactions involved triplet sensitizations of the dyes by the fluorescent brightening agents