Articles

Compounds containing dioxygen bonded to metal atoms – such as metal-peroxo or -superoxo species – are models of enzymes that can activate oxygen. Now a mononuclear side-on nickel(III)-peroxo complex has been made, which is stabilized by a macrocyclic ligand. The complex can transfer the bound dioxygen to another metal, and conduct nucleophilic reactions.

The cycloaddition of N-metalated azomethine ylides to C₆₀ can result in the formation of a number of different stereoisomeric products. Now, it has been shown that the stereochemical outcome of this reaction can be controlled by carefully choosing the the correct combination of metal and ligand to form the complex that catalyses this process.

Industrial chemicals can pose serious health risks in the workplace, and monitoring them is of vital importance. Researchers now show that an optoelectronic nose based on a colorimetric sensor array of nanoporous pigments can rapidly identify a wide range of toxic gases at their IDLH (immediately dangerous to life or health) concentrations.

A synthesis of 6-deoxyerythronolide B is reported that uses a late-stage C–H oxidative macrocyclization reaction to forge the key macrocyclic core found in the erythromycins. By installing oxygen at a late-stage, this strategy improves synthetic efficiency by minimizing the ‘oxygen load’, and provides stereochemical versatility at the site of oxidation.

H/D exchange reactions in the high vacuum of a mass spectrometer reveal how crown ethers move between ammonium ion binding sites of an oligolysine peptide. This study enables the dynamics of non-covalent interactions to be probed in a unique environment and could be applied to more complex artificial or natural systems.

Protein imbalances in serum can be correlated with disease, but measurement and subsequent diagnosis is made difficult by the complex composition of serum. Now an array-based sensor, containing synthetic gold nanoparticles and biocompatible green fluorescent protein, has been developed that can detect proteins in undiluted human serum at physiologically relevant concentrations.

Single-walled carbon nanotubes wrapped with a carbohydrate-based polymer bearing diaminophenyl groups can be used to detect nitric oxide (NO) — an important messenger molecule for biological signalling. These polymer–nanotube hybrids are capable of real-time and spatially resolved sensing of NO in living cells, and could ultimately prove useful for in vivo detection.

Porous metal–organic frameworks are promising for hydrogen storage applications, but adsorption capacities have remained too low for practical use. Now, the adsorption behaviour of such a framework has been modulated by exchanging cations within its pores resulting in either kinetic trapping or enhanced hydrogen affinity.

Better understanding of the fundamental bonding interactions at electrified metal–liquid interfaces is critical for improving the electrochemical reactions of fuel cells, but now traditional models are shown to be insufficient. Using experimental measurements of various electrocatalytic reactions on platinum and density functional theory it is shown that non-covalent interactions must be considered.

An analysis of key intermediates relevant to gold(I) catalysis has been performed using density functional theory. A bonding model is proposed whereby the reactivity of gold(I)-coordinated carbenes is dependent on carbene substituents and ancillary ligands that dictate where these gold structures lie on a continuum ranging from a metal-stabilized singlet carbene to a metal-coordinated carbocation.

New economic and environmentally benign methods for achieving carbon–carbon bond formation are in constant demand. Here, a remarkably efficient and functional-group-tolerant, metal-free reductive cross-coupling of carbonyl compounds with boronic acids is described.

Carbon-nanotube networks have been used to study the sensitivity to molecular oxygen of a dendrimer complexed with europium ions. Optically transparent devices made by coating nanotubes with the metal-containing dendrimer show a linear and reversible electrical response to O₂, and may prove useful for oxygen-sensing applications.

Incorporating binding sites for metal ions into DNA strands that assemble into well-defined three-dimensional structures has enabled researchers to build metal-nucleic acid cages. There is potential for the geometry, pore size and chemistry of such materials to be easily tuned, which may prove useful for applications in molecular sensing and encapsulation.

When a racemic mixture of tartaric acid is adsorbed on a Cu(110) surface, the (R,R) and (S,S) enantiomers separate to form enantiopure domains that cover equal amounts of the substrate. Repeating the experiment with just a small excess of one enantiomer, however, has a drastic effect on the surface assembly with only the majority isomer forming ordered superstructures.

Building artificial chemical systems that mimic the behaviour of cells could offer new insights into biological processes. Now, researchers show that by compartmentalizing the autocatalytic formose reaction inside lipid vesicles, and using small-molecule precursors as a ‘metabolic’ fuel, they can create a system that is capable of communicating with living bacterial cells.

Spin transitions — metal ions changing from high- to low-spin states — can be triggered by a range of stimuli and have normally only been observed in octahedrally coordinated ions. Now, a four-coordinate, square-planar iron(II) compound, SrFeO₂, exhibits such a spin transition, accompanied by a transition from an antiferromagnetic insulator to a ferromagnetic half-metal.

Platinum nanoparticles are excellent catalysts, but maintaining that effectiveness at ever smaller particle sizes is crucial to make best use of the precious metal. Now, a dendrimer has been used as a template to make subnanometre clusters, with a defined number of atoms, that exhibit high catalytic activity.

Bifurcating reaction pathways are those for which a single transition-state structure leads to two separate products, and they have been seen previously in the reactions of certain small molecules. Now, calculations provide evidence for a pathway that bifurcates in the synthesis of a terpene — leading to distinctly different structures.

Electron energy-loss spectroscopy (EELS) is broadly used to examine chemical composition, but single-atom analysis is hampered by the damage caused by incident electrons. Now, with an EELS technique that does not cause such damage, single calcium atoms have been identified and various elemental analyses demonstrated using metallofullerene-doped nanotubes.

The unusual properties of graphene make it a promising candidate for nanoelectronics applications, but it remains a difficult material to make. Now, on the basis of spectroscopic data that characterize the graphene-precursor graphite oxide, researchers have devised an efficient reduction process for the large-scale production of nearly pure, highly conductive graphene sheets.