Evaluation of the Toxicity of Two Electron-Deficient Half-Sandwich Complexes against Human Lymphocytes from Healthy Individuals

Electron-deficient half-sandwich complexes are a class of under-studied organometallics with demonstrated potential as metallodrug candidates. This study investigates the effect of two 16-electron organoruthenium complexes ([(p-cym)Ru(benzene-1,2-dithiolato)] (1) and [(p-cym)Ru(maleonitriledithiolate)] (2)) on the cell viability of non-immortalised human lymphocytes from healthy individuals. The genotoxic effects of 1 and 2 in lymphocytes are also investigated by using the Comet and cytokinesis-block micronucleus assays. Gene expression studies were carried out on a panel of genes involved in apoptosis and the DNA damage-repair response. Results show that the two 16-electron complexes do not have significant effect on the cell viability of human lymphocytes from healthy individuals. However, an increase in DNA damage is induced by both compounds, presumably through oxidative stress production.

Synthesis, Characterisation and In Vitro Anticancer Activity of Catalytically Active Indole-Based Half-Sandwich Complexes

The synthesis, characterisation and evaluation of the in vitro cytotoxicity of four indole-based half-sandwich metal complexes towards two ovarian cancer cell lines (A2780 and A2780cisR) and one normal prostate cell line (PNT2) are presented herein. Although capable of inducing catalytic oxidation of NADH and able to reduce NAD+ with high turnover frequencies, in cells and in the presence of sodium formate, these complexes also strongly interact with biomolecules such as glutathione. This work highlights that efficient out-of-cells catalytic activity might lead to higher reactivity towards biomolecules, thus inhibiting the in-cells catalytic processes.

Preclinical Anticancer Activity of an Electron-Deficient Organoruthenium(II) Complex

Ruthenium compounds have been shown to be promising alternatives to platinum(II) drugs. However, their clinical success depends on achieving mechanisms of action that overcome Pt-resistance mechanisms. Electron-deficient organoruthenium complexes are an understudied class of compounds that exhibit unusual reactivity in solution and might offer novel anticancer mechanisms of action. Here, we evaluate the in vitro and in vivo anticancer properties of the electron-deficient organoruthenium complex [(p-cymene)Ru(maleonitriledithiolate)]. This compound is found to be highly cytotoxic: 5 to 60 times more potent than cisplatin towards ovarian (A2780 and A2780cisR), colon (HCT116 p53+/+ and HCT116 p53-/-), and non-small cell lung H460 cancer cell lines. It shows no cross-resistance and is equally cytotoxic to both A2780 and A2780cisR cell lines. Furthermore, unlike cisplatin, the remarkable in vitro antiproliferative activity of this compound appears to be p53-independent. In vivo evaluation in the hollow-fibre assay across a panel of cancer cell types and subcutaneous H460 non-small cell lung cancer xenograft model hints at the activity of the complex. Although the impressive in vitro data are not fully corroborated by the in vivo follow-up, this work is the first preclinical study of electron-deficient half-sandwich complexes and highlights their promise as anticancer drug candidates.

Correction: Pseudo electron-deficient organometallics: limited reactivity towards electron-donating ligands

Correction for ‘Pseudo electron-deficient organometallics: limited reactivity towards electron-donating ligands’ by Anaïs Pitto-Barry et al., Dalton Trans., 2017, 46, 15676–15683.

Effect of Temperature on the Nucleation and Growth of Precious Metal Nanocrystals

Understanding the effect of physical parameters (e.g., temperature) on crystallisation dynamics is of paramount importance for the synthesis of nanocrystals of well-defined sizes and geometries. However, imaging nucleation and growth is an experimental challenge owing to the resolution required and the kinetics involved. Here, by using an aberration-corrected transmission electron microscope, we report the fabrication of precious metal nanocrystals from nuclei and the identification of the dynamics of their nucleation at three different temperatures (20, 50, and 100 °C). A fast, and apparently linear, acceleration of the growth rate is observed against increasing temperature (78.8, 117.7, and 176.5 pm min^-1 , respectively). This work appears to be the first direct observation of the effect of temperature on the nucleation and growth of metal nanocrystals.

