Cytotoxic Activities of Bis?cyclometalated <i>M</i> (III) Complexes ( <i>M</i> =Rh, Ir) Containing 5?substituted 1,10?Phenanthroline or 4,4’?substituted 2,2’?Bipyridine Ligands

The synthesis and characterization of eight new bis-cyclometalated compounds [M(ptpy)2(N^N)]PF6 (ptpy=2-(p-tolyl)pyridinato; N^N=5-chloro-1,10-phenanthroline: M=Rh, 1; M=Ir, 2); N^N=5-methyl-1,10-phenanthroline: 3; 4; N^N=4,4’-diphenyl-2,2’-bipyridine: 5; 6; N^N=4,4’-diamino-2,2’-bipyridine: 7; 8) are described. All were characterized by spectroscopic means. Additionally, the molecular structures 4, 5, 6, 8 in crystal determined single-crystal X-ray diffraction studies. To explore cytotoxic properties all compounds, colorimetric assays (MTT assay) against prominent cancer cell lines, MCF-7 HT-29, performed. IC50 values low micromolar range, between 1.3-5.6 ?M. most effective 1 2 with 5-chloro-substituted phenanthroline ligands, whereas diamino-substituted bipyridine ligands (5 6) least compounds. tested complexes showed a significant increase cytotoxicity, up to 25-fold cells, 60-fold HT-29 line compared established anticancer compound cisplatin under identical conditions.