Research articles

The reaction O(³P) + H₂ → OH(X²Π) + H has, until now, eluded detailed experimental investigation. Now, a laser-induced fluorescence study of the deuterated analogue has revealed product-state distributions that defy the current descriptions of non-Born–Oppenheimer mixing on coupled potential energy surfaces, issuing new challenges to theory.

The presence of Ca²⁺ is essential for the activity of the oxygen-evolving complex (OEC) of Photosystem II, although its exact role is still unclear. Now, electrochemical measurements of structural mimics of the OEC — based on mixed-metal trimanganese dioxido complexes — reveal a correlation between the Lewis acidity of the redox-inactive metal and the reduction potential of the complex.

An enzyme-free system that translates DNA into sequence-defined non-nucleic acid polymers including polyethylene glycol, α-(D)-peptides and β-peptides is described. Sequence-defined polymers with molecular weights of 26 kDa containing 16 consecutively coupled building blocks and 90 densely functionalized β-amino acids were translated from DNA templates using this strategy.

Hydrogen is an attractive alternative to fossil fuels, but the slow rate of the hydrogen oxidation reaction in alkaline fuel cells hinders their development. It is now proposed that bifunctional materials can be devised to offer the optimal balance between hydrogen and hydroxyl adsorption, thus significantly reducing the amount of precious metal on the anode.

A strategy to endow vinyl polymers with pseudo-crystalline order has been devised that relies on host–guest cross-polymerization, through functionalization of the channels of a porous coordination polymer with divinyl moieties. Polymerization of vinyl monomers within the channels is accompanied with lateral crosslinking, which ensures the polymer chains remain highly ordered after removal of the host.

The photochemical-induced dimerization of bromine-terminated oligo(ethynylene)s in the solid state is shown to give 1,2-dibromoeneynes on a preparative scale. This single-crystal-to-single-crystal transformation proceeds through a multistep reaction that involves the making and breaking of several bonds in addition to large atom displacements. The reaction represents an atom-efficient and catalyst-free pathway towards functional carbon-rich molecular scaffolds.

When monolayers of π-conjugated organic semiconductors interact with metal surfaces, most remain semiconducting. In some cases, however, the metallic character of the substrate is seen to extend onto the molecules. A mechanism for this intriguing phenomenon is now suggested and new strategies for chemical surface engineering are proposed.

Electricity can be produced by the oxidation of hydrogen in fuel cells, but the best catalyst for this is platinum, a precious metal of low abundance. Now a molecular complex of iron, a very abundant, inexpensive metal, has been rationally designed for the oxidation of H₂ at room temperature.

Basic fibroblast growth factor (bFGF) is crucial for a range of diverse cellular processes, from wound healing to bone regeneration, yet is inherently unstable. This important biologic has now been covalently linked to a polymer that mimics the polysaccharide heparin to produce a conjugate that shows remarkable stability to a wide range of therapeutically and environmentally relevant stressors.

A molecular tweezer has been shown to bind to the surface of a 14-3-3 protein through a particular lysine residue. This interaction — characterized in detail by protein crystallography and computational modelling — disrupts the protein's binding with partner proteins. These findings ascertain supramolecular chemistry as an enticing tool in chemical biology, here towards modulating protein functions.

Substituted allenes with axial chirality are of great utility in organic chemistry owing to their unique structure and reactivity, but synthetic methods to access them are limited. Here, a catalytic asymmetric synthesis of tetrasubstituted allenes is described that builds on the use of phase-transfer-catalysed asymmetric functionalization of 1-alkylallene-1,3-dicarboxylates.

Metal–organic framework (MOF) nanoparticles and their assembly into three-dimensional superstructures are attracting attention in various fields. Now, a general spray-drying method has been developed to create more complex hollow spherical MOF superstructures and entrap guest species within them, thereby providing new routes to capsules, reactors and composite materials.

Time-resolved X-ray crystallography on photoactive yellow protein shows the existence of a short-lived, highly distorted intermediate whose reaction trajectory bifurcates along ‘bicycle-pedal’ and ‘hula-twist’ pathways. The bifurcating reaction pathways can be controlled by weakening the hydrogen bond between the chromophore and an adjacent residue, which switches off the bicycle-pedal pathway.

Conformational changes are known to occur during binding of the anti-AIDS drug rilpivirine to HIV-1 reverse transcriptase, an essential enzyme for the replication of HIV. Vibrational spectroscopy, X-ray crystallography and simulations now show that water molecules play an essential role in this binding process, which may help it retain potency despite mutations within the binding pocket.

A structure-specific antibody generated and employed to visualize DNA G-quadruplex structures in human cells shows that these structures are modulated during the cell cycle and can be stabilized by a small-molecule ligand. This provides substantive evidence for endogenous DNA G-quadruplex formation in mammalian cells.

Pyrroles are a highly important class of compounds with a wide variety of applications in biochemistry, pharmacy and materials science. Here, an iridium-catalysed synthesis of pyrroles is described, starting from renewable resources, alcohols that may be derived from lignocellulosic feedstocks and amino alcohols. The reaction proceeds by a condensation reaction that liberates two equivalents of hydrogen gas.

An approach for the construction of complex and diverse compound libraries is described, whereby natural products are altered through a series of ring system distortion reactions. The compounds produced have markedly different physiochemical properties from those in standard screening collections and thus could offer advantages in the search for lead molecules that can be developed into drug candidates.

A crystalline porous organic cage molecule is shown to have exceptional specificity for separating different structural isomers of C9 aromatics. Uniquely, this solid-state specificity is preconfigured in the discrete molecular building block, which shows an analogous specificity in solution. Both solution and solid-state behaviours can be understood by molecular dynamics simulations.

Combinations of enzymatic and chemo-catalysis can result in powerful synthetic transformations. Here, encapsulation of Au(I) or Ru(II) within a supramolecular assembly prevents diffusion of the organometallic complexes into solution where they can compromise the activity of an enzyme. This strategy has been applied to tandem reactions employing supramolecular host–guest complexes and enzymes in the catalysis of organic transformations.

The development of a catalytic, mild and atom-economical transformation of alcohols to carboxylic acid salts and hydrogen gas is described. The reaction uses water as a source of oxygen, with a homogenous Ru catalyst at low (0.2 mol%) catalyst loadings in basic aqueous solution.