Increasing the selectivity of biologically active tetranuclear arene ruthenium assemblies

A series of arene ruthenium metalla-rectangles of general formula (eta(6)-p-cymene)(4)Ru-4(mu(4)-embelin)(2)(mu(2)-N boolean AND N)(2)(4) was prepared from the embelin-derived metalla-clip (eta(6)-p-cymene)(2)Ru-2(mu(4)-embelin) Cl-2 (1), silver triflate and several linear ditopic N-ligands (N boolean AND 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 anti-proliferative 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, (eta(6)-p-cymene)(4)Ru-4(mu(4)-embelin)(2)(mu(2)-bpy)(2)(4) and (eta(6)-p-cymene) Ru-4(4)(mu(4)-embelin)(2)(mu(2)-bpo)(2)(4), display excellent activity and selectivity for cancer cells. (C) 2015 Elsevier B.V. All rights reserved.