A fluorescent polypyridyl ruthenium complex was successfully prepared using an amide bond linkage to link two rhodamine moieties through bipyridine groups. Although photo-induced electron transfer (PET) quenched the fluorescent intensity, the quantum yield of the rhodamine-modified Ru(II) complex was 0.17 in water, sufficient for observing the fluorophore behaviour in biological systems. The rhodaminemodified Ru(II) complex was found to inhibit the bacterial growth of E. coli. In vitro fluorescence images of human hepatoma cells (SK-Hep1) showed that a fluorescent polypyridyl ruthenium complex not only supported the above observation but also preferably accumulated in the cytoplasmic region inside the cell. These observations suggest that in addition to strong Ru–DNA interactions, Ru-protein interactions in the cytoplasmic regions are strong and are therefore important to the development of metallopharmaceuticals.
Journal of the Chinese Chemical Society 59(9), pp.1053–1057