Potential for nitrogenase: Milton, Minteer, and co-workers report the first evidence for the bioelectrochemical reduction of N₂ to ammonia by nitrogenase. This complex enzyme could be wired to an electrode by using the soluble mediator methyl viologen; this very simple approach makes it possible to develop a variety of biotechnological devices.

Owing to its unique ability to generate spectroscopic fingerprints, Raman spectroscopy is an emerging technique in bioanalysis and biomaterial imaging. The theory behind this method as well as instrumentation and data-processing methods are discussed in this Review, and the progress in medical Raman imaging since 2012 is summarized.

Supramolecular chemistry meets geometric frustration in axially polar bulk phases of benzene-1,3,5-trisamides (BTAs). The macrodipole moments generated through the formation of supramolecular stacks frustrate during progressive aggregation into hexagonal rod packings. It is shown by total X-ray scattering that the frustration can be utilized to induce spontaneous polarization on the mesoscale.

Mn₂FeSbO₆ ilmenite (R ) is found to show a massive non-linear magnetoelectric coupling at 260 K, breaking local symmetry through the cationic off-centering under the application of an external magnetic field.

Regenerating molecular circuit components: Watson–Crick base-pairing imparts a unique structural programmability to DNA, enabling the design of molecular reactions that perform computations. However, many of the current architectures limit devices to a single operational cycle. To overcome this limitation, a device based on coupled enthalpic and entropic reactions that permits the regeneration of molecular circuit components is introduced.

Formally achieved: Enantioenriched α-alkylated aldehydes (2) are synthesized by exploiting the ability of chiral enamines (A) to generate radicals from (phenylsulfonyl)alkyl iodides (1) and trap them in a stereoselective fashion. Coupling this step with the simple desulfonylation of 2 provides a method to install either a methyl or a benzyl moiety with high stereoselectivity. SET=single-electron transfer.

In motion: A polyrotaxane monolith has been fabricated using a direct-writing 3D printing method. The monolith exhibits reversible shape deformation and recovery capabilities controlled by the cyclodextrin ring motions on the axle of the polyrotaxane. DMSO=dimethylsulfoxide.

Bioactive tricyclic peptide ligands: A small phenyl molecule with four isosteric thiolate-reactive groups of varied reactivity was discovered. This molecule was used in combination with cysteine/penicillamine thiolate groups of different nucleophilic reactivity for precisely regulated and efficient locking of a linear peptide into multicyclic topologies through a one-pot reaction.

A golden opportunity: Traveling-wave ion mobility (TWIM) mass spectrometry (MS) was used to separate isomeric metalated peptide ions derived from gold(I) complexes, enabling the acquisition of distinct product ion spectra for each isomer (blue and red). Measurements of the collision cross-sections showed that the aurated peptide has a slightly more compact structure than the parent zinc finger.

Lighting up resistance: A fluorogenic probe for the detection of carbapenemase activity has been developed. The utilization of carbapenem as the enzyme recognition motif in this reagent leads to remarkable specificity for carbapenemases over other prevailing β-lactamases, enabling the rapid detection of carbapenemases.

A polyoxometalate double-anion complex, H₁₃[(CH₃)₄N]₁₂[PNb₁₂O₄₀(V^VO)₂⋅(V^IV₄O₁₂)₂]⋅22 H₂O, with a unique structure has been synthesized and characterized. It effectively catalyzes both hydrolysis of a nerve agent simulant and fast, selective oxidation of a mustard simulant.

The conversion of aryl halides to phenols under mild reaction conditions is a longstanding and formidable challenge in organic chemistry. The rational design of a broadly applicable Pd-catalyzed method to prepare phenols with benzaldehyde oxime as a hydroxide surrogate is now reported. These reactions occur under mildly basic conditions and enable the late-stage hydroxylation of functionally dense aryl halides.

A BN-doped coronene derivative in which the central benzene ring has been replaced by a borazine core is described. UV/Vis absorption, emission, and electrochemical investigations show that the introduction of the central BN core induces a dramatic widening of the HOMO–LUMO gap and an enhancement of the blue-shifted emissive properties with respect to its all-carbon congener.

Hierarchically structured Ni-Cu alloys composed of 3D network-like microscopic branches with nanoscopic dendritic feelers on each branch were crafted by a facile and efficient hydrogen evolution-assisted electrodeposition approach. The resultant structures showed excellent electrochemical response and electrocatalytic activity towards methanol oxidation.

Turning bad into good: By using a simple yet facile annealing treatment, the surface-bound surfactants can be utilized to stabilize Au colloids on supports, rather than cause issues of surface blockage and particle sinter.

