A rarely used element: The chemistry of ligand-stabilized complexes in oxidation state zero was recently extended to the s block with the discovery of a Be₁ complex stabilized by a cyclic (alkyl)(amino)carbene. Combined experimental and theoretical studies provided conclusive evidence that the complex contains beryllium(0).

Separation goes small: Two-dimensional materials of atomic thickness have emerged as high-performance separation membranes. The latest advances in the design and fabrication of 2D-material membranes are reviewed, along with a discussion about the challenges for future applications.

Crossing over: Janus membranes have received widespread interest over the past years. In this Minireview, a special definition of a Janus membrane is proposed and common fabrication methods of such membranes are outlined. Also summarized are the current and potential applications of Janus membranes in directional transport, switchable permeation, and performance optimization.

In a bind: Targeted covalent inhibitors (TCIs), such as HKI-272 (shown in the picture in complex with a protein), first form a reversible association and then a covalent bond between an electrophile on the ligand and a nucleophilic center in the protein. This can offer benefits such as high potency and extended duration of action, and new approaches can limit the risk of serious adverse reactions.

Bubble wrap: Novel hollow prisms formed from CoS₂ nanobubbles have been synthesized via a facile two-step self-templating strategy. The diffusion-controlled processes are responsible for the formation of internal voids in the prism-like precursors and the ZIF-67 building blocks. The as-obtained hierarchical CoS₂ hollow prisms show enhanced electrochemical properties when evaluated as an anode material for lithium-ion batteries.

Metal-ion sensor: An insulated π-conjugated polymer containing metal-binding sites was synthesized. The coordination of metal ions to these sites alters the electronic properties of the polymer considerably. As a consequence the emission wavelength of the polymer varies and the polymer acts as a sensor for metal ions.

Gas-phase reactions: The calculated barriers for the bimolecular reactions of Criegee intermediates and H₂X inversely correlate with the bond strength of the X−H bond of H₂X or directly correlate with the first pK_a value of H₂X. Thus, it is not only the substitutions of Criegee intermediates but also the properties of the heteroatom in H₂X that play a crucial role in determining the reactivity.

Which way to go? A novel synthetic strategy for the divergent synthesis of different classes of aspidosperma alkaloids is described. Key step is the highly chemoselective iridium(I)-catalyzed reduction of cyclic lactams to enamine intermediates, followed by either a highly diastereoselective formal Diels–Alder reaction or a competitive Michael addition/reduction (see scheme; two examples shown).

Single site Pd₁O₄ anchored in microspores of zeolite with 2.0 w % CuO is active for transforming of CH₄ to CH₃OH in aqueous solution in the temperature range of 50–95 °C. Selectivity for production of CH₃OH in this temperature range was found to be 78 %-86 % at 50–95 °C, offering a clear improvement over harsh alternative conditions.

Under pressure: A new superconducting intermetallic compound, Cu₁₁Bi₇, the first in the Cu−Bi binary system, was formed by high-pressure synthesis. The unique structure was determined from single-crystal X-ray diffraction, and the stabilization of the structure by pressure was confirmed by DFT calculations.

A chemical reaction network for small molecules is reported that provides a rapid adaptation response to out-of-equilibrium conditions inside an evaporating droplet. The chemical network provides control over the molecular constitution and spatial arrangement of the deposited solute.

Minimalistic approach: Min proteins (green or red), which are spatial regulator proteins of bacterial cell division, and the cell-division protein FtsZ (blue) were encapsulated in lipid monolayer microdroplets as a simple model of cellular compartments. Through interaction with a lipid membrane at the droplet boundary, the proteins self-organize into patterns that show distinct localization and oscillation modes.

High-quality phase-pure MA_1−xFA_xPbI₃ (x=0.1–0.9) perovskite planar films were deposited in a facile manner by a one-step method. 2D HMA_1−xFA_xPbI₃Cl perovskite (left) was transformed into 3D MA_1−xFA_xPbI₃ perovskite (right) by ion exchange. This 2D–3D perovskite conversion is a promising strategy for fabricating mixed-cation lead halide perovskites. MA=methylammonium, FA=formamidinium.

Thermal oligomerization of a pyridoannulated silylene leads to the formation of remarkably stable silenes. Bonding situations in the resulting products are best described as silenes with a significant zwitterionic distribution of electron density.

Polyelectrolyte (PE) capsules: Using two immiscible aqueous solutions, dextran and PEG, transient double emulsions were created in a microfluidic system and used as templates to fabricate PE capsules. The capsule shell was formed by complexation of oppositely charged PEs, PE+ and PE−, at the interface of the two aqueous phases. This platform enables encapsulation and release of proteins without impairing their activity.

Vesicular microreactors: Fatty acid based, membrane-free coacervates spontaneously sequester proteins and can reversibly form membranous vesicles upon changing the pH value, which leads to protein encapsulation within the vesicles. These micrometric capsules also provide a suitable environment for enzymatic reactions.

