Mesoporous silica materials with covalently anchored phenoxazinone dyes as fluorescent hybrid materials for vapour sensing

Mesoporous silica matrices functionalized with a fluorescent solvatochromic dye have been employed as optical sensor materials for volatile organic compounds. Re-functionalisation of the polar silica surface of the parent solid by passivation of the silanol groups with hexamethyldisilazane yielded a hydrophobic hybrid sensory material with improved performance in terms of the spectroscopic response, the detectable polarity range of organic vapours, response times and reversibility, and minimized interference from environmental humidity. Polar vapours such as methanol and acetone for instance are indicated by a shift in absorption of ca. 40 and 30 nm, and a ca. 10-fold fluorescence enhancement. With the present system, acetone vapours can be detected down to 300 ppmV.