Chemistry - A European Journal

Win or robust: Selective Sonogashira reactions with 1,3,5-tribromobenzene allowed the introduction of both ferrocenylethynyl and pentametylferrocenylethynyl redox groups around stiff dendrimers, which led to the synthesis of both fully oxidized (ferricinium) dendrimers with 6 or 12 redox groups and a class-II mixed-valence dendrimer (see figure).

Fast, faster, ultrafast: Grafting three identical Bodipy units on a triptycene core allowed regioselective transformation of a single Bodipy through a Knovenagel reaction. The use of two different aromatic aldehydes produced a triptycene platform modified by three different Bodipy dyes. Luminescence properties and transient absorption spectroscopy indicate a fast (ps) stepwise energy transfer from higher- to lower-energy Bodipy units (see figure).

Layer-by-layer assembly of polyelectrolyte films on modified glass substrates, followed by micropatterning by deep-UV photolysis though a mask and immersion of the patterned substrates in a solution of lipid vesicles, afforded lipid bilayer arrays (see figure). The migration behavior of charged lipids in the lipid bilayer arrays under an electric field suggests that these patterned supported bilayers may have applications in studies on the manipulation of charged species in the membrane.

Made in a microwave reactor: Nickel complexes templated around a NO₃⁻ or CO₃²⁻ μ₆ anion are prepared by microwave-assisted synthesis. The magnetic properties and nanostructuration of the Ni₁₂ species on mica surfaces are studied by AFM and grazing-incidence X-ray diffraction. The formation of polycrystalline thin layers is revealed (see figure).

CC coupling: Direct oxidative coupling reactions are an attractive tool for environmentally benign chemistry. The oxidative biaryl coupling reaction of phenols with various arenes at the para positions with hypervalent iodine reagents may also be included in this category. The reaction proceeds under very mild conditions without metal catalysts in a very short time under ambient conditions (see scheme; HFIP=hexafluoroisopropanol).

In a hurry to leave! Nosylates act as an excellent leaving group in various palladium-catalyzed cross-couplings, such as Suzuki, Stille, Heck, and Sonogashira reactions (see scheme). Crystalline, stable, and cheap vinyl and aryl nosylates proved better than classical halides and triflates, consistently giving higher yields of coupling products. Their usefulness in CC bond formation was also demonstrated by the rapid synthesis of the alkaloid dubamine.

In tune with temperature! The transformation of the melting thermodynamic parameters into cohesive free-energy densities (CFED) for 4′-(n-oxy)-i′-methyl-j-methyl-4-cyanobiphenyl (CnL^i′,j) provides a novel linear correlation for predicting melting temperatures in a simple way.

“Black belt” S_Ni and S_Ni′: Deuterium labeling revealed an inherent preference of N- and C-metalated nitriles for S_Ni, rather than S_Ni′ displacement. The fundamental reactivity preferences are harnessed in a series of cyclizations to cis- and trans-decalins that install contiguous quaternary–tertiary and quaternary–quaternary stereocenters (see scheme).

Tantalizingly simple: The common organometallic starting material TaMe₃Cl₂ can be used for the catalytic CH functionalization reaction, hydroaminoalkylation. The substrate scope for this readily accessed compound includes unactivated terminal and internal alkenes, styrene derivatives, and both alkylaryl- and dialkyl secondary amines (see scheme).

Facet-selective growth: Regular ZnO/TiO₂ heterojunctions have been successfully synthesized using a facile hydrothermal technique (see figure). Due to the interfacial lattice matching, wurtzite ZnO can only grow on the eight {101} facets of the anatase TiO₂ single crystals, while the other two {001} facets are untouched. The as-prepared regular ZnO/TiO₂ heterojunctions exhibited enhanced photocatalytic generation of ^.OH radicals and enhanced photodegradation of methyl orange when irradiated with UV light.

Ru being served? Photochromic structural changes of Ru^II/TPA (TPA=tris(2-pyridylmethyl)amine) complexes that contain a diimine ligand are reported. Further metal coordination to the diimine ligand allows interconversion between its open/closed forms (see scheme).

Ta very much: The combination of a niobium or tantalum pre-catalyst that contained an imine-based ligand set and a MeAlCl₂ (MADC) co-catalyst is capable, in the presence of ethyl trichloroacetate (ETA), of polymerising ethylene with activities in excess of 11 000 g mmol⁻¹ h⁻¹ bar⁻¹ for niobium and 20 000 g mmol⁻¹ h⁻¹ bar⁻¹ for tantalum. These systems produced essentially linear, high-molecular-weight polyethylene.

Substrate dependence: The stereospecificity of an enzymatic reduction depends on the way a substrate binds to the active site. By using vibrational circular dichroism, it was shown that the stereospecificity and stereoselectivity of the ketoreductase Tyl-KR1 from a polyketide synthase complex in Streptomyces fradiae are inverted for different surrogates of polyketide-like substrates (see figure).

Golden(I): A convergent asymmetric total synthesis of quinocarcin employed Sonogashira and Au-catalyzed hydroamination reactions (see scheme). The regioselectivity of the intramolecular hydroamination of an unsymmetrical alkyne was switched by substrate control.

Energize your chemistry! 1,3-Dichloro-2-nitro-2-azapropane is the precursor to energetic dense functionalized dipyrazolyl-N-nitromethanamines (see figure). The new compounds exhibit high thermal stability, high performance, and moderate to low sensitivities.

Eco-couple: The cross-coupling of anilines with aryl boronic acids has been achieved under ligand-, base-, and salt-free conditions at room temperature (see scheme). The reaction mechanism, investigated through experimental and theoretical studies, proceeds through the formation of an aryl palladium alkoxo complex, which enables the transmetalation step without any external base, and gives only environmentally friendly byproducts.

To π or not to π? The ratiometric phosphorescent ion-selective responses of axially rotating binuclear assemblies have been investigated by using X-ray crystallography, DFT calculations, and various spectroscopic techniques to provide an insight into the binding mechanism (see figure). These results may carry important implications for stimuli-responsive luminescent host complexes that engage in intramolecular interactions.

Chasing the active impurity: In the validation of a screening hit it was discovered that a polymeric trace impurity was responsible for the biological activity. Such a side product can be formed with similar compounds. During the investigations it was discovered that the negatively charged macromolecule interacts very efficiently with the protein surface of E. coli RNAP via electrostatic interactions.

Two-in-one fluorescent compounds: Blending the strong emitter, diquinaldinato aluminum, and the good electron transporter, tetraphenyl silole, resulted in highly fluorescent compounds that are promising candidates for light-emitting devices without the need of dopants (see figure).

Coming to the surface: Surface-bound molecular assemblies (MA-1 to MA-3) were constructed by an iterative solution deposition approach. The formed MAs consist of either oligofuran or oligothiophene chromophores coordinated to a palladium salt.

A one-pot wonder: 1,2,3,4-Tetrahydroisoquinolines with a C4 stereocenter can be formed by using a one-pot multicomponent chiral-phosphoric-acid-catalyzed transformation of a mixture of oxetane-tethered benzaldehydes, amines, and the dimethyl ester derivative of the Hantzsch ester (see scheme). This transformation can be used to prepare the spermidine alkaloid, (+)-(8S,13R)-cyclocelabenzine.

Spectroscopic optimization: Optimum conditions for the lithiation of tetrahydroisoquinolines were established by in situ IR and NMR spectroscopy. The use of n-butyllithium in THF at −50 °C for less than 5 min is preferable to the reaction at −78 °C. The organolithium was quenched with electrophiles to give 1-substituted tetrahydroisoquinoline products (see scheme).

Still elusive: Several attempts to yield the elusive, unsupported Lewis adduct between a Lewis basic transition-metal complex and a Lewis acidic borane are presented, including NMR spectroscopic characterization at low temperatures, isolation of secondary products and detailed DFT calculations (see figure).

New dimensions: Three selenidostannate phases yielded from complex transformation pathways in ionic liquids include (in part reversible) dimensionality changes of the anionic Sn/Se substructures (see figure). As rationalized by DFT investigations, the transformations are provoked by competing influences of temperature and amine addition (DMMP=2,6-dimethylmorpholine, en=ethane-1,2-diamine).

