Volume 4 Issue 10, October 2012

Bringing knowledge management to bear on the process of scientific research may have benefits for everyone, explains Bruce Gibb.

Nucleic acid aptamers have been employed to shield small molecules so that one among many similar reactive functional groups can be modified. This provides access to new chemical entities with potentially interesting properties while avoiding the use of covalent protecting groups.

The combination of addressable synthetic macromolecules with proteins of precise structure and function often leads to materials with unique properties, as is now shown by the efficient multi-site initiation of polymer growth inside the cavity of a virus capsid.

Force fields have been generated that enable accurate simulations of interactions occurring between CO₂ molecules and metal–organic frameworks featuring 'open' metal sites, which are promising for carbon capture applications.

Limitation controls reactivity — structural constraint of phosphorus has now enabled the development of a phosphine-catalysed transfer hydrogenation process akin to transition metals.

The site-selective initiation and propagation of an atom-transfer radical polymerization reaction forms an addressable crosslinked polymer constrained within the interior cavity of a virus-like particle derived from the bacteriophage P22. This protein–polymer hybrid is useful as a new vehicle for high-density delivery of small-molecule cargos.

Selective modifications of structurally complex molecules bearing multiple reactive functional groups often require cumbersome multistep synthetic efforts. Here, aptameric protective groups based on short RNA sequences are described — they bind to neamine antibiotics, simultaneously protecting several functionalities and enabling regio- and chemoselective functionalizations.

So far, reports of molecular electrochemical water oxidation have involved catalytic transition metal complexes. Now it is demonstrated that water can be oxidized, and oxygen evolved, using a simple organic, flavin derivative.

Rapid diagnostic methods that can be applied in resource-limited settings are important in the fight against tuberculosis. Here, fluorogenic probes are described that are activated by BlaC — an enzyme secreted by tubercle bacilli. The probes have enabled detection in unprocessed human sputum of live pathogen in less than 10 min.

Metal–organic frameworks featuring unsaturated metal sites have emerged as promising materials for CO₂ capture, but the host–guest interactions at play have remained poorly understood. An approach based on quantum chemical calculations has now been devised to generate force fields that accurately describe a MOF's metal sites and predict its gas uptake abilities.

Arylpyrrolidino amidothiourea catalysts are shown to catalyse the enantioselective ring-opening of episulfonium ions by indole derivatives. Catalysis and enantioinduction are achieved by selective transition-state stabilization of the major pathway in the rate- and selectivity-determining step through a network of attractive anion-binding, cation–π and hydrogen-bonding interactions between the catalyst and the reacting partners.

Understanding the nature of complex zeolite particles, used as catalysts in industrial reactors, is vital for their further development. Now, an integrated approach to visualizing granules of a hierarchical MFI-type zeolite, on length scales from nanometres to millimetres, is reported.

Life-science research and biomedical diagnostics call for robust fluorescence barcodes of compact size and high multiplexing capability. Here DNA-origami technology was used to construct a new kind of geometrically encoded barcode with excellent structural stiffness. They hold promise for both in situ and ex situ imaging of diverse biologically relevant entities.

Better understanding of the mechanisms of singlet fission may facilitate its implementation in solar cells, improving their efficiency. Although singlet fission in tetracene is endothermic, it is now observed not to be thermally activated; rather a quantum coherent process allows access to the higher-energy multi-exciton state, which then forms two triplet excitons through an entropic driving force.

Many biological processes involve the binding of proteins to cell membrane receptors, making these proteins valuable disease biomarkers and therapeutic targets. A label-free plasmonic microscopy method has now been devised to determine the distribution and local binding kinetics of these ‘membrane proteins’, on the surface of single living cells rather than ex situ.

Visible-light-mediated photocatalytic generation of carbon-centred radicals from alkyl, alkenyl and aryl iodides, which then undergo subsequent hydrogen-atom abstraction or reductive cyclizations, is reported. The protocol is characterized by the use of inexpensive reagents, mild conditions, exceptional functional group tolerance, and good to high yields.

Catherine Renouf describes how indium went from being a rather inconspicuous element to one whose role as a component of high-technology devices and gadgets may deplete its worldwide resources.