Mission possible: Today, catalytic asymmetric variants of nearly all fundamental bond-forming reactions are known, yet catalyst-controlled enantioselective construction of carbon–halogen bonds (see scheme; X=F, Cl, Br) was still missing. This gap has now been filled by a cornucopia of conceptually diverse approaches that provide a novel tool for asymmetric organic synthesis.

The chemistry of triangles: Various types of functional cyclopropane structures (see picture) can be prepared through efficient and selective activation of the triple bond of enynes with electrophilic metal (Au, Pt, and Ru) derivatives. Nucleophilic addition of the double bond then generates metal–cyclopropylcarbenoid intermediates, which undergo skeleton rearrangements and formation of fused rings that contain at least one cyclopropane subunit.

Not just hot air: Complete catalytic cycles under strictly thermal conditions can be studied by means of modern mass spectrometry, and the underlying elementary processes have been uncovered (see picture for the Fe⁺-mediated oxidation of methane by molecular oxygen, with methanol as a catalytic co-reductant). Examples cover aspects of catalysis pertinent to areas as diverse as atmospheric chemistry and surface chemistry.

Incipient hydrogen bonds in water–noble gas complexes, which increase in strength from He to Xe, are manifested by progressive alignment along the OH bond (see picture) according to ab initio calculations. The strength of the interaction in excess of that expected for pure van der Waals forces was assessed experimentally by molecular beam scattering.

Conforming couples: Coupling constants ¹J_CH and CH bond lengths were calculated for various conformations of tetrahydropyran, ethyl methyl ether, and dimethyl ether. The dependence of ¹J_CH on the H-C-O-C dihedral angle does not parallel the n_O→ delocalization (see picture). Dipolar interactions that affect electron densities are proposed to be responsible.

A limited number and variety of polyphosphorus cations exist in comparison to their neutral (polyphosphines) and anionic (polyphosphides) counterparts. A general and facile method has now been developed for the preparation of phosphinophosphonium, diphosphinophosphonium, and cyclotetraphosphinophosphonium cations from polyphosphines. Furthermore, the stability of the cyclopentaphosphorus ring is emphasized (see crystal structure of [Ph₆P₅]⁺).

Treatment of terminal and internal alkynes with diphenylphosphane in the presence of catalytic amounts of a base and cobalt(II) acetylacetonate affords, with perfect and universal syn selectivity, the (E)-alkenyldiphenylphosphane derivatives in good yield (see scheme, acac=acetylacetonate).

At least two possible pathways were found for the Beckmann rearrangement of acetophenone oxime to acetanilide over zeolite catalysts. In the first step, the N atom of the oxime is protonated over the Brønsted acid sites of an aluminum siliceous zeolite (see picture), but not over the silanol groups of a pure siliceous zeolite.

The reversible photoconversion of self-assembling dithienylcyclopentene photochromic switches between an aggregated and nonaggregated state is manifest at the macroscopic level by a fully reversible sol–gel phase transition and results in spatially confined structure formation in an inhomogeneous optical field. The reversibility of aggregation is exploited in dynamic pattern formation (see images).

Intermolecular alkene acylation reactions between acyl silanes and α,β-unsaturated amides with metallophosphite catalysis afford α-silyl-γ-ketoamides with high diastereoselectivities (see scheme). These can be converted into the corresponding γ-ketoamides and α-bromo-γ-ketoamides. Asymmetric catalysis of the acylation delivers the γ-ketoamide in the highest enantioselectivity yet reported for an intermolecular Stetter-type reaction.

Highly versatile intermediates are formed through the Pd-catalyzed cyanoboration of alkynes, which proceeds in a cis fashion. When 1-aryl alkynes are used, the corresponding α,β-unsaturated β-boryl nitriles are obtained regioselectively in good yields with the cyano group α to the aryl group. Suzuki–Miyaura coupling of the products leads to highly substituted α,β-unsaturated nitriles (see scheme).

Bent up energy: Contrary to intuitive expectations, excitation of the low-frequency CH₄(ν₄=1) bending motion enhances the cross section for reaction with Cl atoms by a factor of two or more. This enhancement, which is constant over the collision energy range 0.12 eV to 0.26 eV, implies that shearing motion, in addition to stretching motion, can facilitate CH bond cleavage in this direct abstraction reaction (see scheme; green Cl, purple C, gray H).

A potent crystallization strategy for the synthesis of homogeneous calcite crystals in a variety of morphological forms (see picture) from solutions containing Mg ions and using self-assembled monolayers as nucleation templates is reported. The approach is based on a new phenomenon – template-dependant crystal morphogensis.

Remember how it was …︁? A mechanistic explanation for the chiral-memory effect in Norrish–Yang photoreactions has been obtained by computing the reaction pathway (see figure) at the ab initio level. The results show that both the ultrafast excited-state decay, which occurs at a conical intersection (CI), and the specific hydrogen-bonded structure of the primary diradical intermediate determine the high stereoselectivity of the reaction.

New nucleophiles in the arena of asymmetric catalysis, fused and nonfused N-heterocycles undergo conjugate addition to unsaturated imides and enones in the presence of a chiral [(salen)Al^III] complex with generally high enantioselectivities (see scheme; salen=N,N′-bis(salicylaldehydo)ethylenediamine).

Saving solvent: An aqueous–ethyl acetate biphasic system allows an efficient synthesis of medium- and large-sized lactones by an intramolecular Tsuji–Trost reaction (see scheme, n=1–5). The macrocyclization protocol does not require a large quantity of solvents or a slow-addition technique.

No longer in a class of its own: By using a gel-free platform for activity-based protein profiling (ABPP; see figure), it was shown that the enzyme sialic acid 9-O-acetylesterase (SAE), which shares no sequence homology with other enzymes, is a member of the serine hydrolase superfamily. The site of fluorophosphonate labeling in SAE was identified as serine 127; this residue is essential for catalytic activity.

A gem of a structure: A mixed-metal species with a structure very similar to the beryl structure found in nature is the 1:1:2 title complex (see structure). Its core structure contains a ring of alternating Al and Be atoms bridged by the aliphatic hydroxy group of the citric acid. A 1:1:1 complex isolated from phosphate buffer has a larger cluster structure consisting of six Al–Be–citrate species linked by bridging phosphate groups.

From a theoretical prediction to an experimental finding: Oxidation of two bridging diphenylphosphanido ligands to a neutral tetraphenyldiphosphane is predicted theoretically and achieved experimentally in a trinuclear Pt₂Pd complex (see scheme, R^F=C₆F₅, P*=PPh₂).

Liquid films: Ionic liquids containing dispersed single-walled carbon nanotubes (bucky gels), allow the first layer-by-layer casting fabrication of a fully plastic actuator. This actuator adopts a simple three-layered configuration of soft electrodes and electrolyte layers (see picture) and can operate in air at low voltages.

Residence time controlled reaction: The Swern oxidation of alcohols has been accomplished by using a microscale flow system, consisting of micromixers and microscale tube reactors (see schematic representation; DMSO=dimethylsulfoxide, TFAA=trifluoroacetic anhydride), at higher temperatures (−20 to 20 °C) than those for conventional macroscale batch systems (−50 °C or below).

Networking: In contrast to 3D structured [Ru₂(O₂CR)₄]₃[M^III(CN)₆] (M=Cr, Fe, Co) in which R=Me, 2D layered network structures form when R=tBu (see structure orange Ru, dark blue Cr, light blue N, red O, black C). The magnetic properties of 2D materials are investigated to further understand the magnetostructural relationship of 2D extended networks, and why the 2D material magnetically orders at higher temperatures than the 3D structured magnets.

Bionanoparticles, such as the cowpea mosaic virus, can stabilize oil droplets in aqueous solutions by self-assembly at liquid interfaces. Subsequent cross-linking of the bionanoparticles transforms the assemblies into robust membranes that have covalent inter-bionanoparticle connections. The resulting membranes are nanoscopically thin sheets (see SANS image (SANS=small-angle neutron scattering)), which were examined by fluorescent labeling.

A refrigerator when the light is on. In leaflets of 1 (0.1×50×50 μm³) the large planes display a strong, anisotropic solid-state fluorescence. Owing to its small Stokes shift, this perylene dye may have potential for cooling with light.

The key to the cells: The N-terminal organometallic complex shown greatly improves cellular uptake of a bioconjugate containing the NLS peptide (NLS=nuclear localization sequence) and cobaltocenium carboxylic acid. Nuclear localization of this novel organometallic bioconjugate in HepG2 cells is demonstrated by live-cell fluorescence microscopy (see picture). FITC=fluorescein isothiocyanate.

Na₄N₈ cuboctahedra containing nearly planar N₄ polygons make up, in the solid state as well as in solution, the core of the dimer structures of remarkably persistent bishomoaromatic dianions, which are generated by reduction of preoriented bisdiazenes by sodium. As to the nature of the transannular NN interactions (d_N-N= 2.5–2.8 Å) quantum chemical calculations disclose long bonds.

Something to fret about: Luminescent semiconductor nanocrystals are covered with polymeric ligands which form many bonds to the nanocrystal (NC) and increase their solubility. The ligands are decorated with an organic dye molecule (see picture) so that the electronic interaction in individual nanocrystal–dye complexes can be investigated by fluorescence resonance energy transfer (FRET) experiments. The results show many factors influence the FRET results.

Partly present, partly absent: The solid-state NMR spectra (figure, right side) of the amyloid form of the HET-s prion protein (EM image at left) show the resonances for 43 residues with high resolution, whereas 29 residues give no observable NMR signals. A possible explanation could be that the protein structure consists of both highly ordered and strongly disordered domains.

Air-stable diamino- and dioxophosphine oxides were used as ligands in palladium-catalyzed Suzuki reactions of aryl chlorides. Additionally, a diaminophosphine chloride was applied to palladium- and nickel-catalyzed CC and CN bond-forming reactions.

Unusual conductivity effects: Suitably functionalized dendrimers (see picture) are capable of forming truly covalent three-dimensional networks with remarkably high conductivity on electrochemical doping. Depending on the charging level of the electroactive components used as building blocks for the dendrimer core and the perimeter, two separated regimes of electrical conductivity can be observed.