Coordination-Driven Self-Assembly and Anticancer Potency Studies of Arene–Ruthenium-Based Molecular Metalla-Rectangles

The two new large molecular metalla-rectangles <b>6</b> and <b>8</b> were obtained by the reaction of the two different arene–ruthenium acceptors [Ru₂(<i>p-</i>cymene)₂(μ-η⁴-C₂O₄)­Cl₂] (<b>2</b>) and [Ru₂(<i>p-</i>cymene)₂(donq)­(Cl)₂] (donq = 5,8-dioxido-1,4-naphthoquinonato) (<b>4</b>) with a symmetrical <i>N</i>,<i>N</i>′-bis­(4-(pyridin-4-ylethynyl)­phenyl)­terephthalamide (<b>1</b>) donor ligand. Both metalla-rectangles were isolated in good yields as triflate salts and were characterized by multinuclear NMR, ESI–MS, and UV–vis spectroscopy. X-ray crystallography of <b>6</b> confirmed a molecular metalla-rectangle. The cytotoxicities of metalla-rectangles <b>6</b>–<b>9</b> were established in SK-hep-1 (liver cancer), AGS (gastric cancer), and HCT-15 (colorectal cancer) human cancer cell lines. The cytotoxicity of metalla-rectangle <b>8</b> was found to be considerably stronger against all cancer cell lines, even much more effective than the well-known anticancer drugs doxorubicin and cisplatin. In addition, expressions of APC and p53, colorectal cancer suppressor genes, were significantly increased following exposure to the metalla-rectangle <b>8