Growing strains: The hydrocarbons 1-cyclopentylidene-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene and 1-cyclobutylidene-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene undergo photolysis in solution at ambient temperature to produce cyclohexyne and cyclopentyne, respectively (see scheme). These strained cycloalkynes, formed via the putative cycloalkylidenecarbenes, were intercepted as Diels–Alder adducts.

Coralloid-like W_0.5Co_0.5−xFe_x oxyhydroxides with a precisely controlled amount of Fe were directly grown on the conducting substrate in a facile wet-chemical approach. This material exhibits volcano-type oxygen evolution reaction (OER) activity as a function of the Fe content, and the optimized variant, W_0.5Co_0.4Fe_0.1 is particularly active and stable towards OER catalysis.

Shields designed to last: When cyclic polymer ligands are grafted onto inorganic nanoparticles (NPs), ultra-dense and highly compact brush shells are generated. Core-cyclic shell NPs are significantly more stable than their linear brush-functionalized counterparts and show full bio-inertness towards serum proteins.

Light my fire: The metal pentazolate anion complex Co(N₅)₂(H₂O)₄⋅4 H₂O was obtained by reacting (N₅)₆(H₃O)₃(NH₄)₄Cl with Co(NO₃)₂⋅6 H₂O in a methanol/water solution at room temperature. Single-crystal X-ray crystallographic characterization and the physical properties of the comburent material are presented.

HACA quo vadis? Hydrogen-abstraction/acetylene-addition (HACA) has been central to rationalize the origin and the formation routes leading to the polycyclic aromatic hydrocarbons (PAHs). The detection of phenanthrene in the reaction of ortho-biphenylyl radical with acetylene under combustion-like conditions validates the formation of PAHs beyond naphthalene and provide legitimacy to alternative scenarios such as a vinylacetylene-mediated mechanism.

Going strong: A strong Brønsted base catalyzes 1,4-addition reactions of alkylazaarenes for the first time. The desired reactions with α,β-unsaturated amides proceed under mild reaction conditions to afford the 1,4-adducts in high yields. KHMDS=potassium hexamethyldisilazide, THF=tetrahydrofuran.

But first, coffee: A rapid ligand-to-ligand energy transfer observed in the first example of a donor–acceptor corannulene-based scaffold is similar to the energy that a cup of coffee could provide. Many components can be added to the corannulene bowl, similar to cream and sugar added to coffee, highlighting the possibility of merging the intrinsic properties of π-bowls with the tunability of hierarchical materials for applications in optoelectronic devices.

C−H functionalization: A three-component palladium-catalyzed aminocarbonylation of sp² C−H bonds using nitroarenes as the nitrogen source was achieved using Mo(CO)₆ as the reductant and origin of the CO. This intermolecular C−H bond functionalization does not require any exogenous ligand to be added.

From CO to ketones with the introduction of α-chirality: A Pd^II/Brønsted acid-catalyzed enantioselective carbonylation–carbocyclization of enallenes has been developed, proceeding through an efficient CO and olefin insertion cascade to yield ketones with α-chirality. A number of chiral cyclopentenones could be easily synthesized in good to excellent enantioselectivity and good yields.

Enantioenriched five-membered-ring 4-spiro-5-pyrazolones were synthesized by the rhodium-catalyzed C(sp²)−H functionalization of 4-aryl-5-pyrazolones followed by a [3+2] annulation reaction with alkynes. The use of a chiral SCpRh catalyst (see scheme) led to excellent enantioselectivity, reactivity, and regioselectivity in this cascade process.

1+1>2: A redox-neutral protocol for the visible-light catalyzed radical alkynylation of unactivated olefins is disclosed. The intramolecular migration of an alkynyl group, by cleaving an inert C−C σ bond, is realized for the first time. A broad range of synthetically useful trifluoroethylated linear alkynes are efficiently produced under mild reaction conditions.

PET tracers from ¹¹CO: ¹¹C-Labeling of peptides by selective N-acetylation at the terminal nitrogen or at internal lysine positions was achieved by applying biphosphine palladium–methyl complexes in the presence [¹¹C]carbon monoxide.

Breaking not so bad: Crack formation of can be effectively harnessed by restricting the drying of a colloidal suspension using a flow-enabled self-assembly (FESA) strategy to yield large-area periodic cracks (i.e., microchannels) with tunable spacing in the colloidal nanoparticle film.

Polyamorous catalysis: Rare-earth-metal precursors supported by moderately bulky ligands mediated polymerization of renewable 3-methylenecyclopentene (MCP) monomers. The rare-earth-metal catalysts were highly active and yielded regiopure 1,4-poly(MCP) with targeted molecular weights across a wide range of polymerization temperatures.

