Optically active organic molecules have been entrapped in a porous silica gel host for use as an opto-chemical transducer. Organic dye molecules were incorporated into the inorganic glassy matrix via the so called "sol-gel" technique. Sol-gel derived glasses are typically synthesized at room temperature and result in the formation of a relatively low density network structure, capable of supporting the rapid transport of atoms and small molecules. This "cage-like" network, however, serves to entrap larger molecules, such as organic dyes. The guest probe molecules do not migrate through the silica host. Fluorescence characteristics of optically active dye species, in many cases, are known to change in solution with respect to the activity of factors such as oxygen and pH. We have fabricated silica gel films containing organic probes, and measured changes in emission spectra of entrapped pyranine dye due to variations in the pH of ambient aqueous solution.
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