Volume 15 Issue 1, January 2023

Radical-mediated functionalization streamlines access to complex synthetic targets. Now, a sulfonium-based donor–acceptor pair enables photoinduced charge-transfer interactions to access electronically diverse aryl radicals. Reaction with enol ethers or isocyanide provides a metal-free method for arene functionalization.

Interactions between proteins and non-proteinaceous biopolymers are essential for life; however, many methods used to characterize these interactions lack precision and display significant biases. Now, a genetically encoded method employing sulfur(vi) fluoride exchange (SuFEx)-based chemical crosslinking has been developed for capturing and analysing protein–RNA and protein–carbohydrate interactions in vivo.

Ribosomes cannot synthesize peptides using hydroxy acids to replace canonical amino acids as no codons encode hydroxy acid building blocks. Now, this challenge has been addressed by rewriting the genetic code, enabling the direct cellular biosynthesis of non-natural depsipeptides containing non-canonical amino acids.

Molecular computing programmed with complementary nucleic acid strands allows the construction of sophisticated biomolecular circuits. Now, systems with partially complementary strands have been shown to enable more compact and faster molecular circuits, and may illuminate biological processes.

An organic quantum magnet has been prepared in short chains of porphyrin derivatives through a combination of on-surface synthesis and atom manipulation using the tip of a scanning probe microscope.

Polymerization methods that control the cis/trans stereochemistry of repeating alkenes in polyalkenamers remain scarce. Now, an acyclic diene metathesis process has been developed that enables control over the stereochemistry of the polymer backbone. The method harnesses the reactivity of dithiolate Ru carbenes, in combination with cis,cis-diene monomers, to access several classes of polymers with tailored properties.

Protein–RNA interactions regulate RNA fate and function, and are generally non-covalent and reversible. Genetically introducing a latent bioreactive amino acid into a protein is now shown to enable the protein to covalently crosslink a bound RNA molecule in vivo. This method offers innovative avenues for developing protein–RNA research and applications.

Protein–carbohydrate interactions remain challenging to study due to their low binding affinity and non-covalent nature. Now, a genetically encoded bioreactive unnatural amino acid containing sulfonyl fluoride has been shown to crosslink a protein with its bound glycan, offering a solution to probe and exploit protein–carbohydrate interactions.

Photoactivation of EDA complexes was previously limited to electronically biased partners to secure productive charge-transfer interactions. Now, the participation of triarylsulfonium salts—formed by selective C–H sulfenylation—in photoactive EDA complexes with catalytic triarylamine donors provides a site-selective and metal-free strategy for the generation of aryl radicals and the formal C–H functionalization of native arenes.

Quantum nanomagnets, which display collective quantum behaviours, serve as important components in modern quantum technologies, but their fabrication has remained challenging. Quantum nanomagnets have now been constructed spin by spin in metal-free porphyrin chains, using on-surface synthesis and hydrogen manipulation using a scanning tunnelling microscope, and their collective quantum behaviours have been clearly resolved.

Macrocyclic peptides can be genetically encoded and synthesized in cells; however, the programmable diversity is limited. Now, macrocycles containing two non-canonical amino acids have been genetically encoded and synthesized in codon-reassigned Syn61Δ3 cells. Incorporating diverse hydroxy acids in Syn61Δ3 cells enables the synthesis of non-natural depsipeptides containing either one or two ester bonds.

The complementarity of the two strands in the DNA double helix provides a mechanism for the storage and processing of genetic information. Now, an alternative ‘strand commutation’ mechanism of data processing with DNA/RNA has been revealed based on the reversible low-affinity interactions of essentially non-complementary nucleic acids.

Room-temperature phosphorescence in organic solids is attractive for practical applications but remains rare. Now, highly phosphorescent boroxine-linked covalent organic frameworks have been prepared by covalent doping with halogen atoms through the use of halogenated precursors. The resulting porous COFs exhibited oxygen-sensing capabilities with millisecond response time over a wide range of partial oxygen pressures.

Sterically demanding 2′-modified nucleotides used in antisense therapeutics have thus far been challenging to synthesise enzymatically. Now, it has been shown that mutation of two gatekeeper residues in an archaeal DNA polymerase unlocks efficient synthesis of the modified nucleic acid oligomers 2′-O-methyl-RNA and 2′-O-(2-methoxyethyl)-RNA and enables the evolution of 2′-O-methyl-RNA enzymes.

Technologies for profiling biological environments with high spatiotemporal resolution are in demand to enable the discovery of new targets for addressing unmet clinical needs. Now, a deep red light-mediated photocatalytic strategy for the targeted activation of aryl azides has been developed. This platform enables mapping of protein microenvironments in physiologically relevant systems.

The circadian rhythm generates out-of-equilibrium metabolite oscillations controlled by feedback loops under light/dark cycles. Now, it has been shown that these life-like properties can emerge from a non-equilibrium nanosystem comprising a binary population of enzyme-containing polymersomes capable of light-gated chemical communication, controllable feedback and coupling to macroscopic oscillations.

Creating hierarchical synthetic materials that can modulate microbial communities remains a great challenge due to the complex interactions between microbiota and their colonized environments. Now, a soil-inspired chemical system that responds to chemical, optical and mechanical stimuli has been developed. The soil-inspired chemical system can enhance microbial cultures and biofuel production, enrich gut bacterial diversity and alleviate ulcerative colitis symptoms.

Iodic acid (HIO₃) forms aerosols very efficiently, but its gas-phase formation mechanism is not well understood. Atmospheric simulation chamber experiments, quantum chemical calculations and kinetic modelling have now revealed that HIO₃ forms as an early iodine oxidation product from hypoiodite. The mechanism explains field measurements and suggests a catalytic role for iodine in particle formation.

Incorporating silicon into organic molecules and materials leads to interesting changes in electronic structure and properties; silabenzenes are attractive species for this purpose, but their high reactivity in solution poses challenges. Now, 1D and 2D covalent organic frameworks featuring disilabenzene rings (C₄Si₂) as linkers have been prepared by reacting silicon atoms and polyaromatic hydrocarbon precursors on a Au(111) surface.

Synthesis of peptidyl-tRNAs is challenging because there are no enzymes that can directly attach the desired peptide to tRNA. Now it has been shown that a chemoenzymatic approach based on native chemical ligation can be used for the semi-synthesis of peptidyl-tRNAs for structural/biochemical studies of arrested and non-arrested ribosome complexes.

Carina Crucho and Maria Teresa Barros consider the rich chemistry of sucrose, a carbohydrate that makes life sweeter.