Influence of the Medium on the Photochemical and Photophysical Properties of [Ru(phen)2(pPDIp)]2

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 metal‐to‐ligand charge transfer (3*MLCT; Ru, dπ→phen, π*) and singlet intraligand charge transfer (1*ILCT; pPDIp, π→ π*). However, the medium induces increased π–π intermolecular interactions that lead to the generation of a pPDIp.−moietyin DMSO, pPDIp.− (518 nm) and pPDIp.− and pPDIp2−(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/cm2; [1O2]=0.03–0.47 μmol L−1 for [Ru(phen)2(pPDIp)]2+=10–150 μmol L−1). No cytotoxic effects on B16F10‐Nex2 murine melanoma cell viability were observed up to a concentration of 10 μmol L−1 of complex. However, under green LED illumination (dose=0.41 J/cm2) the complex exhibits a strong photocytotoxic effect, displaying IC50=1.2 μmol L−1. A matter of choice: Photolysis of [Ru(phen)2(pPDIp)]2+ (phen=1,10‐phenanthroline, pPDIp=a bis‐phenanthrolineperylene diimide) leads to 3*MLCT and 1*ILCT emission. The medium induces aggregation leading the generation of different photoproducts in different media. No dark cytotoxicity (up to 10 μmol L−1) against B16F10‐Nex2 cells was measured whereas under green‐LED irradiation the compound was strongly photocytotoxic (IC50=1.2 μmol L−1).