A transparent colored thin gel layer (100 - 300 nm thick) was formed on a glass surface by the dipping-withdrawing coating (1 - 3 mm s-1) method. The colored coating layer was dried at ambient atmosphere, and then heated at 100 degree(s)C for 15 min. Cationic dyes, such as triphenylmethane, phenoxazinium, phenazinium, and phenothiazinium dyes, can be soluble uniformly under the silica sol processing conditions where hydrolysis and condensation of tetraethoxysilane or methyltriethoxysilane in the presence of water and acid occur. Superfine particles of some organic pigments also are dispersed uniformly in such sol in high concentration, and they are coated on the glass by similar method. The effects of nickel complexes and matrix gels on the photofading of the colored thin gel film using organic cationic dyes by the irradiation of filtered visible light (> 390 nm) using 500 W-Xe lamp have been studied. Anthraquinone, phenazinium, and phenoxazinium dyes with terminal triethoxysilyl group to connect them directly with silica matrix of the gels were prepared, as reactive dyes, and reactivity of the reactive dyes under conditions of sol-gel processing has been investigated.
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