To mix or not to mix: The N-oxygenase AurF of S. thioluteus has an unusual carboxylate-bridged dinuclear active site (see picture; gray C, blue N, red O, green Mn, turquoise Mn/Fe). The similarity with a recently discovered Mn/Fe-oxygenase subunit of the ribonucleotide reductase of C. trachomatis suggests that it might contain both Mn and Fe. The N-oxygenase of S. thioluteus very likely represents the first member of a new family of Mn/Fe-oxygenases.

Path of least resistance: Reaction pathway bifurcations have been identified for many complex organic transformations. This type of potential energy surface describes a two-step-no-intermediate reaction mechanism that is neither stepwise nor concerted. Selective formation of one product over another is governed by the potential energy surface shape and resulting dynamic effects, not by transition state energetics.

Hybrids of biomolecules and semiconductor quantum dots (QDs) are functional units for the optical, photoelectrochemical, and electrochemical analysis of biorecognition events or biocatalyzed transformations. The size-controlled fluorescence properties of QDs enable multiplexed bioanalysis, and by their coupling to appropriate quencher units, the optical probing of dynamic biocatalytic processes is feasible. The integration of electrodes into biomolecule–QD hybrids allows the measurement of biorecognition processes or transformations by photocurrents.

The complete pathway of the association of a proline-rich motif to an SH3 domain was probed by molecular dynamics simulations. The results indicate a bimodal binding mechanism, in which nature uses the reduction in dimensionality and hydrophobic dewetting as tools to find a simple solution to a seemingly complicated binding process.

Low melting, highly luminescent: [C₃mim][Eu(Tf₂N)₄] (1), [C₄mim][Eu(Tf₂N)₄], and [C₄mpyr]₂[Eu(Tf₂N)₅] are the first lanthanide ionic liquids that do not need stabilization of the liquid state by neutral coligands. They show excellent photophysical properties, such as long lifetimes of luminescence at large Eu^III concentration, small line width, and high color purity (see emission spectrum of 1 and photograph of a sample under UV light).

Attractive liquids: Dysprosium-based ionic liquids 1–3 show the highest response to external magnetic fields to date, allowing magnetic manipulation of the liquid (see pictures). At the same time, the liquids have excellent photophysical properties, such as long luminescence decay times τ and high color purity. The figure shows emission spectra of the ionic liquids.

Shape control: Gold nanorods are synthesized in high yields in the absence of shape-regulating agents in 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ES]). A two-step seeded-growth process is used that capitalizes on the binding affinity of imidazolium cations to gold crystal facets, the stabilization of Au^I in [EMIM][ES], and the reduction of particle growth rates that is facilitated by weak reducing agents.

Photoswitchable: The activity of a dithienylethene-based human carbonic anhydrase inhibitor (hCAI) can be regulated using light. Converting the flexible, ring-open isomer of the photoswitch into the rigid, ring-closed isomer using UV light reduces the inhibition and increases the activity of hCAI by 50-fold. The inhibitor can be turned back on by using visible light, which has many advantages in biological applications.

Sensitive functional groups, including ketone, aldehyde, and ester groups, may be present in aryl indium reagents prepared in good to excellent yields by the treatment of aryl and heteroaryl iodides with indium powder in the presence of LiCl (see example). These functionalized organoindium(III) reagents readily undergo Pd-catalyzed cross-coupling with functionalized aryl iodides, including those containing NH or OH groups.

A final tweak: A new phosphoramidite iridium catalyst (see scheme) allows allylic substitutions to be run with a higher degree of regioselectivity than with other iridium catalysts and under aerobic conditions. Mechanistic aspects, in particular, the reversibility of the catalyst formation by CH activation, are also presented. =dibenzocyclooctatetraene.

Aldol cyclodehydration of 4-substituted-2,6-heptanediones leads to enantiomerically enriched 5-substituted-3-methyl-2-cyclohexene-1-ones, which serve as perfume ingredients and valuable synthetic building blocks. Primary amines derived from cinchona alkaloids in combination with acetic acid are efficient catalysts for this transformation, which deliver both enantiomers of the celery ketone.

Lewis superacidity? In analogy to Brønsted superacids, Lewis superacids can be defined as Lewis acids that are stronger than the strongest conventional and commercially employed Lewis acid SbF₅. The fluorobenzene complex PhF→Al(OR^F)₃ (R^F=C(CF₃)₃) qualifies as an easily accessible, non-oxidizing and stable Lewis acid that conforms with our Lewis superacidity criterion.

