Articles in 2018

A series of in vitro and in vivo studies has now shown that 5fC is linked to increased nucleosome occupancy and stability. Moreover, there is evidence that Schiff base formation between histones and 5fC impacts RNA polymerase II transcription activity in mouse embryonic stem cells.

The applicability of metal-organic frameworks (MOFs) — in spite of their obvious potential — is hindered by stability issues, in particular towards water. Now, a ‘crumple zone’ concept has been proposed in which the presence of sacrificial bonds protects a MOF without significantly altering its structure or functionality.

Bruce Gibb focuses on fatty acids and wonders whether we’ll all be eating cyanobacteria before too long.

Liz Williams explores the synthesis of tennessine, a story in which elements in supporting roles play a crucial part.

So far, monosubstituted carbenes have only been spectroscopically characterized at very low temperatures. Now, it has been shown that a bulky, chemically inert, amino substituent is enough to tame the intrinsic tendency of carbenes towards dimerization, enabling their isolation at room temperature.

Steric effects in a fundamental energy-transfer reaction at collision energies from over 1,000 K down to 20 mK have now been studied. At high energies a pronounced dependence of the reactivity on the reactant orientation is observed, but this effect is not present at the lowest energies because of dynamic reorientation.

A chemical proteomic strategy has now been developed for profiling pyridoxal-phosphate dependent enzymes (PLP-DEs) in cells. Pyridoxal-based probes are phosphorylated in situ and bind to cellular PLP-DEs as cofactor mimics. The method accessed 73% of the Staphylococcus aureus PLP-dependent proteome and annotated uncharacterized proteins as novel PLP-DEs.

A direct conversion of carboxylic acids to alpha-olefins without the need for a stoichiometric additive has now been reported. The transformation is enabled by a dual cobalt/iridium proton-reduction–photoredox catalyst system, and can proceed on abundant fatty acids as well as on complex carboxylic acids.

Inhibiting the interaction between amyloid-β (Aβ) and a neuronal cell surface receptor, LilrB2, could offer a potential route for treating Alzheimer’s disease. Now, binding sites between Aβ and LilrB2 have been discovered and computational selection has identified inhibitors that block this binding site. Cell-penetrating inhibitors were found to block the Aβ–LilrB2 interaction and limit Aβ-induced cytotoxicity.

Binding interactions, whether between a biological receptor and ligand or between a synthetic host and guest, are frequently stronger for larger molecules than for smaller ones. This is commonly believed to arise from increased dispersion interactions, but it has now been shown that cavitation energies—always required to dissolve molecules in solution—can be more important.

The inherent synthetic tuneability of organic materials makes them attractive in photocatalysis, but they tend to have low quantum efficiencies for water splitting. A crystalline covalent organic framework featuring a benzo-bis(benzothiophene sulfone) moiety has now been shown to exhibit high activity for photochemical hydrogen evolution from water.

Catalytic superoxide dismutase mimics typically involve manganese centres. Now, a complex based on redox-inactive zinc(ii) and a redox-active quinol ligand is found to catalytically degrade superoxide. The reaction, proposed to occur through oxidation of the ligand to a quinoxyl radical, is hastened rather than inhibited by the presence of phosphate.

Dynamic covalent chemistry combines the error-correcting behaviour of supramolecular chemistry with the robustness of covalent bonding, but relies on a somewhat limited set of reactions. Now, the classic nucleophilic aromatic substitution (S_NAr) reaction has been shown to be reversible and self-correcting.

Michelle Francl considers how metaphor breathes life into chemistry.

Shawn C. Burdette and Brett F. Thornton examine hafnium’s emergence from ores containing a seemingly identical element to become both a chemical oddity and an essential material for producing nuclear energy.

Probing single-atom alloys has shown that, when interactions between the components are weak, the electronic structure of the dilute element resembles that of a free atom, making bonding with reactants more like that in molecular homogeneous catalysts.

The structure of an antibiotic that is effective against Gram-positive bacteria, but not against Gram-negative bacteria, has now been modified to improve its effectiveness against Gram-negative bacteria. The approach could help broaden the spectrum of activity of other antibiotics.

A paradoxical case of a well-defined diradicaloid that has an unusually large singlet–triplet energy gap (ΔE_S-T) imparted by the thiophene sulfur atom is reported. Quantum chemistry, organic synthesis, molecular spectroscopies, X-ray crystal analysis and high-temperature magnetic measurements help account for the dichotomy between the large diradical character and large ΔE_ST.

MoS₂ single layers spontaneously undergo a slow oxygen substitution reaction under ambient conditions giving rise to solid-solution-type 2D molybdenum oxy-sulfide crystals. The oxygen substitution sites of the 2D MoS_2−xO_x crystals act as efficient single-atom catalytic centres for the hydrogen evolution reaction.

Chemically depolymerizing biomass polysaccharides to simple sugars is often controlled by the balance between depolymerization and degradation kinetics, which has limited the concentration of solutions that can be obtained and overall yields. The reversible stabilization of carbohydrates by acetal formation pushes back these limits and creates stabilized sugars that have advantageous properties for further upgrading.