Study of the Adsorption Process of Sulforhodamine B on the Internal Surface of Porous Sol−Gel Silica Glasses through Fluorescence Means

Abstract

Fluorescence means (fluorescence spectroscopy, lifetime measurements, and fluorescence anisotropy) are used to study the extension in which sulforhodamine B (SB) is adsorbed on the internal surface of porous sol−gel silica glasses. The formation of fluorescent J-dimers as a consequence of the SB adsorption on the internal surface of the porous matrix is also studied for dye concentrations ranging from 4.0 × 10-6 to 3.2 × 10-4 M. It is observed that the configuration adopted by the fluorescent dimers and also the concentration value at which the fluorescent dimers become nonfluorescent dimers differ from those reported for rhodamine B (RB). Fluorescence anisotropy provide evidence of how the structural differences in the phenyl pending groups between both rhodamines govern the strength of the chemical interactions that SB and RB molecules establish with the surface and thus their capability of rearrangement on such a surface.