“Iron made it”: Recent breakthroughs in the hydrogenation of esters to alcohols by well-defined iron pincer complexes are highlighted. These complexes demonstrate promising efficiency and selectivities.

A new perspective on enzymes: Free-electron lasers are increasingly used to obtain crystal structures of interesting enzymes like photosystem II from nanocrystals at room temperature, to avoid radiation damage, and to detect structural differences between specific states in the catalytic cycle.

Read the small print: Sophisticated sequencing methods have been developed for deciphering the sequences of proteins and nucleic acids. Can these tools be transfered to the characterization of monomer sequences in synthetic polymers? The techniques employed in both fields are compared and critically analyzed.

Short peptides can be constrained by cyclization to recreate key folded elements of protein structure, like β-strands and β-sheets, α-helices, and turn motifs. Coupled with internal molecular constraints, cyclization has led to many protease-resistant, potent and target-selective, biologically active compounds for use in biology and medicine.

The first nickel-based homogeneous water oxidation catalyst has been reported, which can efficiently electrocatalyze water oxidation at neutral pH in phosphate buffer. The cis conformation of the catalyst is the key active intermediate (see scheme; PCET=proton-coupled electron transfer).

Teamwork enantioselectivity: An asymmetric amination of racemic allylic alcohols with various functionalized amines proceeded with high regio- and enantioselectivity under cooperative catalysis by the chiral phosphoric acid 1 and a palladium complex with the phosphoramidite ligand 2 (see scheme; R¹=aryl, R²=alkyl or H; dba=dibenzylideneacetone). The transformation was efficient even with less reactive alkyl allylic alcohols.

Crowning proteins: By a combination of structural and biophysical methods, it was observed that crown ethers modify protein surfaces dramatically, stabilizing molecular interactions. Hence, crown ethers could potentially be used to modulate a wide range of protein surface behaviors, such as oligomerization, domain–domain interactions, and crystallization.

A stretched luciferin: Synthetic infra-luciferin is a dual-color, far-red to near-infrared (NIR) emitting analogue of beetle luciferin, which akin to native luciferin gives rise to different far-red to NIR emission maxima (up to λ_max=706 nm) with different firefly luciferase mutants. This red-shifted bioluminescence is suitable for imaging in mammals with less attenuation than luciferin.

Ca doping into the A site of NdBaCo₂O_5+δ (NBCO) leads to NdBa_1−xCa_xCo₂O_5+δ (NBCaCO), a new class of double-perovskite compounds that are highly stable both in air and in a CO₂-containing atmosphere. They display fast oxygen ion diffusion and high catalytic activity toward oxygen reduction while maintaining excellent compatibility with the electrolyte.

Face changer: Taurocholic acid (TCA), a biomolecule found in bile, is doped into 1D nanoarchitectured conducting polymers designed to aid cell growth on bone implants. The orientation of the hydrophobic α-face and hydrophilic β-face of TCA in the polymeric matrix can be changed by applying an electrical potential. This switching also causes a reversible change in wettability and protein adsorption as well as in adhesion and spreading of osteoblasts on the polymer surface.

The charge-transfer interactions between dicationic viologen (acceptor) and trianionic pyranine (donor) were exploited to realize charge-reversal in nanochannels. Ion transport was switched from anion selective to ambipolar to cation selective by controlling the extent of viologen bound to the pyranine. Ion-transport regulation with respect to pH was achieved by selecting a donor with pH-responsive functional groups.

Luminescent materials: In a two-dimensional Ca_2−xTb_xTa₃O₁₀ nanocrystal, the presence of one- and two-Tb-atom emission centers was confirmed. Although some Tb³⁺ emission centers existed in close proximity to each other, no concentration-based quenching was observed. The Tb³⁺-doped nanosheets showed a higher photocatalytic activity relative to undoped nanosheets.

Put it in reverse: A regio-, diastereo-, and enantioselective [4+3] cycloaddition between vinylcarbenes and dienes was achieved using the dirhodium tetracarboxylate catalyst [Rh₂(S-BTPCP)₄]. This method provides facile access to 1,4-cycloheptadienes which are regioisomers of those formed from the tandem cyclopropanation/Cope rearrangement reaction of vinylcarbenes with dienes. TBS=tert-butyldimethylsilyl, TIPS=triisopropylsilyl.

Anions play a crucial role in locking alkali metals on the interior of metal–organic capsules that contain structural water gates. This role is further evidenced when stitching-up the capsule seam, resulting in either expulsion or trapping of cesium ions depending on the anion employed.