A carotenoid from the chemical kitchen: Two sequential Stille couplings of an unsymmetric distannane building block with a bromoolefin and a bromoalkyne terminated a highly convergent synthesis of the title compound, pyrrhoxanthin (see scheme).

One trumps two: Monosubstituted chiral bicyclo[2.2.2]octadiene ligands, derived from carvone, form complexes with rhodium to catalyze the asymmetric addition of boronic acid substrates to α,β-unsaturated ketones (see scheme). The 1,4-adducts are produced in good yield and high enantioselectivity.

Two for the price of one: A method has been developed for the regiocontrolled synthesis of multisubstituted biaryl derivatives. This protocol involves the use of the tert-butyldimethylsilyl (TBDMS) group to direct the regioselective Diels–Alder reaction of a 3-TBDMS-benzyne with a furan derivative and a subsequent Hiyama cross-coupling reaction of the TBDMS group with aryl iodides (see scheme).

Paint by number: High-quality InAs quantum dots (QDs) for near-IR fluorescence (see picture) were synthesized by exploiting interparticle diffusion and self-focusing instead of using the traditional focusing of size distribution. InAs/CdSe core–shell QDs were grown and analyzed by a technique combining TEM and elemental analysis to determine the sizes and molar extinction coefficients of the extremely small InAs particles.

Net result: Two-dimensional nanonets form spontaneously in a chemical vapor deposition reaction. All beams in the nanonet are single-crystalline nanobelts that are connected by 90° joints. The nanonets are roughly 15 nm thick and a few micrometers long and wide (see pictures for three images at different tilting angles), and they assume a C49 TiSi₂ structure.

A bottom-up approach has been used to tune the morphology of single-crystalline hematite from hollow spheres to nanocups. The mechanism involves the formation of nanocups through buckling of the spheres, similar to a deflated ball (see picture). As the shape changes, there is a drastic change in magnetic properties.

Radically Improved: OH radicals formed by quasi-equilibrated steps on oxide surfaces introduce homogeneous pathways that lead to higher rates and C₂ yields in oxidative methane coupling relative to those attained by CH₄ activation with chemisorbed oxygen (see picture; O*: dissociated oxygen atom; R: abstractor). The reactivity of OH^. leads to a weaker influence of the CH bond energies on the relative rates of H abstraction from CH₄, C₂H₆, and C₂H₄.

Designing catalysts: The five-coordinate platinum(IV) complex A and the platinum(II) trans complex B act as precatalysts for the hydroarylation of unactivated olefins. The catalytic cycle features an aryl–olefin insertion at Pt^II and a CH bond activation of the arene solvent as key steps. The Pt^II cis complex C has been observed in hydroarylation reactions of ethylene with benzene.

Cleaning up chlorite: A water-soluble iron porphyrin catalyzes the dismutation of chlorite to dioxygen and chloride. Labeling experiments demonstrate a novel mechanism for OO bond formation. These mechanistic insights should aid in the design of catalysts for remediation of oxychlorine contaminants.

An uncommon catalyst: The β-agostic NSiH⋅⋅⋅M complex 1 (Ar=2,6-diisopropylphenyl) catalyzes a variety of hydrosilylation reactions. Stoichiometric reactions of 1 with unsaturated compounds proceed via the silanimine intermediate A and, in the case of olefins or nitriles, give products of SiC coupling, such as 2.

In the twist: The extent of twisting from planarity in a series of perylenetetracarboxylic diimides (PDIs) modulates the attractive π–π stacking force, revealing an array of inherent molecular recognition codes. Such coded self-assembly directs specific reaction pathways so that a mixture of reactive monomers with different codes results in identical products as when the reactions were carried out in separate flasks (see picture).

Synergy makes it possible: Bifunctional cinchona alkaloids are found to promote the first highly enantioselective organocatalytic aza-Michael reactions with α,β-unsaturated ketones. In addition to utilizing practical catalysts, readily accessible substrates, and commercially available reagents, this reaction affords a synthetically valuable scope that is complimentary to existing methods catalyzed by chiral metal complexes.

It's so simple! Organocatalysts formed through the self-assembly of simple α-amino acids and alkaloid thiourea derivatives (see scheme) are used as highly efficient catalysts for the direct nitro-Michael addition of ketones and nitroalkenes, affording excellent ee values up to 99 %. Enantioselectivity may be tuned by changing components of the self-assembled catalyst.

A small library of modular P,P ligands was screened and a potent Cu-based catalyst system was identified for highly enantioselective 1,4-additions to cyclohexenone with an unprecedented broad spectrum of Grignard reagents. Surprisingly, the highest selectivities were achieved in most cases in 2-methyl-THF, a “green” solvent underestimated so far.