The time capsule: Three ferrocenyl-functionalized tripodal hexaurea anion receptors were designed for sulfate recognition. Owing to its trigonal-bipyramidal shape, a meta-phenylene-bridged ligand can encapsulate two SO₄²⁻ ions in two distinct steps. CV studies showed two types of electrochemical response of the Fc/Fc⁺ redox couple upon anion binding, that is, a shift of the wave and the appearance of a new peak.

Suggesting novel disconnections: A powerful Ni-catalyzed cascade reaction involving cyclization followed by cross-coupling allows the formation of up to three alkyl–alkyl bonds in a single operation by using alkene-containing alkyl iodides and Grignard reagents (see scheme; acac=acetylacetonate; TMEDA=N,N′,N′-tetramethyl ethylenediamine). Mechanistic experimental and computational studies suggest a Ni^I–Ni^II–Ni^III catalytic cycle and the intermediacy of radicals.

Shrink wrap: A “threading followed by shrinking” method, which was used to extrude both arylmethyl sulfone motifs from the macrocyclic components of dialkylammonium-ion-based [2]pseudorotaxanes, afforded robust [2]rotaxanes that were sufficiently stable to maintain their molecular integrity in CD₃SOCD₃ at 393 K for at least 5 h (see figure).

Lining ′em up: Strong Brønsted acids, H(OEt₂)[1] and H(OEt₂)(NCMe)[1] ([1]⁻=[TRISPHAT]⁻=P(1,2-O₂C₆Cl₄)₃]), were prepared and characterized. It is shown that H(OEt₂)₂[1] is a very effective weighable single-component initiator for the cationic polymerization of vinyl ether, α-methylstyrene, styrene, and isoprene at reduced temperatures (<−50 °C) to afford moderate- to high-molecular weight polymers (see figure).

HAH1, the Hg^IIcarrier? Trafficking of Cu^I in human cells is achieved through complexation by the metallochaperone, HAH1. In addition, HAH1 strongly binds Hg^II; the solution behavior of Hg^II–HAH1 complexation (see figure) has remained obscure, but is elucidated in this work. We report structures which may represent central intermediates in the processing of Hg^II ion.

Bulky phosphinines: An asymmetrically substituted, bulky, and atropisomeric phosphinine has been prepared and characterized (see figure). Rapid CH activation on the 2-aryl substituent of the phosphorus heterocycle was achieved with [{Cp*IrCl₂}₂] (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) as a metal precursor. A racemic mixture of the phosphinine acted as a π-accepting low-coordinate phosphorus ligand in the Rh-catalyzed hydroformylation of 2-octene.

Lewis and Brønsted catalysis: In this work it is shown that iron(III) catalyses as efficiently as gold(I) the hydroaddition of a wide array of nucleophiles including water, alcohols, thiols, amines, alkynes, and alkenes to multiple CC bonds (see scheme).

Tunable quinone methide formation: Aromatic substituents and the benzylic leaving group strongly affect the H₂O₂-induced formation of quinone methides (QMs) from arylboronic esters (see scheme). The reactivity of arylboronic esters can be predictably adjusted by varying substituents.

Rule breakers: Silyl hydride complex [(ArN)Mo(H)(SiH₂Ph)(PMe₃)₃] undergoes a silane-assisted exchange of coordinated and free phosphines and catalyzes the hydrosilylation of carbonyl groups through an unexpected mechanism (see scheme), as studied by using DFT.

Two solvents, two enantiomers: Enantiodivergent hydroquinidine 1,4-phthalazinediyl diether ((DHQD)₂PHAL)-catalyzed chlorocyclization of unsaturated carbamates, controlled solely by the choice of solvent, yields oxazolidinones in high enantioselectivity (see scheme; DCDMH=1,3-dichloro-5,5-dimethyl hydantoin). The origin of the observed enantiodivergence is traced back to a solvent-selected entropy–enthalpy balance between pro-R and pro-S pathways that dictates the course of the reaction.

Position is everything: The position of the nitrogen atoms and groups of cruciforms containing both pyridine and N,N-dimethylaniline moieties has a profound effect on the photophysical properties (solvatochromism, fluorescence quantum yields, fluorescence lifetimes, and their response to a change in the pH of the environment) of these compounds. This effect is in part due to the meta-positioned nitrogen atoms and groups of the excited states having surprisingly large orbital coefficients in the HOMO (see picture). Additionally, these compounds show promise as pH sensors.

Cascade reactions: A variety of novel cascade reactions can be performed when the known and well-studied radical 5- or 6-exo-cyclization of an aryl diazonium salt is conducted in the presence of alkenes and further optional scavengers (see scheme).

Get asymmetric! Asymmetric [4+1] annulation of sulfur ylides and N-(ortho-chloromethyl)aryl amides allowed the formation of the desired cycloadduct with moderate to high yields and enantioselectivities (see scheme). The described strategy, taking advantage of chiral sulfur ylides, represents a direct procedure to access chiral 2-substituted indolines.

Two is better than one! Dual activation of isatins and formaldehyde tert-butyl hydrazone by 2,2′-diamino-1,1′-binaphthalene (BINAM)-derived bis(ureas) is the key to achieve high reactivity and excellent enantioselectivities in the synthesis of azo and azoxy-functionalized 3-hydroxy-2-oxindoles (see scheme).

One for all, all for one: A single fluorescent probe is shown to recognize eight different aqueous anions and eight urine samples when embedded in ten different polyurethanes in an array that displays 100 % classification accuracy (see figure). To demonstrate the potential of the concept for quantitative studies, an estimation of non-steroidal anti-inflammatory drugs ibuprofen and diclofenac in water and in saliva was performed.

Healing power: Easy access to a tris-urea motif, with the possibility of forming six H-bonds, has been demonstrated. This concept was further extended to the formation of soft functional materials based on polydimethylsiloxane moieties amenable to self-repair (see figure).

All under control: Structural variation of bispidines allows for the preparation of ferrous complexes that adopt magnetic properties of choice under environmentally benign conditions in water at room temperature. Pairs of constitutionally similar, robust chelates with a binary off–on magnetic relationship are obtained (see figure).

See jellyfish in a new light: The origin and differences in the chemiluminescence, bioluminescence, and fluorescence of the proteins of the aequorin jellyfish were theoretically investigated by performing hybrid quantum mechanics and molecular mechanics methods combined with a molecular dynamics method. The findings are important for understanding the bioluminescence of jellyfish and other marine organisms (see figure).

A green way to amino acids: α-Tetrasubstituted α-amino-acid derivatives are formed in high yield and enantioselectivity by using a Rh-catalyzed enantioselective alkynylation of α-ketiminoesters. This reaction, which involves a proton transfer and can be conducted at room temperature, has high substrate scope (see scheme; Cbz=benzyloxycarbonyl, Fmoc=9-fluorenylmethyloxycarbonyl).

A Bigger Bang! 5-(Tetrazol-1-yl)-2H-tetrazole (1,5′-bistetrazole) was prepared according to a modified literature procedure and its chemistry was investigated by the preparation of several new salts with various metal and nitrogen-rich cations, as well as complexes with copper(II). The compounds were characterized and investigated as potential new energetic materials for various applications like primary and secondary explosives or pyrotechnic colorants.

Switching it up! A versatile redox-active diazabutadiene (DAB) ligand containing photochromic dithienylethene rings in the backbone has been synthesized. The coordination of both B^III and P^III has been demonstrated, along with the facile functionalization of the P^III heterocycle with a polymerizable group and the synthesis of a photochromic side-chain functionalizable polymer (see figure).

More Juice: The kinetics of the sulfur/long-chain polysulfide redox couple (S₈↔Li₂S₄; theoretical capacity= 419 mA h g⁻¹) are experimentally demonstrated to be very fast in the Li–S system. A Li–S battery with a blended-carbon interlayer retains excellent cycle stability and high discharge capacity over 250 cycles at 10 C and 15 C rate. The meso-/micropores in the interlayer are responsible for storing the migrating polysulfides and offering sufficient electrolyte accessibility.

A highlyZ-selective asymmetric conjugate addition of alkynyl carbonyl compounds with 3-substituted oxindoles has been developed by using scandium complexes of chiral N,N′-dioxides (L) under mild conditions. The products were obtained in excellent yields and high enantiomeric and geometric control. The catalyst was also found to be effective in the asymmetric acetylenic substitution reaction of 3-substituted oxindoles, giving excellent enantioselectivities (see scheme).

