Synthesis and Photophysical Studies of Hydrophilic Zinc Phthalocyanine Dendrimers
Pcs exhibit a strong absorption band in the visible region of the UV/vis spectrum from 630 to 750 nm and, in the presence of an appropriate central atom, they yield long-lived triplet excited states and high singlet oxygen photo-production2. Yet, although several Pcs disclose their capability to act as photosensitizing agents3, not many of them are soluble in aqueous media4.
In this communication, we report the synthesis, photochemical and photophysical characterization of a series of new metallodendrimers built around a zinc phthalocyanine core. Within the last step of the synthetic route, the terminal esters were hydrolyzed, giving rise to a dramatic change in polarity upon formation of multiply charged species that are very soluble in aqueous media.
Through photochemical and photophysical studies, we corroborated the capacity of these water-soluble species to produce singlet oxygen in air-saturated solution. Moreover, along with increasing dendritic shell, a significant increase in the generation of singlet oxygen was observed. These highly hydrophilic Pc dendrimers may thus be advantageous for the purpose of producing 1O2 in biological media by photosensitization.
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