Modular redefinition: A long-standing paradigm in modular polyketide synthase enzymology, namely the definition of a module, has been challenged by Abe and co-workers in their recent study. With this new understanding has emerged renewed hope for engineering these assembly lines to produce new materials and medicines.

Cleaning up: The efficiency of polymeric water purification membranes, which are capable of removing many impurities from water but frequently suffer from fouling, can be improved by surface modification. Common techniques used to modify membrane surfaces, including grafting, coating, chemical treatment, UV irradiation, plasma treatment, and polydopamine application, are reviewed.

Phase-dependent: When a catalyst consisting of isolated rhodium atoms dispersed on the surface of VO₂ nanorods was employed for ammonia–borane hydrolysis, the activation energy changed when the substrate underwent a phase transition. Mechanistic studies indicate that the catalytic performance depends directly on the highest occupied state of the single Rh atoms, which is determined by the band structure of the substrate.

Two recipes for success: Two distinct mechanisms are described for the enantiodiscrimination of 2-bromopentane by haloalkane dehalogenases. Highly enantioselective DbjA has a very open, solvent-accessible active site. The engineered enzyme DhaA31 has a more occluded and less solvated cavity (see picture) but shows similar enantioselectivity as a result of steric hindrance imposed by two specific residues, rather than hydration as in DbjA.

Cellfi-Flash: A new fixative for light microscopy of living cells was obtained by functionalizing glutaraldehyde with a photocleavable protecting group. Ester substituents ensure that the masked compound can enter the cell and accumulate therein after esterase-mediated hydrolysis. Incubated cells are instantly fixed and ready for microscopy upon irradiation, whereas conventional aldehyde fixation is diffusion-controlled.

From the waste bin: C. elegans uses simple building blocks from primary metabolism to construct a modular library of signaling molecules, the ascarosides. It is demonstrated that lysosome-related organelles, which are essentially cellular waste-disposal centers, play a major role in the assembly of these compounds, which requires the activation of building blocks by a specific acyl-CoA synthetase.

C−H functionalization: A ferrocene-catalyzed electrochemical cross-coupling reaction of C(sp³)-H and C(sp²)-H centers has been developed to give access to C3-fluorinated oxindoles using fluorinated malonate amides. The electrosynthetic method is characterized by mild reaction conditions, broad substrate scope, high functional group tolerance, and easy scalability.

Solar energy conversion: A simple and reliable vapor-phase deposition technique is developed for fabricating GaN/Ta₃N₅ thin films that achieve state-of-the-art solar water splitting performance and stability. The GaN overcoating strategy is readily applicable to stabilize various promising (oxy)nitrides for practical photo-electrochemical applications.

Cl-early a winning combination: Hydrosilanes underwent selective chlorination upon treatment with HCl in the presence of a catalytic amount of B(C₆F₅)₃ with the liberation of H₂ (see scheme). For the chlorination of di- and trihydrosilanes, the adduct Et₂O⋅B(C₆F₅)₃ was found to be a more selective catalyst.

Full circle: EriG, a member of the UbiA superfamily, was identified as the enzyme responsible for the cyclization of the cyathane skeleton in the mushroom Hericium erinaceum. Genome mining using the EriG protein sequence led to the identification of a new family of widespread UbiA-related diterpene cyclase genes in bacteria and fungi.

Solving the solvent problem: Silica aerogels are ideal thermal insulation materials, but are expensive owing to the large solvent consumption during their production. A simplified synthesis combines all reagents in a single step and minimizes the production time, solvent use, and carbon footprint, but retains the outstanding properties associated with silica aerogels.

Pimp my light: Amine-rich nitrogen-doped carbon nanodots (NCNDs) are introduced as co-reactant in electrochemiluminescence (ECL) processes. The luminophore, Ru(bpy)₃²⁺, displays an enhanced ECL intensity when covalently linked to NCNDs as a result of an intramolecular electron-transfer process.

Selective on-surface synthesis of cis-enediyne-type compounds is reported for the first time. Bromide-substituted terminal alkynes transform into cis-enediynes on a Ag(111) surface at 420 K. Coadsorbed bromide ions help the formed cis-enediynes aggregate into close-packed islands through Br⋅⋅⋅H bonds, which impose a high steric barrier to further reaction of cis-enediyne.

Tipping the balance: By coating the tip of a nanopipette with crystalline zeolitic imidazolate framework-90 (ZIF-90), super-high ionic rectification was detected. The rectification results from the interaction between the sub-nanometer channels of the glass-nanopipette-supported ZIF-90 (GNS-ZIF-90) and the ions in solution.

