Photoswitchable arene ruthenium and pentamethylcyclopentadienyl rhodium complexes containing o-sulfonamide azobenzene ligands: Synthesis, characterization and cytotoxicity

• New Ru and Rh complexes containing o-sulfonamide azobenzene ligands have been synthesized.
• “Three-legged piano-stool” configuration of Ru and Rh complexes has been confirmed by single crystal X-ray structure diffraction analysis.
• Photoisomerization of all complexes have been investigated.
• The cytotoxicity of the complexes against four cancer cell lines was evaluated.
• Cancer cell apoptosis has been investigated with western blotting and flow cytometric analyses.

A new series of arene chlorido ruthenium and pentamethylcyclopentadienyl chlorido rhodium complexes containing o-sulfonamide azobenzene ligands with an exocyclic NN bond coordination pattern have been synthesized. These complexes undergo readily E→Z photoisomerization followed by thermal Z→E isomerization (upon resting in the dark). The ruthenium complexes showed low-micromole-ranged cytotoxicity towards a panel of cancer cells. Western blotting and flow cytometric analyses suggest that 1) they are potent apoptotic inducers for cancer cells, probably through a caspase-3 dependent apoptotic pathway, and that 2) they have a much stronger ability to induce HeLa cancer cell apoptosis than cisplatin, a commercial anticancer drug.

Figure optionsDownload as PowerPoint slide