Volume 3 Issue 6, June 2011

A highly inventive route for the synthesis of a key substance that stimulates potato cyst nematodes to hatch has been developed. This discovery has potential to impact food supplies, as treatment of crops with this compound could alleviate the devastating effect of these parasites.

Isotopic labelling is widely used to unravel reaction mechanisms, but are conclusions from such studies always robust? Now, studies on the photolysis of CD₃CHO reveal extensive isotopic scrambling before dissociation, which could have implications for our mechanistic understanding of some key aspects of atmospheric photochemistry.

Single-molecule spectroscopy allows fluctuations of conjugated polymer conformation to be monitored during solvent vapour annealing. Dramatic changes in fluorescence behaviour are observed and interpreted in terms of transformations between extended and collapsed polymer geometries.

A diuranium compound featuring an arene bridge shows single-molecule-magnet behaviour, which could arise from a mechanism different from the traditional 'super-exchange' spin coupling.

A microfluidic device design that allows a nanolitre droplet to be trapped and sequentially diluted without the need for any moving parts opens up new possibilities in high-throughput screening.

Observing the diffusion of guest molecules in large single crystals of a metal-organic framework reveals surprising insights into the blockage of the channels at the material's surface and the role of defects within its bulk.

The efficient engineering of nanostructures with semiconducting properties is vital to the development of organic electronics. This Perspective discusses a variety of techniques for fabricating such macromolecules, including graphene carving, the stimulus-induced synthesis of conjugated polymers and surface-assisted synthesis, and considers their potential for reproducing chemically and spatially precise molecular arrangements, that is 'molecular blueprints'.

Droplet microfluidics offer a convenient platform for high-throughput experimentation. It has been difficult, however, to rapidly and controllably vary concentration — a key process used in macro-scale experiments. Here, a droplet dilution module is described that traps a mother droplet and then repeatedly dilutes it releasing a series of droplets that define a digital concentration gradient.

Unexpected and significant isotope exchange is observed in the near-threshold photodissociation of isopically labelled acetaldehyde. Theoretical modelling indicates that, at the lowest energies considered, an average of 20 H- or D-shifts occur before dissociation — evidence for extensive isomerization.

The first total synthesis of conolidine — representing the first asymmetric synthesis of a C5-nor-stemmadenine — is described. The chemical synthesis proceeds in just nine steps and gives an 18% overall yield from a commercially available pyridine — an achievement that led to the discovery that (+)-, (–)- and (±)-conolidine are potent non-opioid analgesics.

Single-molecule magnets (SMMs) are multinuclear clusters whose behaviour typically relies on intramolecular spin-coupling interactions between neighbouring metal ions. A diuranium–arene complex has now been prepared that shows behaviour characteristic of an SMM without relying on this type of superexchange mechanism. This may enable the construction of SMMs that maintain their magnetism at higher temperatures.

The development of an effective, cheap and robust water oxidation catalyst is crucial to the development of solar water-splitting technology. A manganese catalyst inspired by the water oxidizing centre of photosystem II is now shown to dissociate and reform into nanoparticles resembling the known natural oxidant mineral birnessite.

High operating temperatures in heterogeneous catalytic processes compromise energy efficiency, catalyst lifetime and product selectivity. Plasmonic silver nanoparticles are shown to couple thermal energy and a low-intensity photon flux to drive commercially important oxidation reactions at lower temperatures than conventional thermal processes.

Spirooxindoles are important structural motifs found in an array of bioactive compounds. Here a Michael–aldol domino reaction for the construction of bispirooxindoles is presented, creating four stereocentres, including three quaternary carbon centres. Novel multifunctional organocatalysts have been developed for this transformation.

Bimetallic core@shell nanoparticles often have properties that are different from those of single-metal or alloy nanoparticles. Here, a route to such nanoparticles that binds the second metal to the core surface prior to reduction is described. The unique catalytic properties of the nanoparticles are demonstrated in the selective production of chloroaniline.

The first chemical synthesis of solanoeclepin A is described. The novel 5-4-6-7-5-5 polycyclic architecture was constructed in a stereoselective manner via a cyclopentene annulation strategy, the intramolecular cyclization of an epoxy nitrile intermediate, and an intramolecular Diels–Alder reaction of a furan derivative.

The photocatalytic production of hydrogen from renewables such as ethanol and water could be a key means of future fuel production. There are few, if any, catalysts available for such a reaction, and our understanding of photocatalytic reactions generally remains poor. It is now demonstrated that gold–titania nanoparticles are effective catalysts for producing hydrogen from ethanol, and the rate is independent of gold particle size.

David Lindsay and William Kerr remind us that where cobalt is concerned, good has triumphed over evil.