“Ruth” helps iron! A novel method for the non-enzymatic dynamic kinetic resolution (DKR) of secondary aryl alcohols by the use of the planar chiral ferrocene derivative (+)-1 in combination with the ruthenium racemization catalyst 2 yields acetylated alcohols in high enantioselectivity and yield. This development opens opportunities for new developments in the field of non-enzymatic dynamic kinetic resolution.

A convergent and operationally simple method for the preparation of N-linked glycopeptides (see picture) was highlighted in the preparation of three glycopeptide fragments of erythropoietin. These fragments were assembled by ligation chemistry in the first total synthesis of erythropoietin bearing four glycans. This methodology should find far-reaching applications in the synthesis of a whole range of glycoproteins for biological study.

Balance of power: The simultaneous binding of a ligand to two binding sites of a receptor can leads to high selectivity as an agonist and/or antagonist and may induce pathway-specific signaling. This concept offers access to GPCR modulators with an unprecedented receptor-subtype and signaling selectivity profile and, as a consequence, to drugs with fewer side effects (GPCR=G protein coupled receptor).

Opposites attract: This simple realization is the basis for asymmetric counteranion-directed catalysis (ACDC). All reactions proceeding via cationic intermediates are accompanied by a counteranion. Inducing high enantioselectivities in these reactions merely by ion pairing with an enantiomerically pure counteranion has been achieved for the first time during recent years.

Framing the field, this review provides an overview of four ion-pairing strategies that have emerged for asymmetric catalysis of transformations proceeding through charged intermediates or reagents (see picture). Particular emphasis is placed on the mechanistic features that enable high asymmetric induction in these systems.

Aggravating aggregation: An N-terminal domain that is in close proximity to the polyQ domain in the huntingtin protein, htt105–138, is shown to be highly aggregation prone (see scheme). Potential cross-talk between this domain and the polyQ region may play a central role in regulating the aggregation and toxicity of Htt-N-terminal fragments.

Si in sight: A one-pot, single-step synthesis of an acyclic silylsilylene, Si{Si(SiMe₃)₃}{N(SiMe₃)Dipp} (Dipp=2,6-iPr₂C₆H₃), from a silicon(IV) starting material is reported, together with evidence for a mechanism involving alkali metal silylenoid intermediates.

In suspension: The reaction of aziridines with heterocumulenes in the presence of Fe(NO₃)₃⋅9 H₂O in aqueous suspension provides access to functionalized five-membered heterocycles in good to high yields. This protocol has a wide substrate scope, is simple, and uses a nontoxic and cheap catalyst.

Emulsions stabilized by stimuli-responsive microgels were used to perform enzyme catalysis. Many substrates are poorly water-soluble, while enzymes naturally require aqueous environments, thus resulting in a two-phase aqueous–organic system. Smart microgels allow an enzyme-catalyzed reaction to be performed in an emulsion that can be broken under controlled conditions to separate the reaction product and to recycle the enzyme (E) and the microgel.

Doubling up: A chemo- and regioselective oxidative cross-coupling between various N-heteroarene-containing arenes and heteroarenes has been carried out by rhodium- or ruthenium-catalyzed twofold CH activation, to deliver an array of highly functionalized π-conjugated systems.

Cinchona alkaloids were used as Lewis base catalysts in the title reaction. The [4+2] cyclization of α,β-unsaturated acyl chlorides with electron-deficient alkenes derived from oxindole gave the corresponding spirocarbocyclic oxindoles.

A class of well-defined reversible σ-dimerizations of 9,10-dialkoxyanthracene radical cations are presented. Yellow crystals of the σ-dimerized dication dissociate to purple solutions of monomeric radical cations in solution (see scheme). The identity and stability of radical cations were unequivocally confirmed, providing evidence for reversible σ-dimerizations of persistent radical cations of aromatic systems.

Chiral diols with three contiguous stereocenters were synthesized by a highly enantioselective ruthenium-catalyzed asymmetric hydrogenation of racemic α,α′-disubstituted cycloketones involving dynamic kinetic resolution. This new catalytic asymmetric method provides a concise route to the alkaloid (+)-γ-lycorane.

It's a snap: A novel catalytic three-component coupling reaction using simple and easily available substrates leads to a wide range of substituted pyrroles with high regioselectively (see scheme; Xantphos=9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene).

