Volume 5 Issue 6, June 2013

The interactions between a virus capsid and its cargo are essential for viral infection as well as in the design of synthetic virus-like particles. Now a combination of analytical techniques has unravelled key steps in the transformation of a model virus and the release of its RNA cargo.

The rechargeable Li–O₂ battery has low energy efficiency, which is mainly due to kinetic difficulties in the electrochemical oxidation of the insulating discharge product, Li₂O₂. Now a redox mediator, acting as an electron–hole transfer agent, has been used to promote this oxidation reaction.

A combined theoretical and experimental approach has revealed that radicals can be significantly stabilized by the presence of a remote anionic site in the same molecule. This finding has implications for understanding and potentially controlling the reactivity of these important reactive intermediates.

A pH-responsive inorganic membrane has been devised that acts as a gatekeeper for the transport of charged solutes into and out of its interior volume. This behaviour was further used to regulate an enzymatic reaction.

A complex featuring a uranium(VI) terminal nitride functional group has been isolated through mild oxidation, and shown to be highly reactive. Under photolysis, it converts into a compound that is capable of C–H bond activation.

Two-dimensional polymers, which exhibit periodic bonding in two orthogonal directions, offer mechanical, electronic and structural properties distinct from their linear or irregularly crosslinked polymer counterparts. Their potential is largely unexplored because versatile and controlled synthetic strategies are only now emerging. This Review describes recent developments in two-dimensional polymerization methods.

Thin lanthanide fluoride nanoplates are shown to self-organize at the liquid/air interface into long-range-ordered two-dimensional planar tilings. In this joint experimental–computational, multiscale investigation, the assembly behaviour is shown to be dictated by entropic forces arising from particle shape and enthalpic forces arising from interaction anisotropy.

In most radicals the unpaired electron occupies the highest-energy molecular orbital. Here, it is shown that for certain stabilized radicals the presence of a remote negatively charged group not only inverts this ordering, but also leads to a dramatic increase in radical stability that is easily manipulated by pH.

A terminal uranium(VI)–nitride has been shown to be accessible and isolable by a redox strategy whereas a photochemical approach resulted in decomposition. Computational analyses suggest that the U≡N triple bonds are surprisingly comparable to analogous group 6 transition metal nitrides, with a covalent character dominated by 5f rather than 6d contributions.

Recharging Li–O₂ batteries requires oxidation of the discharge product solid Li₂O₂. Now a redox-mediating molecule is shown to assist this process by transferring electron–holes between solid Li₂O₂ and the positive electrode in a non-aqueous Li–O₂ cell. This allows the cell to be charged at rates that are otherwise impossible.

Darwinian evolution involves competition between members of a population. Here, the synthesis of a hydrophobic dipeptide catalysed by a second dipeptide in a model protocell — a vesicle — is described. The reaction product partitions to the vesicle membrane, which grows by accumulating fatty acids derived from neighbouring vesicles. Thus, an encapsulated catalyst drives competition between the model protocells.

The stability of the capsid of a virus is strongly affected by its genome. Here the interplay between capsid and genome is explored using native mass spectrometry and atomic force microscopy. A mechanism is proposed to explain how the genome of the Triatoma virus stabilizes the capsid at neutral pH, but triggers disassembly under alkaline conditions.

Natural products are enduring leads for exploring cell biology, yet structure–activity relationship studies and 'arming' of these small molecules for subsequent cellular probe synthesis remains a challenge. Here, a strategy for derivatization of natural products by C–H amination, aziridination and unusual N-aminations is described. Selective derivatization of eupalmarin acetate led to identification of this natural product's target.

A polymerization method for converting elemental sulfur into a chemically stable, processable and electrochemically active copolymer has been described. This methodology — termed inverse vulcanization — is conducted by a one-step process using liquid sulfur, as both reaction medium and reactant, and vinylic comonomers to form polymeric materials with a high content of sulfur (50–90 wt%).

Removing Mg²⁺ from RNA and replacing it with Fe²⁺ confers on some RNAs the ability to catalyse single-electron transfer. Here, it is hypothesized that Fe²⁺ was an RNA cofactor on the early Earth, when iron was benign and abundant, and was replaced by Mg²⁺ during a period known as the great oxidation, brought on by photosynthesis.

Colloidosomes based on silica nanoparticles self-assembled at water droplet/oil interfaces are promising inorganic protocells, but they often leak small molecules on transfer into bulk water. Through silane crosslinking and copolymer grafting, colloidosomes have now been endowed with membranes that exhibit pH-responsive permeability to small molecules. The resulting water-dispersible colloidosomes further serve to host and control enzyme reactions.

Pyrolysis of defined nitrogen-ligated cobalt acetate complexes onto a commercial carbon support transforms the complexes into heterogeneous Co₃O₄ materials. These reusable non-noble-metal catalysts are highly selective for the industrially important hydrogenation of structurally diverse and functionalized nitroarenes to anilines.

From toothpaste to Tebbe reagents, Michael Tarselli takes a look at the many different faces of titanium.