Articles in 2019

The Z phase, one of three fundamental Frank–Kasper phases—topologically close-packed structures commonly found in metal alloys—is associated with a relatively large volume ratio between its constituents. This means it is typically not formed in single-component soft materials. Now, a shape amphiphile has been shown to self-assemble in a variety of unconventional structures, including the Z phase.

It is difficult to prepare 2D polymers that are crystalline over large areas. Now, few-layer 2D polyimides and polyamides with good crystallinity on the micrometre scale have been synthesized on a water surface. A surfactant monolayer is used to organize amine monomers before their polymerization with anhydride moieties.

Super-resolution microscopy has enabled optical imaging of individual biomolecules on the nanometre scale. Now, a new method has been developed that allows active manipulation of single-molecule targets on visualization in a sequential manner. This method, called ‘Action-PAINT’, combines real-time super-resolution microscopy (DNA-PAINT) and photoinducible crosslinking chemistry to deliver a single-molecule cargo with <30 nm selectivity.

The emergence of pristine RNA and DNA on the early Earth would have been hindered by a lack of specificity in their prebiotic syntheses. Now, it has been shown that chimeric sequences—with a mixture of RNA and DNA backbones—mediate the template-directed ligation of oligomers present in mixtures of nucleic acids, enabling the simultaneous appearance of RNA and DNA.

Understanding how structural dynamics contribute to protein function is a longstanding challenge in structural biology. Now, time-resolved X-ray solution scattering following an infrared laser-induced temperature jump has been used to probe functional, intramolecular motions in the dynamic enzyme cyclophilin A.

Colibactin is produced by human enterobacteria and assumed to be a gut bacterial genotoxin. Now, colibactin-645 has been identified as a macrocyclic colibactin metabolite that contains a C-terminal 5-hydroxy-4-oxazolecarboxylic acid moiety and induces DNA double-strand breaks in vitro and in human cell cultures via a unique copper-mediated oxidative mechanism.

The UbiD family of reversible decarboxylases interconvert propenoic or aromatic acids with the corresponding alkenes or aromatic compounds, using a transient 1,3-dipolar cycloaddition between the substrate and the prenylated flavin mononucleotide cofactor. Atomic-resolution crystallography shows targeted destabilization of the intermediate covalent adducts, allowing the enzyme to harness 1,3-dipolar cycloaddition as a readily reversible reaction.

Polytheonamides are potently cytotoxic hypermodified ribosomal peptides that are produced by an uncultivated bacterium. Now, a bioinformatic mining strategy has enabled the development of a bacterial production host that can be cultivated in a laboratory. The host generates polytheonamide-like compounds within 2 days, and can efficiently introduce multiple d-amino acids, asparagine N-methylations and C-methyl groups into various peptides.

Polyacetylene is an ideal system to probe to gain a better understanding of the nature of charge transport in conducting polymers. Now, individual atomically precise polyacetylene chains have been synthesized on a copper surface and characterized using a range of techniques, revealing a doping-induced semiconductor-to-metal transition.

Previous methods for functionalizing hydrocarbons with CO₂ to form carboxylic acid derivatives have required stoichiometric energy-intensive reagents such as strong bases or electrophilic activators. Now, a simple solid base has been developed that transforms aromatic hydrocarbons, CO₂ and methanol into aromatic esters via a two-step cycle requiring no additional reagents.

The electroreduction of CO₂-derived CO is a promising technology for the sustainable production of value-added chemicals. Now, it is shown how C–N bonds can be formed electrochemically through CO electroreduction on a Cu surface in the presence of amines. The formation of acetamides is observed through nucleophilic addition to a ketene intermediate.

The regulation of cellular response to stimuli by genetic regulatory networks (GRNs) suggests how in vitro chemical reaction networks might be used to direct the dynamics of synthetic materials or chemical reactions. Now, multiple functional in vitro transcriptional circuit modules have been integrated to form composite regulatory networks capable of complex features analogous to those found in cellular GRNs.

In coordination and organometallic chemistry, back-bonding between an electron-rich, typically mid- or low-oxidation-state d-block metal centre and a ligand with accepting π* orbitals is widespread. Now, such an interaction has been observed between unlikely partners—high-oxidation-state uranium(v) 5f¹ ion and the poor π-acceptor ligand dinitrogen—in a U(v)–bis(imido)–N₂ complex stabilized by a lithium counterion.

The solid–electrolyte-interphase layer is extremely important for reversible electrochemical cycling of Li-ion batteries. Now it has been observed that lithium ethylene mono-carbonate, instead of the previously reported lithium ethylene di-carbonate, is the major initial organic species in this layer and it has a high Li-ion conductivity.

During the synthesis of inorganic materials nickel oxysulfide and nickel–cobalt hydroxide, clusters with well-defined structures—such as polyoxometalates—can co-assemble with nuclei to produce uniform binary assemblies. The resulting materials can, in turn, incorporate a third, and fourth, type of nanocluster deposited on their surface to form ternary and quaternary assemblies, respectively.

Although they are synthetically tunable, organic molecules that undergo singlet fission (the generation of two excitons from one photon) have not demonstrated the excited-state properties necessary to improve optoelectronic devices. Now, a general ‘energy cleft’ molecular design scheme has been demonstrated that enables rapid generation and long lifetimes of multiple triplet excitons that are for device applications.

Studies into gold-catalysed cross-coupling reactions have expanded over recent decades; however, oxidative addition to gold(i) complexes remains challenging. Now it has been shown that a dual catalytic transformation involving iridium photosensitization to trigger oxidative addition to organogold intermediates enables C(sp²)–C(sp) cross-coupling reactions that are useful for the alkynylation of benzofurans.

High concentrations of prebiotic molecules and dry–wet cycles are difficult to achieve in a submerged system. Now, it has been shown that temperature gradients across gas bubbles in submerged rock pores can provide these conditions. Molecules are continuously accumulated at the warm side of bubbles at the gas–water interface, which enables or enhances many prebiotically relevant processes.

Precipitation enables the straightforward production of a variety of inorganic materials, but the rapid reaction rates involved typically make controlling their morphologies difficult. Now, the growth of either one-, two- or three-dimensional materials has been promoted by tuning of the reactants’ electrolytic dissociation and solution supersaturation, without the need for capping agents and templates.

The production of ammonia from dinitrogen is a well-studied process; however, the catalytic conversion of ammonia into dinitrogen is underdeveloped. Now, ammonia oxidation has been achieved using ruthenium complexes as catalysts. The production of dinitrogen is observed when ammonium salts are treated with a single-electron oxidant, base and ruthenium catalyst.