Sweetening up jadomycin A: The first total synthesis of jadomycins B, S, T, and ILEVS1080 has been achieved, featuring construction of the unique 8H-benz[b]oxazolo[3,3-f]phenanthridine skeleton by biomimetic condensation of a quinone aldehyde with amino acid sodium salts and elaboration of the glycosides by Mitsunobu condensation (see figure).

Cerium and nanocubes: CeO₂-supported Pd–Cu-alloy nanocubes (Pd–Cu NCs/CeO₂) with high content and good dispersion of the Pd–Cu NCs were prepared in high yields by heating a solution containing Pd, Cu, and Ce precursors (see figure). The prepared Pd–Cu NCs/CeO₂ has excellent catalytic activity and stability toward formic acid electro-oxidation due to the synergism between the Pd–Cu-alloy catalysts and the CeO₂ support.

It follows the leader: In this article, the biosynthesis of different ribosomally synthesized and post-translationally modified peptides (RiPPs) is discussed. Mechanisms for recognition of the precursor peptide by post-translational modification enzymes are proposed; it is suggested that the leader peptides function as allosteric regulators, and speculations on how enzymes that generate polycyclic products may have been selected for during evolution are discussed.

Batteries not included: A hierarchical flexible electrode that consisted of aligned Ca₂Ge₇O₁₆ nanowire arrays on carbon textile exhibited a highly reversible capacity, remarkable cycling stability, and good rate capability (see figure).

Size matters: The temperature that is required for the elimination of H₂ in magnesium hydride clusters is dependent on the cluster size (see scheme). Detailed experimental and/or theoretical data of magnesium hydride and magnesium(I) clusters are reported.

The assembly of RNA oligomers relies principally on solid-phase approaches, although some alternative methods have been developed to date. A highly efficient and practical method of liquid-phase synthesis for RNA oligomers by using alkyl-chain-type soluble support is reported. The utility of the liquid-phase method through 21-mer RNA synthesis on a gram scale is described (see scheme).

How much should we switch? Two Fe^II₄L₄ tetrahedral capsules were shown to undergo thermally induced spin crossover (SCO). Guest binding to one of these capsules was observed to affect the thermodynamics of its SCO in solution, leading to different spin transition temperatures between the empty host (blue) and the host–guest complex (red). HS: high spin; LS: low spin.

Mix/morph gelators: Chiral dioxalamide dimethyl esters and dicarboxylic acid derivatives (containing flexible methylene bridges with an odd (n=7) and even (n=4) number of methylene groups) are good gelators of polar and lipophilic organic solvents, which are capable of forming diverse gel aggregates of chiral and achiral morphologies sometimes simultaneously present in the same gel system.

Iodine/gold exchange: A gold-catalyzed iodine transfer allows the efficient synthesis of benzofulvenes with iodo substituents on the fulvene core (see scheme). The new dual-activation catalysts are efficient catalysts for this new type of cycloisomerization.

Hydrogen liberation: An attractive approach to reversible hydrogen storage applications is based on the decomposition of formic acid. The efficient and selective hydrogen liberation from formic acid is catalyzed by an iron-pincer complex in the presence of trialkylamine (see scheme). Turnover frequencies up to 836 h⁻¹ and turnover numbers up to 100 000 were achieved at 40 °C. A mechanism including well-defined intermediates is suggested on the basis of experimental and computational data.

Adding value: The direct vinylogous Michael addition of γ-substituted butenolides with a series of 3-aroyl acrylates and 1,2-diaroylethylenes has been demonstrated. This organocatalytic method delivers highly enantio- and diastereomerically pure γ,γ-disubstituted butenolides with adjacent quaternary and tertiary stereocenters (see scheme).

Star quality: Goniopectenoside B, a minor asterosaponin from starfish Goniopecten demonstrans with antifouling activity, has been synthesized in a convergent 21 steps and in 4.3 % overall yield starting from adrenosterone. This represents the first synthesis of a complex asterosaponin, which are ubiquitous and characteristic in starfish as defense chemicals (see figure).

Subsequent mild cyclization of aromatic substrates by Pictet–Spengler condensation to stereoselectively gave new tricyclic compounds. Examples are described in decent yield over two steps in one pot, and a crystal structure is also presented to support the proposed structures (see figure).

Ironing out the details: Proline and pyrrolidine derivatives (Hayashi–Jørgensen catalysts) are considered “work horses” in organocatalysis. This report describes a new effective ferrocenyl pyrrolidine catalyst able to perform well in benchmark organocatalytic reactions (see figure). The ferrocene moiety controls the conformational space and a simple alkyl group effectively covers a face of the derived enamine. This new framework can find applications in organocatalysis, and in general, in new ligand design.

Plasmon-enhanced solar cells were fabricated by using polycrystalline TiO₂ nanotubes (NTs) with embedded Ag nanoparticles (NPs), obtained by coating composites of electrospun poly(ethylene oxide) and Ag NPs with TiO₂ by atomic layer deposition (ALD), as the photoanode. Their plasmon effect can be controlled by varying the thickness of a dielectric Al₂O₃ spacer between the Ag NPs and dye molecules by means of the ALD process (see figure).

Playing the hand-stacking game: The reaction of [2]catenane-containing struts with Cu(NO₃)₂ produces extended frameworks, from whence both co-conformational selection and diastereoselection are observed following crystallization. Solid-state structures reveal the selective formation of stereoregular π–π stacks of enantiomeric pairs of donor–acceptor catenanes, despite the presence in solution of up to eight co-conformational and stereoisomers exhibiting planar chirality (see figure).

Janus-nanoparticle-based nanomachine: This article reports an integrated sensing–actuating nanomachine based on Janus Au–mesoporous silica nanoparticles with gatelike scaffolding for enzyme-controlled cargo release (see figure).

Sieve and take: A biomimetic strategy was designed to fabricate two-dimensional silica sieve plates (SSP) by use of catanionic surfactants as a composite template and L-tartrate with hydroxyl and carboxyl groups as a regulator. Tartrate was found to combine two capabilities in the formation of SSP structures: the connection of adjacent silica structures through H bonding and the separation of adjacent structures through electrostatic repulsion.

Go catalytic! A selective iron-based catalyst system for the hydrogenation of α,β-unsaturated aldehydes to allylic alcohols is presented (see scheme). By applying the defined iron–tetraphos complex [FeF(L)][BF₄] (L=P(PhPPh₂)₃) in the presence of trifluoroacetic acid, a broad range of aldehydes were reduced in high yields using low catalyst loadings.

Pt–CeO₂: Flowerlike Pt–CeO₂ hybrids on reduced graphene oxide (RGO) can be prepared by treating Pt cubes with Ce(NO₃)₃ in the presence of graphene oxide. The density of the CeO₂ coating around the Pt cubes depends on the amount of Ce(NO₃)₃ used. The as-obtained samples exhibit high stability and activity for the catalytic hydrolysis of ammonia borane (AB).

Shining a nanobeacon: Single-label nanobeacon sensors were constructed by using graphitic carbon nanoparticles (CNPs) and their oxides as energy acceptors (see figure). Excellent sensing performances were achieved with simplified operation and lowered cost.

Death of the coffins: Large coffin-shaped H-ZSM-5 zeolite crystals were used as model catalysts for the methanol-to-hydrocarbons reaction (see figure). Their activity and deactivation behavior were tested by the combined use of fixed-bed reactor and optical microspectroscopy experiments. Deactivation by carbonaceous deposit formation was studied by an integral approach to result in a comprehensive coking model.

Never say nivariol again: The interpretation of NMR coupling constants and chemical shifts with the aid of DFT calculations allowed the structural determination of a complex polyether triterpene (see figure). This approach is of particular importance when studying chiral quaternary carbon centers or distant stereoclusters.

Green enlightenment: Electron-withdrawing sulfone groups introduced into the cyclometalating phenylpyrazole ligands lead to very efficient green-emitting ionic iridium complexes. Green electroluminescence from efficient light-emitting chemical cells is obtained (see figure).