Hand in hand: The outlined diversity-oriented synthesis of a library of macrocycles is based on the orthogonal combination of multiple diversity-generating organocatalytic steps with alkene metathesis. In total, 51 macrocyclic structures bearing 48 unique scaffolds, drug-like chemophysical properties, and natural-product-like shape diversity were synthesized in only 2 to 4 steps without the need for protecting groups.

Caught in a trap: The title reaction of N,N-disubstituted anilines with diazo compounds and imines is reported for the efficient construction of α,α-diaryl benzylic quaternary stereocenters in good yields with high diastereoselectivities and excellent enantioselectivities. Efficient electrophilic trapping of the metal-carbene-induced zwitterionic intermediate is crucial for the enantiocontrol under Rh^II/chiral phosphoric acid (PPA) co-catalysis.

Two in one: Intergrowth polymorphism refers to the existence of distinct structural domains within a single crystal of a compound. For felodipine form II, the phenomenon is revealed by the nanoindentation technique which shows a bimodal response on specific single-crystal faces. The associated microstructure is a significant feature of the compound's structural identity, and has implications for structure–property correlations in molecular crystals.

Germanium zero: Reduction of a chlorogermyliumylidene chelated by an imino-N-heterocyclic carbene ligand with potassium graphite produced a novel cyclic germenium species, which can be viewed as both a germanium(0) species and a mesoionic germylene. X-ray diffraction analysis and computational studies revealed one of the lone pairs on the Ge atom is involved in the π system on the GeC₂N₂ five-membered ring.

Quartets unite to call the tune: The transcription of G-rich DNA produces G-rich RNA transcripts. G-tracts from DNA and RNA were found to form hybrid G-quadruplexes (HQs) of two or more G-quartets (see picture) with a possible role in transcription regulation. DNA:RNA HQs composed of two G-quartets were less stable and more flexible than HQs composed of three G-quartets, and their folding and unfolding were more responsive to transcription activity.

Cubics with a twist: Polycatenar 5,5′-diphenyl-2,2′-bithiophenes (see picture) form two types of bicontinuous cubic phases. Though the molecules are achiral the cubic phase is always chiral, while the phase is achiral. The explanation is that in the phase the opposing chiralities of the two enantiomorphic networks cancel, but not so in the three-network phase.

Carbon nanohorns were functionalized with a dye to develop a new type of light-driven nanomodulator. This system generates heat and reactive oxygen species (ROS) under biologically transparent near-infrared (NIR) laser irradiation. These properties can be applied for single-cell analyses and innovative cell therapies.

Simultaneous delivery of an anticancer drug and siRNA was achieved with cationic vesicles self-assembled from a novel ferrocenium-capped amphiphilic pillar[5]arene. These systems exhibit low cytotoxicity to healthy cells and are redox-responsive in the presence of a reductant/oxidant.

The chain length of α,β-hybrid oligomers containing the highly constrained (S)-1-aminobicyclo[2.2.2]octane-2-carboxylic acid residue determines if either the 11/9 or the 18/16 helix is favored. The transition between these two helices involves a single ϕ angle rotation of the α residues.

Enantioselective trapping: The asymmetric three-component reaction of aryldiazoacetates, aromatic amines, and β-nitroacrylates affords γ-nitro-α-amino-succinates in good yields and with high diastereo- and enantioselectivity. This reaction is proposed to proceed through the enantioselective trapping of Rh^I-associated ammonium ylides by nitroacrylates and represents the first example of Rh^I-carbene-induced ylide transformation.

Making room for guests: By directing the heterodimerization of helically folded oligomers, the size of the foldamer cavity could be doubled on demand by the principle of maximal site occupancy. The postsynthetic modification in this way of capsules composed of helical aromatic oligoamide foldamers could potentially be used to control their receptor properties without altering the initial monomer sequences.

Needle in a haystack: A chip-based electrochemical assay using metal nano-particles (MNPs, see picture) allows simultaneous detection of multiple different biomarkers on the surfaces of cancer cells, enabling discrimination between cancer cells and normal blood cells. As few as two cells captured per electrode can be detected.

A new partnership with a future: N-Heterocyclic carbene (NHC) boranes coupled with arynes in a hydroboration reaction to produce various B-aryl-substituted NHC-boranes (see scheme), which are stable and have many potential uses. The proposed hydride-transfer character of the mechanism was supported by the ortho regioselectivity observed for the hydroboration of arynes with an electron-withdrawing substituent.

Silicon stabilizers: The reaction of the Si^II–Ge^II adduct 1 with KC₈ afforded the N-heterocyclic silylene-stabilized di-germanium(0) complex 2. X-ray crystallography and theoretical studies show conclusively that the N-heterocyclic silylene ligands stabilize the singlet digermanium(0) moiety by a weak synergic donor–acceptor interaction.

