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Selective pyridine dearomatization processes traditionally use precious metal catalysts with reagents in stoichiometric excess, and are not well-understood mechanistically. Now, efficient 1,2-regioselective pyridine dearomatization is achieved using equimolar pinacolborane and an earth-abundant lanthanide catalyst. Mechanistic and theoretical studies elucidate the reaction mechanism and explain observed reactivity trends.
Self-assembled ribbons of perylene amphiphiles have been shown to crystallize in the presence of a nickel-based hydrogen production catalyst, allowing efficient electronic coupling between the perylene chromophores. This hydrogel material photocatalyses the production of H2, and can be shaped and placed on surfaces for incorporation into devices.
Comprehensive solution and solid-state characterization of an adduct between a Lewis acidic perfluoroaryl borane and an electron-rich silane is demonstrated. This has long been proposed as an intermediate in the ‘frustrated’ Lewis-pair hydrosilylation of C=C, C=O and C=N double bonds, but its existence has, so far, only been inferred from indirect experimental evidence.
Recognition, differentiation and sensing of small molecules displaying only sparse functionalities using artificial receptors is extremely challenging. Now a method to selectively bind and recognise low-epitope targets has been developed. The approach uses the formation of ternary complexes between small-molecule targets, their non-specific organic (or organometallic) receptors, and aptamers.
The Star of David topology is an iconic symbol that has been used in religious and cultural contexts for thousands of years. Now it is assembled in molecular form through a hexameric circular helicate generated by six tris(bipyridine) ligands entwined about six iron(II) cations. The structure of the two triply-entwined 114-membered rings is revealed by X-ray crystallography.
Reduction of 5-hydroxymethylcytosine (hmC) levels in DNA often occurs in cancers. Using isotope tracing experiments, this epigenetic DNA modification, which was thought to be an intermediate of demethylation, is now shown to be stable. A delay in the generation of hmC on newly synthesized DNA is responsible for the reduction of hmC levels in cancers.
Non-haem iron(III)-peroxo complexes that bind redox-inactive metal ions are synthesized to investigate the role of the Ca2+ ion in the oxidation of water to dioxygen in photosystem II. The electrochemical properties and reactions of these compounds with an electron donor and an acceptor are found to be markedly dependent on the Lewis acidity of redox-inactive metal ions.
Constructing molecular architectures using dynamic covalent chemistry combines the robustness of covalent bonds with the reversibility of supramolecular chemistry. Now, a surface-mediated approach has been used to control the thermodynamic and kinetic features of dynamic processes at a surface, leading to constituent selection and selective pattern formation.
Self-assembly is commonly used to construct complex nanostructures from soft matter. Now, using the living crystallization-driven self-assembly approach, controlled nanostructure growth in both one and two dimensions has been achieved. Uniform lenticular multiblock platelets, as well as hierarchical structures analogous to nanoscale single- and double-headed arrows and spears have been prepared with controlled sizes in two dimensions.
The production of biologically active compounds by microbial fermentation has proved highly successful in drug discovery. Now, a method that mimics this process has been used to prepare unnatural peptides from small building blocks without the need for additional reagents, and in a fashion that is immediately compatible with biological screening.
Intercalation in graphite is generally driven by partial oxidation or reduction of the graphene sheets. Now, it has been shown that graphite microcrystals can be intercalated by Brønsted acids by heating a liquid suspension to dryness. The intercalated acid molecules interact weakly with the carbon sheets but assist in their exfoliation to single- and few-layer graphene.
Analysing the dynamic adsorption of small molecules in porous materials is a significant challenge. Now, in situ single-crystal X-ray diffraction has shown that molecular adsorption in a crystalline nanochannel occurs through multiple steps. Transient states during the process were also visualized, demonstrating the potential of X-ray analysis for probing non-covalent adsorption processes.
FeS clusters are a universal motif in organisms and are central to many processes, including nitrogen fixation and respiration. By carrying out the first many-electron calculation of the [2Fe-2S] and [4Fe-4S] clusters, they are shown to have an unusual set of closely packed energy levels, which are key to understanding their reactivity.
The spontaneous resolution of racemic mixtures can occur when the molecules are confined in a crystal lattice, on surfaces or in other well-ordered assemblies. Now, mirror symmetry breaking within an isotropic liquid of achiral molecules has been observed. These liquids show strong chiral amplification and provide a possible mode of emergence of chirality in prebiotic fluids.
Disulfide bonds formed between two cysteine residues are important in the folding and stability of proteins. Now, unnatural amino acids with side-chains that contain two thiol groups are described. Incorporation of these dithiol amino acids into a serine protease inhibitor and a nicotinic acetyl choline receptor antagonist is shown to increase their inhibitory activity.
The relationship between electron-transfer properties and the structure of molecular electronics is still not fully understood. Now, a rigid and flat molecular wire has been shown to significantly enhance the rate of electron transfer compared with conventional flexible molecular wires. This enhancement is attributable to both conjugation-induced electronic coupling and inelastic electron tunnelling-enabled electron–vibration coupling.
A discovery approach termed activity-directed synthesis is described; it exploits arrays of reactions whose outcome is critically dependent on the conditions used, and prioritizes reactions that yield bioactive product mixtures. The discovery of both bioactive small molecules and associated synthetic routes thus occurs in parallel.
The oxygen reduction reaction limits fuel cell performance and currently requires costly electrocatalysts with high platinum content to achieve adequate power densities. Now a silver–cobalt surface alloy electrocatalyst has been developed for the oxygen reduction reaction that is stable in alkaline electrolytes and is more economical than traditional platinum-based materials.
Anion transporters that disrupt cellular ion homeostasis could represent a new approach for generating therapeutic lead compounds. Now, two pyridine diamide-strapped calix[4]pyrroles have been shown to induce coupled chloride anion and sodium cation transport in liposomal models and cells. These compounds promote cell death by increasing intracellular chloride and sodium ion concentrations.