Fawcettimine alkaloids: The total syntheses of four fawcettimine-related Lycopodium alkaloids, (±)-fawcettimine, (±)-fawcettidine, (±)-lycoposerramine-Q, and (±)-lycoflexine, are described. The key steps in these syntheses are the Pauson–Khand reaction of 4-methylidene-6-siloxyoct-1-en-7-yne followed by regio- and stereoselective hydrogenation to provide the bicyclo[4.3.0]nonenone intermediate bearing a methyl group with the required stereochemistry (see scheme).

Modified graphene oxide: A simple method has been developed for the simultaneous exfoliation and reduction of graphene oxide (GO) to reduced GO (rGO) by using alkynyl-terminated dopamine as the reducing agent. The reaction was performed under mild conditions to yield rGO functionalized with the dopamine derivative (see figure). The chemical reactivity of the alkynyl function was demonstrated and the surfaces of the rGO characterized by a variety of techniques.

Iron brews biofuels: Highly crystalline, supermicroporous iron(III) phosphonate nanoparticles have been synthesized through a hydrothermal reaction between benzene-1,3,5-triphosphonic acid and FeCl₃. The resulting material was used as an efficient and recyclable catalyst for the synthesis of biofuels under mild reaction conditions (see scheme).

Rechargeable Li–air battery: An efficient catalyst for rapid superoxide (O₂⁻) disproportionation is reported. The negative impact of the reaction between the electrolyte and O₂⁻ produced by the O₂ reduction was minimized (see scheme).

Thioamide bonds: The polymerisation of a thioamide-based supramolecular motif is elucidated by combining depolarised dynamic light scattering and temperature-dependent spectroscopic measurements (see figure). A cooperative polymerisation mechanism and strong amplification of chirality makes this a highly versatile structuring motif.

Molecular (photo)switch: A WCo photomagnetic discrete complex has been prepared through the self-assembly of preformed building blocks. [Co(bik)₃][{W(CN)₈}₃{Co(bik)₂}₃]⋅2 H₂O⋅13 CH₃CN (see figure) exhibits a thermally-induced electron-transfer-coupled spin transition between the two states: W^V↔W^IV. It also shows photomagnetic effects at low temperature.

Domino effect: An enantioselective domino-Wacker/carbonylation/methoxylation process and an enantioselective Wacker oxidation are the key steps in the first total synthesis of the fungal metabolite blennolide A (see scheme).

Redox chemistry: Redox active europium complexes based on a new tris(2-pyridyl)plumbate ligand are described. Reactions of [LiPb(2-py^R)₃(thf)] (py^R = C₅H₃-6-OtBu) with tri- or divalent lanthanoid metals resulted in the first stable Pb–Ln-bonded complexes or unprecedented redox reactions, involving, for example, the pentametallic complex depicted.

Organocatalysis: A concise synthesis of L-pyrrolysine has been accomplished in six steps from simple starting materials. The facile synthetic strategy relies on an organocatalytic Michael addition, an efficient amide coupling, and a challenging method for the imine-bond construction (see scheme).

One MOF, many modifications: The postsynthetic transformation of CC double bonds is a versatile synthetic strategy for the introduction of functional groups in metal-organic frameworks (MOFs). A zinc-based, olefin-tagged MOF was applied to develop the epoxidation, dihydroxylation, hydroboration, and thiol-ene click reaction as new postsynthetic modifications (PSM). The discussed PSMs are high yielding, maintaining the crystallinity and porosity of the frameworks (see scheme).

Ringing in the changes: A one-pot synthesis of 1,2,3,4-tetrasubstituted cyclopentadienes by zirconocene- and CuCl-mediated intermolecular coupling of two alkynes and diiodomethane (see scheme; Cp=η⁵-C₅H₅; DMPU=1,3-dimethyl-3,4,5,6-tetrahydro-2(1 H)-pyrimidinone) gave products that were successfully applied for the synthesis of corresponding zirconocene derivatives.

A simple bifunctional surface-enhanced Raman scattering assay based on primer self-generation strand-displacement polymerization (PS-SDP) can be applied to sensitive SERS assays of either ATP or lysozyme in parallel to using a DNA cycle amplification signal technique (see scheme).

Self-assembly makes good sense: Fluorescent nanoparticles were prepared by two main supramolecular interactions: ionic bonding and hydrophobic/hydrophilic interactions. The fluorescence of the nanoparticles is sensitive to a quenching effect by various ions with high selectivity (see figure).

Nickel HAS it: A Ni(cod)₂/dppp catalyst system promotes the direct alkylation of electron-rich heterocycles with α-bromo carbonyl compounds and involves an alkyl radical intermediate (see scheme; cod=1,5-cyclooctadiene, dppp=1,3-bis(diphenylphosphino)propane). This homolytic radical aromatic substitution (HAS)-type reaction enables the C3-selective direct functionalization of 2-pyridones.

Get selective! Enantioselective allylation of ketimines derived from isatins by using chiral 1,3-bis(imidazolin-2-yl)benzene (Phebim)–Pd^II complexes afforded products with good enantioselectivity (see scheme). The reaction was applied to a wide variety of ketimines. The obtained product can be converted to homoallylic amines and a spirocyclic amine without the loss of enantiopurity.

Synthetic methods: An asymmetric catalytic, desulfonylative Mannich reaction of α-keto imines with aldehydes, which is catalyzed by diarylprolinol silyl ether 1, was developed. It gave the Mannich product in good yield with excellent anti and enantioselectivity (see scheme).

Seeing is believing: Different miRNAs were used as templates for the photoreduction of an azide-based immolative linker by Ru^II-peptide nucleic acid (PNA) conjugates to uncage rhodamine (see figure). The method was validated by using two sets of γ-serine-modified PNA derivatives with varying affinities to their target (perfect match and mismatch).

Boron–phenylpyrrin dyes: In the presence of BF₃⋅OEt₂, 4-(diethylamino)salicylaldehyde reacts with substituted pyrroles to give boron–phenylpyrrin dyes, which contain a central boron-containing seven-membered ring. Upon protonation in acidic solution, the complexes with a large Stokes shift, exhibit a color change, and a unique red shift in both the electronic absorption and fluorescence emission spectra (see picture), thus rendering them new analogues of boron–dipyrrin dyes that can be used as pH sensors.

A hive of activity: The total synthesis of the tetrahydropyran-containing acetogenin (+)-chamuvarinin has been completed through a modular coupling strategy utilizing key bond couplings at C8–C9 and C20–C21 (see figure). This enabled the unambiguous stereochemical assignment of the natural product. A revised synthetic approach provided material for biological studies and enabled access to analogue structures that displayed selective trypanocidal activity.

Borate not graphene: The [B₆O₁₂]_∞⁶⁻ single borate layer is a graphene-like layer (see figure). The weak Na⁺Br(Cl)⁻ ionic connection between the layers leads to the layer cleavage, and difficulty of the block crystal growth.

The supramolecular self-assembly of the core-substituted naphthalene diimide bearing pyridyl motifs leads to the formation of a variety of nanostructures with pH and solvent control. The detection of HCl can be monitored by UV/Vis and fluorescence spectroscopy, as well as the naked eye, with a change in colour (blue to red, see figure). The cycle is fully reversed by the addition of triethylamine (TEA).

Love at first…smell: An asymmetric total synthesis, gas chromatographic analyses, and field tests confirm the structure of the first isolated sex pheromone of a twisted-wing parasite Stylops muelleri (see figure). Its biosynthetic origin and complexity demonstrate the considerable efforts undertaken by the motionless and fully host-dependant female to attract the very short-lived free-living male, thus securing success in the perpetuation of the species.

GO get ‘em: The toxicity of graphene is governed by the amount and type of oxygen-containing groups on its surface and is important for practical applications. The influence of differing oxidative treatments (Staudenmaier, Hofmann, Hummers, and Tour) on the toxicological behavior of graphene oxides have been investigated in adherent lung epithelial cells (see figure)

Olefin metathesis is used as an elegant method to construct a series of catenanes and rotaxanes based on olefin-containing viologen threads and cavity-containing porphyrin macrocycles. By varying the olefin substituents of the viologens, the outcome of the metathesis reactions can be controlled. The interlocked porphyrin structures show acid/base-controlled switching behavior (see figure).

