Ruthenium− and Osmium−Arene Complexes of 2-Substituted Indolo[3,2-<i>c</i>]quinolines: Synthesis, Structure, Spectroscopic Properties, and Antiproliferative Activity

Abstract

The synthesis of new modified indolo[3,2-<i>c</i>]quinoline ligands <b>L</b>^<b>1</b>−<b>L</b>^<b>8</b> with metal-binding sites is reported. By coordination to ruthenium− and osmium−arene moieties 16 complexes of the type [(η⁶-<i>p</i>-cymene)M(L)Cl]Cl (<b>1a</b>,<b>b</b>−<b>8a</b>,<b>b</b>), where M is Ru^II or Os^II and L is <b>L</b>^<b>1</b>−<b>L</b>^<b>8</b>, have been prepared. All compounds were comprehensively characterized by elemental analysis, electrospray ionization mass spectrometry, IR, UV−vis, and NMR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction (<b>2a</b>,<b> 4a</b>,<b> 4b</b>,<b> 5a</b>,<b> 7a</b>, and <b>7b</b>). The complexes were tested for antiproliferative activity <i>in vitro</i> in three human cancer cell lines, namely, CH1 (ovarian carcinoma), SW480 (colon adenocarcinoma), and A549 (non-small-cell lung cancer), yielding IC₅₀ values in the submicromolar or low micromolar range