Anticancer Activity of Electron-Deficient Metal Complexes against Colorectal Cancer in vitro Models

An evaluation of the in vitro cytotoxicity of nine electron-deficient half-sandwich metal complexes towards two colorectal cancer cell lines (HCT116 p53+/+, HCT116 p53-/-) and one normal prostate cell line (PNT2) is presented herein. Three complexes were found to be equally cytotoxic towards both colorectal cancer cell lines, suggesting a p53-independent mechanism of action. These complexes are 12 to 34× more potent than cisplatin against HCT116 p53+/+ and HCT116 p53-/- cells. Furthermore, they were found to exhibit little or no cytotoxicity towards PNT2 normal cells, with selectivity ratios greater than 50. To gain an insight into the potential mechanisms of action of the most active compounds, their effects on the expression levels of a panel of genes were measured using qRT-PCR against treated HCT116 p53+/+ and HCT116 p53-/- cells, and cell-cycle analysis was carried out.

Influence of boron doping on the dynamics of formation of Os metal nanoclusters on graphitic surfaces

Unprecedented metal–boron interactions within nanomaterials and insights into the role of doping heteroatoms in nucleation processes are reported herein.

Controlled Release of Carbon Monoxide from a Pseudo Electron-Deficient Organometallic Complex

A 16-electron iridium organometallic is reacted with carbon monoxide to form an 18-electron CO-adduct. This CO-adduct is stable for weeks in the solid state, but quickly reverts to its parent 16-e complex in tetrahydrofuran solution, releasing CO_(g). Using a simple methodology, we show that this gas can subsequently be used to perform a carbonylation reaction on another molecule.

In Vivo Selectivity and Localization of Reactive Oxygen Species (ROS) Induction by Osmium Anticancer Complexes That Circumvent Platinum Resistance

Platinum drugs are widely used for cancer treatment. Other precious metals are promising, but their clinical progress depends on achieving different mechanisms of action to overcome Pt-resistance. Here, we evaluate 13 organo-Os complexes: 16-electron sulfonyl-diamine catalysts [(η6-arene)Os( N, N')], and 18-electron phenylazopyridine complexes [(η6-arene)Os( N, N')Cl/I]+ (arene = p-cymene, biphenyl, or terphenyl). Their antiproliferative activity does not depend on p21 or p53 status, unlike cisplatin, and their selective potency toward cancer cells involves the generation of reactive oxygen species. Evidence of such a mechanism of action has been found both in vitro and in vivo. This work appears to provide the first study of osmium complexes in the zebrafish model, which has been shown to closely model toxicity in humans. A fluorescent osmium complex, derived from a lead compound, was employed to confirm internalization of the complex, visualize in vivo distribution, and confirm colocalization with reactive oxygen species generated in zebrafish.

Schizophrenia: synthetic strategies and recent advances in drug design

Schizophrenia is a complex and unpredictable mental disorder which affects several domains of cognition and behaviour. It is a heterogeneous illness characterised by positive, negative, and cognitive symptoms, often accompanied by signs of depression. In this tutorial review, we discuss recent progress in understanding the target sites and mechanisms of action of second-generation antipsychotic drugs. Progress in identifying and defining target sites has been accelerated recently by advances in neuroscience, and newly developed agents that regulate signalling by the main excitatory neurotransmitters in the brain are surveyed. Examples of novel molecules for the treatment of schizophrenia in preclinical and clinical development and their industrial sponsors are highlighted.

New Class of Hybrid Materials for Detection, Capture, and "On-Demand" Release of Carbon Monoxide

Carbon monoxide (CO) is both a substance hazardous to health and a side product of a number of industrial processes, such as methanol steam reforming and large-scale oxidation reactions. The separation of CO from nitrogen (N₂) in industrial processes is considered to be difficult because of the similarities of their electronic structures, sizes, and physicochemical properties (e.g., boiling points). Carbon monoxide is also a major poison in fuel cells because of its adsorption onto the active sites of the catalysts. It is therefore of the utmost economic importance to discover new materials that enable effective CO capture and release under mild conditions. However, methods to specifically absorb and easily release CO in the presence of contaminants, such as water, nitrogen, carbon dioxide, and oxygen, at ambient temperature are not available. Here, we report the simple and versatile fabrication of a new class of hybrid materials that allows capture and release of carbon monoxide under mild conditions. We found that carborane-containing metal complexes encapsulated in networks made of poly(dimethylsiloxane) react with CO, even when immersed in water, leading to dramatic color and infrared signature changes. Furthermore, we found that the CO can be easily released from the materials by simply dipping the networks into an organic solvent for less than 1 min, at ambient temperature and pressure, which not only offers a straightforward recycling method, but also a new method for the "on-demand" release of carbon monoxide. We illustrated the utilization of the on-demand release of CO from the networks by carrying out a carbonylation reaction on an electron-deficient metal complex that led to the formation of the CO-adduct, with concomitant recycling of the gel. We anticipate that our sponge-like materials and scalable methodology will open up new avenues for the storage, transport, and controlled release of CO, the silent killer and a major industrial poison.

