No abstract

This study reports the influence of the medium on the aggregation processes of the complex [Ru(phen) 2 (pPDIp)] 2 + (phen = 1,10-phenanthroline; pPDIp = a bis-phenanthroline-substituted perylene diimide)and its consequences for the photochemical and photophysical properties of the system. Photolysis leads, initially, to emission of both chromophores: Triplet metalto-ligand charge transfer ( 3* MLCT; Ru, dp!phen, p*) and singlet intraligand charge transfer ( 1* ILCT; pPDIp, p! p*). However, the medium induces increased p-p intermolecular interactions that lead to the generation of a pPDIp * À moietyin DMSO, pPDIp * À (518 nm) and pPDIp * À and pPDIp 2À (420 nm) in the cell culture medium RPMI, and 3* pPDIp in buffer (pH 7.4) and starch films. The complex activates singlet oxygen in buffer solution without oxygen bubbling and under green light irradiation (dose = 0.41J/cm 2 ; [ 1 O 2 ] = 0.03-0.47 mmol L À1 for [Ru(phen) 2 (pPDIp)] 2 + = 10-150 mmol L À1 ). No cytotoxic effects on B16F10-Nex2 murine melanoma cell viability were observed up to a concentration of 10 mmol L À1 of complex. However, under green LED illumination (dose = 0.41 J/cm 2 ) the complex exhibits a strong photocytotoxic effect, displaying IC 50 = 1.2 mmol L À1 .