Stable? or not? A recent Communication in this journal reported the stabilization of low-valent iron(I) in a fully oxidized polyoxovanadate. As this defies ligand-field theory, a re-evaluation of the data reveals the redox chemistry is localized to the polyoxovanadate, while the iron(III) center undergoes a spin-transition upon when the cluster is reduced.

Stable: The authors of the Communication “Stabilization of Low-Valent Iron(I) in a High-Valent Vanadium(V) Oxide Cluster” reply to a Correspondence which offered an alternative interpretation of the metal oxidation states in the one electron reduced iron vanadate (NH₂Me₂)[(FeCl)V₁₂O₃₂Cl]³⁻ and the two electron reduced species (NH₂Me₂)[(FeCl)V₁₂O₃₂Cl]⁴⁻.

Crystal clear? The ambiguity related to the single-crystal nature of elastically and plastically deformable crystals as well as the correct use of the terms “single crystal/crystalline” and “polycrystal/crystalline” are clarified in this Minireview with selected examples of recently reported bending molecular crystals.

Polar opposites: Macroscopic polarization, piezoelectric polarization, ferroelectric polarization, and surface polarization have emerged as promising strategies for accelerating the separation of photogenerated charge carriers either in the bulk phase or on the surface of semiconductor photocatalysts. Recent progress as well as future challenges are discussed.

Back and forth: This Review discusses a particular set of reactions wherein the number and type of functional groups are maintained throughout the reaction and, as a consequence, these reactions tend to be reversible. Examples of metathesis and shuttle reactions that meet these criteria are described to illustrate the breadth of this field and underline the utility of these reactions to the synthetic community.

Making the cut: Some of Cu^II nodes in the metal–organic framework (MOF) HKUST-1 can be transformed into Cu^I by a reducing vapor treatment (RVT). This treatment partially changes the coordination mode of the Cu nodes and thus breaks coordination bonds, resulting in the formation of hierarchical pores from the original microporous HKUST-1.

Better late: The total synthesis of salinosporamide A was accomplished via a late-stage C−H insertion. The core of the molecule was assembled through an aza-Payne/hydroamination sequence starting from an enantiomerically enriched azidiridine alcohol to yield a pyrrolidinone with functionalities in place for further elaboration into the target molecule.

Easy as pecan pie: A high-throughput enzyme assay was developed, based on a combination of click chemistry, fluorous affinity purification, and nanostructure-initiator mass spectrometry. The utility of the technique, called PECAN, was demonstrated by screening a library of cytochrome P450s for activity on valencene.

Cascades to alkaloids: One-pot in vitro enzyme cascades to give tetrahydroisoquinolines from low-cost starting materials were developed based the combination of tyrosinase, tyrosine decarboxylase, transaminase and norcoclaurine synthase enzymes. By introducing substrates or enzymes at different stages in the cascades, this “mix and match” strategy was used to synthesise a range of non-natural alkaloids in good yields and with high stereoselectivity.

See things in a new light: A cobalt(III)–nitrosyl complex has been designed and synthesized for the study of NO-dependent cell signaling. Photolysis of this complex releases NO with high spatiotemporal control, both intracellularly and extracellularly, allowing the study of the cell signaling pathways activated by endogenously and exogenously produced NO, respectively.

New tool for forensic science: Polycyclic aromatic hydrocarbons modified with a BN unit show outstanding luminescence properties. In powdered form, these compounds can be used for fast and high-resolution imaging of latent fingerprints under simple operating conditions. Even the second level of unique details of the fingerprint can be visualized.

It's a nano-trap! A MOF-based methane nano-trap that features oppositely adjacent open metal sites is proposed for capturing methane from CMM. The nano-trap has a record-high methane uptake at ambient pressure and a new benchmark for CH₄/N₂ separation. The binding mechanism was investigated by single-crystal X-ray diffraction experiments and molecular simulation studies.

Ligand-free POSS nanoparticle surfactants can assemble at a liquid–liquid interface and lock in non-equilibrium shapes. Their use thus constitutes a facile alternative strategy for Pickering emulsification and structuring liquids, complementing typical approaches based on the use of colloidal microparticles and ligand-stabilized nanoparticle surfactants.

Forging rings with iron: A biocatalytic strategy for the highly stereoselective cyclopropanation of benzofurans is reported. This enables the efficient construction of enantiopure 2,3-dihydrobenzofuran-based tricyclic scaffolds that are useful for the synthesis of drugs and natural products. Computational and structure–activity studies provide insights into the mechanism of this reaction and the protein-mediated control of its stereochemical outcome.