Nanocrystal evolution: A multi-spectroscopic approach has revealed that the hydrolysis of tetravalent cerium (Ce^IV) produces a colloidal solution of fine cerium dioxide (CeO₂) nanocrystals (see figure). A simple synthetic concept of nanocrystalline metal oxides is proposed based on the obtained results.

Not one, but two: Metalation of a mono-Pd^II hexaphyrin (1) with [Pd(OCOCF₃)₂] gave a bis-Pd^II complex (2), which possesses a characteristic 26 π-aromatic circuit with two outer amino-pyrroles within a rectangular molecular framework. Complex 2 was readily deprotonated to afford dianion, which was regioselectively methylated to give a methyl derivative. Similar methylation reaction of 1 produced skeletal rearranged product that contained an N-confused pyrrole.

Follow that dream: By combining a reversible transesterification between benzylic alcohols and dialkyl oxalates with catalytic decarboxylation of the resulting esters, a regiospecific CC-bond-forming reaction to give α-arylacetates was achieved. In the overall process, CO₂ and a volatile alcohol are the only byproducts. Various α-arylacetates were thus synthesized in high yields from easily accessible starting materials in the presence of catalytic amounts of Pd(OAc)₂, dppp, and DABCO (see scheme).

Surface inspired: A new zeolitic–imidazolate framework that has the zeolite A framework topology and contains relatively inexpensive organic linkers has been grown on the structure-directing surface of ZIF-76 ([Zn(imidazolate)_1.5(5-chlorobenzimidazolate)_0.5]) crystals (see figure). Structural aspects, crystal growth mechanisms and possible surface terminations of both materials are revealed using in situ atomic force microscopy. The work exemplifies the use of this methodology to discover new MOFs with desirable frameworks.

Channel tunneling: We have prepared functional biomimetic nanochannels in polyethylene terephthalate (PET) polymer films (see illustration). We used p-sulfonatocalix[4]arene to modify the channel surface by flexible layer-by-layer electrostatic assembly. Using this method we were able to detect acetylcholine with high sensitivity.

Reagents of change: General methods are reported for the preparation of a family of (NHC)-iridium(I)-hydroxides and their structural characteristics are explored. The Ir-hydroxide motif was shown to be a valuable synthon for bond activation and its activity towards various organic substrates was explored. The Ir-hydroxide (see figure) is able to deprotonate NH, OH and CH bonds to afford valuable organometallic species.

Just a pinch of copper! An efficient system for the formation of C(sp²)C(sp) bonds has been developed. In sub-mol % quantities various copper sources showed excellent catalytic activity. Different combinations of aryl(hetero) iodides and terminal aryl(hetero) alkynes were applied, leading to the desired products in moderate to excellent yields (see scheme). Mechanistic details of this process have been revealed by kinetic measurements and DFT calculations.

A rare sight: A family of rare-earth-metalalkynyl/alkyl complexes was accessed from their tetramethylaluminates, [Ln(AlMe₄)₃], and phenylacetylene. These structures feature new acetylide binding modes and interesting paramagnetic behavior (see figure).

Model under the spotlight: The first X-ray diffraction study of a model for the photoactive yellow protein (PYP) provided direct evidence for the single-crystal-to-single-crystal dimerization of the chromophore under weak visible light (see figure).

CH activation: The ruthenium-catalyzed direct sp² CH amidation of arenes by using sulfonyl azides as the amino source is presented (see scheme). A wide range of substrates were readily amidated including arenes bearing weakly coordinating groups. Synthetic utility of the thus obtained products was demonstrated in the preparation of biologically active heterocycles.

Ultrasound as a pound: Halogen-bonding assembled nano-cocrystals that were prepared by using a sonochemical method showed sensitive temperature-dependent luminescence, owing to a transformation from nano-cocrystals into nanocrystals (see figure).

Polymorphism power rangers: A new borazine derivative that bears mesityl substituents at the boron centers and displays exceptional chemical stability has been prepared (see figure). Detailed crystallographic and solid-state fluorescence characterizations revealed the existence of several polymorphs, each of which shows different emission profiles.

Heterometallic adamantane ligand [CuSn₃S₉]⁵⁻ is coordinated to a lanthanide center in [Hen]₂[Ln(en)₄(CuSn₃S₉)]⋅0.5 en (Ln=La, Ce), while [Hen]₄[Ln(en)₄]₂[Cu₆Sn₆S₂₀]⋅3 en (Ln=Nd, Gd, Er) contain [Cu₆Sn₆S₂₀]¹⁰⁻ cluster anions (see figure). Both compound types were obtained by solvothermal reactions of Ln₂O₃, Cu, Sn, and S in ethylenediamine (en) at 160–190 °C. Their formation reveals the influence of the lanthanide contraction on the quaternary Ln/Cu/Sn/S system.

[2+2+2] Little boys: Fluorine-containing multisubstituted phenanthridines have been synthesized through Rh-catalyzed alkyne [2+2+2] cycloaddition reactions (see scheme; FG=functional group). Polycyclic compounds were also obtained through Rh-catalyzed CH difluoromethylenation.

Smart helical assembly: A symmetrical helical assembly was constructed from surfactant-enwrapped Lindqvist polyoxometalate (POM) complex (DODA)₂[Mo₆O₁₉] (DODA=dioctadecyldimethylammonium). Reversible smart transformation between helical and spherical assemblies associated with photochromism was achieved by controlling the redox properties of the POM component through UV irradiative reduction and H₂O₂ oxidation (see figure).

A model subject: The catalytic mechanism of the key enzyme in the biosynthesis of branched O-glycans, the metal-ion-independent β1,6-GlcNAc-transferase (C2GnT), was investigated by using quantum mechanical (QM) (density functional theory)/molecular modeling (MM) methods (see figure).

Peripheral expansion: A series of peripherally tetrathiafulvalene (TTF)-annulated subphthalocyanines was synthesized (see scheme). These compounds exhibited unique perturbed optical properties, such as a comparatively broad Q band absorption and gradual quenching of fluorescence upon increasing the number of the TTF units, while electrochemical measurements revealed TTF-centered oxidation processes.

Flustering oxindoles: An enantioselective synthesis of 3,3′-disubstituted oxindoles by conjugate addition of malonates to isatylidene-3-acetaldehydes in high yield and enantioselectivity is developed (see scheme). The synthetic utility of this reaction is demonstrated by the synthesis of three oxindole core structures and the asymmetric total synthesis of debromoflustramine E.

Shape shifters: Viscoelastic vesicle gels were prepared by mixing C₁₂EO₄ and AzoNa. The vesicle gels were found to be sensitive to temperature, pH, and light. The vesicle gels thicken when heated and thin when cooled and are stable from pH 7 to 11. Outside of this range, the gels become thinner. UV irradiation can also trigger a transition from a micelle solution to multilamellar vesicle gels (see figure).

A formal [5+1] cycloaddition of divinylketones and an in situ-generated glycine-derived azlactone was catalyzed by a chiral bis-palladacycle and provided highly enantioenriched, spirocyclic, masked amino acid products. The latter were used to synthesize biologically interesting constrained cyclohexane analogues of phenylalanine in just two steps (see scheme).

Easy way to tetra-nostics: The chelator DOTPI (see figure) allows for the facile multimerization of targeting vectors, for example, peptides addressing cell-surface receptors. Subsequent radiolabeling with the positron-emitter ⁶⁴Cu or the beta-emitter ¹⁷⁷Lu yields a theranostic pair, that is, two nearly equivalent radiopharmaceuticals for nuclear imaging and therapy.

Scaffold design: A novel class of ruthenium(II)–arene complexes containing chelating N,N-pyrazolo–pyrimidine ligands was rationally developed to be selective antagonists of human A₃ adenosine receptors based on the proven pyrazolo–triazolo–pyrimidine design (see figure).

Thin-shelled catalysts: Well-defined Pd@Pt core–shell nanoparticles with sub-1 nm Pt shells have been synthesized through in situ heteroepitaxial growth of a Pt layer on a Pd nanoparticle core in a solution phase without the assistance of a sacrificial layer. These Pd@Pt_x (x=molar Pt/Pd ratio) nanoparticles showed shell-thickness-dependent catalytic activity toward the oxygen reduction reaction (see figure) and high durability.

