Research articles

Criegee intermediates play an important role in atmospheric chemistry but their direct study has proved difficult. Transient infrared absorption spectroscopy has now been used to probe the decay kinetics of the Criegee intermediate CH₂OO directly, revealing that its self-reaction is extremely rapid. This may have important consequences for the interpretation of previous laboratory experiments.

FeFe hydrogenases, the enzymes that oxidize or produce H₂, are inactivated under oxidizing conditions. Here, it is shown that this inactivation results from H₂ binding to coordination positions that are normally blocked by intrinsic CO ligands. This flexibility of the active site prevents irreversible oxidative damage.

Amyloid fibril formation is often catalysed by mature fibrils or other aggregates on the fibrillization pathway; however, fibrils cannot normally catalyse other chemical reactions. Here, small seven-residue peptides designed from first principles are shown to form amyloid fibrils that can efficiently catalyse ester hydrolysis.

Restoring a protein's function in response to specific stimuli can enable a signalling pathway to be activated and the effect monitored over time. Here, a chemical rescue strategy for restoring protein function inside live cells is described, in which palladium catalysts are used to deprotect a propargylcarbamate group of a lysine analogue.

Strained hydrocarbons are more than molecular curiosities — they often have promising materials properties, and even just making them offers challenges that push the limits of synthetic methods. Now, a short, efficient and room-temperature synthesis of [5]cycloparaphenylene, a carbon nanohoop with 119 kcal per mol of strain energy, is reported.

Radical polymerization of a metastable lactone intermediate — formed from carbon dioxide and butadiene using a palladium catalyst — produces a high-CO₂-content (29 wt%) polymer. This approach circumvents the thermodynamic and kinetic barriers typically associated with direct copolymerization of carbon dioxide and olefins, and can also be applied to one-pot co- and terpolymerization of carbon dioxide and 1,3-butadienes.

A Ni-Ga catalyst that reduces CO₂ to methanol at ambient pressure has been discovered through a descriptor-based computational analysis, and has been shown experimentally to be particularly active and selective. This represents a first step towards the development of small-scale low-pressure processes for CO₂ reduction to methanol from distributed hydrogen production.

The availability of facile cross-coupling protocols is sometimes blamed for the high occurrence of ‘flat’ aromatic molecules in drug-screening collections. Here, reagents are described that make possible the one-step transformation of aldehydes into medium-ring saturated N-heterocycles. The methodology has exceptional substrate scope and functional group tolerance and provides a route to heterocycles not easily prepared by other methods.

A family of dipeptide-based metal–organic frameworks has been shown to respond to the presence of guests in a cooperative manner controlled by one amino acid residue. When the linker features a serine residue, guest removal enables the formation of hydrogen bonds between the residue's side-chains, causing a conformational change that closes the MOF's porous domain.

The conversion of water to oxygen is an essential process for both natural and artificial photosynthesis. Important intermediates in the stepwise mechanism of water oxidation on the surface of cobalt oxide have now been spectroscopically identified, providing key insights for the development of higher-efficiency catalysts made from Earth-abundant materials.

The chemistry of group 13 metals (M) is dominated by +1 and +3 oxidation states, so MX₂ species are typically metal–metal-bonded dimers, M(II)₂X₄ or mixed-valence species M(I)M(III)X₄. Now, monomeric M(II)(boryl)₂ radicals have been prepared for gallium, indium and thallium. The compounds — structurally characterized by X-ray crystallography — are stable up to 130 °C and exhibit dominant metal-centred radical character.

Compartmentalization of complex chemical networks is an essential step towards the creation of cell-scale molecular systems. The encapsulation of a synthetic biochemical oscillating reaction system into cell-sized emulsion droplets is now demonstrated; a large variability in its oscillatory dynamics is observed, which is attributed to partitioning effects.

Ion mobility–mass spectrometry has enabled the study of conformation and dynamics of membrane proteins in the gas phase. Here, the enhanced flexibility of macromolecular ATPase was investigated by comparing arrival time distributions of distinct species and relating them to different solution conditions, leading to the proposal of a nucleotide-triggered regulatory mechanism.

When molecules collide with atoms or other molecules their quantum mechanical character can lead to the diffraction of matter waves. Making use of advances in molecular beam technology, such diffraction oscillations have now been observed with unprecedented sharpness and angular resolution in the benchmark NO + He, Ne, or Ar systems.

An artificial reaction centre has been designed that contains a benzimidazole–phenol model of the Tyr–His relay in photosystem II. It has been seen to mimic both the short internal hydrogen bond of the natural relay, and — using electron paramagnetic resonance —the relaxation behaviour that accompanies proton-coupled electron transfer in photosystem II.

Helices are found at every level of natural systems, where their dynamic potential is exploited to achieve a variety of functions. Here, liquid-crystalline molecular switches embedded in a polymer are used to prepare biomimetic spring-like materials that can convert molecular motion into macroscopic work.

In cold chemistry, quantum phenomena in reactants' translational motion lead to the temporary trapping of reactants in a collisional complex. It is now shown that this metastable complex is responsible for a dramatic quantum kinetic isotope effect as observed in Penning ionization reactions at low temperatures.

Light-driven proton pumps are used in biology to create a proton gradient that can be subsequently converted into chemical energy. Here, an artificial light-harvesting system based on a membrane doped with a spiropyran is described. Irradiation with UV light generates a proton flux across the membrane and results in the generation of an electrical current.

A dye that both maximizes electrolyte compatibility and improves light-harvesting properties has been designed for dye-sensitized solar cells. In cells based on the cobalt(II)/(III) redox mediator, use of the dye resulted in a power-conversion efficiency of 13%, revealing the great potential of porphyrin dyes for future solar cell applications.

Self-organization that occurs far from thermodynamic equilibrium is ubiquitous in nature but has remained challenging to control in synthetic supramolecular systems. A complex system has now been devised that displays such behaviour. Porphyrin derivative monomers undergo living supramolecular polymerization, a reaction underpinned by the interplay of two supramolecular polymerization pathways.