Preparation and photochromism of sulfonated spiropyran-silica nanocomposites

Abstract

Reversible and stable photochromic properties of sulfonated spiropyran (SP-SO 3 −) were achieved by trapping SP-SO 3 − in a silica matrix by the sol-gel route. The presence of organic anions was essential for the photochromic properties, indicating the importance of the coexistence of polar and non-polar regions. The half-life time ( t 1/2) of the photoinduced merocyanine (MC) trapped in the silica matrix in the presence of dodecylbenzenesulfonic acid (DBS) was larger than 30 days ( k<2.7 × 10 −7 s −1). The reversibility of SP-SO 3 − was improved by the addition of triplet quenchers such as benzophenone, naphthalene and anthracene.