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Polymethine dyes are bright and red-shifted fluorophores that lack an intrinsic turn-on mechanism, which leads to non-specific staining when applied to biological samples. Now the fluorescence of polymethine dyes was masked through an intracellular cyclization strategy that gets reversed upon binding an intended macromolecular target, providing specificity for live-cell imaging.

Late-stage functionalization of complex drug molecules is challenging. To address this problem, a discovery platform based on geometric deep learning and high-throughput experimentation was developed. The computational model predicts binary reaction outcome, reaction yield and regioselectivity with low error margins, enabling the functionalization of complex molecules without de novo synthesis.

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.

Long polyynes have fascinating properties but they are difficult to synthesize as a consequence of their high reactivity. Now, it has been shown that cobalt carbonyl complexes can be used as masked alkyne equivalents, enabling the preparation of stable polyyne polyrotaxanes with up to 34 contiguous triple bonds.

The inherent rigidity of the azaarene ring structure has made it challenging to achieve remote stereocontrol through asymmetric catalysis on these substrates. Now, through a photoenzymatic process, an ene-reductase system facilitates the production of diverse azaarenes with distant γ-stereocentres, highlighting the potential of biocatalysts for stereoselectivity at remote sites.

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.

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.

The synthesis of optically enriched atropisomers has so far been limited to molecules containing aryl groups. Now a variant of non-aryl atropisomerism has been identified in vinyl sulfoxonium ylides, and an organocatalytic method has been developed to produce these molecules. This type of axial chirality is characterized by restricted rotation of the central C(sp²)–C(sp²) bond.

Sequences of synthetic polymers are generally heterogeneous and dictate many of their physiochemical properties, but are challenging to determine. Now an imaging method, termed CREATS (coupled reaction approach toward super-resolution imaging), can count, localize and identify each monomer of single polymer chains during (co)polymerization.

Radium complexes are of interest for use as cancer therapeutic agents, but the structure and bonding are poorly understood. Here, the synthesis of a Ra²⁺ complex is reported, and the structure and bonding characteristics are elucidated using single-crystal X-ray diffraction.

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.

Bottom-up assembly of protocells into networking superstructures represents a further key step towards rudimentary formation of life. Now it has been shown that a pool of biomolecules can self-organize into an interactive binary population of protocell coacervates with a self-sorting chain-like configuration, allowing for biomolecular extraction, translocation and macroscale separation.

Open-shell organic molecules with properties that can be modulated by external stimuli are of interest for spintronics applications. Now, an overcrowded alkene with open-shell tetraradical character has been synthesized in which the interaction between the π-conjugated subunits depends on the charge and spin state.

Site-specific modification of RNA in cells is crucial for analysis and functional investigations. Natural enzymes that promote RNA methylation using S-adenosyl-l-methionine (SAM) exist, but leveraging these proteins for RNA modification is limited by cell permeability, stability and specificity of their substrates. Now, a de novo ribozyme that acts on a stabilized and cell-permeable SAM analogue enables site-specific RNA modification with a click handle in living cells.