The synthesis, photophysical properties and antiparasitic efficacy against Toxoplasma gondii β-gal (RH strain tachyzoites expressing β-galactosidase) grown in human foreskin fibroblast monolayers (HFF) of a series of 15 new conjugates BODIPY-trithiolato-bridged dinuclear ruthenium(II)-arene complexes are reported (BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza- s -indacene, derivatives used as fluorescent markers). The influence of the bond type (amide vs ester), as well as that of the length and nature (alkyl vs aryl) of the spacer between the dye and the diruthenium(II) complex moiety, upon the fluorescence and the biological activity were evaluated. The assessed photophysical properties revealed that despite an important fluorescence quenching effect observed after conjugating the BODIPY to the diruthenium unit, the hybrids could nevertheless be used as fluorescent tracers. Although the antiparasitic activity of these series of conjugates appears limited, the compounds demonstrate potential as fluorescent probes to be used for investigating the intracellular trafficking of trithiolato-bridged dinuclear Ru(II)-arene complexes in vitro .
