Answers are grounded in this paper and cite their sources.
Reversible color fading of various kinds of papers coated with thionine-reductant compositions with irradiation by visible light were investigated. Water-repellent papers, when coated with aqueous compositions containing thionine, triethanolamine, and PVA, indicated the most rapid reversible color-fading (photochromism); the color-fading rate occured in decreasing order: thionine, azure C, azure B, and methylene blue. Infrared spectral changes around 1600 cm−1 with irradiation corresponded exactly to visible spectral changes, denoting that the photoredox reaction of thionine occurs even in the solid PVA matrix.
No takes yet. Share an insight, caveat, or question.
Kamogawa et al. (1982) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: