It takes two to tango: The “reduced”, divalent lanthanides M²⁺ have electronic ground-state configurations of either 4fⁿ⁺¹5d⁰ (blue) or 4fⁿ5d¹ (red). The latter may be incorporated in the spacious anions [M(Cp′)₃]⁻ and thus the single d¹ trapped in a z² like SOMO. This chemistry has now been transcribed to U²⁺ (5f³6d¹), a much sought-after species.

Recent metal-free approaches to the hydrogenation of nonpolar double and triple bonds using molecular hydrogen are described. Despite transition-metal-based methodologies for these fundamental chemical transformations, metal-free alternatives are highly desirable. Such technology has only been recently introduced with the aid of frustrated Lewis pairs.

Revealing electrochemistry: Key issues related to the electrochemistry of nanoparticles are being uncovered through innovative techniques capable of relating activity and structure, ultimately at the level of a single nanoparticle. Recent advances in experimental approaches are discussed and assessed, with particular emphasis on those that enhance the fundamental understanding of electrocatalysis and nanoscale electrochemistry.

Oxidized: The reaction of graphene oxide (GO) with ozone results in a high level of oxidation that leads to a significantly improved ionic (protonic) conductivity of GO. This effect originates from enhanced proton hopping, which is due to the higher content of oxygenated functional groups in the basal planes and edges of the ozonated GO as well as the morphology changes that are caused by the ozonation.

Do we know, when designing a new peptidomimetic scaffold like the one shown, how it can resemble secondary structures? Design and modular synthesis of this elongated mimic is reported, and the structure is related to ideal and real structures at PPI interfaces.

A double helping: The title compound was prepared by hydrothermal reaction of NaBiO₃⋅n H₂O, Ba(OH)₂⋅8 H₂O, and KOH at 220 °C. The structure of the double perovskite was determined to be (Na_0.25K_0.45)(Ba_1.00)₃(Bi_1.00)₄O₁₂, and thermally decomposed to a simple perovskite structure above 400 °C. The synthesized compounds exhibit superconductive diamagnetism, and zero resistivity below 8 K.

Varying degrees of hospitality: An M₂L₄ coordination capsule and an M₂L₂ coordination tube formed from Hg^II hinges and bent bispyridine ligands underwent reversible interconversion at room temperature in response to changes in the metal-to-ligand ratio (see picture). Only the capsule accommodated large spherical molecules, fullerenes C₆₀ and C₇₀, and the bound guests were released upon transformation into the tube by the addition of metal ions.

Pores for thought: A vanadoborate with a 38×38×20-ring channel system and a mesoporous pore size (24.7×12.7 Å) has been assembled from zinc-containing elliptical vanadoborate clusters and Zn polyhedra (see picture). CO₂ adsorption studies confirmed the porosity of the as-synthesized material. This structure demonstrates the possibility of constructing 3D ordered mesopores from inorganic cluster compounds.

Thirsty, thirsty PHOMs: The continuous collection of oil spills in situ from the surface of water can be accomplished through external pumping on porous hydrophobic/oleophilic materials (PHOMs). Based on this novel design, oil/water separation and oil collection can be simultaneously achieved, and the oil sorption capacity is no longer limited to the volume and weight of the sorption material.

Changing partner on cue: The interaction between poly(acrylamide)-based hydrogels modified with β-cyclodextrin (βCD gel), ferrocene (Fc gel), and sodium p-styrenesulfonate (SSNa gel) was investigated. The βCD gel and the Fc gel selectively assembled with one another through a host–guest interaction (see picture). On the other hand, when Fc was oxidized to Fc⁺, the Fc⁺ gel selectively adhered to the SSNa gel through a cation–anion interaction.

Making the switch: A fluorophore-spacer₁-receptor₁-spacer₂-receptor₂ system has been developed that shows ionically tunable proton-induced off-on switching of fluorescence, reminiscent of thermionic triode behavior. The three-electrode concept of the triode is also followed in the photo-ionic system by the use of three active units within the structure (see picture).

Unorthodox: Ruthenium catalysts allow stannanes to be added in a trans fashion across the triple bonds of terminal, internal, silylated, and chlorinated alkynes. This pattern violates the basic mechanism of transition-metal catalysis which otherwise secures high cis selectivity in hydrometalations. Cooperative effects between the ruthenium species and protic functionality render reactions of unsymmetrical substrates regioselective. Cp*=η⁵-C₅Me₅.

A new category of crystalline polymer electrolyte has been prepared by the supramolecular self-assembly of PEO (see picture, black), α-cyclodextrin (α-CD, blue), and LiAsF₆. In this polymer electrolyte, the nanochannels formed by α-CD provide the pathway for the directional motion of Li⁺ ions (colored spheres, 5 different environments) and at the same time prevent access of the anions by size exclusion, thereby resulting in good separation of the Li⁺ ions and the anions.

On a plane: An unusual sterically hindered diphosphagermylene (R₂P)₂Ge has been synthesized (see picture; R=2,6-iPr₂C₆H₃). This compound possesses a trigonal planar phosphorus atom; the planarity is due to extensive delocalization of the phosphorus lone pair into the vacant p-orbital at germanium. DFT calculations indicate that the GeP bond has significant multiple bond character.

A preferential catalytic mechanism has been identified for the transformation of acetylene to vinylidene on Pt-Sn surfaces. Unlike a direct H shift along the CC bond in organometallic compounds, this mechanism requires three adjacent Pt atoms. The same requirement is identified for CH bond cleavage. Without three-fold Pt sites, the reaction mechanism changes, and reactions of H transfer and CH bond cleavage are suppressed.

Wafer-thin and mint condition: Fluorinated hexagonal boron nitride nanosheets (F-BNNSs) can be prepared by using ammonium fluoride to exfoliate and fluorinate hexagonal boron nitride. The as-prepared products can exhibit ferromagnetic characteristics at room temperature, which would have good potential applications in spintronic devices.

The importance of β-sheet structures at the interface of protein–protein interactions has prompted the development of a range of synthetic strategies to template and stabilize this secondary structural motif. A tetrasubstituted diphenylacetylene is examined as a central nucleating point for the projection of extended sheet structures in two directions.

A scoff at non-nobles: The reduction of water to hydrogen using a metal-free carbon nitride (C₃N₄) electrocatalyst in neutral and alkaline environments is demonstrated. An efficient, easy, and general method for growing ordered carbon nitride on different electrodes was developed. The metal-free catalyst demonstrates low overpotential values, which are comparable to non-noble metals, with reasonable current densities.

Exchange program: Divergent active-site residues contribute to the substrate recognition and demethylation specificity of RNA/DNA demethylases AlkB, FTO, and ALKBH5. Swapping these residues results in partially switched demethylation activities (see picture). In the implicated inhibitor design principle, such divergent active-site sequences could aid the design of selective inhibitors that discriminate these demethylases.

The use of low-frequency modes (towards 100 cm⁻¹) for structural assignment of peptides is explored. This far-IR region possibly contains detailed information on the secondary structure. The use of Born–Oppenheimer molecular dynamics simulations is discussed to calculate the far-IR signature of peptides.

Hard facts about solution species: Nanoparticles of WO₃ crystallize from a complex precursor structure, as shown by in situ total scattering. The precursor structure exists in solution.

Embracing the CAOS: A click-assembled oxygen-sensing (CAOS) nanoconjugate was developed for studying oxygenation in complex tissue regions. Click-based ligation of preassembled subunits (shown as colored segments) was used to create tissue-penetrating near-infrared-emissive molecular probes, which enable oxygen-sensitive imaging within a 3D tumor spheroid model through the use of confocal phosphorescence microscopy.

Oxygen reduction: Hollow spheres comprising uniform iron carbide (Fe₃C) nanoparticles encased by graphitic layers were synthesized (see picture). The spheres show excellent electrocatalytic activity and high stability in both acidic and alkaline media for the oxygen reduction reaction. A synergistic mechanism is proposed.

Graphite or diamond? The relative stabilities of graphite and diamond are revisited with hybrid density functional theory calculations. The electronic energy of diamond is computed to be more negative by 1.1 kJ mol⁻¹ than that of graphite at a temperature of 0 K and in the absence of an external pressure.

Chiral BINAMs on demand: A highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities.

A two-step process has been developed for the formation of enantioenriched seven-membered-ring aza ketones under mild conditions. The approach consists of a rhodium-catalyzed asymmetric amination of allylic trichloroacetimidates with 2-aminobenzaldehydes (CN bond) followed by intramolecular hydroacylation (CC bond) of the alkenal products and exhibits broad substrate scope and functional-group tolerance (see example).

