A comprehensive study of the luminescence quenching behavior of ruthenium(II)-tris-4,7-diphenyl-1,10-phenanthroline perchlorate dissolved in various sol-gel matrices was performed. Thin films of submicron thickness were formed by depositing tetraethyl orthosilicate (TEOS) gel solutions, organically modified with methyltrimethoxysilane (MTMS), onto glass slides using conventional spin-coating methods. Systematic changes in composition were conducted to examine the structural properties of the sol-gel silicate thin films for possible use in fluorescence sensing applications. Luminescence quenching in the presence of oxygen was analyzed as a function of varying sol-gel composition. Modeling techniques were employed to determine the best exponential decay curve fit of different thin film samples. The degree of luminescence quenching was found to be greatest in the polar TEOS thin films. However, whereas cracking was prevalent in the pure TEOS thin films, certain levels of organic modification with non-polar MTMS prevented cracking while maintaining a high degree of fluorescence quenching. These organically modified sol-gel thin films appear to be the most suitable for fluorescence-based oxygen sensing applications.
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