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

YesThe fabrication of osmium nanoclusters from single atoms has been studied in real-time on B-doped and B-free graphitic surfaces. The dynamics of nucleation on both surfaces are identified, captured, and reported. The nucleation is ca. 2× faster on B-doped surface compared to the B-free surface (38 pm min−1versus 18 pm min−1), suggesting osmium–boron interactions within the nanomaterials

Polymers and boron neutron capture therapy(BNCT): a potent combination

YesBoron neutron capture therapy (BNCT) has a long history of unfulfilled promises for the treatment of aggressive cancers. In the last two decades, chemists, physicists, and clinical scientists have been coordinating their efforts to overcome practical and scientific challenges needed to unlock its full therapeutic potential. From a chemistry point of view, the two current small-molecule drugs used in the clinic were developed in the 1950s, however, they both lack some of the essential requirements for making BNCT a successful therapeutic modality. Novel strategies are currently used to design new drugs, more selective towards cancer cells and tumours, as well as able to deliver high boron contents to the target. In this context, macromolecules, including polymers, are promising tools to make BNCT an effective, accepted, and front-line therapy against cancer. In this review, we will provide a brief overview of BNCT, and its potential and challenges, and we will discuss the most promising strategies that have been developed so far

Effect of temperature on the nucleation and growth of precious metal nanocrystals

YesUnderstanding 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.The Royal Society. Grant Number: UF150295 Leverhulme Trust. Grant Number: ECF-2013-414 The Academy of Medical Sciences. Grant Number: SBF003\117

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

YesA 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.Royal Society; Academy of Medical Sciences/the Wellcome Trust/the Government Department of Business, Energy and Industrial Strategy/the British Heart Foundation Springboard Awar

Anti-inflammatory activity of electron-deficient organometallics

YesWe 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-pcymene)( 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.We thank the Royal Society (University Research Fellowship No. UF150295 to NPEB), and the University of Bradford for financial support

Enhancement of Cytotoxicity by Combining Pyrenyl-Dendrimers and Arene Ruthenium Metallacages

Three generations of pyrenyl bis-MPA dendrimers with two different end-groups, acetonide (pyrGn) or alcohol (pyrGn-OH) (n = 1–3), were synthesized, and the pyrenyl group of the dendritic molecules was encapsulated in the arene ruthenium metallacages, [Ru6(p-cymene) 6 (OO∩OO)3(tpt)2]6+ (OO∩OO = 5,8-dioxydo- 1,4-naphtaquinonato (donq) [1]6+ and 6,11-dioxydo-5,12- naphtacenedionato (dotq) [2]6+; tpt =2,4,6-tri(pyridin-4-yl)-1,3,5-triazine). The host–guest properties of [guestC1]6+ and [guestC2]6+ were studied in solution by NMR and UV–vis spectroscopic methods, thus allowing the determination of the affinity constants. Moreover, the cytotoxicity of these water- soluble host–guest systems and the pyrenyl-dendrimers was evaluated on human ovarian cancer cells

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

YesThe 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 18-electron complexes of general formula [Os(η6-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)(L)] (L = pyridine (2), 4-dimethylaminopyridine (3), 4-cyanopyridine (4), 4-methoxypyridine (5), pyrazine (6), pyridazine (7), 4,4’-bipyridine (8) and triphenylphosphine (9)) is reported. All 18-electron complexes are in equilibrium in solution with the 16-electron precursor, and thermochromic properties are observed in some cases (2, 3, 5, 8, and 9). The binding constants and Gibbs free energies of the equilibria are determined using UV-visible titrations and their stabilities investigated. Synthetic routes for forcing the formation of the 18-electron species are proposed, and analytical methods to characterise the equilibria are described.We thank the Leverhulme Trust (Early Career Fellowship No. ECF-2013-414 to NPEB), and the University of Warwick (Grant No. RD14102 to NPEB)

Designing supramolecular liquid-crystalline hybrids from pyrenyl-containing dendrimers and arene ruthenium metallacycles

YesThe association of the arene ruthenium metallacycle [Ru4(p-cymene)4(bpe)2(donq)2][DOS]4 (bpe = 1,2-bis(4-pyridyl)ethylene, donq = 5,8-dioxydo-1,4-naphtoquinonato, DOS = dodecyl sulfate) with pyrenyl-functionalized poly(arylester) dendrimers bearing cyanobiphenyl end-groups is reported. The supramolecular dendritic systems display mesomorphic properties as revealed by polarized optical microscopy, differential scanning calorimetry and small-angle X-ray scattering measurements. The multicomponent nature of the dendrimers and of the corresponding host–guest supramolecules (i.e., end-group mesogens, dendritic core, pyrene unit, aliphatic spacers, and metallacycle) leads to the formation of highly segregated mesophases with a complex multilayered structure due to the tendency of the various constitutive building-blocks to separate in different organized zones. The pyrenyl dendrimers exhibit a multilayered smectic A-like phase, thereafter referred to as LamSmA phase to emphasize this unaccustomed morphology. As for the corresponding Ru4–metallacycle adducts, they self-organize into a multicontinuous thermotropic cubic phase with the Im3̅m space group symmetry. This represents a unique example of liquid-crystalline behavior observed for such large and complex supramolecular host–guest assemblies. Models of their supramolecular organizations within both mesophases are proposed.R.D. thanks the Swiss National Science Foundation (Grant No 200020-140298) for financial support