News & Views in 2009

Chemists are like detectives: they like to know 'whodunit' during a catalytic reaction. Combining advanced electron microscopy with intelligent molecular design has now provided strong evidence for the presence of a highly active site within a complex catalytic solid.

Shining circularly polarized light into a suspension of racemic amino-acid-derivative crystals in a saturated solution and then grinding them results in enantiomerically pure crystals. This evolution is shown to be directed by an unknown chiral product.

The conformational structure of a molecule can have important effects on its interactions and properties, but studying such effects is made difficult by the challenge of separating different conformers. Their spatial separation has now been achieved using an electric field — allowing the possibility of isomer-specific studies.

Proton-conducting solids are crucial components in a variety of electrochemical and energy-conversion devices. A porous metal–organic framework loaded with guest molecules displays both proton-conducting and gas-tight properties, affirming its potential as a fuel cell membrane.

In spite of the many functions of copper proteins within biology, those that contain a single copper ion can be divided into two classes, based in part on their spectroscopic properties. An artificial 'type 0' protein combines some properties of both, and may offer a route to stable catalytic processes.

The formation of a phosphine oxide with its strong P=O bond is the driving force for the classical Wittig reaction, but is wasteful and can pose problems during purification. A new development allowing the use of catalytic phosphorus reagents promises to clean up olefination chemistry.

Chemists have long relied on techniques that give indirect hints and clues as to the structure of the molecules they study, but advances in scanning probe microscopy provide a glimpse of the individual atoms and bonds within pentacene.

Synthetic vesicles with membranes made from amphiphiles that are fluorescence acceptors encapsulate donor molecules in their cores, and emit different proportions of red, blue and green light depending on pH. The balance of these coloured emissions at pH 9 results in white fluorescence.

The host–guest properties of metal–organic frameworks have usually relied on molecular separation by the pore aperture or non-specific binding with the pore walls. Incorporating supramolecular recognition units into the frameworks has now enabled the docking of a specific guest.

Identifying inhibitors of protein–protein interactions is an ongoing challenge in the field of drug design, but the use of peptide fragments based on a known binding interface is showing promise.

Inorganic semiconductors have long been used to construct rectifying diodes, but making them out of single molecules has remained a challenge. Now, two separate studies have induced rectification behaviour within molecular systems through different approaches.

Improvements to the efficiency and lifetime of polymer electrolyte membrane fuel cells can be realized by finding more active and stable electrocatalytic cathode materials. A computational search has found two such alloys and confirmed their enhanced properties experimentally.

By studying non-covalent assemblies in the gas phase, it is possible to examine the mobility of the components within a single complex — rather than between different complexes — using hydrogen/deuterium exchange reactions.

Dinitrogen ligands — key for understanding how atmospheric nitrogen can be reduced — almost exclusively have even-numbered oxidation states. Now, however, lanthanide complexes with [N₂]³⁻ ligands have been synthesized and investigated.

The highly selective oxidation of just one carbon–hydrogen bond out of almost 50 in a late-stage precursor can be used to construct the macrocyclic core on which the erythromycin antibiotics are based, and demonstrates the potential of such C–H activation approaches for natural product synthesis.

An amphiphilic molecule that contains a protein-specific ligand and an NMR-active tag forms the basis of a protein sensor. A measurable NMR signal results only in the presence of active protein that causes disassembly of clusters of the amphiphile.

Exponential signal amplification is achieved when a single molecule of analyte initiates a chain reaction in which a dendrimer releases a coloured 'reporter' molecule, and ultimately four further molecules of the analyte.