Photochromic properties of cationic oxazolylfulgimides in hydroxylic media

Water-soluble cationic oxazolylfulgimides have been prepared to examine their photochromic properties in neutral aqueous solution and hydroxylic solid films. Introduction of the electron-withdrawing cationic substituents led to large shifts of the electronic transitions and significant changes in the photochromic response rates. In bare films of solid poly(vinyl alcohol) and κ-carrageenan gel exposed to the air, high photochemical reversibilities were found. Though extensive photochemical and thermal degradations occurred in bare Nafion film, they were substantially depressed by sealing the surface with PVA film.