Boron can do it! The first carbene that was stable at room temperature had a pseudo allenic structure, but owing to its high flexibility, it featured classical carbene reactivity. Similarly, a stable boron compound, isoelectronic with singlet carbenes, has an allenic structure, and is able to activate CO and H₂.

The sunny side of the sheet: Perovskite nanosheets of HCa_2−xSr_xNb₃O₁₀ and HCa₂Nb_3−yTa_yO₁₀ with tunable band-edge potentials were prepared. They worked as highly efficient heterogeneous photocatalysts for hydrogen evolution from water, with the maximum apparent quantum yield of approximately 80 % at 300 nm, the highest value among nanosheet-based photocatalysts reported to date.

A new twist: Reductive metalation of [44]decaphyrin with [Pd₂(dba)₃] (dba=dibenzylideneacetone) provided a Hückel aromatic [46]decaphyrin Pd^II complex, which was quickly oxidized with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone to produce a Hückel antiaromatic [44]decaphyrin Pd^II complex. On standing in CH₂Cl₂ solution this complex slowly tautomerizes to a Möbius aromatic [44]decaphyrin Pd^II complex, giving an equilibrium mixture.

A mutual dependency between ferromagnetic iron chains and stacked B₆ rings (see picture) is found in the new ferromagnetic material, Nb₆Fe_1−xIr_6+xB₈ (T_C=350 K) by combining experiment and density functional theory (DFT). The strong magnetic Fe–Fe interactions found in the iron chains induce an unexpected strengthening of the B–B interactions in the B₆ rings.

Crystal gazing: A study of the (pseudo)polymorphs of cocrystals formed from binary and ternary phloroglucinol–dipyridylethylene and –phenazine systems has shown that polymorphism in multicomponent crystals is less likely than in single-component crystals. The generation of several crystal forms during the crystallization of a multicomponent system can be viewed as combinatorial crystal synthesis with synthon selection from a solution library.

All in the family: A new family of chiral nucleophilic catalysts, biphenyl-derived phosphepines, and their use in the title reaction is reported. A range of one-carbon coupling partners can be employed to generate cyclopentenes bearing a fully substituted stereocenter. Initial mechanistic studies are described.

Ironed out: An iron-catalyzed asymmetric intramolecular cyclopropanation was realized in high yields and excellent enantioselectivity by using the iron complexes of chiral spiro-bisoxazoline ligands as catalysts. NaBAr_F=sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

Gated Proteins: By using zinc-finger proteins, AND, OR, and NOR logic gates were created that respond to short oligonucleotide inputs by activating or deactivating a split-luciferase enzyme. The gate designs are simple and modular, thus enabling integration with larger multigate circuits and providing flexibility in the choice of protein outputs. Response to microRNA inputs was achieved through the use of translator circuits.

Double bonanza: The title reaction in the presence of an imidazolidinone-based catalyst furnished N-bridgehead bicyclic alkaloids bearing [3.3.0], [3.4.0], [4.4.0], and [4.5.0] skeletons. By using this protocol, the total syntheses of (−)-epilupinine, (−)-tashiromine, and (−)-trachelanthamidine were achieved.

Green chemistry: A highly efficient one-pot transformation of readily accessible furans into 4-hydroxy-2-cyclopentenones in H₂O (see picture), using singlet oxygen as oxidant, has been developed.

An all-around player: Numerous classical flavin-dependent alcohol oxidases, such as alditol oxidase (AldO), which are well-known for their activity towards CO and CN bonds, can also catalyze the oxidation of thiols (see picture). This method provides a potential biocatalytic route to reactive thiocarbonyl compounds.

ADORable zeolites: A series of zeolites with continuously tuneable porosity was prepared using the assembly–disassembly–organization–reassembly (ADOR) method. The pores of the zeolites that are accessible with this method cover the whole range of useable sizes: from small to extra-large.

Revision: Key steps in the total synthesis of (−)-haouamine B pentaacetate (see structure) are the enantiocontrolled construction of indane-fused tetrahydropyridine based on Ellman's diastereoselective Mannich reaction and the newly developed mild Friedel–Crafts alkylation. The synthesis led to the revision of the structure, as proposed by Trauner and Zubía.

On the surface: The thermal decomposition of organometallic complexes with N-heterocyclic carbene ligands affords Pt nanoparticles that are soluble and stable in water for an indefinite period. The ¹³C–¹⁹⁵Pt coupling observed by solid-state NMR spectroscopy confirms carbene coordination to the nanoparticle surface.

Multitalented special agents: Cytotoxic cis-[Pt(NH₃)₂(py)Cl]⁺ (py is a pyridyl ligand) was conjugated to the magnetic resonance imaging contrast agent Gd–DTPA (DTPA=diethylenetriaminepentaacetate) to form Gd–Pt complexes of the type shown in the picture. The conjugates satisfy the requirements for tumor therapy and imaging at the same dose and are thus promising theranostic agents for cancer treatment.

