Volume 2 Issue 7, July 2010

Twitter is more than just the place to go to find out what celebrities have had for breakfast — if you look hard enough, it can be a useful source of chemistry news, highlights and debate.

As we learn more about the complexities of water, Bruce Gibb argues that organic chemists shouldn't be afraid to take the plunge into aqueous environments.

A systematic study that combines both theory and experiment now provides direct evidence for the existence of anion–π interactions in compounds that facilitate the transport of anions across phospholipid membranes. This study offers new insight into the factors that affect the strength, selectivity and functional relevance of anion–π interactions.

A photo-reversible metal–semiconductor phase transition can be induced in a nanocrystalline transition-metal oxide at room temperature by short-wavelength light irradiation, holding promise for the development of new optical storage media.

The plant-derived sesquiterpene englerin A is a potent inhibitor of several renal cancer cell lines. Two recent total syntheses have utilized cationic gold(I)-complexes to coax readily available open-chain precursors into englerin's challenging oxotricyclic core with enzyme-like precision.

The catalytic reduction of atmospheric N₂ to NH₃ under mild conditions is one of the challenges of organometallic chemistry. An iron-based complex that binds and activates N₂ has now been developed. Its electrochemistry and coordination properties shed light on potential mechanisms by which N₂-to-NH₃ reduction might be achieved.

The cell's dynamic skeleton, a tightly regulated network of protein fibres, continues to provide inspiration for the design of synthetic nanostructures. Genetic engineering has now been used to encode non-biological functionality within these structures.

Ethers — such as the widely used tetrahydrofuran — are mostly known in chemistry labs as inert solvents. A bimetallic base has now been shown to dismember this simple cyclic ether, breaking six of its bonds and capturing all the atoms in quantitative products.

Olefin metathesis is a flexible and efficient method for making carbon–carbon bonds and has found widespread application in academia and industry. Now, a detailed mechanistic study looking at key catalytic intermediates offers new insight into this reaction, and may prove useful in the development of more active and selective catalysts.

Sunlight is potentially an ideal green 'reagent' for chemical synthesis, but poor absorption by organic substrates makes direct solar photochemistry generally inefficient. Here, recent progress in the use of the simple organometallic complexes to harness the power of the sun is summarized, and prospects for the future of this exciting field highlighted.

For quadrupole moments up to +39 Buckinghams, increasing π-acidity of aromatic surfaces is shown to cause tighter anion binding in tandem mass spectrometry experiments, higher binding energies in molecular models, stronger charge-transfer absorption bands, and increasingly effective and selective anion transport across lipid-bilayer membranes.

Optically driven phase transitions are widely used in optical memory devices, and the materials showing this effect are normally chalcogenides or organic compounds. Now a room-temperature light-induced phase transition between metal and semiconducting phases has been observed in a titanium oxide material.

Iron is an abundant, low cost and environmentally benign metal. Here, iron complexes are shown to be the most effective catalysts for asymmetric O–H insertion reactions. These results should encourage the use of iron, rather than more traditional precious metals, in the development of greener organometallic catalysts for asymmetric transformations.

The difficulty in the stereoselective introduction of 1,2-cis-glycosides is a major stumbling block in the solid-supported synthesis of oligosaccharides. Now, this has been achieved for a biologically important glucoside containing multiple 1,2-cis-glycosidic linkages with complete anomeric control by using glycosyl donors having a participating (S)-(phenylthiomethyl)benzyl chiral auxiliary at C-2.

In nature, iron takes a direct role in converting nitrogen to ammonia through a variety of N_xH_y intermediates. A series of synthetic iron complexes that mimic these intermediates could lead to an increased understanding of the process and eventually to effective catalysts.

In analogy to classical living polymerizations, the controlled formation of highly monodisperse cylindrical micelles — ranging from approximately 200 nm to 2 µm in length — has been demonstrated using very small and uniform crystallite seeds as initiators for the crystallization-driven living self-assembly of block copolymers with a crystallizable, core-forming metalloblock.

A kinetic and thermodynamic analysis of the ruthenium-catalysed ring-closing metathesis reaction has been achieved through the study of key intermediates accessible, for the first time, from 14-electron phosphonium alkylidene catalyst precursors. High intrinsic activities and a thermodynamic preference for ring-closing versus ring-opening reactions is observed.

Converting dioxygen into more reactive species is extremely useful for direct oxygenation of organic compounds, but doing this with cheap and non-polluting elements is difficult. Now, a carbene-activated silylene has been shown to activate dioxygen, resulting in the isolation of elusive silicon–oxygen species at room temperature.

Thermal reduction of graphene oxide is an attractive route towards the preparation of graphene, but complete removal of residual oxygen is problematic. Now, molecular dynamics simulations elucidate the chemical changes involved in this process.

Tetrahydrofuran can be unexpectedly cleaved by bimetallic sodium–magnesium and sodium–manganese bases. At least six bonds are broken in the one-pot reaction, but all fragments are separately captured to form crystalline compounds.

The development of benign methods for carbon–carbon bond formation is a continuing challenge. Here, a simple procedure for the hydroacylation of α,β-unsaturated esters is described, in which auto-oxidation of aldehydes and subsequent acyl radical addition to α,β-unsaturated esters occurs without the need for additional reagents.

Rhenium and technetium not only share the same group in the periodic table, but also have some common history relating to how they were — or indeed weren't — discovered. Eric Scerri explains.