Scan here for info: Novel Tm³⁺-sensitized NIR-II nanocrystals with 1208 nm excitation and 1525 nm emission for in vivo information storage and decoding through a lifetime-gated fluorescence imaging approach are reported.

Hindsight is 20/20: anti-[2.2](5,11)Indeno[1,2-b]fluorenophane, which contains a rare 20/20 π-electron system with a large overlapping π orbital and a short π–π distance, has a unique structure. This compound exhibits remarkable transannular interactions, resulting in photophysical and electrochemical properties, as well as photodynamics. The transition from the monomeric excited state to the redshifted H-type dimeric state was observed for the first time.

Uranium sandwiches: Abstraction of iodide from [(η⁵-C₅ⁱPr₅)₂UI] produced the cationic uranium(III) metallocene [(η⁵-C₅ⁱPr₅)₂U]⁺ as its [B(C₆F₅)₄]⁻ salt (see scheme). Appreciable covalency involving 5f and 6d orbitals in the uranocenium cation partially quenched the orbital angular momentum and led to slow magnetic relaxation in an applied field by a Raman mechanism.

The epoxide-opening cascade cyclization of polyepoxides affords tetrahydrofuran (THF) products in acidic aqueous media and tetrahydropyran (THP) in neutral water. THP formation proceeded by simply heating polyepoxides in neutral water and followed a different cyclization mode from those observed so far.

Superflatcaps: A universal interface self-assembly strategy is reported for patterning 2D porous polymers with cylindrical pores on graphene nanosheets. The resultant 2D sandwich-like nanohybrids show great potential for flexible planar micro-supercapacitors.

A single method that allows access to a variety of different conjugated polymers within seconds at room temperature was developed. Key to this privileged reactivity is an air- and moisture stable dinuclear Pd^I catalyst. The method is operationally simple, robust and tolerant to air.

We go together: Two dysprosium clusters with 48 and 76 metal atoms, respectively, were generated under solvothermal conditions by using 3-furancarboxylic acid. The bi-nanopillar Dy₇₆ was formed by the fusion of two Dy₄₈ nanopillars.

Keep calm and carry on (doing kinetics): Two different kinetic analysis methods, based on variable time normalization analysis (VTNA), are described for studying reactions with catalyst deactivation and activation processes. The cases studied are a hydroformylation reaction catalyzed by a supramolecular rhodium complex and an aminocatalytic Michael reaction.

Very positive is the influence of doubly charged antimony Z-type ligand on the electrophilic properties of the corresponding gold complex. The accentuated σ-accepting properties of this new antimony ligand impart atypical reactivity to the gold center, which readily promotes the polymerization and hydroamination of styrene.

Ultrathin porphyrin-based MOF nanosheets with an ultrahigh loading (12 wt %) of single Pt atoms were synthesized by a novel surfactant-assisted coordination strategy. The 2D single-atom catalysts (SACs) exhibit outstanding photocatalytic activity, with a high H₂ production rate of 11 320 μmol g⁻¹ h⁻¹ by water splitting under visible-light irradiation (λ>420 nm).

The fast and the tunable: A bipolar and self-polymerizable phthalocyanine complex is used as the polarity-switchable and high-performance electrode material for lithium-based and graphite-based dual-ion batteries, even all-organic symmetric dual-ion batteries. This approach can bridge the gap between organic batteries and dual-ion batteries.

Blatant favoritism: A class of microporous water-stable MOFs enabled the simultaneous removal of trace amounts of propyne and propadiene from propylene (see picture) to produce polymer-grade propylene with high selectivity (99.996 %) at ambient temperature. A method for the visualization of propyne and propadiene molecules in the single-crystal structure of the MOF helped to explain the strong binding affinity for propyne and propadiene over propylene.

Carbene-like P-C-O: An unprecedented highly reduced form of 2-phosphaethynolate is trapped in a mixed-valence diuranium(III/IV) complex that is best formulated as a uranium-stabilised OCP^2−. radical dianion. It imparts some carbene character to the P-C-O linkage as evidenced by its highly bent geometry and a weak U−C donor–acceptor interaction.

C−I meets π: Homo- and cross-[4+2] cycloadditions of 2-alkenylindoles are reported. The halogen-bond donor catalyst interacts with the alkenylindoles through a C−I⋅⋅⋅π interaction to provide diverse 3-indolyl-substituted tetrahydrocarbazoles.

