High pressure loading of organic dyes into a silica matrix

High density, transparent and crack-free compacts of silica gel doped with naphthazarin, quinizarin and rhodamine 6G, were produced by sol-gel synthesis with high pressure at room temperature. Compacts are very stable, being resistent to polishing and leaching by ethanol and acetone. They show optical properties, as absorption and fluorescence, similar to those at dilute solutions, indicating that the dyes are dispersed in the silica matrix as individual molecules. Heat treatment to 150 degrees C for 1 h led to almost no degradation. (C) 1997 Elsevier Science B.V.