Volume 15 Issue 9, September 2023

Scientists have been studying how polymers break in solutions for decades, but the mechanism by which chains are stretched to the point of covalent bond scission is not trivial. Now, an experiment series provides ample support for a dynamic model in which chains uncoil from end to middle, while concurrently relaxing.

When atoms first appeared in the Universe, molecules were needed to help coalesce them into stars. The trihydrogen cation H₃⁺ is among the prime candidates for that process, and now two independent studies provide detailed insight into the ultrafast dynamics of the formation of this important ion from two hydrogen molecules.

Plants produce a wide range of compounds with important bioactivities. Celastrol, an anti-obesity agent found in the root of certain plants, can now be produced de novo in yeast.

Although Li–O₂ batteries offer high theoretical energy storage capacities, few approach these limits. Now, a class of redox mediators is shown to send the discharge reaction from the electrode surface into the electrolyte solution, boosting device capacities and providing selection criteria for future efforts.

Although light-driven conversion of carbon dioxide receives widespread attention, it is also criticized due to the challenge of discerning true product formation from that of impurities. Now, significantly advanced guidelines for proper product identification have been developed, so we can better trust in what we see.

Despite advances, understanding of the quantum state-to-state scattering dynamics between charged ions and neutral molecules at low collision energies remains limited. A high-resolution crossed-beam experiment with quantum state-selected ions prepared by laser photoionization and supporting trajectory surface-hopping calculations now provides insight into the quantum state-to-state collisional dynamics of a model charge-transfer reaction.

Rapid solvent flows stretch dissolved polymer chains to their breaking point by hitherto-elusive molecular mechanisms. Now, analysis of competing mechanochemical reactions suggests a broad distribution of molecular geometries of fracturing chains. This occurs because, in each chain, fracture and kinetically destabilizing backbone stretching compete on submillisecond timescales.

Trihydrogen cations are abundant in interstellar space and play a vital role in both star and organic molecule formation. Now it has been shown that D₃⁺ cations can be directly produced through photoionization of molecular D₂–D₂ dimers.

H₃⁺ and D₃⁺ serve as initiators of many chemical reactions in interstellar clouds. Now the ultrafast formation dynamics of D₃⁺ from a light-driven bimolecular reaction starting from D₂–D₂ dimers have been measured. It has also been shown that the emission direction of D₃⁺ can be controlled by driving the reaction with a more complex two-colour laser pulse.

Celastrol is a potent anti-obesity agent found in the root of Tripterygium wilfordii, but its medicinal application is compromised by limited availability. Now, by combining plant biochemistry with metabolic engineering and chemistry, the biosynthetic pathway of celastrol has been elucidated and has afforded its scalable production in yeast.

Although Li–O₂ batteries offer high theoretical capacities, redox mediators are necessary to control intermediate reaction kinetics and to limit electrode passivation. Now it has been shown that a family of triarylmethyl cations can rival top-performing quinone-based redox mediators. Cations with sluggish catalytic rates were found to suppress surface-mediated O₂ reduction and achieve higher capacitances.

Quantum state-to-state understanding of collisional charge transfer is a long-time goal of chemical dynamics. Now, using high-resolution molecular-beam experiments with spin–orbit state-selected ions and surface-hopping calculations, a vibrational-state-specific mechanism has been observed for the reaction Ar⁺(²P_3/2) + N₂ → Ar + N₂⁺(v′, J′). Besides the well-known long-range harpooning mechanism, a hard-collision glory scattering mechanism was also identified.

Traditionally, ozone has been primarily used to oxidatively deconstruct carbon–carbon bonds. Now, it has been shown that ozone can be used for the construction of carbon–oxygen bonds without oxidative cleavage of the olefin substrate through capturing primary ozonides. Furthermore, intercepting primary ozonides with nucleophiles in continuous flow enabled the green, syn-dihydroxylation of olefins to be realized.

The covalent capture of a ligand by its target protein(s) is important for drug-target identification. Now an electrochemically active warhead—diazetidinone—can be leveraged in a chemoproteomics platform for electroaffinity labelling of a ligand’s target protein to afford target-ligand identification in live cells.

The inability to access well-defined polysaccharides in sufficient quantities has hampered our understanding of their structure–function relationships. Now it has been shown that native precision polysaccharides can be readily prepared via living polymerization of 1,6-anhydrosugars. The obtained polymers display excellent chemical recyclability, suggesting their potential utility as a class of sustainable materials.

Acylhydrazones are often found in compounds across screening databases, and numerous bioactive acylhydrazones exist. This functional group can isomerize between E and Z in response to light or upon exposure to thiols. Now, E/Z isomerization is found to impact activities of bioactive acylhydrazones and should be routinely analysed.

Stabilization of RNAs for storage, transport and biological application remains a profound challenge. Now, it has been shown that reversible 2′-OH acylation with easily accessible acylimidazoles unlocks efficient protection of RNA. RNA can be deprotected by non-basic nucleophiles or spontaneously in cells to restore RNA functions.

The mechanism of α-synuclein amyloid aggregation via liquid–liquid phase separation has so far remained elusive. Now, the existence of nanoscale clusters of α-synuclein in sub-saturated concentrations is observed using mass photometry. These nanoscale clusters can act as precursors to both macroscopic condensate droplets as well as amyloid fibrils.

Clinton Veale and Fanie van Heerden discuss the story of natamycin. From its humble telluric origins in Pietermaritzburg, this unique antimicrobial agent has risen to become a mainstay of the food and beverages industry.