Naphthyl-substituted titanocene dichloride complexes: Synthesis, characterization and in vitro studies

The synthesis, characterization and the cytotoxic studies of several naphthyl-substituted titanocene complexes, [Ti(η5–C5H5){η5–C5H3R(CHR’(C10H7))}Cl2] (R = H, R′ = Me (8), Ph (9); R = SiMe3, R′ = Me (10), Ph (11)), are reported. In addition, the molecular structure of 9 has been determined by single-crystal X-ray diffraction studies. The cytotoxic activity of 9–11 has been examined against five human tumour cell lines: 8505C (anaplastic thyroid carcinoma), A549 (lung adenocarcinoma), A2780 (ovarian cancer), DLD-1 (colon carcinoma) and FaDu (head and neck carcinoma). Complex 11 showed the highest cytotoxic activity on all studied cell lines (IC50 values from 35.65 ± 4.95 to 69.02 ± 1.67 μM). All compounds are more active than reference compound [Ti(η5–C5H5)2Cl2] on all cell lines (except complex 8 against A549) leading to the conclusion that the presence of different substituents on the cyclopentadienyl ring may improve cytotoxicity of titanocene dichloride.