Halide Control of N,N-Coordination versus N,C-Cyclometalation and Stereospecific Phenyl Ring Deuteration of Osmium(II) p-Cymene Phenylazobenzothiazole Complexes

We report the synthesis of halido Os(II) p-cymene complexes bearing bidentate chelating phenylazobenzothiazole (AZBTZ) ligands. Unlike the analogous phenylazopyridine (AZPY) complexes, AZBTZ-NMe2 is capable of both N,N-coordination to Os(II) and cyclometalation to form N,C-coordinated species. N,C-Coordination occurs via an azo nitrogen and an ortho carbon on the aniline ring, as identified by 1H NMR and X-ray crystallography of [Os(p-cym)(N,N-AZBTZ-NMe2)Cl]PF6 (1a), [Os(p-cym)(N,N-AZBTZ-NMe2)Br]PF6 (2a), [Os(p-cym)(N,C-AZBTZ-NMe2)Br] (2b), and [Os(p-cym)(N,C-AZBTZ-NMe2)I] (3b). The N,C-coordinated species is more stable and is not readily converted to the N,N-coordinated complex. Analysis of the crystal structures suggests that their formation is influenced by steric interactions between the p-cym and AZBTZ-NMe2 ligands: in particular, larger monodentate halide ligands favor N,C-coordination. The complexes [Os(p-cym)(N,N-Me2-AZBTZ-NH2)Cl]PF6 (4) and [Os(p-cym)(N,N-Me2-AZBTZ-NH2)I]PF6 (5) were synthesized with methyl groups blocking the ortho positions on the aniline ring, forcing an N,N-coordination geometry. 1H NMR NOE experiments confirmed hindered rotation of the arene ligand and steric crowding around the metal center. Complex 2b exhibited unexpected behavior under acidic conditions, involving regiospecific deuteration of the aniline ring at the meta position, as observed by 1H NMR and high-resolution ESI-MS. Deuterium exchange occurs only under acidic conditions, suggesting an associative mechanism. The calculated partial charges on 2b show that the meta carbon is significantly more negatively charged, which may account for the regiospecificity of deuterium exchange.

Anti-inflammatory activity of electron-deficient organometallics

We report an evaluation of the cytotoxicity of a series of electron-deficient (16-electron) half-sandwich precious metal complexes of ruthenium, osmium and iridium ([Os/Ru(η⁶-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)] (1/2), [Ir(η⁵-pentamethylcyclopentadiene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)] (3), [Os/Ru(η⁶-p-cymene)(benzene-1,2-dithiolato)] (4/5) and [Ir(η⁵-pentamethylcyclopentadiene)(benzene-1,2-dithiolato)] (6)) towards RAW 264.7 murine macrophages and MRC-5 fibroblast cells. Complexes 3 and 6 were found to be non-cytotoxic. The anti-inflammatory activity of 1-6 was evaluated in both cell lines after nitric oxide (NO) production and inflammation response induced by bacterial endotoxin lipopolysaccharide (LPS) as the stimulus. All metal complexes were shown to exhibit dose-dependent inhibitory effects on LPS-induced NO production on both cell lines. Remarkably, the two iridium complexes 3 and 6 trigger a full anti-inflammatory response against LPS-induced NO production, which opens up new avenues for the development of non-cytotoxic anti-inflammatory drug candidates with distinct structures and solution chemistry from that of organic drugs, and as such with potential novel mechanisms of action.

Controlled fabrication of osmium nanocrystals by electron, laser and microwave irradiation and characterisation by microfocus X-ray absorption spectroscopy

Osmium nanocrystals are fabricatedvia3 methods and characterised by XAS, revealing different surface oxidation and metallicities depending on their fabrication technique.

Pseudo electron-deficient organometallics: limited reactivity towards electron-donating ligands

This work presents the unusual reactivity of a family of electron-deficient half-sandwich metal complexes.

Dynamics of formation of Ru, Os, Ir and Au metal nanocrystals on doped graphitic surfaces

The fabrication of precious metal (ruthenium, osmium, gold, and iridium) nanocrystals from single atoms has been studied in real-time.

