Fluorescence studies of the sol–gel transition using aminopyrene

The process of tetraethylorthosilicate gelation in the acidic medium was monitored by a fluorescence probe of aminopyrene using its concentration and excitation wavelength. Steady-state and time-resolution fluorescence measurements were recorded on the consecutive days of gelation. The results were compared with experimental data for model water solutions of aminopyrene at different pH. On this basis, the character of probe molecule interaction with a changing microenvironment was determined. The state of equilibrium of two forms of aminopyrene: APH+↔AP + H+ on the consecutive days of sol–gel transition was discussed. It was a measure of changes that took place during gel net formation.