Decacationic [70]fullerenyl-light harvesting chromophore conjugates for efficient photokilling of infectious bacteria (Conference Presentation)

We report a novel class of highly water-soluble decacationic methano[60]fullerene decaiodides C60[>M(C3N6+C3)2]-(I−)10 [1-(I−)10] capable of co-producing singlet oxygen (Type-II) and highly reactive hydroxyl radicals, formed from superoxide radicals in Type-I photosensitizing reactions, upon illumination at both UVA and white light wavelengths. The O2‒·-production efficiency of 1-(I−)10 was confirmed by using a O2‒·-reactive bis(2,4-dinitrobenzenesulfonyl)tetrafluorofluorescein probe and correlated to the photoinduced electron-transfer event going from iodide anions to 3C60*[>M(C3N6+C3)2] leading to C60‒·[>M(C3N6+C3)2]. Incorporation of a defined number (ten) of quaternary ammonium cationic charges per C60 in 1 was aimed to enhance its ability to target pathogenic Gram-positive and Gram-negative bacterial cells. We used the well-characterized malonato[60]fullerene diester monoadduct C60[>M(t-Bu)2] as the starting fullerene derivative to provide a better synthetic route to C60[>M(C3N6+C3)2] via transesterification reaction under trifluoroacetic acid catalyzed conditions. These compounds may be used as effective photosensitizers and nano-PDT drugs for photoinactivation of pathogens.