Photochromic behaviour in the fluorescence spectra of 1,2-bis(9-acetoxy-10-anthryl)ethane in silicate glass prepared by the sol–gel method

Abstract

The fluorescence excitation and emission spectra of xerogels containing 1,2-bis(9-acetoxy-10-anthryl)ethane (AAEA) encapsulated into –O–Si–O– networks, prepared by the sol–gel processing of tetraethyl orthosilicate (TEOS), have been observed at room temperature. AAEA encapsulated in a xerogel pore showed photochromic behaviour in its fluorescence spectra, indicating excited–state conformational relaxation from the trans to the gauche form by photoexcitation. Differences in the water–TEOS mixture ratio in the starting solution led to different photochromic behaviour in the xerogel state. A rise and decay of fluorescence intensities were observed in water-rich specimens. The diameter of the pores of the prepared xerogel was estimated at >20Å.