The synthesis and unexpected solution chemistry of thermochromic carborane-containing osmium half-sandwich complexes

The functionalisation of the 16-electron complex [Os(η⁶-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)] (1) with a series of Lewis bases to give the corresponding 18-electron complexes is reported.

Nanoparticles of chitosan conjugated to organo-ruthenium complexes

The synthesis of nanoparticles of conjugates of caffeic acid-modified chitosan with ruthenium arene complexes is described.

Osmium Atoms and Os2 Molecules Move Faster on Selenium-Doped Compared to Sulfur-Doped Boronic Graphenic Surfaces

We deposited Os atoms on S- and Se-doped boronic graphenic surfaces by electron bombardment of micelles containing 16e complexes [Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-diselenate/dithiolate)] encapsulated in a triblock copolymer. The surfaces were characterized by energy-dispersive X-ray (EDX) analysis and electron energy loss spectroscopy of energy filtered TEM (EFTEM). Os atoms moved ca. 26× faster on the B/Se surface compared to the B/S surface (233 ± 34 pm·s(-1) versus 8.9 ± 1.9 pm·s(-1)). Os atoms formed dimers with an average Os-Os distance of 0.284 ± 0.077 nm on the B/Se surface and 0.243 ± 0.059 nm on B/S, close to that in metallic Os. The Os2 molecules moved 0.83× and 0.65× more slowly than single Os atoms on B/S and B/Se surfaces, respectively, and again markedly faster (ca. 20×) on the B/Se surface (151 ± 45 pm·s(-1) versus 7.4 ± 2.8 pm·s(-1)). Os atom motion did not follow Brownian motion and appears to involve anchoring sites, probably S and Se atoms. The ability to control the atomic motion of metal atoms and molecules on surfaces has potential for exploitation in nanodevices of the future.

Precious metal carborane polymer nanoparticles: characterisation of micellar formulations and anticancer activity

We report the encapsulation of highly hydrophobic 16-electron organometallic ruthenium and osmium carborane complexes [Ru/Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolate)] ( and ) in Pluronic® triblock copolymer P123 core-shell micelles. The spherical nanoparticles and , dispersed in water, were characterized by dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), and synchrotron small-angle X-ray scattering (SAXS; diameter ca. 15 and 19 nm, respectively). Complexes and were highly active towards A2780 human ovarian cancer cells (IC(50) 0.17 and 2.50 μM, respectively) and the encapsulated complexes, as and nanoparticles, were less potent (IC(50) 6.69 μM and 117.5 μM, respectively), but more selective towards cancer cells compared to normal cells.

Synthesis and controlled growth of osmium nanoparticles by electron irradiation

Defined-size osmium nanoparticles (1.5–50 nm) were synthesized on a B- and S-doped turbostratic graphitic structure from an organometallic osmium complex encapsulated in self-spreading polymer micelles and characterised by (HR)TEM, AFM and XPS.

Fabrication of crystals from single metal atoms

Metal nanocrystals offer new concepts for the design of nanodevices with a range of potential applications. Currently the formation of metal nanocrystals cannot be controlled at the level of individual atoms. Here we describe a new general method for the fabrication of multi-heteroatom-doped graphitic matrices decorated with very small, ångström-sized, three-dimensional (3D)-metal crystals of defined size. We irradiate boron-rich precious-metal-encapsulated self-spreading polymer micelles with electrons and produce, in real time, a doped graphitic support on which individual osmium atoms hop and migrate to form 3D-nanocrystals, as small as 15 Å in diameter, within 1 h. Crystal growth can be observed, quantified and controlled in real time. We also synthesize the first examples of mixed ruthenium–osmium 3D-nanocrystals. This technology not only allows the production of ångström-sized homo- and hetero-crystals, but also provides new experimental insight into the dynamics of nanocrystals and pathways for their assembly from single atoms.

Metal nanocrystals are used in an ever growing list of applications, but precise control and understanding of their formation can be difficult. Here, the authors show a route that allows the controlled formation of metal nanocrystals to be carried out and observed at an atom-by-atom level.

