Non-covalent complexes of polycationic fullerene C 60 derivative with xanthene dyes – Spectral and photochemical properties in water and in liposomes

By the use of absorption spectroscopy, steady-state and time resolved fluorimetry xanthene dyes fluorescein, eosin Y and erythrosin B were shown to form complexes with polycationic fullerene derivative due to electrostatic interactions in aqueous solution and in the structure of the liposomes. It was found that the singlet excited states of dyes are effectively quenched either due to excitation energy transfer or electron transfer from singlet excited state of the dye to the fullerene core. Photodynamic activity of the complex is much higher than the activity of the dye or the fullerene derivative as the individual compounds. Photostability of the dyes increases in the complex structure as well. These effects allow predicting the development of a new generation hybrid photosensitizers. Noteworthy, one can use a dye excited only in a singlet state in combination with fullerene, which greatly enhances the directional design of such hybrid structures.