Electrochemical studies and potential anticancer activity in ferrocene derivatives

<p>Several ferrocene derivatives (five mononuclear and two binuclear), including the new <i>N</i>-(<i>p</i>-chlorophenyl)-carboxamidoferrocene (<b>1</b>), were synthesized and their anticancer activity investigated. Two of them, <b>3</b> and <b>7</b>, bearing a benzimidazole backbone were the most active against HeLa cells achieving IC₅₀ values of ~5 μM along with <b>4</b> with a dipyridylamine ligand (~6 μM). Complex <b>6</b>, also with a benzimidazole backbone, displayed slightly higher values (~11 μM). Cyclic voltammetry studies show that while the non-cytotoxic ferrocene derivatives <b>1</b>, <b>2</b>, and <b>5</b> follow a ferrocene-based redox behavior, derivatives <b>3</b>, <b>4</b>, <b>6</b>, and <b>7</b> exhibit a more complex mechanism. These complex mechanisms are consistent with a more effective cytotoxic activity. Mössbauer spectroscopy parameters reflect a very small influence of the substituents.</p