Photophysical Properties of Supported Dyes. Quantum Yield Calculations in Scattering Media

Abstract

Aluminum tricarboximonoamidephthalocyanine and Rose Bengal were immobilized by adsorption and covalent linkage to different solid supports: silica, silanized silica, silanized silica modified with polylysine chains and NovaSyn® TG amino resin (low cross-linked polystyrene with polyethyleneglycol chains). Specially designed tools were used to evaluate absolute quantum yields in scattering media. A previously developed model was used to calculate fluorescence quantum yields in the solid state and a method is presented for the evaluation of singlet molecular oxygen quantum yields in suspensions. The method yields reliable results for dilute suspensions of particles with diameters much greater than the irradiation wavelength. Diffuse reflectance and, in the case of suspensions, total transmittance spectra are the basic inputs required. In this way the efficiencies of suspended solid photosensitizers were obtained for all samples and correlated with the dye concentration and the way of linking to the surface.