Synthesis, photophysical studies and ¹O₂ generation of ruthenium phthalocyanine dendrimers

A series of ruthenium phthalocyanine centered dendrimers has been prepared with up to 32 ethyl ester end groups. The photophysical properties have been assessed in THF to reveal a correlation between the degree of dendritic environment and the ability to generate singlet oxygen. In the attempt to prepare the correponding highly water-soluble polyelectrolyte dendrimers upon saponification we observed the cleavage of the central esters moieties adjacent to the pyridine unit in all cases. However, despite the lack of shielding by a growing branched shell surrounding the photoactive center, the obtained tetracarboxylate-terminated ruthenium phthalocyanine derivative was still able to generate singlet oxygen in aqueous medium.