Research on Phototropic Behavior of Materials for Flash Blindness Protection

摘要

Five thiazines, two xanthines and a naphthalene derivative were qualitatively screened for application to flashblindness protection. The xanthines, fluorescein and rhodamine were dropped after preliminary studies indicated that the leuco form was unstable. The naphthalene, naphthol yellow S was examined perfunctorily, and no conclusions have, as yet, been reached. The thiazines were methylene blue, methylene green, azure A, azure B, and azure C. The thiazenes showed desirable properties in that they were readily reduced to a leuco form which was then oxidized to the colored form by a flash of light. Reduction was accomplished by chemical means (Zn and HC1) and by electrolytic methods. Studies were begun on the mechanism of the reduction and the subsequent photooxidation. The first step in these studies was the purification of commercial methylene blue in order to isolate the component of interest. This purification was accomplished by thin layer chromatography in acid and basic solvents and by recrystallization. The data suggest the existence of an equilibrium between differently charged cationic dye species. (Author)