Stereoscopic Analysis of Fatigue Products of Photochromic Triarylemethane Leucocyanide Dyes

Thin layer chromatography and infrared spectroscopy were used to identify the fatigue products of malachite green, crystal violet, and new fuschine leucocyanides in dimethylsulfoxide and reagent alcohol. In DMSO solutions, a yellow substance with an absorption peak near 350 nanometers and a decomposition product of DMSO were found. The latter product appeared to be a mixture of several compounds, including water, dimethylsulfite , and dimethylsulfone, and was found to cause unfatigued solutions to fatigue with no exposure. In leucocyanide in reagent alcohol solutions , the leucohydroxide and leucoethoxide forms of the dyes were found in fatigued solutions. The Rf values of these compounds were used to identify the fatigue products of the leucocyanide solutions. These compounds were found to have worse photochromism than the leucocyanide forms of the dyes. The photochromic properties of the leucocyanides were determined for up to 200 exposures. The maximum density was found to decrease linearly for a number of exposures and then level off. The fade time stayed constant and then increased exponentially. The yellow fatigue product concentration in DMSO increased exponentially and then leveled off, and the leucoethoxide fatigue product in reagent alcohol concentration increased linearly. A three factor ANOVA was performed on malachite green and crystal violet leucocyanide in DMSO, with oxygen level, water level, and tempurature as the factors. Some water was found to be beneficial to photochromism and fatigue. Temperature had an adverse effect on maximum density and fatigue, and oxygen had little effect by itself, but did interact with water to increase photochromism and fatigue. A subsequent investigation showed an optimum level of water for both photochromism and fatigue at fifteen percent water