Volume 15 Issue 12, December 2023

Recent improvements in de novo protein design are likely to support a broad range of applications, but larger complexes will be easier to create if a building block approach is adopted. Now protein filaments with tunable geometry can be made using assemblies that have both cyclic and superhelical symmetries aligned along the same axis.

Stereoselective decarboxylative protonation can produce diverse chiral molecules from widely available carboxylic acids. However, general and practical strategies are lacking. Now, a chiral spirocyclic phosphoric acid-catalysed decarboxylation of aminomalonic acids has enabled the modular synthesis of α-amino acids.

Fluoroalkyl fragments are ubiquitous motifs in pharmaceuticals and agrochemicals, but their introduction to a given molecule typically involves expensive or difficult-to-handle reagents. Now, the photocatalysed hydrofluoroalkylation of alkenes has been achieved using simple and readily available fluoroalkyl carboxylic acids.

Ribonucleoprotein granules are ubiquitous in living organisms with the protein and RNA components having distinct roles. In the absence of proteins, RNAs are shown to undergo phase separation upon heating. This transition is driven by desolvation entropy and ion-mediated crosslinking and is tuned by the chemical specificity of the RNA nucleobases.

To develop covalent inhibitors with high potency and low off-target effects, combinatorial approaches that search for candidates from large libraries are desired. Here, sulfur(VI) fluoride exchange (SuFEx) in vitro selection is established for the evolution of covalent aptamers from trillions of SuFEx-modified oligonucleotides. Through this technique, covalent aptamers with optimally balanced selectivity and reactivity are identified.

Molecular systems with coincident cyclic and superhelical symmetry axes have considerable advantages for materials design as they can be lengthened or shortened by changing the length of the monomers. Now a systematic approach to generate modular repeat protein oligomers with combined symmetry that can be extended by repeat propagation has been developed.

Asymmetric decarboxylation can transform abundant carboxylic acids into valuable chiral molecules but faces major limitations due to the challenging enantiocontrol of proton transfer. Now the use of Brønsted acid catalysis in conjunction with an anchoring group strategy has enabled the decarboxylative protonation of aminomalonic acids to access diverse amino acids.

Alkene hydrofluoroalkylation offers a promising route to diverse fluoroalkylated compounds but current methods have limitations, such as needing expensive fluoroalkylating reagents. Now, leveraging iron photocatalysis and hydrogen-atom-transfer catalysis, a hydrofluoroalkylation method has been developed that utilizes feedstock chemicals such as trifluoroacetic acid as direct fluoroalkyl radical precursors, providing a redox-neutral, general protocol to introduce fluoroalkyl moieties.

The physicochemical driving forces of protein-free, RNA-driven phase transitions were previously unclear, but it is now shown that RNAs undergo entropically driven liquid–liquid phase separation upon heating in the presence of magnesium ions. In the condensed phase, RNAs can undergo an enthalpically favourable percolation transition that leads to arrested condensates.

Covalent inhibitors offer high potency but their potential is hindered by off-target reactivity. Now, an in vitro selection method has been developed to enable the discovery of covalent inhibitors from trillions of oligonucleotides endowed with the sulfur(VI) fluoride exchange chemistry. This strategy generates covalent inhibitors of protein–protein interactions with optimally balanced selectivity and reactivity.

The design and improvement of enzymes based on physical principles remain challenging. Now, the vibrational Stark effect has been used to demonstrate how an electrostatic model can unify the catalytic effects of distinct chemical forces in a quantitative manner and guide the design of enzyme variants that outperform their natural counterpart.

Functionalizing two-dimensional transition-metal carbide (MXene) surfaces can alter their properties, but covalent functionalization has been synthetically challenging. Now, it has been shown that various organic groups can be covalently attached to MXene surfaces through amido and imido bonds. The resulting hybrid organic–inorganic structures exhibit Fano resonances and superior stability compared with traditional MXenes with a mixture of –F, –O and –OH surface terminations.

Although noble metal coordination complexes typically show promising photophysical properties that enable applications in lighting, photocatalysis and solar energy conversion, first-row transition metal complexes rarely display properties as attractive. Now, two Cr(0) complexes are shown to afford excited-state lifetimes of ~50 ns and photophysical properties analogous to noble metal complexes, enabling efficient photoredox catalysis.

Monomeric N-heterocyclic carbenes (NHCs) can act as molecular modifiers of metal surfaces and thus affect heterogeneous catalytic behaviour. Now NHC polymers have been formed on gold surfaces, consisting of ballbot-type repeating units bound to single gold adatoms. Conformational, electronic and charge transport properties explain the high surface mobility of the incommensurate NHC polymers.

Two-dimensional hybrid perovskites have gained substantial interest recently due to their controllable optoelectronic properties; however precise control over layer thickness has been synthetically challenging. Now a crystal growth method is shown to achieve high-quality single crystals of organic semiconductor-incorporated perovskites with control over their thickness and length through judicious solvent choice, affording precisely tuned optoelectronic properties.

Biological membranes are asymmetric bilayers, but little is known about how this asymmetry modulates membrane protein folding or stability. Now, folding and stability assays with bacterial outer membrane proteins reveal an exquisite sensitivity to asymmetric membrane charge distribution and a required matching of protein charge for efficient folding.

While aromaticity is a useful concept for assessing the reactivity of organic compounds, the connection between aromaticity and on-surface chemistry remains largely unexplored. Now, scanning probe experiments on cyclization reactions of porphyrins on Au(111) show that the peripheral carbon atoms outside of the aromatic 18-π electron pathway exhibit a higher reactivity.

Current strategies for recycling cross-linked polyurethane foam waste are economically unattractive and/or lead to recycled products with inferior properties. Now it has been shown that a cost-effective chemical strategy can be used to turn the foam into high-performance value-added three-dimensional photo-printing resins.

The Au²⁺ oxidation state is rarely stable in molecules or extended solids, where extreme synthetic conditions or exotic ligands are often necessary. Now, Au²⁺ has been stabilized with simple Cl⁻ ligands in Cs₄Au^IIAu^III₂Cl₁₂, an extended solid with a perovskite-derived structure that is readily synthesized under mild conditions and is stable to ambient conditions.

Daniel Rabinovich outlines the story of insulin, the essential drug for the treatment of diabetes during the past century.