Ru enlightened: Long-lived, directional photoinduced charge separation in Ru^II complexes with laminate polypyridyl ligands is demonstrated. Charge separated states are exhibited by complexes bearing laminate acceptor and bithienyl donor ligands (see scheme). Unusual excited state lifetimes reflect equilibration of ³MLCT_prox or ³MLCT_dist states with a ³LC state or a ³ILCT state that formally localizes a hole on the bithiophene and an electron on the laminate acceptor ligand.

Through the tunnel: It is known that atomic quantum tunneling in chemical reactions may take a different path to classical reactions. A method is introduced that calculates the tunneling path. Information on the length of the path (the width of the barrier) is important to judge the probability of tunneling. This explains stability and decay in singlet carbenes (see figure).

Gold’s gotta catechol! A bioinspired approach for the facile synthesis of gold nanostructures of different shapes has been developed. The structure and functional groups of the reducing/stabilizing agent play a vital role for the shape evolution of nanostructures (see figure).

Facing up to Re: The stereochemical pathways of the stereoselective aldol addition of carbonyl compounds to Re^I complexes and pH-driven dimerizations of these adducts (see scheme; Tf=trifluoromethanesulfonyl) have been studied by crystallographic analysis. The aldol addition only occurs on one face of the carbonyl compound, whereas the dimerization occurs with a concomitant epimerization of the metal center.

Chemical building blocks: Enantiopure alcohols and amines are very important building blocks used in the pharmaceutical, flavors, and fragrances industry. In this review we focus on the preparation of these compounds by using iridium catalysis. The methods presented include the reduction of ketones or amines by using hydrogen (hydrogenations), isopropanol, formic acid, or formate (transfer hydrogenations; see scheme).

SAR of (+)-neopeltolide: A modular synthetic route to (+)-neopeltolide, a potent antiproliferative marine macrolide, was established by exploiting the esterification/olefin metathesis strategy, and a 16-member stereoisomer library of 8,9-dehydeoneopeltolide was developed to elucidate the stereostructure–activity relationships (see figure).

Paving the way: The synthesis towards 8-desmethoxy psymberin, a putative biosynthetic precursor of psymberin, was accomplished in 25 steps including a formal synthesis of the marine natural product itself. The key step towards the THP core was an enantioselective Mukaiyama aldol reaction paving the way for other related THP units. The target compound was submitted for further testing to evaluate its role in the biosynthesis of psymberin.

Clicked to fit: Macrocyclic protease inhibitors, constrained into a β-strand geometry by using Huisgen cycloaddition, are shown to inhibit a range of proteases. The geometries of the component peptide backbones were defined by NMR spectroscopy, X-ray crystallography, and docking studies (see scheme; Cbz=carbobenzyloxy).

Exploring the surface: The assembly of gold nanoparticles (AuNPs) on a hydrogenated Si surface is mediated by a series of hierarchical complexation processes. The multi-step sequence involves a redox-active ditopic guest and suitable functional organic monolayers of the two inorganic components (see figure). Surface reactions and controlled release of AuNPs were monitored.

A convenient synthetic approach to a new class of chiral zwitterionic phosphorus-containing heterocycles starting from methylene-bridged bis(imidazolines) was designed and executed. Stability and properties of the synthesized compounds were investigated. The applicability of the designed compounds as chiral solvating agents for the determination of the enantiomeric excesses of chiral acids was demonstrated.

Aluminum-rich zeolites: An aluminum-rich MSE-type zeolite (Si/Al as small as 7) has been synthesized in a remarkably short crystallization period of only 3 d by the hydrothermal conversion of an FAU-type zeolite, presumably by the assembly of four-membered-ring (4-R) aluminosilicate oligomers supplied by the double 6-R (D6R) components of the FAU framework with the aid of structure-directing agents and seed crystals (see figure).

Playing the triangle: A series of electron-deficient heterotriangulenes with pendant alkyl chains have been synthesized and their propensity for self-assembly in solution, on a surface, and in the bulk was studied (see figure). A pronounced dependence of the self-assembly behavior on the nature of the spacer between the rigid heterotriangulene core and the flexible alkyl chains was identified.

Paved with gold: The chemisorption of exchange-coupled [Ni₂L(O₂C₆H₄PPh₂)]⁺ complexes on gold through the ambidentate 4-(diphenylphosphino)benzoate co-ligand is reported (see figure). The binding of the macrocyclic Ni₂ complexes was studied by water contact angle measurements, atomic-force microscopy, X-ray photoelectron spectroscopy, and ellipsometry, by using a discrete trinuclear Ni^II₂Au^I complex [Ni₂L(O₂CC₆H₄PPh₂)AuPPh₃]⁺ as a spectroscopic and structural probe.

On the contrary! Alkyne metathesis powered a synthesis-driven (re)evaluation of bipartite glutarimide antibiotics, including lactimidomycin and isomigrastatin, which feature highly strained polyunsaturated macrolide head groups. Rather than being potent cell migration inhibitors as previously claimed, lactimidomycin and progeny was found acutely cytotoxic, causing cell death before any specific interference with cell motility could set in.

Let’s stick together. One-pot click or co-clicking procedures have been developed to directly obtain mono- and heptavalent conjugates from unprotected alkynyl-armed heptyl mannoside (HM) and azido-β-cyclodextrin synthons (see figure). These anti-adhesives aggregate both FimH adhesin and uropathogenic bacteria in solution. The in vivo evaluation of synthetic multivalent FimH inhibitors showed the heptavalent β-CDs to be more effective anti-adhesive agents than the corresponding monovalent HM conjugates.

Glycolipids from bacteria: A method for the stereocontrolled synthesis of a bacterial phosphoglycolipid (PGL1) isolated from thermophilic bacteria is described. The key features of the synthesis include a highly α-selective glycosylation reaction between a trichloroacetimidate donor and a D-lyxose-derived primary alcohol acceptor and the late-stage incorporation of the phospholipid (see scheme; TBDMS=tert-butyldimethylsilyl).

Cysteine grapple: A new strategy for the development of a cysteine (Cys)-specific probe, based on a response-assisted electrostatic attraction, is demonstrated. We constructed three fluorescent probes with isomeric structures (see scheme). We demonstrate that the spatial charge configuration plays an important role in the Cys-preferred selectivity and sensitivity.

Acetate aid: The activation of the CH bond of 1-phenylpyrazole and 2-phenyl-2-oxazoline by [Ru(OAc)₂(p-cymene)] is an autocatalytic intermolecular process aided by free acetate (see figure). In contrast, activation by Pd(OAc)₂ proceeds through a concerted metalation–deprotonation (CMD) mechanism through an intramolecular and irreversible process that is assisted by ligated acetate. A cyclometalated dimeric Pd^II^Pd^II is formed whose bielectronic electrochemical oxidation leads to a dimeric [Pd^III^Pd^III]²⁺.

Intrinsic pK_ashifts between 0 and 0.8 pK units of the eight N sites in the single-stranded DNA hexanucleoside pentaphosphate d(ApGpGpCpCpT) were determined by NMR spectroscopic analysis and comparison with the pK_a values of the individual nucleosides. Extensive neighboring effects are due to stacking and charge repulsion. The existing tautomeric equilibria are characterized in detail.

Flow and pharmaceuticals? An investigation into whether machine-assisted technologies can be of true help in the multistep synthesis of a potent neurotensin receptor-1 probe, Meclinertant (SR48692; see structure), is reported.

Interaction to inactivation: Hydrazines act as mechanism-based inactivators of cytochrome P450 enzymes, which are responsible for drug metabolism in the human body. A density functional theory study provides a clear view on how an aminonitrene-type metabolic intermediate is generated from 1,1-dimethylhydrazine through reaction with the reactive compound I intermediate of cytochrome P450 (see figure).

Conjugation approaches were developed to expand a series of chemical probes by attachment of functional tags (nitrobenzoxadiazole (NBD), fluorescein, and biotin) to linkers attached to a stable and selective receptor (VTA2; see figure) for vicinal-dithiol-containing proteins (VDPs). These versatile probes will offer new tools for the potential labeling of various types of VDPs in different microenvironments in living cells.

Crossing bridges: Oxazoles are generated in up to 96 % yield from readily available imines, acid chlorides, and alkynes by using a gold(III) catalyst (see scheme). The use of a sacrificial benzyl group enables the bridging of an imine–alkyne coupling and a cycloisomerization manifold to form the oxazole products in a single domino reaction.

