Volume 6 Issue 11, November 2014

To convert solar energy into viable fuels, coupling light-harvesting materials to catalysts is a crucial challenge. Now, the combination of an organic supramolecular hydrogel and a non-precious metal catalyst has been demonstrated to be effective for photocatalytic H₂ production.

Interwoven supramolecular structures are often held up as examples of beauty in chemistry, but these assemblies can be fragile depending on the environments they are exposed to. Post-assembly covalent modification can, however, trap them in robust molecular form, and a triply entwined [2]catenane is one of the most sophisticated examples so far.

The synthesis and isolation of a silane adduct of an electrophilic boron species provides insight into the mechanism of metal-free catalytic reductions based on frustrated Lewis pairs.

High-throughput screening of solvothermal crystallization conditions for MOFs and other solids may receive a boost from the application of 3D printing techniques to low-cost, disposable pressure vessels.

Understanding the intrinsic properties of molecules that protect our skin from the harmful rays of the Sun is critical to developing more efficacious sunscreen products. Now, gas-phase spectroscopy and microsolvation studies of model ultraviolet-filter molecules have shown that they may provide a route to developing improved sunscreens.

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.

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.

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.

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.

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.

The adenine analogue 2-aminopurine has been considered as intrinsically fluorescent and is widely used in biochemical assays to probe DNA and RNA structure. It is now shown that the molecule alone is nearly non-fluorescent, however, its fluorescence is increased by up to 95 times through hydrogen bonding to a single water molecule.

The programmed assembly of single DNA strands into bricks and ultimately micrometre-sized two-dimensional crystals with prescribed depths up to 80 nm is described. These crystals display intricate three-dimensional features including continuous or discontinuous cavities and channels with nanometre precision, and can pack DNA helices in parallel or perpendicularly to the plane of the crystals.

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.

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.

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.

From Earth to the stars and back again, John Emsley surveys the uses, occurrences and mysteries of an element that is playing an increasing role in human affairs.