Lineup four: A novel multicomponent synthesis of β-amino amides from aldehydes, anilines, carboxylic acids and ynamides has been developed (see scheme). This process is practical, efficient, and scalable. An isotope labeling study was conducted to elucidate a plausible reaction mechanism.

Leaves discreetly when the job is done: A one-pot reaction of trifluorodiazoethane and higher perfluorinated homologues with various nitroolefins takes advantage of the nitro group as a traceless activating and directing group that is released in the aromatization step to produce 4-substituted 3-perfluoroalkyl pyrazoles with complete regioselectivity (see scheme). The method was applied to the synthesis of the fungicide penthiopyrad.

Ring, ring: Aza-ullazines, which represent a new heterocyclic core structure, were synthesized through a four-step reaction, including a Sonogashira reaction and metal-free cyclization promoted by p-toluenesulfonic acid. The optical and electrochemical properties of selected derivatives were investigated, and they were found to have similar absorption and emission spectra but a higher oxidation potential than the parent ullazine core.

(Sul)fone a friend: The iridium-catalyzed asymmetric hydrogenation of benzothiophene 1,1-dioxides provided access to highly enantiomerically enriched sulfones with substituents at the 2- and 3-position (see scheme). Sulfones of this type are of interest as core structures of agrochemicals and pharmaceuticals. They can also be further reduced to chiral 2,3-dihydrobenzothiophenes, which are not always directly accessible by asymmetric hydrogenation.

An organocatalytic strategy for the asymmetric N-alkylation of indoles and carbazoles was developed in which in situ generated aza-para-quinone methides are employed as the alkylating reagent. With the proper choice of a chiral phosphoric acid and N-protective group (P), the intermolecular C−N bond formation with various indole and carbazole nucleophiles proceeds under mild conditions with excellent efficiency and enantioselectivity.

Ge is not C: Reduction of a stable germabenzene with KC₈ resulted in the formation of the germanium analogue of phenylpotassium, under concomitant elimination of the aryl group from the Ge atom. Its ambident character with contributions from aromatic and germylene resonance structures was supported experimentally and theoretically.

The potassium salt of a borasilene–chloride adduct was synthesized and isolated. Its reactivity and single-crystal X-ray diffraction analysis revealed the double-bond character of its Si=B bond and reduced Lewis acidity. This adduct provides a cyclic product by formal intramolecular C−H insertion across the Si=B bond, possibly via the corresponding base-free borasilene.

The heart of the crystal: A dumbbell-shaped molecule R−C₆H₁₀−CH=CH−C₆H₄−CH=CH−C₆H₁₀−R (R=nC₅H₁₁) generates a liquid crystal phase (X phase) between two N phases. The X phase was investigated by X-ray diffraction, scanning electron microscopy, atomic force microscopy and molecular dynamics simulation. A self-organization mechanism is postulated for formation of the layered structure.

Agarose hydrogels are stiff but chemical carboxylation of the polysaccharide backbone leads to formation of soft gels. Carboxyl groups prevent interchain organization of the polysaccharide into double helices, thereby promoting a β-strand conformation instead. Raman optical activity was used to identify and quantify the higher order polysaccharide structure directly in the gel phase.

When green means stop: The fusion of a bacterial cobalamin (vitamin B12) binding domain (CBD) and a mammalian kinase domain (KD) results in constitutively active signaling in the dark. Signaling leads to developmental defects in zebrafish that can be avoided by green-light illumination to permit normal development (AdoCbl=5′-deoxyadenosylcobalamin, MYR=myristoylation membrane anchor).

Solid chemistry: A convenient method for the preparation of solid zinc enolates with enhanced air and moisture stability is described. These enolates undergo Pd- and Cu-catalyzed cross-couplings. The reactive N-morpholino amides can be readily converted into aldehydes or various ketones. These new zinc enolates were employed in the short synthesis of a 3-formylindole derivative that is a potent inhibitor of tubulin polymerization.

A heavy hitter: Metallothioneins are small proteins that are capable of binding heavy metals through Cys residues, thereby forming distinct metal clusters. It is demonstrated that the MT from the snail Littorina littorea displays a novel three-domain structure that increases its metal-loading capacity. This biologically significant feature may help the organism to survive in environments polluted with heavy metals.

Released in print: Formulations of positively and negatively charged mesoporous silica nanoparticles or spherical gold nanoparticles with a hydrogel bioink were used for biofabrication. Negatively charged nanoparticles are released rapidly and positively charged nanoparticles slowly. This generic principle may allow nanoparticles to be used in biofabrication for spatiotemporal control of drug release.