Co-produced: Using [Co(en)₃]^2+/3+ based-electrolytes in p-type dye-sensitized solar cells (p-DSCs) gives record energy conversion efficiencies of 1.3 % and open-circuit voltages up to 709 mV under simulated sun light. The increase in photovoltage is due to the more negative redox potential of [Co(en)₃]^2+/3+ compared to established mediators.

Al and friends: Asymmetric conjugate addition of Me₃Al to β,β-disubstituted α,β-unsaturated ketones in the presence copper and L1 leads to a highly efficient construction of an all-carbon-substituted chiral quaternary center. This result is the first example of an asymmetric conjugate addition of Me₃Al to acyclic enones to give a chiral quaternary carbon center with excellent yield and enantioselectivity under mild reaction conditions.

The early days: Although considered a species to be avoided in peptide chemistry, the intermediacy of 5(4H)-oxazolones is demonstrated to be essential for the formation of peptides through cyanamide and carbodiimide activation in aqueous solution (see scheme).

A wide range of biaryls were synthesized by palladium-catalyzed Negishi cross-couplings at ambient temperature or with low catalyst loading. This protocol features the use of a recently reported aminobiphenyl palladacycle precatalyst to generate the catalytically active XPhosPd⁰ species. Significantly, a wide range of challenging heterocyclic and polyfluorinated aromatic substrates can be employed to give products in excellent yields.

Convergent approach: The total syntheses of (−)-flueggine A and (+)-virosaine B (see scheme) have been accomplished in a concise and convergent manner. Key steps in these approaches were relay ring-closing metathesis reactions for rapid construction of the key intermediates, and 1,3-dipolar cycloaddition reactions for the formation of the natural products.

Complexity from simplicity: Polycyclic ethers are synthesized by cascade reactions involving the use of epoxides as electrophilic traps in the transposition of allylic alcohols. Stereogenic centers are created by functionalizing prochiral sites under thermodynamic control, and remote stereoinduction can be achieved through the use of ketones as conduits.

Ring in the new: A new annulation for the efficient synthesis of substituted furans and pyrroles is reported. The Rh^III-catalyzed reaction of O-methyl α,β-unsaturated oximes with aldehydes and N-tosyl imines affords secondary alcohol and amine intermediates, respectively. Cyclization and aromatization occurs under the reaction conditions to provide access to biologically relevant furans and pyrroles in good yields. Cp*=C₅Me₅, DCE=1,2-dichloroethane, THF=tetrahydrofuran.

Surface analysis: Two-dimensional infrared spectroscopy (2D-IR) was used to probe amide and carboxylate functional groups in the vicinity of gold nanoparticles and their aggregates. The data presented shows that the unique ability of 2D-IR spectroscopy to characterize broadening mechanisms and cross peaks offers new insights into gold nanoparticle capping layer structure and dynamics (see picture).

Frustration leads to overreaction: When diametrically opposed regioselective debenzylation is frustrated, an unexpected double debenzylation reaction affords original tetrafunctionalized cyclodextrins in a controlled and efficient manner. A rationale of the reaction is proposed based on a kinetic study.

Superstar: Branched concave Au/Pd bimetallic nanocrystals (see picture) were synthesized in high yield by seed-mediated co-reduction of Au and Pd metal precursors in an aqueous solution at room temperature. The branches are concave and have high-index facets on their surfaces. These nanocrystals show superior electrocatalytic activity for the oxidation of ethanol and highly efficient SERS enhancement.

Common ground: Copper-catalyzed coupling reactions can be used for the high-yielding preparation of widely used oxazine and xanthene fluorophores from a common diaryl ether intermediate on a gram-scale (see scheme). This general approach may facilitate the future development of novel fluorophores and probes with unique properties.

Guests in a gated community: Introduction of two anthracene groups into a linker in a hemicarcerand creates a new type of photochemically controlled gated hemicarcerand. The reversible opening and closing of the “gate” of the host is controlled photochemically. The encapsulation and release of the guest molecules such as 1,4-dimethoxybenzene is controlled by irradiation with light of different wavelengths.

Banish the villains to their own realm: Biomass has gained widespread attention as a renewable energy source. However, commercial catalysts used in power plants (co-)fuelled by biomass are deactivated by the alkali-rich flue gas (see graph, black line). In contrast, one of two types of active sites in a promising alkali-resistant hollandite catalyst traps alkali-metal ions to free up the catalytically active sites for the reduction of NO by NH₃.

