Dye-doped inorganic/organic composite films as fluorescence sensors for methanol vapor

The sol–gel method has been employed in the fabrication of mesoporous composite films consisting of a non-ionic surfactant, Pluronic P123, as the organic component, and silica as the inorganic component. The hybrid nature of these films resulted in them having an internal structure consisting of nanometer size self-assembled organic mesostructures surrounded by a silica framework. These films served as the host matrix for the laser dye coumarin 481 (C481), and an energy transfer complex formed between C481 and J-aggregated meso-tetra(4-sulfonatophenyl)porphyrin (TSPP). Upon exposure to methanol vapor, a rapid and reversible decrease in fluorescence intensity occurs for films containing C481 alone, as well as the energy transfer complex. Steady-state and time-resolved spectroscopic studies indicated that the decrease in fluorescence intensity was primarily due to an excited state interaction between methanol and C481. Additionally, morphological changes within the film appear to play a role for films containing the C481/TSPP energy transfer complex.