Spectroscopic and photodynamic properties of novel cationic fullerene derivatives

AGAZZI, MAXIMILIANO L.; SPESIA, MARIANA B.; GSPONER, NATALIA S.; MILANESIO, M. ELISA; DURANTINI, EDGARDO N.

Carlos Paz, Córdoba.

Conferencia; 13th Latin American Conference on Physical Organic Chemistry (CLAFQO-13); 2015

Instituto de investigaciones de físico-químca orgánica. Facultad de Ciencias Químicas.UNC

In recent years, photodynamic inactivation (PDI) of microorganisms has been proposed to controlling bacterial infections. PDI involves the administration of a photosensitizer that is accumulated in the microbial cells and the subsequent irradiation with visible light. The photodynamic activity mediated by the agent produces cell inactivation. Appropriate photosensitizers are demanded to have specific chemical and biological properties. Thus, the combination of visible light absorption and a long lifetime of triplet excited state allow fullerenes to act as photosensitizers.In the present work, novel fullerene C60 derivatives was synthetized by 1,3-dipolar cycloaddition using different benzaldehydes. Exhaustive methylation was used to obtain cationic photosensitizers. The structures of these fullerenes are formed by a hydrophobic carbon sphere containing cationic groups that provide an amphiphilic character. Absorption spectra of DPC602+ and TPC603+ in N,N-dimethylformamide (DMF) showed strong absorptions in the UV region, with a peak at 430 nm and broader range of absorption up to 710 nm. Fluorescence emission spectra of these compounds exhibited a band centered at 715 nm with quantum yields of 10-4. On the other hand, photooxidation of 1,3-diphenylisobenzofuran (DPBF) (was used to evaluate the ability of the fullerenes to produce singlet molecular oxygen, O2(1g). Values of 0.44 and 0.30 were obtained for O2(1g) quantum yield of DPC602+ and TPC603+, respectively. Also, the formation of superoxide anion radical induced by fullerenes was detected in presence of NADH. In vitro studies showed that DPC602+ and TPC603+ were effective to photoinactivate Staphylococcus aureus cell suspensions. Therefore, these results indicate that these cationic fullerenes are interesting agents with potential applications in PDI of bacteria.