By specifically labeling leucine/valine methyl groups and lysine side chains “inside” and “outside” dynamics of proteins on the nanosecond timescale are compared using neutron scattering (see picture). Surprisingly, both groups display similar dynamics as a function of temperature, and the buried hydrophobic core is sensitive to hydration and undergoes a dynamical transition.

Light switch: A dendronized salt exhibiting photoswitchable conductivity was designed and synthesized. The salt consists of tetrabutylammonium cations and large, rigidly dendronized borate anions, each bearing eight photoresponsive azobenzene moieties. The conductivity of solutions of this salt can be reversibly switched by irradiation, owing to light-induced changes in the overall size of the dendronized anion and the density of its polyphenylene shell.

Fighting the resistance: Biodegradable and injectable/moldable hydrogels with hierarchical nanostructures (see picture) were made with broad-spectrum antimicrobial activities and biofilm-disruption capability. They demonstrate no cytotoxicity in vitro, and show excellent skin biocompatibility in animals. These hydrogels have great potential for clinical use in prevention and treatment of various multidrug-resistant infections.

Color conversion: A quantum dot (QD) structure consisting of an alloy core (CdSe//ZnS) and multishells (CdSZnS) was prepared (see picture). The photoluminescence of the QDs could be tuned especially in the green-light region by controlling the thickness of the inner CdS shell. The alloy core/multishell (AC/MS) QDs showed a quantum efficiency of 100 % and a narrow spectrum width.

Keeping a broad (RNA) perspective: Conventional biochemical detection systems only have a 100-fold linear response range. The range of potassium concentrations detected by an RNA G-quadruplex sequence can be broadened by intentionally populating multiple intermediate folding states (see scheme). The folding of the RNA G-quadruplexes was monitored by both circular dichroism and intrinsic fluorescence spectroscopy.

Conformational analysis: An approach to the prediction of RDCs from disordered protein chains, integrating the effect of nearest neighbors and the alignment characteristics of the statistical coil, is reported. NMR residual dipolar couplings (RDC) are sensitive probes of conformational sampling in unfolded proteins (see picture).

Two opposing SUMO wrestlers: Simultaneous measurement of multiple SUMOylations was achieved at the single-molecule level by integrating SNAP/CLIP-tag-mediated translation with single-molecule detection (see scheme; SUMO=small ubiquitin-like modifier). This method gives exceptional sensitivity, and is capable of measuring the SUMOylation of different proteins under various physiological conditions.

Release me: Polyelectrolyte capsules with different cargo in their cavities and plasmonic and magnetic nanoparticles in their walls were synthesized. Enzymatic reactions were triggered inside cells by light-mediated opening of two individual capsules containing either an enzyme or its substrate, by using photothermal heating. Furthermore, this technique allows controlled release of mRNA from capsules, thereby resulting in synthesis of green fluorescent protein (GFP).

Copper leads to a breakup: Simple Cu^II salts are shown to be highly reactive as water oxidation electrocatalysts in neutral to weakly basic aqueous buffer solutions of CO₂/HCO₃⁻/CO₃²⁻ or HPO₄²⁻/PO₄³⁻. Coordination to the buffer anions under these conditions prevents the precipitation of Cu(OH)₂, CuCO₃, or Cu₃(PO₄)₂ and appears to stabilize higher oxidation states of copper.

Variation's what you need: Variation of the assembly sequence in which layers of two isostructural metal complexes are built up leads to molecular materials with electrochemical properties that depend on the assembly sequence. These properties vary from reversible electron transfer to unidirectional current flows and even charge trapping. The sequence-dependent assembly strategy has implications for various disciplines that involve self-assembly.

A real turn-on: A luminescent lanthanide metal–organic framework shows strong and fast turn-on responses to N,N-dimethylformamide (DMF) vapor. The selective turn-on effect is triggered mainly by DMF–ligand interactions, along with the removal of quencher, water, from the metal coordination sphere.

Competition with a monovalent cyclodextrin host (blue cones) in solution drives the multivalent binding of a Eu³⁺ complex and a sensitizer molecule to cyclodextrin monolayers through a nonlinear self-assembly process. Adamantyl groups (light-blue spheres) are attached to the EDTA ligand (black) and the antenna molecule (orange), which has a carboxylate group for coordination to the Eu³⁺ ion (yellow or red in free or complexed form, respectively).