Rare finding: Iodosobenzene adducts LFe₃(PhPz)₃OMn(^sPhIO)][OTf]_x (x=2 or 3; PhPz=phenylpyrazolate) on multinuclear scaffolds were synthesized and characterized. The reactivity of these rare adducts was investigated in light of remote redox state changes in a triiron core (Fe^III₂Fe^IIMn^II vs. Fe^III₃Mn^II), thereby highlighting significant reactivity differences (>10²) in oxygen atom transfer and C−H bond oxygenation.

A platform to improve the outlook: The palladium-catalyzed asymmetric coupling of 2-iodo-3-methylcyclohex-2-enones and aryl boronic acids provided axially chiral enone–arene systems with several potential sites for further transformation (see scheme). In particular, these cyclohexenone-based atropisomers serve as a valuable platform for the synthesis of biaryl atropisomers with different ortho substituents.

Hit for six: Four α-ketoglutarate-dependent dioxygenases (red) that hydroxylate sp³ carbon atoms, a flavin-dependent dehydrogenase (blue) that forms the unsaturated lactone, and the highly unusual ferric-reductase-like enzyme RbtH (green) are involved in the biosynthesis of rubratoxin A. RbtH regioselectively reduces one of the maleic anhydride moieties in the intermediate rubratoxin B to the γ-hydroxybutenolide group that is critical for the biological activity.

Minding manners: Unusual regioselective intramolecular cyclization of 1,3-cyclohexadiene epoxides with alcohol nucleophiles in a 1,4-addition manner enabled the first asymmetric total syntheses of (−)-ansellones A and B and (+)-phorbadione in 16–23 steps from (+)-sclareolide. This strategy is expected to be applicable to the synthesis of other ansellane sesterterpenoids.

Copper-bottomed: A nanostructured copper/copper oxide material, based on CuO nanoparticles deposited on a conductive CuO-passivated porous dendritic copper foam, is a highly efficient water oxidation catalyst.

Ghent what it used to be: A combination of large- and microscale chemical/elemental imaging supplied compositional information for the entire paint surface of the verso wing panels of van Eyck's Ghent Altarpiece. MA-XRF scanning allowed visualization and assessment of the original paint layers hidden below the overpainted surface. In this way, elemental imaging provided objective arguments supporting the decision for full removal of the overpaint.

A two-stage dissociation system based on multifunctionalized polydopamine-coated gold nanoparticles (AuNPs) for the multilayer imaging and monitoring of various biomarkers and their interactions is described.

Triple salt: The first lithium nitridoborophosphate Li₄₇B₃P₁₄N₄₂ was synthesized by two different approaches using a Li₃N flux. It consists of noncondensed [P₄N₁₀]¹⁰⁻, [P₃N₉]¹²⁻, and [B₃P₃N₁₃]¹⁵⁻ ions in a matrix of Li⁺ ions. The formation of the novel [B₃P₃N₁₃]¹⁵⁻ ion suggests a great potential of the Li₃N flux method for synthesis of unprecedented anion topologies.

An exchange is as good as a rest: Nitridosilicates are solid-state materials consisting of cations embedded in highly condensed anionic tetrahedra networks. A new synthetic method enables the exchange of cations, while the networks remain preserved. This route gives a significant increase in synthetic control, thus providing the possibility of synthesis planning in nitridosilicate chemistry. The predicted compounds Mg₂Si₅N₈ and β-Ca₂Si₅N₈ were prepared using this route.

Opposites attract: A phosphorus bora-ylide stabilized by an N-heterocyclic carbene ligand was synthesized. Experimental electron density analysis and DFT calculations indicate enhanced phosphorane character (rather than ylide character) with an exceptionally strong B→P π-back bonding compared to related compounds; this is due to the electronegativity difference between boron and phosphorus atoms.

Sulfonium catalyst: Whereas chiral quaternary ammonium and phosphonium salts are commonly used for asymmetric organocatalysis, chiral tertiary sulfonium salts have not been employed for such purposes. It is now shown that chiral bifunctional trialkylsulfonium salts catalyze the enantioselective conjugate addition of 3-substituted oxindoles to maleimides under base-free neutral phase-transfer conditions.

Three to one! A [2+2+2] modular synthesis of multisubstituted pyridines with excellent regioselectivity has been realized by copper catalysis and involves three distinct components: vinyliodonium salts, nitriles, and alkynes. The reactions proceeded with the facile formation of an aza-butadienylium intermediate by alkenylation of the nitrile with a vinyliodonium salt.

