A comparative photophysicochemical study of mono substituted phthalocyanines grafted onto silica nanoparticles

In this study, we report on the covalent linking of carboxylic acid functionalized silica nanoparticles with zinc phthalocyanine mono-substituted non-peripherally and peripherally with either a 4-amino phenoxy (1, peripheral and 2, non-peripheral) or an amino group (3 peripheral). The grafting is achieved via the formation of an amide bond between the carboxylic acid of the silica nanoparticles and the amino group of the phthalocyanine complexes. The hybrid nanoparticles retained the amorphous nature of silica nanoparticles after conjugation. A slight decrease in fluorescence and a general improvement in triplet quantum yields compared to free Pcs were observed. Triplet lifetimes for 2-SiNPs and 3-SiNPs also improved when compared to the free phthalocyanine. The changes in singlet oxygen quantum yields upon conjugation were minimal.