Surface Perturbation of Vibrational Transitions of Pyrenesilanes Bound to Silica Gel

Article abstract of DOI:10.1021/j100270a025

Enhancement of weakly allowed vibrational transitions is reported for pyrenesilane molecules covalently bound to porous microparticulate silica.The appearance of these new bands is attributed to adsorptive interactions which alter the symmetry and electron density of the surface bound molecules.The intensity of the surface-perturbed vibrational modes is shown to vary as function of the bound silane surface concentration and the water content of the chemically modified silica.Thermal pretreatment of the modified silica produces large intensity differences indicating that the proton-donor properties of surface silanols are significantly influenced by the concentration of surface adsorbed water.Differences in the orientation and associative inetractions of bound and surface adsorbed molecules are also inferred.