Collect the full set of four! A chiral amino alcohol was used as the directing group for the asymmetric allylboration of ketimines with nonchiral γ,γ-disubstituted allylboronic acids (see scheme). The amino alcohol not only serves as a cheap source of nitrogen and chirality, but also dramatically enhances reactivity. This versatile method can be used to access all four stereoisomers of a product with respect to the adjacent quaternary carbon centers.

Efficiency that will bowl you over: The activation of aromatic C−F bonds in the presence of more labile C−Br and C−Cl bonds enabled the fully controlled synthesis of halogenated bowl-shaped polycyclic aromatic hydrocarbons through intramolecular aryl–aryl coupling (see picture). Besides its simplicity and high reproducibility, the technique provides access to halogenated bowl-shaped systems that are not accessible by other methods.

Zirconocene zipper: An efficient fivefold reductive cyclization demonstrates the promise of a new strategy for the construction of graphene nanostructures. Protodemetalation of the resulting zirconacyclopentadiene-annulated polycyclic aromatic hydrocarbons provides a conceptually unique means for the generation of valuable ortho-quinodimethane structures.

Seeing double: Low-coordinate iron(II) complexes have been used in the hydrophosphination of isocyanates to produce, by mono- and/or diinsertion, phosphinocarboxamides, a new family of derivatized organophosphorus compounds. Small changes in reaction conditions drastically alter the product selectivity.

Adding a fluorosulfonylvinyl group: Catalytic Pd(OAc)₂ with a stoichiometric amount of silver(I) trifluoroacetate enables the coupling process between either an (hetero)aryl or alkenyl iodide with ethenesulfonyl fluoride. The method is demonstrated in the successful syntheses of eighty-eight otherwise difficult to access compounds, in up to 99 % yields. The method does not require base, phosphine ligand, anhydrous solvent, or an inert atmosphere.

Collect. Select. Reflect: para-Selective C−H borylation of benzamide and pyridine adducts is controlled by a combination of iridium and bulky aluminum-based Lewis acid catalysts. Variously substituted (hetero)arylboronates were prepared, which are versatile synthetic intermediates for complex multi-substituted aromatic compounds.

Oxygen-containing amorphous cobalt sulfide porous nanocubes with Co−S dangling bands, a distorted CoS_4.6O_0.6 octahedral structure, and incorporated oxygen in the CoS_x have been prepared. The material shows outstanding electrocatalytic activity for water oxidation in alkaline and neutral electrolytes. vac=vacancy; Co blue, S yellow, O red, H white.

A sustainable plastic was synthesized by dinuclear chromium-complex-mediated copolymerization of CO₂ with an epoxide that could be recycled back into the monomer in quantitative yield under mild conditions. Temperature was used as a reversible switch in the recycle process. These characteristics are in accordance with the concept of perfectly sustainable polymers.

Fixed to fix: Carbon nitride nanosheets bind strongly with a binuclear ruthenium(II) complex even in basic aqueous solution, enabling durable, selective CO₂ reduction into formate under visible light.

Small cause, big effect: A covalent polyoxometalate (POM)–benzospiropyran (BSPR) dyad is an unprecedented example of an organic–inorganic molecular switch that displays a specific fluorescence feature in each photochromic form. The fluorescence of the BSPR unit of the POM-based hybrid is considerably enhanced compared to BSPR reference compounds, which is attributed to a more easily accessible emitting state in the hybrid.

Cross-couplings under electrochemical conditions selectively provide protected 2,2′-diaminobiaryl derivatives. For clean conversion, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and glassy carbon should be used as the electrolyte and anode material, respectively. Easily removable protecting groups enable the stepwise and selective liberation of the amine functional groups.

The transfer of an Fe₂S₂ core along with exchange of the capping ligands is a key step during Fe/S cofactor biogenesis. The details of a related process have now been elucidated by mechanistic investigations of the ligand rearrangement in a unique biomimetic [2Fe-2S] cluster.

Where are the protons? Hydrogen atoms are usually difficult to visualize experimentally but are key for a proper understanding of protein–ligand recognition. Using neutron crystallography, it was found that, despite its low pK_a, the amino group of aniline picks up a proton upon binding to the archetypical serine protease trypsin. In contrast, 2-aminopyridine becomes protonated at the pyridine nitrogen atom to give the more stable tautomer of this molecule.