Dendritic porphyrins as promising sensitizers in aqueous media. From synthesis to potential applications

Abstract

A homologous series of first generation dendritic phorpyrins (Pf-Ds) were recently synthesized and characterized by conventional methodologies. The main goal of this work was to achieve a practical way of solubilizing this class of efficient sensitizers in high water content aqueous-alcoholic media, by functionalization of a free-base tetraphenyl-porphyrin with polyamido-amine dendritic branches. A high solubility of the Pf-Ds was obtained in such media, whereas the non-functionalized porphyrin was insoluble. Moreover, the photophysical properties of the compounds were evaluated in aqueous solvent by several steady-state and time resolved spectroscopic techniques. The comparison between these data and those in a typical solvent demonstrated that the porphyrin does not show aggregation, retaining its sensitizing capability completely unaltered. Finally, preliminary tests were performed in order to evaluate the ability of Pf-Ds to sensitize the photodegradation of some probe molecules. Effective degradation of the probes was observed after less than 30 min of irradiation with visible LEDs, which is promising for the future application of these compounds as efficient pollutant removers.