Heavy and heavier: Polyoxocations of the heavy metals bismuth and lead were nested inside uranyl polyoxoanion capsules, creating very distinctive X-ray scattering profiles. Matching symmetry and electrostatic attraction between the core and shell clusters enabled the formation of endohedral Pb@U₂₄ and Bi@U₂₄ in high yield and purity.

Chiral promiscuity: During a structure-led herbicide development program, both enantiomers of the lead compound were found to bind at the active site of the target with equal nanomolar potency. The main substituent groups lie in a plane, thus facilitating their equivalent interactions with the chiral surface of the enzyme by mirror-image packing, thus mimicking an achiral reaction intermediate.

Tool up: A new electrophilic difluoromethylthiolating reagent (MesNHSCF₂PO(OEt)₂) was treated with various nucleophiles under mild and metal-free conditions, thus offering an efficient and operationally simple tool for the construction of C−SCF₂PO(OR)₂, N−SCF₂PO(OR)₂, and S−SCF₂PO(OR)₂ bonds. The versatility of this method was illustrated through the synthesis of the non-stereoidal anti-inflammatory compound diflumidone.

The light combo: Through radical translocation, a photoredox-mediated C(sp³)−H activation was combined with asymmetric catalysis. Upon irradiation with visible light, α,β-unsaturated N-acylpyrazoles react with N-alkoxyphthalimides in the presence of a rhodium-based chiral Lewis acid catalyst and the photosensitizer fac-[Ir(ppy)₃] to provide a C−C bond-formation product with high enantioselectivity and, where applicable, with some diastereoselectivity.

The value of nothing: The role of positively charged oxygen vacancies in proton conduction is demonstrated in acceptor-doped BaZrO₃ and BaCeO₃. A combination of density functional theory calculations, impedance spectroscopy, and atomic-column images shows that the control of acceptor-vacancy clustering is an efficient way of overcoming proton trapping toward acceptors.

Hollow structural materials were fabricated from cuprammonium cellulose composite filaments by fast pyrolysis. The whole process could be completed within 100 s. The formation mechanism is related to the heterogeneous structure of the fibers and the gradient distribution of the metal oxides in the cellulose matrix.

Slower dynamics, faster catalysis: Dynamic processes that are key to catalysis can be controlled through remote substituents in the outer coordination sphere, in a manner similar to the role of the protein architecture in enzymes. This approach was used to increase the H₂ production rates of nickel catalysts by three orders of magnitude with a minimal increase in overpotential.

Red-shifted tetra-ortho-substituted azobenzenes were synthesized in a rapid manner with high functional group tolerance (see picture). The privileged tetra-ortho-methoxy, -chloro, and -fluoro azobenzenes become readily accessible, which paves the way for future applications of red-shifted azobenzenes in material and biological sciences.

Two helicenes were synthesized by double fusion of an acene with two perylene diimide (PDI) subunits. These PDI-helicene homologs show different structural and electronic properties, despite differing by only a single ring in the link between the PDI units. The shorter link brings the two PDI subunits closer together, and this results in the collision of their respective π-electron clouds.

Anti-angiogenic Ru(III): A macrocyclic ruthenium(III) complex is found to inhibit endothelial cell angiogenesis and cancer cell invasiveness, to suppress the protein and mRNA expression of VEGFR2 and the VEGFR downstream signaling pathways and to display in vivo anti-tumor activities.

Magnum (DH)PI: Application of dihydropyrido[1,2-a]indolone (DHPI) substrates in Pd-catalyzed asymmetric allylic alkylation chemistry enables rapid access to multiple alkaloid frameworks in an enantioselective fashion. The first catalytic enantioselective total synthesis of (−)-goniomitine, along with divergent formal syntheses of (+)-aspidospermidine and (−)-quebrachamine are reported.

Second that emulsion: For the first time the utilization of a metal complex leads to the formation of water-in-scCO₂ microemulsions. Such a microemulsion provides a promising route for in situ CO₂ reduction to produce formic acid at the water/scCO₂ interface, in a process that provides a high efficiency, adjustable activity, and easy product and catalyst separation.

A layer-by-layer approach was adopted for the synthesis of microcapsules containing two-photon dyes (FITC) and traditional photosensitizers (RB) for two-photon-activated photodynamic therapy. The photosensitizers were indirectly activated by dyes in the same multilayer through one- or two-photon-induced Förster resonance energy transfer (FRET).

Branch out: A general protocol for iso-selective olefin aminocarbonylation has been developed. Key to success is the use of a specific 2-phosphino-substituted pyrrole ligand in the presence of PdX₂. Bulk industrial and functionalized olefins react with various aliphatic amines, including amino acid derivatives, to give the corresponding branched amides in good yields and regioselectivities.

Looks good on paper: An approach that exploits the dual properties of thiol-grafted cellulose paper for promoting copper-catalyzed [3+2]-cycloaddition of organic azides with alkynes and adsorbing residual copper species in solution was developed. Thiol-grafted cellulose paper effects the reduction of Cu^II to catalytically active Cu^I and acts as a powerful adsorbent for copper, thereby facilitating the work-up process.