The potent oxidant anticancer activity of organoiridium catalysts

Platinum complexes are the most widely used anticancer drugs; however, new generations of agents are needed. The organoiridium(III) complex [(η⁵-Cp^xbiph)Ir(phpy)(Cl)] (1-Cl), which contains π-bonded biphenyltetramethylcyclopentadienyl (Cp^xbiph) and C∧N-chelated phenylpyridine (phpy) ligands, undergoes rapid hydrolysis of the chlorido ligand. In contrast, the pyridine complex [(η⁵-Cp^xbiph)Ir(phpy)(py)]⁺ (1-py) aquates slowly, and is more potent (in nanomolar amounts) than both 1-Cl and cisplatin towards a wide range of cancer cells. The pyridine ligand protects 1-py from rapid reaction with intracellular glutathione. The high potency of 1-py correlates with its ability to increase substantially the level of reactive oxygen species (ROS) in cancer cells. The unprecedented ability of these iridium complexes to generate H₂O₂ by catalytic hydride transfer from the coenzyme NADH to oxygen is demonstrated. Such organoiridium complexes are promising as a new generation of anticancer drugs for effective oxidant therapy.

Challenges for metals in medicine: how nanotechnology may help to shape the future

Encapsulation of the platinum(IV) prodrug mitaplatin in block copolymer nanoparticles increases drug circulation time in the blood and reduces accumulation in the kidneys, as reported by Lippard and colleagues in this issue of ACS Nano. Importantly, controlled drug release from the nanoparticles produces long-term anticancer efficacy, with the prospect of reduced side effects. We highlight the potential that such a strategy holds for the future development of metallodrugs. Metal coordination complexes offer the prospect of novel mechanisms of activity on account of their unique architectures, as well as potential activation mechanisms, including ligand substitution and metal- and ligand-centered redox properties. Nanoparticles offer exciting prospects for improving delivery, cell uptake, and targeting of metallodrugs, especially anticancer drugs, to make them more effective and safer.

Delivery of floxuridine derivatives to cancer cells by water-soluble organometallic cages

The self-assembly of 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine (tpt) triangular panels with p-cymene (pPr(i)C(6)H(4)Me) ruthenium building blocks and 2,5-dioxydo-1,4-benzoquinonato (dobq) or 5,8-dioxydo-1,4-naphthoquinonato (donq) bridges, in the presence of a pyrenyl-nucleoside derivatives (pyreneR), affords the triangular prismatic host-guest compounds [(pyrene-R)⊂Ru(6)(pPr(i)C(6)H(4)Me)(6)(tpt)(2)(dobq)(3)](6+) ([(pyrene-R)⊂1](6+)) and [(pyrene-R)⊂Ru(6)(pPr(i)C(6)H(4)Me)(6)(tpt)(2)(donq)(3)](6+) ([(pyrene-R)⊂2](6+)), respectively. The inclusion of six monosubstitutedpyrenyl-nucleosides (pyrene-R1 = 5'-(1-pyrenyl butanoate)-2'-deoxyuridine, pyrene-R2 = 5-fluoro-5'-(1-pyrenyl butanoate)-2'-deoxyuridine, pyrene-R3 = 5'-{N-[1-oxo-4-(1-pyrenyl)butyl]-glycyl}-2'-deoxyuridine, pyrene-R4 = 5-fluoro-5'-{N-[1-oxo-4-(1-pyrenyl)butyl]-glycyl}-2'-deoxyuridine, pyrene-R5 = 5-fluoro-5'-{N-[1-oxo-4-(1-pyrenyl)butyl]-phenylalanyl}-2'-deoxyvuridine, pyrene-R6 = 5-fluoro-5'-{N-[1-oxo-4-(1-pyrenyl)butyl]-phenylalanyl}-2'-deoxyuridine) has been accomplished. The carceplex nature of [(pyrene-R)⊂1](6+) with the pyrenyl moiety firmly encapsulated in the hydrophobic cavity of the cage with the nucleoside groups pointing outward was confirmed by NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS), while the host-guest nature of [(pyrene-R)⊂2](6+) was studied in solution by NMR techniques. In contrast to the floxuridine compounds used in the clinic, the host-guest complexes are highly water-soluble. Consequently, the cytotoxicities of these water-soluble compounds have been established using human ovarian A2780 and A2780cisR cancer cells. All the host-guest systems are more cytotoxic than the empty cages alone [1][CF(3)SO(3)](6) (IC(50) = 23 μM) and [2][CF(3)SO(3)](6) (IC(50) = 10 μM), the most active compound [pyrene-R4⊂1][CF(3)SO(3)](6)being 2 orders of magnitude more cytotoxic (IC(50) = 0.3 μM) on these human ovarian cancer cell lines (A2780 and A2780cisR).

