Reviews & Analysis

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.

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.

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.

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.

A multimodal imaging approach is developed to interrogate microorganism–semiconductor biohybrids at the single-cell and single-molecule level for light-driven CO₂ fixation. Application to lithoautotrophic bacterium Ralstonia eutropha biohybrids reveals the roles of two hydrogenases in electron transport and bioplastic formation, the magnitude of semiconductor-to-single-cell electron transport and the associated pathways.

Tandem cycloaddition reactions have significant applications in organic synthetic chemistry. Now, two enzymes are shown to catalyse tandem hetero-Diels–Alder reactions with a synergistic interplay between a calcium cofactor and N-glycan post-translational modifications during the biosynthesis of bistropolone-sesquiterpene secondary metabolites.

The synthesis of natural products with important biological properties has always fascinated chemists, but the development of rapid, efficient and stereoselective transformations remains challenging. Now, a strategy has been developed to produce several strychnan alkaloids through formation of a common bridged morphan core structure.

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.

Pharmacologically inactive prodrugs that can be activated by near-infrared light are attractive candidates for clinical applications. Now, platinum-based photo-oxidants have been shown to eradicate tumours in mice with a new mode of action.

The concepts of multistep processes and regioselectivity — fundamental in covalent synthesis — have now been applied to the non-covalent synthesis of sequence-controlled multiblock supramolecular polymers.

Genetic code expansion beyond α-amino acids is a major challenge, in which stitching together non-natural building blocks within the ribosome is a critical barrier. Now, the molecular determinants for the efficient incorporation of non-natural amino acids into the ribosome have been unlocked, accelerating ribosomal synthesis.

Lactams and pyridines are privileged scaffolds, but strategies for combining these groups into one molecule are lacking. Now, N–N pyridinium ylides have been shown to form triplet state diradicals under photoinduced energy transfer, and subsequent [3+2] cycloaddition with the tethered alkene enables the synthesis of diverse ortho-pyridyl lactams.

Challenges in the synthesis of heparan sulfate (HS) glycosaminoglycans have limited access to defined HS oligosaccharides bearing a diverse array of sulfation sequences. A concise, divergent synthetic approach now provides a library of 64 HS tetrasaccharides displaying a comprehensive set of sulfation sequences, offering insight into the elusive sulfation code of glycosaminoglycans.

Protein translation is the ultimate paradigm for sequence-defined polymer synthesis. To introduce non-canonical monomers into the genetic code of living organisms, pairs of biomolecules known as aminoacyl-tRNA synthetases (aaRSs) and transfer RNAs (tRNAs) are required. The discovery and engineering of five such pairs, that do not interfere with each other or the aaRS–tRNA pairs of a bacterial host, sets the stage for highly modified genetically encoded biopolymers.

Low-coordinate lanthanide complexes with strong magnetic anisotropy could afford high-performance single-molecule magnets (SMMs) but are challenging to synthesize. Now, through ligand design, a near-linear pseudo-two-coordinate Yb(iii) complex that exhibits slow magnetic relaxation is reported. The complex has a large total splitting of the ground-state manifold, arising from the crystal field imposed by the ligands.

The atomically precise assembly of metal nanoparticles offers vast possibilities for materials chemistry. Ring-shaped polyoxometalates have now served to stabilize Ag₃₀ nanoparticles with exposed surfaces.

Bioresponsive hyperpolarized probes contain magnetic resonance signals that can be many orders of magnitude larger than those of common, thermally polarized probes. This Perspective discusses how bioresponsive hyperpolarized probes can be directly linked to biological events to give functional information, enabling the mapping of physiological processes and diseases in real time using magnetic resonance.

Complexity is a hallmark of biological systems, but scientific experiments are typically conducted in simplified conditions. Now, diverse polymers that mimic the local environments of complex biological mixtures have been shown to improve protein folding, stability and function.

Constructing aptamers with desired target-binding affinities may lead to new applications but is challenging. Now, a new method using a high-dimensional microfluidic approach enables quantitative isolation of aptamers with programable binding affinities.

From humans designing machines, to machines designing biology, deep learning is turning the tables for assisted exploration of biologically active and diverse protein designs. Now, a deep-learning-based strategy has been used to design artificial enzymes that catalyse a light-emitting reaction.