Cyclization: Nickel(0) catalysts with a chiral bulky C₁-symmetric N-heterocyclic carbene ligand enabled the efficient asymmetric reductive [3+2] cycloaddition of enoates and alkynes, providing substituted cyclopentenones under mild conditions. The system provided the products in very high enantioselectivity and led to a regioselective incorporation of unsymmetrically substituted alkynes.

The three C's: An efficient rhodium(III)-catalyzed synthesis of 2H-chromenes from N-phenoxyacetamides and cyclopropenes has been developed. The reaction represents the first example of using cyclopropenes as a three-carbon unit in rhodium(III)-catalyzed C(sp²)H activations. Preliminary mechanistic investigations are discussed.

Inkjet-printing solar cells: By designing carbon plus CH₃NH₃I ink to transform PbI₂ in situ to CH₃NH₃PbI₃, an interpenetrating seamless interface between the CH₃NH₃PbI₃ active layer and the C hole-extraction electrode was instantly constructed, resulting in a 11.60 % efficient, planar perovskite solar cell.

An axe to grind? Novel axially chiral biaryls were synthesized by the direct CH bond olefination of biaryl compounds, using a chiral [Cp*Rh^III] catalyst (1), in good to excellent yields and enantioselectivities. The biaryls were found as suitable ligands for rhodium-catalyzed asymmetric conjugate addition reactions.

Charged up: The title germanodecatungstate [γ-HGeW₁₀O₃₆]⁷⁻ was synthesized under non-aqueous conditions. The activities of germanodecatungstates for base-catalyzed reactions dramatically increased with an increase in the number of negative charges from −6 to −7. In the presence of [γ-HGeW₁₀O₃₆]⁷⁻, various combinations of acylating agents and primary alcohols chemoselectively gave the desired acylated products in high yields.

Modern biocatalysts on the rise: The P450 BM3 monooxygenase mutant A74G/L188Q catalyzes the enantioselective allylic hydroxylation of ω-alkenoic acids and esters under mild conditions using O₂ as an oxidant. This reaction offers access to important chiral building blocks for the synthesis of biologically active compounds and demonstrates the highest chemo- and enantioselectivity observed to date for the CH oxidation of acyclic terminal olefins.

Procedures for the Brønsted acid catalyzed asymmetric synthesis of 9-substituted tetrahydroxanthenones and 3,9-disubstituted tetrahydroxanthenone derivatives have been developed. The procedures are based on the in situ generation of ortho-quinone methides and their subsequent reaction with 1,3-dicarbonyl compounds. The reaction provides products with a high level of asymmetric induction.

Coupling without coinage metals: A combined palladium- and photoredox-catalyzed CH olefination serves to synthesize indoles. Using visible light, direct CH activation of aromatic enamines leads to a variety of indole derivatives in good yields under mild reaction conditions.

Pentacoordinate chlorosilicates are known to be reactive intermediates. They can be stabilized by the introduction of at least two electron-withdrawing C₂F₅ groups, which has allowed the characterization of a series of (pentafluoroethyl)chlorosilicates (see example) in solution as well as in the solid state.

Competition for transition metals: A cationic trinuclear zinc hydride cluster with a Zn₃H₄ core efficiently catalyzes the hydrosilylation of aldehydes, ketones, and nitriles, and notably also carbon dioxide.

No NO cleavage: Transition-metal-free hydrogenation of oxime ethers with bulky groups at the oxygen atom (R³=tBu and SiiPr₃) can be achieved at mild temperatures by using the electron-deficient boron Lewis acid B(C₆F₅)₃ as a catalyst. The reduction is highly chemoselective, leaving the NO bond intact. Subsequent fluoride-mediated cleavage of the SiO bond (for R³=SiiPr₃) provides access to the free hydroxylamines (see scheme).

Aggregation is more than the sum of its parts! An unusual lithium lithiate, made up from three carbanions, two lithium cations, and a single donor base in the anion and a single lithium cation, and coordinated by two donor base molecules, was investigated in a combined study including X-ray diffraction, NMR spectroscopy, and computational approaches in solution and the solid state. Only the combination of this multitude of methods provides a firm picture of the whole.

How does tea fight dangerous radicals? Hydrogen abstraction from catechin and green-tea polyphenols by highly reactive O-centered H-abstracting species was studied at the molecular level and in real time by time-resolved EPR spectroscopy. Our results show that all phenolic OH groups display identical reactivity. Accordingly, statistical (entropic) factors essentially predominate in initial antioxidative events.