Abstract
Nickel 2-hydroxy-4-methoxybenzophenone-5-sulfonate, nickel 2, 2′-dihydroxy-4, 4′-dimethoxybenzo-phenone-5-sulfonate and nickel 2-phenylbenzimidazol-5-sulfonate, UV absorbers containingsinglet oxygen quenching groups, have been synthesized as a means of improving light fastness of dyes. The protecting effects of these compounds against photofading of Rose Bengal (CI Acid Red 94), Crystal Violet (C Basic Violet 3) and Elioglaucine (CI Acid Blue 1) were examined in solution and in a solid state with a UV irradiation (λ> 300 nm).The rates of photofading of these dyes were markedly retarded in the presence of benzophenone type UV absorbers containing nickel sulfonate groups, while the addition of nickel 2-phenylbenzimidazol-5-sulfonate accelerated the fading of Crystal Violet. The effects of added singlet oxygen quencher and and auto-oxidative agent on the photostability of dyes were also examined.
