PHOTOCHROMIC BEHAVIOR IN THE FLUORESCENCE-SPECTRA OF 1,2-BIS(9-ACETOXY-10-ANTHRYL)ETHANE IN SILICATE GLASS PREPARED BY THE SOL-GEL METHOD

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 > 20 angstrom.