Photostability of silylated coumarin dyes in polyceram hosts

Abstract

Numerous silylated coumarin dyes have been incorporated within silica : polydimethylsiloxane Polyceram hosts using the sol-gel process to form crack-free, polishable monoliths. The use of silylated laser dyes allows for covalently bonding the laser dyes to their hosts. Photostability of the samples was evaluated by measuring the decrease in the dye absorption in the Polyceram upon ultraviolet lamp exposure and by monitoring the fluorescence intensity as function of pump pulses from a N2 laser at 337 nm. Both methods showed a significant improvement in photo- and thermal-stability of the silylated dye Polyceram compared to that of the unsilylated dye Polyceram at a dye : Si mole ratio of 10-4 : 1. The improved stability is attributed to the immobilization and higher degree of caging of the silylated dye Polyceram with respect to the unsilylated dye Polyceram.