Research articles

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.

Extremely short quintuple bonds between chromium atoms have recently been discovered. Carboalumination reactions have now been performed to further investigate the properties of these unusual bonds, and show that they have interesting analogies to lower-order bonds, as well as revealing more about the nature of quintuple bonds.

Materials formed by linking metal ions with organic ligands have potential for gas adsorption and storage, and can be flexible in response to stimuli. Now, suitable organic linkers result in a material that undergoes a large structural change, but does not lose crystallinity.

Ion-mobility mass spectrometry has been used to identify and characterize the oligomeric assemblies of amyloid-β proteins under physiologically relevant conditions. Hexamers and dodecamers are formed only from Aβ42 proteins and the dodecamer is identified as a candidate for the primary toxic agent in the development of Alzheimer's disease.

Some clusters of atoms, such as Al₁₃⁻, can behave as though they are themselves atoms. Most of these ‘superatoms’ have filled shells of paired electrons, but calculations now suggest that a vanadium–caesium cluster with a partially filled d-shell acts like manganese, displaying magnetic properties.

A systematic variation of ligand properties allows an in-depth experimental and theoretical study of a highly non-canonical bonding situation in certain organic compounds, and provides insight into the criteria that must be fulfilled for such compounds to be truly considered as carbon(0)-containing entities.

Chemistry of palladium in the 0, I, II and IV oxidation states is well established. Here, concerted reductive elimination from bimetallic Pd(III)–Pd(III) complexes is observed for the first time in carbon–heteroatom bond-forming processes relevant to oxidative palladium catalysis.

In addition to environmental concerns about ozone, there is some debate regarding its role in biological systems. Researchers have now developed a fluorescent molecular probe that can selectively detect ozone — in preference to other reactive oxygen species — in both atmospheric and biological samples.

A topologically non-trivial metallosupramolecular structure is formed by a Pd₄L₄ complex in which interweaving and twisting of the ligands results in both Solomon's Link and figure-of-eight ring motifs. In the solid state, six of these complexes assemble into a hollow spheroid that closely resembles a stellated truncated hexahedron.

An organocatalytic cascade reaction allows the rapid construction of (+)-ricciocarpin A, which exhibits potent molluscicidal activity against the water snails Biomphalaria glabrata. The concise synthesis also allowed the synthesis of five analogues, one of which was shown to have significantly improved biological activity.

Aerogels made from metal–sulfur networks show high absorption of conjugated organic molecules and mercury ions and can easily separate H₂ from CO₂. Compared with the conventional sulfided Co-Mo/Al₂O₃ catalyst, these spongy, random porous networks are twice as active towards the hydrodesulfurization of thiophene.

The unique physical properties of graphene make it a promising material for the construction of nanoelectronic devices. In order to tailor its surface properties and enable it to be integrated with other components, it has now been shown that stable and robust organic monolayers can be formed on graphene at room temperature.

Using carbon nanotubes in electronic or photovoltaic devices generates active metastable states. These elusive species are hard to characterize because of the polydisperse and aggregate nature of nanotube bundles. A complete characterization of the radical–ion pair state has now been achieved using a range of techniques.

Mechanical stretching of a protein can be studied in detail using single-molecule experiments, and is shown to have an accelerating effect on its reaction with a nucleophile. The observation of a dramatic switch in the effect above a threshold force suggests an abrupt change in protein conformation and a change in reaction mechanism.

Deviations from the normal bonding behaviour add to our understanding of bonding models and inform computer simulations. Chlorotrinitromethane has an extremely short carbon–chlorine bond and its solid-state structure has now been determined. Using a combination of crystallography and computation, its intra- and intermolecular interactions have also been studied.

A metallo-organic hybrid material prepared by reduction of a palladium salt in the presence of cinchona alkaloids shows moderate enantioselectivity in organic transformations. The metal retains some chiral character after extraction of the dopant, selectively readsorbing the original alkaloid and showing different responses to clockwise and anticlockwise circularly polarized light.

Self-assembly of discrete and well-defined supramolecular structures often requires a delicate balance of non-covalent forces such as hydrogen bonding and metal–ligand interactions. Now, by studying the formation of G-quadruplexes, it has been shown that the Coulombic energy associated with the separation of ion pairs can also be used to precisely regulate self-assembly processes.