Volume 13 Issue 8, August 2021

Recycling polymers to their monomers would enable a circular polymer economy, but this can be challenging, especially for materials with all-carbon backbones. Now, by lowering the strain of cyclooctene through ring fusion, recyclable polymers with useful physical properties can be made by an olefin-metathesis-based route.

Excited anion states provide doorways for molecular electron capture. Now, two-dimensional photoelectron spectroscopy of cluster anions has been shown to be a powerful tool for revealing the role of the local environment in facilitating the process.

Among the tens of thousands of reported hybrid organic–inorganic crystals, only a small fraction of them are known to form a stable liquid upon heating. Now, a family of hybrid perovskites is shown to melt and, upon cooling, form glasses with a compelling combination of properties.

The origin and evolution of translational machinery — which produces a specific peptide from an RNA sequence — is a major unsolved puzzle in prebiotic chemistry. Now, the coupling of amino acids directed by RNA templates in the absence of a ribosome provides clues on how this protein synthesis process might have started.

Energy transfer from one molecule to another over a distance of nanometres is a fundamental process of widespread relevance. Now, scanning probe techniques have been used to include an intermediary third molecule and to watch how energy flows through it.

On-surface, ultra-high vacuum conditions enable two-dimensional polymerizations to be precisely studied—often with submolecular resolution—but these syntheses are typically thermally activated, which can lead to high defect densities and relatively small domain sizes. Now, a self-assembled monolayer of a three-bladed fantrip monomer on alkane-passivated graphite has been covalently crosslinked into a mesoscale-ordered two-dimensional polymer by [4+4] photocycloaddition.

Although electron-driven chemistry is ubiquitous, how molecular electron capture is altered by solvent remains poorly understood. Now, using anion two-dimensional photoelectron spectroscopy, it is shown that the presence of water molecules can enhance electron capture and that considering the mechanism from the perspective of the anion offers further understanding.

Depolymerizable polymers can potentially address challenges in polymer sustainability, but most existing systems lack the useful thermomechanical properties of traditional ones. Now, it has been shown that depolymerizable polymers based on olefin metathesis show good thermal stability as well as versatile mechanical properties and that the monomers used to make them can be prepared from abundant materials.

Elucidating the origin of translation—the process that produces a specific peptide from an RNA sequence—is one of the most difficult challenges in prebiotic chemistry and evolutionary biology. Now, it has been shown that aminoacylated nucleotides couple to amino-acid-bearing oligoribonucleotides, directed by an RNA template, forming specific di- and tripeptides in the absence of ribosomal machinery.

The molybdenum cofactor (Moco) is found in the active site of numerous enzymes, but the mechanism of molybdate insertion is not clear. Now, the mechanism of the final maturation step, in which adenylated molybdopterin and molybdate are the substrates, has been revealed. X-ray crystallography of an Mo-insertase identified adenylated Moco as an unexpected intermediate in this reaction sequence.

Energy funnelling within multichromophoric assemblies is key to the conversion of solar energy by plants. Now, energy transport between phthalocyanine-based chromophores has been monitored at the submolecular level using scanning tunnelling microscopy, focusing on the role of ancillary, passive and blocking chromophores in promoting and directing energy transfer between distant donor and acceptor units.

Oxidation states help chemists to understand the bonding, properties and reactivity of compounds, but they can be difficult to determine for metal ions in extended crystalline materials. Now, oxidation states manually assigned to metal–organic frameworks have been harvested from the Cambridge Structural Database and used to build a machine-learning model that predicts oxidation states in metal–organic frameworks with good accuracy.

A series of dicyanamide-based hybrid organic–inorganic perovskite structures has been shown to melt at temperatures below 300 °C. On melt-quenching, they form glasses that possess coordination bonding and show very low thermal conductivities and moderate electrical conductivities as well as polymer-like thermomechanical properties.

Droplet interface bilayer measurements have now shown that membranes formed from chiral phospholipid bilayers are enantioselectively permeable to chiral amino acids. The results show that membrane stereochemistry is necessary and sufficient to drive such enantioselective transport, presenting a new potential route to homochirality. These findings could also have implications for pharmacokinetics and drug design.

Lustrous flexible thin films of semiconducting cyclic polyacetylene (c-PA) have been synthesized and characterized. Rapid and efficient tungsten-catalysed acetylene polymerization conditions produce temporarily soluble c-PA, enabling the in situ derivatization of this typically insoluble polymer. Compelling evidence for the cyclic topology—and its influence on the physical properties of the polymer—are presented.

Obtaining mechanistic data after the rate-determining step of a chemical reaction is difficult but essential for its understanding. Now, a Ru(iv) side-on peroxo complex has been isolated following the rate-determining step of the water oxidation reaction (O–O bond formation) carried out using a Ru-based molecular catalyst.

Prodrugs offer one route to treat cancer, but they require activation once they have been delivered to the tumour. Now, a simultaneous chemo-radiotherapy strategy has been demonstrated in mice that uses gamma or X-ray irradiation to locally activate an anticancer prodrug.