Increasing the selectivity of biologically active tetranuclear arene ruthenium assemblies

Abstract

A series of arene ruthenium metalla-rectangles of general formula [(η6-p-cymene)4Ru4(μ4-embelin)2(μ2-N∩N)2](CF3SO3)4 was prepared from the embelin-derived metalla-clip (η6-p-cymene)2Ru2(μ4-embelin)Cl2 (1), silver triflate and several linear ditopic N-ligands (N∩N); pyrazine (prz), 4,4'-bipyridine (bpy), 1,2-bis(4-pyridyl)ethylene (bpe), 4,4'-azopyridine (azp) and di(pyridin-4-yl)oxalamide (bpo). The antiproliferative activity of these multinuclear arene ruthenium metalla-rectangles was evaluated in vitro on the human ovarian cancer cells A2780 and A2780cisR and on the noncancerous cell line HEK-293. Among these complexes, two rectangles, [(η6-p-cymene)4Ru4(μ4-embelin)2(μ2-bpy)2](CF3SO3)4 and [(η6-p-cymene)4Ru4(μ4-embelin)2(μ2-bpo)2](CF3SO3)4, display excellent activity and selectivity for cancer cells.