Effect of surface and interlayer structure on the fluorescence of rhodamine B-montmorillonite: modeling and experiment

The surface and interlayer structure of rhodamine B (RhB)-montmorillonite for various guest concentrations has been studied using a combination of X-ray powder diffraction and molecular modeling (molecular mechanics and molecular dynamics) in the Cerius(2) modeling environment. The joint effect of surface and interlayer structure on the fluorescence spectrum has been observed and discussed in relation to the position and orientation of RhB(+) cations with respect to the silicate layer. Structural analysis showed that the surface and interlayer structures are different as to the arrangement of RhB(+) cations, and both of them strongly depend on the guest concentration in the intercalation solution and on the method of preparation. The repeated intercalation of montmorillonite by rhodamine B used in the present work allowed obtaining RhB-montmorillonite in the maximum degree of ion exchange for every sample.