Construction of a self-assembled cage complex through three different Zn^II centers is achieved using a Zn porphyrin ligand with four 2,2′-bipyridin-5-yl (bpy) groups. The multiporphyrin cage encapsulates guest molecules unsymmetrically by π–π interactions. Well-balanced aqueous conditions, which allow the formation of both tris(bpy) and hydrated bis(bpy) Zn^II units, result in the unsymmetrical yet well-defined supramolecular structure.

Nuclear inelastic scattering of ⁵⁷Fe labeled [NiFe] hydrogenase is shown to give information on different states of the enzyme. It was thus possible to detect and assign FeCO and FeCN bending and stretching vibrations of the active site outside the spectral range of the FeS cluster normal modes.

Cyclic complex 2 with bridging carbonyl ligands was synthesized from a facile and reversible intermolecular carbonyl–borylene ligand coupling reaction at room temperature. Complex 2 exhibits an unprecedented coordination mode for boron–metal complexes, which is also reflected in its remarkable ¹¹B NMR chemical shift of −57.2 ppm. Findings from spectroscopic, X-ray, and computational studies are presented, along with a proposed mechanism.

It's hip to be a square! The ammines [Li(NH₃)₄][Ind] and [Na(NH₃)₄][Ind] both contain a cation coordinated by four ammonia molecules. Whereas the first shows the anticipated tetrahedral coordination, in the second the metal coordination is unexpectedly square-planar. The solvent-separated ion pair forms a rippled layer structure of alternating planar Na(NH₃)₄⁺ cations and indenyl carbanions that is attributed to NH₃⋅⋅⋅π hydrogen bonds.

Cooperativity is the key for mild catalytic epoxidation: The immobilization of fluoroalcohols on dendritic polyglycerol (by “click chemistry”) provides organocatalysts that can form multiple hydrogen bonds. The epoxidation of alkenes with aqueous hydrogen peroxide proceeds efficiently in the presence of dendritic fluoroalcohol catalysts. The supported catalysts can be separated by membrane filtration and reused.

Only one path applies: To date, five different mechanisms have been suggested for the P450-catalyzed N-hydroxylation of primary aromatic amines. Computational analysis employing density functional theory demonstrates that only the H-atom-transfer pathway, that is H abstraction from an amine N followed by a radical rebound step, on a low-spin route can contribute to the aromatic hydroxylamine formation.

The dopamine receptor D2 (DRD2), a G-protein coupled receptor is expressed into PBd₂₂-PEO₁₃ and PMOXA₂₀-PDMS₅₄-PMOXA₂₀ block copolymer vesicles (see scheme). The conformational integrity of the receptor is confirmed by antibody- and ligand-binding assays. Replacement of bound dopamine is demonstrated on surface-immobilized polymersomes, thus making this a promising platform for drug screening.

Chemistry meets graphane: A Birch-type reaction using frozen water as a gentle proton source causes the exfoliation of graphite and formation of hydrogenated graphene with electronically decoupled π-nanodomains. This highly functionalized graphene displays pronounced fluorescence.

The golden state: Selective 5-exo- and 6-endo-cyclizations of an alkynyl benzothioamide have been achieved. The selectivity is controlled by the oxidation state of the gold precursor (+I or +III), yielding two new types of carbene ligand: an (aryl)(heteroaryl)carbene and a six-membered mesoionic carbene (see scheme). Mes=2,4,6-trimethylphenyl.

Making light work of RAFT conjugation: A non-activated RAFT agent at the end of RAFT polymers can readily be coupled with ortho-quinodimethanes (photoenols) in a photo-triggered Diels–Alder reaction under mild conditions without catalyst (see scheme). The method is universal and opens the door for the conjugation of a large number of RAFT-prepared polymers with photoenol-functionalized (macro)molecules. (RAFT=reversible addition-fragmentation chain transfer.)

Vanadium pentachloride and molybdenum and rhenium hexachloride are all thermally unstable but can be prepared by metathesis from the corresponding fluorides with BCl₃ at low temperatures. MoCl₆ is structurally related to β-WCl₆, and ReCl₆ to α-WCl₆. VCl₅ is a dimer in the solid state (see structure; V red, Cl green).