Volume 9 Issue 11, November 2017

Both the topology and the mechanical strength of woven materials have inspired great synthetic efforts to replicate their structures at the nanoscale. Now, a triaxial weave has been prepared by self-assembly of a judiciously designed organic molecule through π–π and CH–π interactions.

Although predicted many years ago, chemically reactive termolecular reactions were thought to be unimportant in defining the behaviour of combustion systems. Now, calculations have shown that such reactions between radicals and long-lived bimolecular complexes can actually play an important role in hydrogen combustion.

Understanding the biological roles of modifications to DNA, RNA and proteins is critical to revealing how cells regulate gene expression in development and disease. Two papers now present a combination of new tools and discoveries that could enable biologists and chemical biologists to better study epigenetic regulation in mammals.

The emergence of synthetic fluorescent nucleobases that can be incorporated into DNA and RNA in place of their natural counterparts has enabled new tools and technologies with applications in chemistry, biology and biomedicine. This Review discusses chemical insights into canonical and non-canonical nucleobase designs, relating structure to properties.

DNA nanotechnology provides a versatile toolbox for engineering synthetic circuits in living cells. This Review discusses how nanostructures made from nucleic acids can enable biocomputation and also be readily interfaced with a variety of intracellular and in vivo components to facilitate synthetic biology applications.

Woven topologies endow macroscopic objects with mechanical stability, but their molecular counterparts have remained difficult to prepare. Now, an extended triaxial supramolecular weave has been formed by the self-assembly of a judiciously shaped organic building block — a rigid oligoproline segment featuring two perylene-monoimide moieties — through π–π stacking and CH–π interactions.

The catalytic asymmetric α-alkylation of aldehydes has historically been a significant challenge within organic synthesis. Now, this elusive transformation has been achieved through the merger of organocatalysis, photoredox catalysis and hydrogen-atom transfer catalysis to enable the coupling of simple olefins and aldehydes.

Chemically termolecular reactions — arising from the collision of ephemeral collision complexes with other chemically reactive species — have been neglected in current gas-phase chemical mechanisms of combustion and planetary atmospheres. First-principles calculations reveal that such chemically termolecular reactions constitute major pathways affecting macroscopic observables.

Both click chemistry and polymer synthesis require reliable transformations with high selectivity, efficiency and fidelity. Now, bifluoride salts can be used as powerful catalysts for the sufur(VI) fluoride exchange (SuFEx) click reaction and they are applied to the synthesis of polysulfates and polysulfonates in a practical and scalable manner.

A 335 base-pair gene encoding the green fluorescent protein iLOV and an epigenetically modified variant have now been assembled by click-DNA ligation of ten functionalized oligonucleotides. The resulting fully synthetic gene contained eight triazoles at the sites of chemical ligation, yet the synthetic gene was shown to be fully biocompatible in Escherichia coli.

With recent and improved understanding of how nuclear and electronic degrees of freedom can interact with each other comes the opportunity to directly control electronic processes. Now it has been shown that ultrafast vibrational excitation can direct light-induced intramolecular electron transfer along a specific path.

Previous methods to transform unsaturated substrates into carbonyl-containing products have generally relied on the use of hazardous carbon monoxide and tailor-made catalysts for each nucleophile employed. Now, shuttle catalysis can be used to perform a CO- and HCl-free transfer hydrochlorocarbonylation to access acid chlorides that can be transformed in situ into virtually any carbonyl-containing product.

Delayed resolution of G-quadruplexes during replication can induce localized loss of epigenetic information and changes in gene expression. Now, this effect has been used to discover biologically potent G-quadruplex ligands and to demonstrate that G-quadruplex stabilization can induce epigenetic changes that are heritable across cell divisions even after the ligand is removed.

Ultrafast-scanning fluorescence correlation spectroscopy has now been used to measure the molecular interactions underlying the phase behaviour of disordered proteins. Sequence-encoded conformational fluctuations of these proteins are shown to give rise to phase-separated droplets of surprisingly low concentrations. These results provide insight into how the structural features of the droplets affect the properties of liquid-phase intracellular organelles.

The direct, selective conversion of linear alkanes to α-olefins — without isomerization — is an important reaction in the field of catalysis from both a fundamental and industrial perspective. Now, a detailed pathway has been described for how a base metal can promote such a reaction with several turnovers, in a non-oxidative set of C–H activation reactions, thus preventing olefin isomerization.

An attractive feature of supramolecular polymers is their reversibility — they typically depolymerize upon heating. Now, in the presence of a scavenger molecule, a metalloporphyrin derivative bearing eight amide-containing side chains has been shown to undergo supramolecular polymerization on heating as well as cooling through π-stacking and multivalent hydrogen-bonding interactions.

Several natural and unnatural lissoclimide cytotoxins have been prepared via semi-synthesis and total synthesis. An X-ray co-crystal structure of chlorolissoclimide with the ribosome and evaluation of cytotoxicity and translation inhibition of new compounds in the series improves our understanding of the molecular basis for cytotoxicity.

Iulia Georgescu explains her fascination with the elusive element 113.