Microviscosities at the Porous Cage of Silica Gel−Glasses and Ormosils through Fluorescence Anisotropy

Tailoring of the chemical properties at the porous cage of silica matrixes is the objective of many works in the last years, since it determines the different allocation of dopants and thus its future reactivity and functionality. One approach for the modification of such chemical properties is the incorporation of surfactants. Ormosils (organically modified silicates) can be prepared by the sol−gel process through the incorporation of cetyltrimethylammonium bromide (CTAB). The study of the fluorescent properties of coumarin 153 (C153), which is also incorporated, will provide information of the environment surrounding the probe within the porosity of the ormosils. The fluorescent study of C153-doped ormosils was based on the following fluorescence measurements: (a) absorption, excitation, and emission spectra, (b) fluorescence lifetimes, and (c) anisotropy. Time-resolved anisotropy will provide a quantitative determination of the different microviscosity values that can be found within the porosity of gel−glasses and ormosils.