Articles in 2022

Iodic acid (HIO₃) forms aerosols very efficiently, but its gas-phase formation mechanism is not well understood. Atmospheric simulation chamber experiments, quantum chemical calculations and kinetic modelling have now revealed that HIO₃ forms as an early iodine oxidation product from hypoiodite. The mechanism explains field measurements and suggests a catalytic role for iodine in particle formation.

Gold nanoparticles typically exhibit hard-sphere-like assembly behaviour, but now the size, morphology and symmetry of crystals of Au₂₅ nanoparticles have been tuned. The presence of excess tetraethylammonium cations has been shown to promote the one-dimensional assembly of the nanoparticles, which in turn form rod-like crystals, by stabilizing dynamically detached ligands from adjacent particles into interparticle linkers through CH⋯π and ion-pairing interactions.

Native mass spectrometry has been used to interrogate both biased signalling and allosteric modulation of the β₁-adrenergic receptor. Simultaneously capturing the effects of ligand binding and receptor coupling to different G proteins has enabled the relative importance of specific interactions to be investigated.

Kinetic isotope effect studies can provide valuable insights into the complex mechanisms of the oxygen reduction reaction; however, inaccessibility to ultra-high-purity D₂O has made this difficult. Now, a methodology to prepare ultra-pure D₂O has been developed and inverse kinetic isotope effects have subsequently been measured for the oxygen reduction reaction on platinum single-crystal surfaces, providing mechanistic insights.

Geminal disubstitution of cyclic monomers is known to improve the chemical recyclability of their polymers, but usually at the expense of performance properties. Now, geminal disubstitution of a six-membered lactone has been shown to synergistically enable chemical recyclability back to the monomer and enhance the materials performance of the resulting polyesters, with properties that rival or exceed those of polyethylene.

Incorporating silicon into organic molecules and materials leads to interesting changes in electronic structure and properties; silabenzenes are attractive species for this purpose, but their high reactivity in solution poses challenges. Now, 1D and 2D covalent organic frameworks featuring disilabenzene rings (C₄Si₂) as linkers have been prepared by reacting silicon atoms and polyaromatic hydrocarbon precursors on a Au(111) surface.

Carbon-labelled α-amino acids are valuable compounds in drug development and nuclear medicine, but are difficult and time consuming to prepare. Now, an aldehyde-catalysed method has been developed for the direct C1-labelling of α-amino acids using *CO₂ (* = 14, 13, 11), providing access to many proteinogenic and non-natural labelled α-amino acids.

The circadian rhythm generates out-of-equilibrium metabolite oscillations controlled by feedback loops under light/dark cycles. Now, it has been shown that these life-like properties can emerge from a non-equilibrium nanosystem comprising a binary population of enzyme-containing polymersomes capable of light-gated chemical communication, controllable feedback and coupling to macroscopic oscillations.

Heavy analogues of carbynes of the type R–\({{{\dot{\mathrm E:}}}}\), where E is a group 14 element, are difficult to isolate in the condensed phase due to their high reactivity. Now, a germylyne radical supported by a sterically hindered hydrindacene ligand has been prepared and structurally characterized. Theoretical calculations show that the spin density mainly resides at the germanium centre.

Despite recent advances in engineering of in vitro translation systems, direct ribosomal incorporation of hydroxyhydrocarbon moieties—which can endow peptides with unique biochemical/folding properties—remains challenging. Now, incorporation of translation-compatible azide/hydroxy acids and their post-translational tandem backbone-acyl shifts have enabled in vitro ribosomal synthesis of peptides containing various hydroxyhydrocarbon units.

Identifying and quantifying the biodistribution of synthetic polymeric nanoparticles in biological milieu is crucial for biomedical applications. Now, it has been shown that encoded polymeric amphiphiles with discrete molar masses undergo sequence- and length-dependent self-assembly into precise digital micelles that can be used in direct sequence reading and ex vivo label-free quantification assays.

Enteropeptins are peptide natural products produced by the gut microbe Enterococcus cecorum. Now, the structure, biosynthesis and function of enteropeptins have been determined. After ribosomal biosynthesis, enteropeptins are post-translationally modified in three reactions carried out by a radical S-adenosylmethionine enzyme, an Mn²⁺-dependent arginase, and an Fe–S-containing methyltransferase, respectively, to form the N-methylornithine-containing peptide natural products.

Synthesis of peptidyl-tRNAs is challenging because there are no enzymes that can directly attach the desired peptide to tRNA. Now it has been shown that a chemoenzymatic approach based on native chemical ligation can be used for the semi-synthesis of peptidyl-tRNAs for structural/biochemical studies of arrested and non-arrested ribosome complexes.

Peptide design remains a challenge owing to the large library of amino acids. Rational design approaches, although successful, result in a peptide design bias. Now it has been shown that AI techniques can be used to overcome such bias and discover unusual peptides as efficiently as humans.

Inverse vulcanization (IV) generates sulfur-rich functional polymers from elemental sulfur and organic crosslinkers, but the harsh reaction conditions required limit the scope of suitable crosslinkers. Now, a photoinduced IV has been shown to proceed at ambient temperatures, enabling the use of volatile and gaseous alkenes and alkynes as crosslinkers and broadening the range of products.

The properties of chiral conjugated molecules, such as the absorption and/or emission of circularly polarized light or electron transport, are highly anisotropic. Now it has been shown that templating layers can control the orientation and anisotropic properties of small chiral molecules in bulk thin films useful for a range of emerging technologies.

Photoelectrochemical cells are hampered by electron–hole recombination. Now, supramolecular machinery has enabled the docking of macrocyclic electron-accepting redox mediators to a dye through pseudorotaxane formation. Upon electron transfer from the dye, the anionic redox-mediator rings are launched away from the surface, reducing charge recombination, establishing charge separation and improving the efficiency of the solar cells in which they feature.

Room-temperature phosphorescence in organic solids is attractive for practical applications but remains rare. Now, highly phosphorescent boroxine-linked covalent organic frameworks have been prepared by covalent doping with halogen atoms through the use of halogenated precursors. The resulting porous COFs exhibited oxygen-sensing capabilities with millisecond response time over a wide range of partial oxygen pressures.

Polymerization methods that control the cis/trans stereochemistry of repeating alkenes in polyalkenamers remain scarce. Now, an acyclic diene metathesis process has been developed that enables control over the stereochemistry of the polymer backbone. The method harnesses the reactivity of dithiolate Ru carbenes, in combination with cis,cis-diene monomers, to access several classes of polymers with tailored properties.

Quantum nanomagnets, which display collective quantum behaviours, serve as important components in modern quantum technologies, but their fabrication has remained challenging. Quantum nanomagnets have now been constructed spin by spin in metal-free porphyrin chains, using on-surface synthesis and hydrogen manipulation using a scanning tunnelling microscope, and their collective quantum behaviours have been clearly resolved.