Golden family: A family of cationic, two-coordinate gold complexes of the form [(PPh₃)Au(π ligand)]⁺SbF₆⁻ were generated in situ and characterized by low-temperature NMR spectroscopy (see scheme). The π ligands of these complexes underwent facile intermolecular exchange with free ligand (ΔG^≠≈9 kcal mol⁻¹) and competitive displacement by weak σ donors.

Electron diffraction and polymorphic forms: A new approach to the determination of organic crystal structures in which electron diffraction patterns from a single crystallite are used to identify the structure from a set of putative crystal structures (generated computationally by crystal structure prediction) is described. The approach can be applied to crystallites of sub-micron thickness and to samples in which the phase of interest is the minor component in a mixture of crystal forms.

Crystal structure of an organic picogram crystal: With a combination of electron diffraction and crystal structure prediction it was possible to propose the structure of a new crystal form of the pharmaceutical compound theophylline. This analysis was performed on a single crystallite (pictured), with a thickness of approximately 0.3 μm, present in a sample consisting predominantly of Form II of theophylline, a situation for which conventional X-ray based approaches to crystal structure determination would not be applicable.

No metal required! Metal-free activation of small molecules such as NH₃, PH₃, AsH₃ and H₂ is an emergent topic in main-group compounds chemistry. Herein, we report the outcomes of a DFT analysis of both ammonia NH bond activation and dihydrogen cleavage occurring at the silicon and germanium centres of N-heterocyclic compounds (see figure). The elucidation of key mechanistic and thermodynamic aspects of the investigated reactions is expected to provide helpful information on similar processes.

Enigmatic beauty: The putative lichen-derived glycolipid gobienine A is structurally rather unique, not least because of its thermodynamically unfavorable all-cis paraconic acid (4-carboxy-γ-butyrolactone) aglycone. A largely catalysis-based and broadly applicable entry into this unusual motif was developed, and the total synthesis of the target glycoconjugate completed, just to find out that the originally proposed structure must have been profoundly misassigned.

Ruthenium catalysis: Ruthenium complexes of the type [(N–N′)RuCl(PMe₃)₃] (see figure) have been synthesised from azolylpyridines possessing different substituents on the azolyl unit. These complexes show good activity in the catalytic hydrogenation of carbon dioxide to formates. The influence of the azolyl substituents on the catalytic activity was elucidated by spectroscopy and DFT calculations.

Hydrogen-bond rupture in mononuclear dysprosium(III) complexes leads to single-ion magnet behaviour with a single relaxation process in frozen solution and magnetically diluted samples, but to multiple relaxation processes for bulk samples (see figure). The origin of these multiple relaxation processes is not attributed to the properties of single molecules.

Put a ring on it: Regiospecificity is the key in the control of the connectivity patterns in [m.n]cyclophanes. Bis-carbene complexes react with diynes to generate all three rings of [m.n]cyclophanes in a single reaction. The regiochemistry of the vinyl groups in the carbene complexes sets the stage for the nature of the linkages in the cyclophanes.

Light of my life: A robust and versatile vesicle, which was prepared from an amphiphile that contained a coumarin unit and two alkynyl groups, could encapsulate hydrophobic and hydrophilic guests and enable their controlled release by using a two-photon trigger. Dose-controlled photorelease, which was achieved by the polymerized membrane of the vesicles, was dependent on the cleavage amount of the amphiphilic structure during irradiation (see figure).

A good synergy: Reaction-progress kinetic analysis and nonlinear chromatography are useful tools for investigating a model aldol reaction performed in continuous-flow microreactors packed with proline-functionalized silica gel (see figure). The study was facilitated by a suitable instrumental arrangement for online monitoring; it also assessed optimal operating and feed variables.

X-ray marks the spot: We present an in situ time-resolved small- and wide-angle X-ray scattering and quick-scanning extended X-ray absorption spectroscopy study on the crystallization of the metal–organic framework ZIF-7, along with density functional theory calculations (see figure).

Fullerene-containing clays: The successful incorporation of pure fullerene from solution into two-dimensional layered aluminosilicate minerals (namely clays) is described. The approach involved the organic modification of the parent clay with quaternary amines by using well-established reactions, thereby achieving expansion of the clay interlayer space and rendering the galleries organophilic. The surfactant molecules can be selectively removed by either simple ion-exchange reactions or thermal treatment.

New imido clusters: Three new routes for the synthesis of rare-earth metal imido clusters were established based on the reactions of rare-earth metal methylidene complexes with imines, azobenzenes, and amines, and resulted in access to a wide variety of imido rare-earth metal complexes (an example is shown in the figure). Primary reactivity studies on these imido clusters toward some small molecular substrates provide good options to the synthesis of their imido derivatives.

Addicted to base: A series of biaryl compounds, including heterocycles, were deprotometalated by using a 2,2,6,6-tetramethylpiperidino-based mixed lithium/zinc base (see scheme). The obtained regioselectivities are discussed in light of the CH acidities of the substrates, as determined in THF by using the DFT B3LYP method.

Split me! A redox-mediator-free Z-scheme water-splitting system capable of working under simulated sunlight was achieved by sing Ir/CoO_x/Ta₃N₅ in combination with the aid of Ru/SrTiO₃:Rh as a H₂-evolution photocatalyst.

Oxidation at graphene: Boron- and nitrogen-doped graphenes are excellent catalysts for promoting the oxidation of benzylic hydrocarbons, cyclooctane, and styrene with molecular oxygen at 0.5 wt % under atmospheric pressure and solvent-free conditions (see figure).

Why [6,6]? The preference for [6,6] over [5,6] bonds in cycloaddition reactions involving C₆₀ is experimentally well-established (see figure). However, the reasons (i.e., physical factors) behind this preference are so far completely unknown. By means of the recently introduced activation strain model of reactivity in combination with the energy decomposition analysis method, a definite answer to the question in the title is provided.

Anti- and pro-oxidants: Hydroxyaryl alkyl tellurides are unconventional antioxidants able to quench chain-carrying peroxyl radicals with rate constants as high as 10⁷ M⁻¹ s⁻¹ by a mechanism involving oxygen atom transfer to tellurium followed by reaction of the RO^. radical with the phenol (see figure). They can also catalytically decompose both the ROO^. radical and H₂O₂ in the presence of excess thiols.

Endohedral metallofullerenes: Sc₃N@C₈₀I_h and D_5h isomers and Sc₃N@C₇₈ were selectively separated by using a chemical oxidation and reduction method based on their different oxidation potentials (see figure).

Upon UV irradiation quinolones A undergo a rapid cyclization at the T₁ level (τ≈1 ns) through the respective 1,4-diradicals (e.g., 1), leading to the [2+2]-photocycloaddition products in high yields. Lifetimes and transient absorption spectra have been carefully measured. The high cyclization rate is one key element in the enantioselective formation of products, such as 3, when sensitized by catalyst (+)-2 (10 mol %)

Tuning the reactivity through pH control: The reactivity of 3-glycidoxypropyltrimethoxysilane (GPTMS) in water at different pH values (pH 2–11) was investigated in detail for the first time by solution-state multinuclear NMR spectroscopic and mass spectrometric analysis (see picture). The extent of the different and competing reactions taking place as a function of the pH value was elucidated.

Natural product reassignment: Total synthesis of the proposed structures for fulicineroside and its aglycone fulicinerine has been achieved (see figure). Key issues were the tetrasubstituted dibenzofuran and the trisaccharide with its β-linkage between L-rhodinose and L-rhamnose. A comparison with the reported data for the natural product and the aglycone suggests a misassignment of the structure of the natural product.

Finely tuned transfer: Chemical modification of the oligo-fluorene linkers between Fc and C₆₀ units enables fine-tuning of photoinduced charge-transfer processes in new donor-bridge-acceptor conjugates (see illustration).

2 proteins, 1 sensor: Protein-directed synthesis of phosphorescent Mn-doped ZnS quantum dots (QDs) is reported. By exploring the phosphorescence and resonance light scattering (RLS) of the QDs, and the specific protein–protein interactions with bovine serum albumin (BSA) as the substrate, a dual-channel sensor was developed that employs only one type of QDs for the detection of two different proteins (see figure).