A mystery NO more: For more than 100 years, copper halides have been known to absorb nitric oxide, but the structures of the products were never elucidated. Rare {CuNO}¹⁰ species that reversibly bind nitric oxide, TBA[Cl₃CuNO] and TBA[Br₃CuNO], have now prepared and structural characterized.

Dimension jump: A new layered zeolite, PST-9, contains an intralayer 2D pore system. Its in situ transformation into a 3D zeolite occurs through the single-layer folding mechanism but not through the traditional dissolution/recrystallization route. The zeolite crystal-growth pathway differs according to the type of organic structure-directing agent employed.

Modulating the charge-transfer pathway in a series of linear donor–acceptor conjugated polymers controls their ability to minimize the exciton binding energy. A low exciton binding energy promotes the photoreaction for artificial photosynthesis

Subunits of MOFs were introduced into traditional zeolite frameworks to obtain applicable adsorbents with advantages of both zeolites and MOFs. The subunits of ZIFs were introduced into zeolite Y and zeolite ZSM-5 for CH₄/N₂ separation. Both the molecular simulation and experimental results confirm that the IAST CH₄/N₂ selectivity of the resulting samples are greatly improved.

Breaking aromaticity: A novel dearomative process is described using arenophile-based chemistry and Pd catalysis. A range of arenes were readily converted exclusively into the corresponding syn-1,4-carboaminated products using Grignard reagents as nucleophiles. The synthetic value of this transformation was demonstrated by several elaborations of the products, including a short synthesis of sertraline from naphthalene.

Poly(difluorophosphazene), an existing polymer with chemical formula of (PNF₂)_n, is predicted to be the first deep-ultraviolet (DUV) nonlinear optical (NLO) polymer material. Calculations show that PNF₂ has a larger band gap, a stronger second harmonic generation effect, a larger birefringence, and a shorter phase-matching cutoff than the DUV NLO material KBe₂BO₃F₂.

Give me wings: The observation of an unusual crystal habit in the common diuretic drug hydrochlorothiazide (HCT) and identification of its subtle molecular chirality reveal that enantiomeric conformers of HCT resolve into a structure of conjoined enantiomorphic twin crystals comprising enantiopure domains of opposite chirality.

AIE polymersomes self-assembled from CO₂ responsive amphiphilic block copolymer PEG-b-P(DEAEMA-co-TPEMA) showed a reversible CO₂-driven vesicle–micelle transition. Vesicles transformed to small spherical micelles upon CO₂ bubbling and micelles returned to vesicles upon subsequent Ar bubbling.

Uranium unencumbered: The first structurally characterized and sterically unencumbered uranium (IV) homoleptic aryl-ate species are reported. MCD spectroscopy and computational studies provide insight into electronic structure and bonding interactions across this series of organouranium complexes with exclusively U−C σ-bonds.

Signal amplification by reversible exchange (SABRE) can provide strong ¹³C pyruvate signal enhancements in seconds through the formation of the novel polarisation transfer catalyst [Ir(H)₂(η²-pyruvate)(DMSO)(IMes)]. By harnessing SABRE, strong signals for [1-¹³C]- and [2-¹³C]pyruvate are readily created.

Tube in tube: A wall- and hybridisation-selective synthetic methodology to produce double-walled carbon nanotubes with an inner tube doped exclusively with graphitic sp²-nitrogen atoms is reported.

Keep it separated: The separation of cis- and trans-1,2-dichloroethene (DCE) isomers by activated crystalline biphen[3]arene materials, MeBP3α, is demonstrated. MeBP3α highly selectively adsorbs cis-DCE from a 50:50 (v/v) cis/trans-isomer mixture, yielding cis-DCE with a purity of 96.4 % in a single adsorption cycle. The uptake of cis-DCE triggers a solid-state structural transformation of the activated MeBP3α crystals.

An ultrafast (1 min) and sensitive (20 ppb LOD) colorimetric nanosensor for organic mercury is presented, based on the combined use of the catalytic and plasmonic properties of gold nanoparticles. The method works in one step, is completely instrument-free, and has ambient conditions operation with clear visual readout.

In two closely related series of lanthanide complexes, a switch in the sign of the dominant ligand field parameter and striking variations in the sign, amplitude, and orientation of the main component of the magnetic susceptibility tensor as the Ln³⁺ ion is permuted mask modest changes in NMR paramagnetic shifts, but are evident in Yb EPR and Eu emission spectra.