Basic chemoselectivity: Combination of aryl bromides, allylbenzene, base, and a palladium catalyst usually results in a Heck coupling reaction. With the same reagents, the Heck reaction can be circumvented when a strong base is used. While the base controls the chemoselectivity, the catalyst handles the regiochemistry, affording 1,1-diarylprop-2-enes that are inaccessible by the Heck pathway (see scheme; DCCP=deprotonative cross-coupling process).

A new electrical effect, the so-called supercapacitive swing adsorption (SSA) effect, is reported for the first time. SSA enabled the reversible and selective adsorption and desorption of carbon dioxide by the capacitive charge and discharge of porous carbon materials.

Reduction of two­ ortho-carboranyl-benzenes (see scheme) reversibly lead to the formation of stable, diamagnetic dianions which were isolated as tris(dimethoxyethane) sodium salts and characterized by X-ray crystallography and NMR spectroscopy. Both clusters in these dianions possess an unusual 2 n+3 skeletal electron count and are stabilized by π conjugation with the para-phenylene unit.

Getting ahead on tams: The intramolecular dehydrogenative amidation of aliphatic amides, directed by a bidentate ligand, was developed using a copper-catalyzed sp³ CH bond functionalization process to deliver β-lactams. The reaction favors the CH bonds of β-methyl groups over the unactivated methylene CH bonds, as well as aromatic C(sp²)H bonds and unactivated secondary C(sp³)H bonds of rings.

NiCo in prism: Uniform hollow Ni_xCo_3−xS₄ prisms with a tunable composition can be facilely synthesized through an efficient self-templating conversion method. Benefiting from the unique structural and compositional features, the as-obtained Ni_xCo_3−xS₄ hollow prisms show excellent electrochemical performance as electrode materials for supercapacitors.

Blazing a new trail: 3-Formylfurans were prepared by a gold(I)-catalyzed cascade reaction that involves oxidation, 1,2-alkynyl migration, and cyclization from simple, easily available 1,4-diyn-3-ols. Isotope-labeling experiments and DFT calculations were carried out to elucidate the reaction mechanism.

An unexpected encounter: The protonation of trimethylsilyl-N,N-dimethylcarbamate in the superacid media HF/AsF₅ leads under certain conditions, in addition to dimethyl ammoniumhexafluoridoarsenate [Me₂NH₂]⁺[AsF₆]⁻, to the hexafluoroarsenic(V) acid HAsF₆.

Especially high selectivities were observed in the hydrogenation of various alkenes, ketones, and imines with bis(anthracene)cobaltate(−I) [K(dme)₂{Co(C₁₄H₁₀)₂}] under mild conditions (1–5 mol % cat., 1–10 bar H₂, 20–60 °C). Mechanistic studies indicate the operation in alkene hydrogenations of a homogeneous catalyst formed by initial ligand exchange and stabilized by the coordination of π-acidic alkenes or arenes.

Inorganic alkanes: The monomeric Group 13/15 building blocks H₂EBH₂⋅NMe₃ (E=P, As) have been linked to form cationic chains in a straightforward synthesis in good yields. The backbone consists of alternating B and P or As atoms bearing only hydrogen substituents. DFT calculations give insight into the formation, the bonding situation, and also the structural parameters of the cationic inorganic alkanes.

From two make one: Chemo-enzymatic stereoinversion and enzymatic kinetic resolution have been combined in a simultaneous cascade process to transform racemic substrates (A, ent-A) into optically pure product P. The concept was exemplified for benzylisoquinolines rac-1 yielding optically pure berbines (S)-2. The reaction system comprised a monoamine oxidase (MAO-N), morpholine-borane, and the berberine bridge enzyme (BBE).

An expression platform for ribosomally produced tricyclic microviridins provides fundamental insights into protease–inhibitor interactions and sets the stage for the tailor-made design of peptides selectively targeting different serine-type proteases. The complex structure of trypsin and microviridin J uncovers the intimate protease–inhibitor interactions.

Close association: A BINOL-based bis(3-pyridyl) ligand assembles into a [Pd₄L₈] complex upon coordination to Pd^II ions. The formation of the aggregate is templated by two BF₄⁻ ions that are encapsulated in peripheral cavities. The palladium ions are arranged in a distorted tetrahedral fashion, which forces the ligand to adopt two different conformations (see picture).

Unusual structures and interesting electronic properties characterize the cyclic products from the reaction of TCNE with tetraaryl[5]cumulene. Mechanistic investigations, aided by DFT calculations, outline a likely pathway to the observed products. The addition of MeOH, EtOH, and Br₂ to various intermediates leads to the interesting dendralene compounds.