π in the sky: Thienylenephenylene oligomers with fluorinated and dialkoxylated phenylene fragments have been designed and prepared. UV photoelectron spectroscopy and DFT calculations highlight how the resulting strong conjugation depends on the energetics of the π orbitals of the molecular fragments, which are related to the nature of the substituents (F, OMe) on the phenylene groups (see figure).

Dipoles apart: In situ formed enamines react with diazoacetates under mild conditions to afford the corresponding polysubstituted pyrazoles in good-to-excellent yields through an inverse-electron-demand 1,3-dipolar cycloaddition process (see scheme).

Target triggering: An ultrasensitive surface enhanced Raman scattering (SERS) method for the detection of lysozyme is reported. Based on aptamer-based target-triggering multiple cycle amplification and gold nanoparticles (AuNPs) bio-barcode Raman probe enhancement on the gold substrate (see figure), the SERS signals are significantly enhanced and concentrations of lysozyme as low as 1 fM could be detected.

All dyed out! Zinc phthalocyanine dyes were designed and optimized in order to increase the absorption of red light in dye-sensitized solar cells (see figure). By optimizing the structure of the adsorption site and reducing the size of bulky substituents, a high power conversion efficiency of 5.9 % was obtained.

Sandwich-like structures: Confinement of Ni(OH)₂ particles in a graphene film has resulted in a new sandwich-like structure with excellent electrode kinetics and electrochemical stability. This system is a promising candidate for supercapacitor materials (see figure).

Bond deal for diboranes: The synthesis of new diborane complexes combined with experimental and DFT investigations show how BH and BB bonds can be specifically activated depending on the chosen transition-metal fragment (see figure).

Agent Defeat Weapons: Fifteen iodo compounds and six iodyl compounds with an iodine content between 45.3 and 89.0 % were synthesized. The high concentration and easy accessibility of iodine and/or iodine-containing species is very important in developing materials suitable as agent defeat weapons (see figure).

Proven not innocent! All four redox-active components of [Ru(pap)(Q)₂]ⁿ behave non-innocently in not immediately predictable ways according to structural, spectroelectrochemical, and computational information for the accessible forms between n=2+ and n=2− (see figure). Cations, anions, and neutral forms are distinguished by significant near-infrared absorptions (λ_max>1000 nm).

Molybdenum magic: Facile perhydrolysis of a highly hindered epoxide was achieved with the aid of a molybdenum catalyst. The resulting hydroperoxide was readily converted into a 1,2,4-trioxane, from which natural qinghaosu (QHS, or artemisinin; see scheme) and a range of analogues were constructed. Some of the newly accessed trioxanes showed in vitro antimalarial activity comparable to or even better than that of chloroquine and artesunate.

Walking on water: Asymmetric Kinugasa reactions on pure water without any organic co-solvents afforded synthetically useful trans-β-lactams in good yields, enantioselectivities, and diastereoselectivities (up to 90 % yield, 98 % ee, and >99:1 d.r.).

Catalyst–substrate complexes containing the ligands tBu-BisP*, Tangphos, Me-BPE, DCPE, DCPB, and mono- ([Rh(PP*)(MeOH)₂H₂]BF₄) or dinuclear ([{Rh(PP*)H}₂(μ₂-H)₃]BF₄) Rh-hydride species, are described (see figure). A sequence for the formation of the trinuclear Rh-hydride complexes is suggested. The presence of these complexes should be taken into account when discussing the mechanism of asymmetric hydrogenation.

Germaphobe: The structure and energetics of tetragermacyclobutadiene and its structural isomers were investigated by using coupled-cluster methods and focal-point analysis to extrapolate to the complete basis-set limit. The Ge₄H₄ isomers exhibited non-planar structures and less double bonding than in C₄H₄.

Mass-ive findings: A systematic analysis of the chemical behavior of arylboronic acids under ESI-MS conditions is reported (see scheme). Such information is critical to understanding the gas-phase chemistry of boronic acids in an ESI mass spectrometer chamber in general and the MS analysis of boronic acids and their macromolecular conjugates in particular.

Heroes in a mixed shell: Core–shell–corona polymeric micelles with a temperature-induced hydrophobic shell can act as an artificial chaperone in a process that involves the capture of thermally denatured proteins, thus preventing their aggregation, followed by assisted refolding during cooling (see figure).

Strained metallacycles: Heterometallacyclic complexes of the type [Cp₂M(L)(κ²-P,P-Ph₂PC(X)PPh₂)] (M=Ti, X=H, SiMe₃, no L; M=Zr, X=H, L=H; M=Hf, X=H, SiMe₃, L=Cl) have been prepared through salt elimination pathways, from which the corresponding metallacycles have been obtained in very high yields. Analysis of the structure and bonding of these complexes has revealed that in-plane aromaticity plays an important role in their stabilization, especially in the case of paramagnetic Ti^III complexes (see figure).

Sliding down with a glow: Incorporation of nitrogen atoms into the dithienophosphole scaffold generates a new building block, dithiazolo[5,4-b:4′,5′-d]phosphole (see scheme), that combines intense luminescence with high electron affinity. A family of conjugated small molecules and a polymer based on this building block have been synthesized by a click reaction that also serves as selective colorimetric and fluorescent sensor for Cu^II.

Rh^IIIand Ir^IIIcomplexes based on the λ³-P,N hybrid ligand 2-(2′-pyridyl)-4,6-diphenylphosphinine (1) react selectively at the PC double bond to give chiral coordination compounds of the type [(1H⋅OH)Cp*MCl]Cl, which can be deprotonated to form [(1H⋅O)Cp*IrCl] and [(1⋅OH)Cp*RhCl] (see figure). These new transformations in the coordination environment of Rh^III and Ir^III provide an easy and general access to new transition-metal complexes containing λ⁵σ⁴-phosphinine ligands.

A new direction! A series of oligovalent β-(1→2)-linked mannosides was synthesized by using click chemistry and biologically evaluated to test their immunostimulating properties (see scheme). An acetylated trivalent assembly of mannobioses was a potent inducer of Treg and Th1-type immune response and showed suppressive effects against the Th2-type allergic inflammatory response. This compound might prove useful as an adjuvant in the specific immunotherapy of allergies.

Much of a muchness: Cytochrome P450 119 Compounds I generated by chemical oxidation (black symbols and lines) and photooxidation (red symbols and lines) have the same UV/visible spectra, the same products for oxidations of fatty acids, and the same kinetics of reactions. Rate constants for reactions of Compound I with lauric acid at −5 °C and GC traces of products from oxidations of lauric acid are shown.

Stressing disulfide bonds! Nucleophilic thiol–disulfide exchange reactions within the I27 domain of titin were previously investigated with force clamp AFM. Here, all possible pathways associated with disulfide bond scission at constant tensile force are revealed in terms of end-to-end distances by using force clamp molecular dynamics. The simulations, together with experimental data unravel the competition between mechanochemical bond activation and solvent-mediated regiospecificity exhibited during SS bond cleavage due to the nucleophilic substitution mechanism within a stretched peptide (see figure).

Pssst—it’s LIESST: Strong intermolecular π–π stacking interactions (see figure) can lead to the light-induced excited-spin-state trapping (LIESST) effect, even for iron(III) spin-crossover (SCO) compounds. This condition, induced through a photoexcitation process, is necessary for trapping the high-spin metastable state of an iron(III) SCO complex.

Unusual sandwiches: Heterometallic sandwich complex 1 reacts with azobenzene to afford [(L)₂Sm₂(μ-η²:η²-N₂Ph₂)₂{K(thf)₂}₂] (2) and [(L)Sm₄(μ-η²:η²-N₂Ph₂)₃(μ₃-NPh)₂(thf)₃] (3), for which crystallographic studies showed that the alkali metal cation–arene π interactions help to stabilize the divalent metal centers. In addition, complex 1 reacts with diazabutadiene ligands to give Sm^III complexes that form one-dimensional networks through cation–arene π interactions.

Deviant behavior: The structure of aggregates in an aqueous solution of [Bmim][BF₄] were examined and revealed to be vesicles (see graphic, white circles are H₂O) and unstable. This ultimately led to the conclusion that their aggregation behavior in water is somewhat different from that of surfactants, although both are surface-active agents.