Less basic: By controlling the pH value of the reaction medium, two different gadolinium-containing nanoscale metal–organic frameworks (NMOFs) based on the same building blocks can be synthesized (see picture). The NMOFs carry a large payload of Gd³⁺ centers and are efficient contrast agents for T₂-weighted magnetic resonance imaging. The NMOFs are highly luminescent when doped with other lanthanide ions such as Eu and Tb.

Simultaneous three-component assembly on surfaces mediated by triple H-bonding interactions leading to the formation of linear supramolecular miniatures has been studied on Ag(111) surfaces by STM. In particular, the complementary assembly of two linear modules (see picture, blue and green) and an anthracenyl-capped molecular stopper (red) led to the formation of discrete linear oligomeric, pentameric, and trimeric nanoassemblies.

Electrochemical tuning and structural modification of thiophene-substituted siloles led to silole chromophores with efficient and stable electrochemiluminescence (ECL). By extending silole π conjugation with thiophene units and by constraining the applied potential range, stable radical cations favorable for ECL emission were generated (see graph for an example).

Pass the spin: The internuclear NOE interactions for pharmacophore mapping (INPHARMA) can be used to derive the structure of receptor/ligand complexes for low-affinity lead compounds identified in the early stages of drug discovery. The relative binding mode and, in favorable cases, the absolute binding mode of pairs of competitive low-affinity ligands can be identified with INPHARMA. This is demonstrated for a system comprising protein kinase A (T in the schematic representation) and two activity inhibitors with known structures (L_A and L_B).

The isostructural metal–organic frameworks [{Zn₂(abtc)(dmf)₂}₃] (1 a), [{Cu₂(abtc)(dmf)₂}₃] (2 a), and [{Cu₂(abtc)}₃] (2 b; H₄abtc=1,1′-azobenzene-3,3′,5,5′-tetracarboxylic acid) have high sorption capacities for H₂, N₂, CO₂, and CH₄. Solid 2 b, which has accessible metal sites (AMSs), has a higher H₂ adsorption capacity than 1 a or 2 a (see picture; T=77 K), neither of which have AMSs, because of its lower molecular weight and greater isosteric heat of H₂ adsorption.

Alarming: Multiple sources of errors in DFT energetics of CC bond-forming reactions were investigated by evaluating structural transformations in Diels–Alder reactions: conversion of π into σ bonds and changes in conjugation, hyperconjugation, and branching interactions. A startling overestimation of the π to σ bond conversion is found with most methods, a central problem to all reactions involving addition of π bonds (electrocyclic processes, ene, aldol).

Controlled precipitation: Silica can control the precipitation of a CoFe Prussian Blue analogue (PBA) by reversibly protecting the Co^II ions. The precursors are introduced into a silica sol and precipitation of the PBA is triggered by acidification after condensation of the silica network (see picture). This original method provides a homogeneous nanocomposite with important photomagnetic properties.

Fascillating: Inhibitory coupling by bromine among nanoliter aqueous droplets containing the Belousov–Zhabotinsky (BZ) reaction solution produces anti-phase oscillations and stationary Turing patterns (see picture; reduced catalyst in red, oxidized catalyst in blue). By choosing the fundamental oscillator and the scavenger added to the connecting medium, it should be possible to construct systems with controllable degrees of inhibitory or excitatory coupling.

Decoding biosynthesis: Cage-like depsipeptides have been investigated by a combination of genetic and chemical analyses. Heterologous expression and MALDI-PSD studies reveal that the cyanobacterial protease inhibitors microviridin B and J are synthesized from ribosomally produced prepeptides that are transformed into tricyclic depsipeptides by ATP grasp ligases and processed by a transporter peptidase.

Electron-transfer makes a magnet: 2:1 assembly of [Ru₂^II,IIL₄] paddlewheel complexes and BDTA-TCNQ yielded a new structural type of electron-transfer system with a three-dimensional network structure which exhibits a long-range ferromagnetic transition at T_c=107 K (see depicted χ vs T curve and inset view of structure along the a axis). L=m-fluorobenzoate, BTDA-TCNQ=bis(1,2,5-thiadiazolo)tetracyanoquinodimethane.

Protein splicing under control: Introduction of an O-acyl isomer of a peptide bond into the naturally split Ssp DnaE intein prevents protein trans splicing, which can be recovered upon triggering an O to N acyl shift by deprotection with protease or light (see scheme). This system allows the splicing of a bacterial toxin to be controlled in response to protease activity.