Zwitterionic and cationic half-sandwich iridium(iii) ruthenium(ii) complexes bearing sulfonate groups: synthesis, characterization and their different biological activities.

Previous studies on the neutral and cationic half-sandwich iridium(iii) and ruthenium(ii) complexes showed that the charge and the substitution pattern of the bidentate ligands, as well as the nature of the accompanying counteranion have a significant effect on their biological activities. In this contribution, a series of zwitterionic and cationic half-sandwich iridium(iii) and ruthenium(ii) complexes containing sulfonate groups have been prepared and characterized. The different locations of counteranions between these two kinds of complexes exert great influence on the cytotoxic activity towards cancer cells. The various possible mechanism of actions (MoAs) of the complexes were determined by flow cytometry. This work has shown for the first time the different biological activities between zwitterionic and cationic half-sandwich complexes.