Recent Progress in Polynuclear Ruthenium Complex-Based DNA Binders/Structural Probes and Anticancer Agents

Ruthenium complexes have stood out by several mononuclear complexes which have entered into clinical trials, such as imidazolium [trans-RuCl4(1H-imidazole)(DMSO-S)] (NAMI-A) and ([Ru(II)(4,4'-dimethyl-2,2'-bipyridine)2-(2(2'-,2'':5'',2'''-terthiophene)-imidazo[4,5-f] [1,10]phenanthroline)] 2+) (TLD-1433), opening a new avenue for developing promising ruthenium-based anticancer drugs alternative to Cisplatin. Polynuclear ruthenium complexes were reported to exhibit synergistic and/or complementary effects: the enhanced DNA structural recognition and DNA binding as well as in vitro anticancer activities. This review overviews some representative polynuclear ruthenium complexes acting as DNA structural probes, DNA binders and in vitro anticancer agents, which were developed during last decades. These complexes are reviewed according to two main categories of homo-polynuclear and hetero-polynuclear complexes, each of which is further clarified into the metal centers linked by rigid and flexible bridging ligands. The perspective, challenges and future efforts for investigations into these exciting complexes are pointed out or suggested.

Electrochromic Behaviour of Polynuclear Ruthenium Complexes on Nanocrystalline SnO2

The trinuclear [{Ru(NH3)4(py-COOH)}(μ-CN){Ru(bpy)2}(μ-CN){Ru(NH3)4(py-COOH)}]6+ (py-COOH = isonicotinic acid, bpy = 2,2'-bipyridine) (1) and dinuclear [{Ru(dcb)2}2L]7- (dcb = 2,2'-bipyridine-4,4'-dicarboxylic acid, H3L = 9-phenyl-2,3,7-trihydroxy-6-fluorone) (2) complexes were prepared and their spectroelectrochemical behaviour characterised in solution and on conductive glass electrodes layered with Sb-doped nanocrystalline SnO2. The systems display a reversible redox response in a narrow potential range (-0.5 to +0.5 V vs SCE) and offer the possibility of controlling colour changes of electrochromic devices through variations of the coordinated and bridging ligands at the metal centres. SnO2(Sb) electrodes loaded with these dyes show switching times of the order of ms.

Rod-like Dinuclear Ruthenium Complexes for Dye-sensitized Photovoltaics

ABSTRACTRuthenium complexes with tridentate terpyridine type ligands have many structural advantages over the complexes with bipyridine ligands. Polynuclear ruthenium complexes prepared using these terpyridine ligands bridged with phenylene rings are potential candidates for photosensitization in dye-sensitized photovoltaic cells. In this study, we have carried out synthesis, characterization and theoretical modeling of rigid, rod-like homometallic dinuclear ruthenium complexes using terpyridine and bipyridine ligands. The photophysical and photovoltaic properties have been investigated. These supramolecular dyes are found to be efficient photosensitizers in dye-sensitized photovoltaic cells when a liquid electrolyte is employed.