Volume 4 Issue 12, December 2012

Michelle Francl suggests that chemists should keep on name-dropping.

Dennis P. Curran invites everyone to join the dawning new era of organic synthesis.

The reversible reduction and evolution of oxygen are the key processes to be mastered before high-energy rechargeable lithium–air batteries can be successfully created. Now an advance towards this goal has been achieved with the synthesis of a pyrochlore catalyst that benefits from a mesoporous structure and oxygen deficiencies.

Bioactive molecules frequently contain several very similarly reactive functional groups and it can thus be difficult to cause one to react selectively. Now, two separate studies present complementary approaches to this desirable goal.

The deposition of cobalt-phosphate onto photocatalytic haematite improves its ability to split water and thus create clean hydrogen fuel. The source of this improvement is, however, not yet understood, and now two separate studies suggest different roles for the deposited cobalt-phosphate.

Uranium and manganese cations have been combined in a wheel-shaped supramolecular assembly that retains its magnetic spin state after the external field is removed, with a high barrier to its relaxation. This cluster supports recent predictions of the usefulness of the actinides in single-molecule magnetic devices.

In 1972, Baird published rules describing aromaticity and antiaromaticity in the lowest triplet excited states of annulenes. The fortieth anniversary of Baird's rules — which are the reverse of Hückel's rules for aromaticity and antiaromaticity in the ground state — ought to be celebrated before 2012 comes to an end.

Liposomes are a leading drug-delivery platform in cancer chemotherapy. Now they can be used to destroy cancer cells through a method that converts chemical energy to mechanical force. These localized disruptions can cause cell death while minimizing the collateral damage to neighbouring cells.

The complexity of living systems makes attempts to gain a molecular-level understanding of them a unique and inspiring challenge. This Review summarizes progress in the development of bioorthogonal reaction-based fluorescent probes used to follow the spatial and temporal dynamics of biologically important analytes within living systems.

Hydroxyl radicals (OH) are important in many chemical systems, including combustion and atmospheric reactions, however experimentally measuring their velocities in specific internal quantum states has proved difficult. Now differential cross-sections for inelastic scattering of fully state-specified OH with He and Ar have been observed for the first time using velocity-map imaging in a crossed-molecular-beam arrangement.

Aspartic acid-based catalysts that are selective for oxidation of either the 2,3 position or the 6,7 position of certain isoprenols have been discovered. The catalysts emerged from a diversity-based approach employing the one-bead-one-compound libraries. The site-selectivity of the catalysis seems to derive from the hydroxyl group in the substrate, although the details of this are not yet known.

Site-selective functionalizations of complex small molecules can generate targeted derivatives with exceptional step-efficiency, but general strategies for maximizing selectivity in this context are rare. Investigations with the ion-channel-forming natural product amphotericin B have revealed that site-selectivity can be tuned by simply modifying the electronic nature of the reagents.

The lithium–O₂ battery can theoretically provide energy densities that greatly exceed that of Li-ion, but it requires more efficient catalysts (or ‘promoters’) than carbon for oxygen reduction and evolution. Here, we report a tailor-made mesoporous metallic oxide that results in high reversible capacities and operates over many cycles.

A {U₁₂Mn₆} wheel-shaped cluster that has been assembled through cation–cation interactions exhibits single-molecule-magnet behaviour. Single-molecule magnets are promising for magnetic storage devices at the nanoscale, and the observation of magnetic bistability with an open hysteresis loop and high relaxation barrier in this 5f–3d complex suggests that uranium-based compounds could be useful components.

Oxatriquinane is a remarkably stable alkyl oxonium ion, despite the fact that its carbon–oxygen bond lengths are 1.54 Å. The robust nature of this fused tricyclic molecule enabled the addition of increasing steric bulk to the system, culminating in a tri-tert-butyloxatriquinane with a record 1.62 Å C–O bond distance.

A short-lived diiron–oxo species — based on a nitrido-bridged bis-porphyrin 1 1platform — capable of efficiently oxidizing the strongest of C–H bonds has been prepared and spectroscopically characterized. The catalytic properties of this high-valent diiron(IV)–oxo complex were elucidated by studying the oxidation kinetics of a range of alkanes.

Templated atomic layer deposition (ALD) is used to create oxide ‘nanocavities’ on the surface of catalyst particles. Subnanometre-nm films containing nanocavities act as sieves for the underlying catalyst, resulting in high selectivities for the smaller of two reactants in competitive oxidations or reductions.

The discovery and synthesis of inorganic clusters can be both time consuming and limited by a lack of reproducibility. An automated flow process coupled with multiple batch crystallization has now been successfully used to rapidly screen and scale-up the syntheses of inorganic clusters, including polyoxometalates and manganese-based single-molecule magnets.

The precise pairing of cysteine residues in proteins is routinely achieved in nature. However, the comparable pairing within polypeptides is a long-standing challenge for the preparation of multicyclic species. Here, a straightforward approach to direct the inter-/intramolecular pairing of cysteine residues within peptides using a minimal CXC motif is presented.

For historical reasons, plutonium brings to mind nuclear weapons. Jan Hartmann brings another side of element 94 to attention, which features an upcoming trip to its eponymous celestial body.

Reaction methodologies that can selectively target one reactive site among many that are functionally similar within a complex molecule could significantly improve synthetic efficiency and help in the identification of new drug leads. A collection of articles in this focus highlight some of the latest advances in this area, explaining the complementary approaches taken by researchers to this challenge.