Porphyrins and Phthalocyanines: Photosensitizers and Photocatalysts

Abstract

The porphyrins and phthalocyanines are among the most representative macrocycles in synthetic chemistry, characterized by specific molecular structures, responsible and associ-ated with their particular properties. They have high versatility and an adequate variability introduced either by macrocycle metallation or by different substituents at its periphery called meso-substituents. The porphyrins could find, together with the synthetic phthalo-cyanines, various scientific and technological applications in chemical and photochemical areas. They can serve as catalysts and photocatalysts in different reactions, or as photosen-sitizers in photodynamic therapy of cancer, due to their high efficiency to generate free radicals and excited state species. The aim of this chapter is to achieve a better understand-ing of the complex and various properties of the porphyrins and phthalocyanines in differ-ent solvents or in heterogeneous media, trying to draw the relationships between these topics with their possible applications in catalytic, photocatalytic area (photodegradation of Kraft-lignin, photooxidation of different unsaturated hydrocarbons, photodegradation of different organic aquatic pollutants, oxirans polymerization) and some preliminary results about the heterogeneous porphyrin sensitizers in the photodynamic therapy area. Their photobleaching mechanisms in different conditions are also discussed.