Dicarba-closo-dodecarborane-containing half-sandwich complexes of ruthenium, osmium, rhodium and iridium: biological relevance and synthetic strategies

This review describes how the incorporation of dicarba-closo-dodecarboranes into half-sandwich complexes of ruthenium, osmium, rhodium and iridium might lead to the development of a new class of compounds with applications in medicine. Such a combination not only has unexplored potential in traditional areas such as Boron Neutron Capture Therapy agents, but also as pharmacophores for the targeting of biologically important proteins and the development of targeted drugs. The synthetic pathways used for the syntheses of dicarba-closo-dodecarboranes-containing half-sandwich complexes of ruthenium, osmium, rhodium and iridium are also reviewed. Complexes with a wide variety of geometries and characteristics can be prepared. Examples of addition reactions on the metal centre, B-H activation, transmetalation reactions and/or direct formation of metal-metal bonds are discussed (103 references).

Synthesis, Characterization and Anticancer Activity of Porphyrin-Containing Organometallic Cubes

Self‐assembly of 5,10,15,20‐tetra(4‐pyridyl)porphyrin (tpp‐H2) and 5,10,15,20‐tetra(4‐pyridyl)porphyrin‐M(ii) (M = Ni (tpp‐Ni); Zn (tpp‐Zn)) tetradentate panels with the dinuclear p‐cymene ruthenium clips [Ru2(p-cymene)2(C2O4)Cl2] and [Ru2(p-cymene)2(C6H2O4)Cl2] (C2O4 = oxalato; C6H2O4 = 2,5‐dioxydo‐1,4‐benzoquinonato) affords the cationic organometallic cubes: [Ru8(p-cymene)8(tpp‐H2)2(C2O4)4]8+ (1); [Ru8(p-cymene)8(tpp‐Ni)2(C2O4)4]8+ (2); [Ru8(p-cymene)8(tpp‐Zn)2(C2O4)4]8+ (3); [Ru8(p-cymene)8(tpp‐H2)2(C6H2O4)4]8+ (4); [Ru8(p-cymene)8(tpp‐Ni)2(C6H2O4)4]8+ (5); and [Ru8(p-cymene)8(tpp‐Zn)2(C6H2O4)4]8+ (6). In addition, the new dinuclear arene ruthenium 2,5‐dioxydo‐1,4‐benzoquinonato clips [Ru2(indane)2(C6H2O4)Cl2] (7) and [Ru2(nonylbenzene)2(C6H2O4)Cl2] (8) react in methanol with tpp‐H2 in the presence of silver triflate to afford the corresponding cationic cubes [Ru8(indane)8(tpp‐H2)2(C6H2O4)4]8+ (9) and [Ru8(nonylbenzene)8(tpp‐H2)2(C6H2O4)4]8+ (10) respectively. All cationic metalla‐cubes were isolated as triflate salts and characterized by NMR, infrared, electro‐spray mass spectrometry and UV‐visible spectroscopy. Moreover, the formation of unsymmetrical metalla‐cubes built using a mixture of the different porphyrin panels during the self‐assembly of the 2,5‐dioxydo‐1,4‐benzoquinonato metalla‐cubes, [Ru8(p-cymene)8(tpp‐H2)(tpp‐Ni)(C6H2O4)4]8+ (11), [Ru8(p-cymene)8(tpp‐H2)(tpp‐Zn)(C6H2O4)4]8+ (12), and [Ru8(p-cymene)8(tpp‐Ni)(tpp‐Zn)(C6H2O4)4]8+ (13), was studied by electro‐spray mass spectrometry. The cytotoxicities of all metalla‐cubes as well as the mixtures containing the unsymmetrical metalla‐cubes were established on human ovarian A2780 and A2780cisR cancer cell lines. All symmetrical compounds are equally cytotoxic (IC50 = 7–15 μM) (IC50 being the drug concentration necessary for 50% inhibition of cell viability) against both A2780 and cisplatin‐resistant A2780cisR cancer cells, with stronger cytotoxicities (IC50 = 2–5 μM) observed for the mixtures containing the unsymmetrical 2,5‐dioxydo‐1,4‐benzoquinonato metalla‐cubes.

Interactions of ruthenium coordination cubes with DNA

The interactions of four octacationic ruthenium coordination cubes with duplex and quadruplex (telomeric and c-myc) DNA have been studied by FID and SPR, showing these cubes to bind strongly to tetrastranded DNA structures.