Electrophilic RNAs were synthesized to generate conjugates with native biomolecules. This strategy is based on diester-squarate-mediated coupling for post-functionalization of RNAs obtained by solid-phase synthesis. The unique reactivity of the squaramate RNAs provided specificity for cross-linking with defined amino groups in complex biomolecules.

Seeing double: A copper/N-heterocyclic carbene catalyzed oxidative vicinal diphosphination of styrenes with diphenyl(trimethylsilyl)phosphine proceeds to deliver the corresponding 1,2-bis(diphenylphosphino)ethanes in good yields. A pyridine N-oxide/MnO₂ combined oxidant uniquely achieves the catalytic turnover of the copper.

Biocatalytic Doyle-Kirmse reaction: Engineered variants of sperm whale myoglobin catalyze the tandem sulfur ylide formation/[2,3]-sigmatropic rearrangement of allylic and propargylic sulfides in the presence of α-diazo esters. This transformation can be applied to a variety of aryl, benzylic, and alkyl sulfide substrates, and gives high product conversion and enantioselectivity up to 71 % ee.

Time to relax: pH capture of small carboxylic acids inside cells allows measurement of their intracellular behavior with a unique pH-dependent chemical shift signature. The intracellular longitudinal relaxation constant (T₁) of these acids is shown to be up to four-fold shorter than the corresponding extracellular T₁. The result has a direct impact on the quantification of real-time cellular kinetics.

[Co(acac)₃]-catalyzed oxidative C−H/C−H bond arylation of unactivated arenes enables the transformation of a wide range of benzamides and arylpyridines to afford bifunctionalized biaryls. A single-electron transfer (SET) and a concerted metalation–deprotonation (CMD) are involved. Moreover, the aryl radicals were trapped by 2,6-di-tert-butyl-4-methylphenol to form benzylated products.

High to low: Two processes that complicate the transition from batch to continuous operations in multistep synthesis are solvent exchange (especially high-boiling- to low-boiling-point solvent) and catalyst separation. Described herein is membrane technology as an enabling platform for coupling these processes in a continuous operation.

Taking position: Preparation of a 4-isoxazolyl anion species from 4-iodoisoxazole using iPrMgCl⋅LiCl enabled introduction of a wide variety of functional groups into the 4-position of the isoxazole ring in good to excellent yields. This approach provides various isoxazolyl metal species which can be used for multifunctionalization of isoxazoles. The step-by-step synthesis of 3,4,5-trisubstituted isoxazoles was achieved by using the this 4-isoxazolyl anion method.

Mobile Li⁺ ions between supertetrahedra: The phosphidosilicates Li₂SiP₂ and LiSi₂P₃ form interpenetrating covalent networks of T2 or T4 and T5 supertetrahedra with diamond- or sphalerite-type topologies. ⁷Li solid-state MAS NMR analysis indicates the high mobility of the Li⁺ ions with small activation energies of 0.07–0.10 eV.

Three in one: In vitro testing of the recombinant polyketide synthase domain AmbDH4 and the C-methyltransferase AmbM reveals their interplay during olefin shift in ambruticin biosynthesis. The AmbDH4 domain shows a triple activity as a dehydratase, epimerase, and enoyl isomerase. Subtle changes in the domain structure probably enable olefin shift via a similar mechanism to that reported for enoyl isomerases.

Jump ahead: Incubation experiments with (11-¹³C,1,1-²H₂)FPP and stereospecifically labelled (1R)- and (1S)-(1-²H)FPP enabled assignment of the previously unknown absolute configurations of three bacterial sesquiterpenes from 1,3-hydride shifts, and provided first experimental evidence for a cyclization mechanism to amorphanes that was previously proposed on the basis of quantum chemical calculations.

The spin within: A carefully designed triarylphosphine oxide scaffold with sterically demanding spirofluorenyl moieties undergoes chemical one-electron reduction at its phosphoryl moiety. The unique stability of the formed radical anion enables the isolation and X-ray crystallographic characterization of this hitherto elusive species.

Iron can: Green and inexpensive iron carbonyl complexes are efficient catalysts for the racemization of chiral alcohols by mimicking the action of Fe-hydrogenases. The combination of the iron-based catalyst with lipase provides a platform for the enzymatic resolution of secondary alcohols. TMS=trimethylsilyl.

Within the membrane: An approach is presented that provides high-resolution ¹H-detected solid-state NMR spectra of water-inaccessible proteins, even in complex environments, such as cellular surfaces. This method was used for studying the molecular motion of the transmembrane section of an ion channel in liposomes and directly in native cell membranes.

A mine of information: The biosynthetic gene cluster for the antiplasmodial natural product siphonazole from gliding bacteria of the genus Herpetosiphon was identified through a combination of genome mining, imaging, and expression studies. Product release proceeds through decarboxylation and dehydration.