On active duty: In situ Raman spectroscopic analysis of ¹⁸O-labeled ultrathin layered double hydroxide has provided evidence for the different active sites of Fe-free and Fe-doped Ni oxides for the oxygen evolution reaction. Whereas lattice oxygen atoms are the active sites in Fe-free Ni-containing oxides, highly reactive surface sites lead to the dramatically increased catalytic activity of Fe-doped Ni oxides.

A one-pot thermodynamic transnitrilation and anion-relay strategy has been developed for the preparation of nitrile-bearing quaternary centers from simple building blocks. This one-pot transformation forms up to three new C−C bonds and involves transfer of a nitrile group from a non-toxic cyanating reagent.

A generous donor: Methyl formate acts as a donor of both methoxycarbonyl and methoxy groups in the Cu-catalyzed alkene difunctionalization reaction. Formation of a diketiminato-Cu^I-styrene ternary complex (1), which was fully characterized, is proposed to accelerate the addition of the nucleophilic methoxycarbonyl radical. TBPA=tert-butyl peroxyacetate, Tf=trifluoromethanesulfonyl.

Character building: A geometrical deviation from the typical square-planar to a distorted tetrahedral geometry has been shown to be responsible for the increased stabilization of a cyclic Rh^I-substituted silylene. The change in the geometry leads to an increase in the π-donating and σ-accepting character of the Rh atom as well as a short Si−Rh bond.

The kinetic resolution of tertiary 2-alkoxycarboxamido-substituted allylic alcohols was achieved through a chiral phosphoric acid catalyzed intramolecular transesterification reaction. Both alkyl,aryl- and dialkyl-substituted tertiary allylic alcohols were resolved with excellent efficiencies, with s factors up to 164.6. This method provides expedient access to enantioenriched oxazolidinones and β-amino alcohols.

Don't cry for me: The direct argentination of fluoroform with t-BuOK and AgOAc in DMF provided a practical approach to AgCF₃. The HCF₃-derived AgCF₃ solution exhibited unique stability and diverse reactivities, such as the hydrotrifluoromethylation of alkenes and C−H trifluoromethylation of arenes.

Put in charge: Methanol synthesis activity has been demonstrated to coincide with the formation of O vacancies during the initial activation period. These vacancies result in a negative charging of the Au nanoparticles during the reaction.

Black gold: In situ formed Au metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form C −C bonds. Turnover numbers up to 29 000 could be achieved by using active carbon as solid support, which allowed convenient catalyst recovery and reuse. This is a rare case where a Au catalyst is superior to Pd catalysts in a cross-coupling reaction of an organic halide and an organometallic reagent.

New markers at the upper end of the THF basicity scale and in terms of P-donor strength are provided by phosphazenyl phosphines. Experimental and theoretical data indicate their suitability as the strongest known electron-donating ligands for application in transition metal complexes.

Need to solve a “problem”? Strong halogen bonding enables the synthesis and investigation of new polypseudohalogen salts and room-temperature ionic liquids (ILs) based on cyanogen bromide, such as [Br(BrCN)₃]⁻. These reactive ILs are capable of dissolving elemental gold and offer themselves as promising compounds in metal recycling.

HOF, step, jump! The cooperative motion of twisted π units serve to develop a thermo-responsive jumping molecular crystal with a hydrogen-bonded organic framework (HOF) of tetra[2,3]thienylene tetracarboxylic acid. The change in the molecular structure triggered by the desolvation of THF in the channels of the HOF induces not only a change in the HOF structure but also a mechanical force.

No bias: Palladium(II)-catalyzed meta-selective C−H allylation of arenes has been developed utilizing synthetically inert and unbiased acyclic aliphatic olefins as allylic surrogates. The reactions are exclusively allylic selective and E-selective, as well as atom economic. DG=directing group.

Salmon and Lister would be proud: The development of new chemiluminescence probes for the direct detection of two of the most widely distributed and deadliest food-borne pathogenic bacteria, Salmonella and Listeria monocytogenes, is described. The two probes could detect their corresponding bacteria with a limit of detection about 600-fold lower than that of fluorescent probes.

Photoelectrode materials for water splitting: As-fabricated poly(2,5-diethynylthieno[3,2-b]thiophene) on Cu foam exhibits a record H₂-evolution photocurrent density of 370 μA cm⁻² at 0.3 V vs. reversible hydrogen electrode, in comparison to current cocatalyst-free organic photocathodes (1–100 μA cm⁻²), during water splitting. This paves a critical way towards the development of high-activity organic photoelectrodes.