Recognition of Different Environments at the Porous Cage of CTAB Based Ormosils

Tailoring of the chemical properties at the porous cage of the ormosils is being the objective of many works in the last years. One approach for the modification of such chemical properties is the incorporation of surfactants. In this work, ormosils (organically modified silicates) were prepared by the sol-gel process through the incorporation of cetyltrimethylammonium bromide (CTAB). Oxazine 1 (OX1) and Coumarine 153 (C153) were incorporated as fluorescent probes. The studied optical properties were absorption and fluorescence spectra, fluorescence lifetimes and fluorescence anisotropy. The combination of those measurements, achieved for two different dyes, provided a useful approach for the elucidation of the different environments that can be created at the porous cage of CTAB based ormosils; i.e. OX1 reported about a highly hydrated and polar environment, while C153 about a non-polar environment. It is noteworthy that the microviscosity calculated in both environments was higher than their analogous at a CTAB micelle in solution, which denotes an increase of the degree of ordering of the confined molecules most likely induced by the porous silica surface.