Ketenes in the limelight: The influential role of ketenes has never been adequately acknowledged in zeolite chemistry and catalysis; unlike other first generation highly reactive intermediates, such as carbocations, carbanions, radicals, and carbenes. In fact, the role that ketenes play during catalysis—whether beneficial or detrimental—is a contentious subject that requires further consideration.

Getting organized: In spite of fundamental roles of carbohydrates in living organisms, the informatization of glycomics is far from complete. The lack of recognized standards, data indices, protocols, and tools, as well as limited connection of the existing projects with each other and with global life-science projects, hinder the successful application of glycoinformatics in modern research.

At the interface between coordination polymers and supramolecular metallopolymers, materials based on molecular weaving, supramolecular clusters, and metal-organic framework-polymer hybrids have emerged. This Minireview provides an intellectual roadmap from the development of supramolecular metallopolymers to new materials that blur the lines between metallopolymers and coordination polymers.

Better batteries: The use of electrolyte additives is considered one of the most viable, economical, and effective approaches to circumvent the problems of rechargeable Li metal batteries (LMBs). This Review assesses the current status of research on electrolyte additives for rechargeable LMBs and considers new avenues for the realization of these appealing devices.

MXene aerogels: Li metal anodes can have a short lifespan and infinite volume expansion, and these challenges become more grievous under high current densities. 3D porous MXene aerogels are proposed as scaffolds for high-rate Li metal anodes. With high metallic electron conductivity, fast Li ion transport capability, and abundant Li nucleation sites, such scaffolds could deliver high cycling stability and low overpotentials at a high rate.

Swift switching: Rigid azobenzene tetramers were assembled into hexamer patterns on a metal surface. The azobenzene unit oriented perpendicular to the surface could be isomerized reversibly with time constants of a few minutes, either remotely by light or locally by a scanning probe tip, thus leading to bright (trans) and dark features (cis) in STM images (see picture). The diffusion of individual species across the surface depended on their isomeric state.

Divided we stand: Time-resolved delivery of small-molecule drugs, which was achieved via an injectable multicompartment hydrogel material, strongly synergizes their apoptotic activity in glioblastoma.

MoP-ed up: MoP is a new catalyst for CO and CO₂ hydrogenation to methanol. By stabilizing only the monodentate binding configuration of formate, the phosphide is able to circumvent the (scaling) relationship between the necessary ability of the catalyst to bind oxygen-containing intermediates and catalyst deactivation resulting from high formate coverage in the presence of CO₂.

Tagging the flu: Conformational and interaction analysis of a sialylated tetradecasaccharide N-glycan with two LacNAc repetitions at each arm is presented. This glycan has been identified as the receptor of the hemagglutinin protein of pathogenic influenza viruses. An N-glycan conjugated with a lanthanide binding tag was synthesized, enabling analysis of the system by paramagnetic NMR spectroscopy.

[Fe]-hydrogenase (Hmd) contains the iron–guanylylpyridinol (FeGP) cofactor, which is sensitive to UV-A/blue light and H₂O₂. In hexameric Hmd from Methanothermobacter marburgensis (mHmd), an expanded loop is detached from the dimer core and intrudes into the active site of a neighboring dimer. An aspartic acid (Asp) residue from the loop ligates to the Fe center. In the hexameric form, mHmd is protected against light and oxidative stress.

Complex structure elucidations of Stig cyclases reveal a common substrate-binding mode and mechanism of action of these enzymes. Located near the bottom of a terminal cavity in the β-sandwich, a strictly conserved aspartate plays a vital role in catalysis, while the surrounding active-site residues including those in the overhanging loop may determine the type of cyclization and the final product.

Short and curly: Curly arrow rules break down in molecular junctions formed by cross-conjugated anthraquinone. In contrast with the destructive quantum interference (QI) predicted by curly arrow rules for a meta-connected anthraquinone core, it is demonstrated here that QI is constructive.

pH range rover: A hybrid material allowing fast electron transfer between cobalt corroles and carbon nanotubes (CNTs) catalyzes the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in pH 0–14 aqueous solutions with high efficiency and stability. This is the first example of bifunctional HER and OER catalysts that work in such wide pH range.

A weighty performance: A heterostructured Fe₂O₃-TiO₂ microdumbbell photocatalyst is fabricated through a facile synthetic approach. With their novel heterojunction structure, the well-defined Fe₂O₃-TiO₂ microdumbbells exhibit enhanced photoelectrochemical performance compared to Fe₂O₃ microrods, TiO₂ nanospheres, and mixtures of the two.

Transmetalation is a key elementary step in cross-coupling reactions. The precise nature of its mechanism and transition state geometry are frequently elusive. This Communication discloses studies of the transmetalation of [Pd^II]-F complexes with the silane- and stannane-based trifluoromethylation agents R₃SiCF₃ and R₃SnCF₃.

Electrical response to atmospheric guests: Experimental data were combined with computational modeling to describe a possible origin for the underlying mechanism of the direct dependence of the electrical response with MOF–guest interaction phenomena in ultrathin films (ca. 30 nm) of Cu-CAT-1.

Rough and tumble: Hydrophobic forces drive α,ω-dienes into cavitands in conformations that best fill the available space. Shorter dienes (C₉ and C₁₀) bind in compressed conformations that tumble rapidly within the cavitands. The cavitands enhanced the synthesis of medium-sized cycloalkenes by ring-closing metathesis compared with reactions of the free dienes in either aqueous media or chloroform.

B,B bicycles: A new class of C₂-symmetric bicyclic bisborane catalysts was synthesized by treating bicyclic dienes with HB(C₆F₅)₂ or HB(p-C₆F₄H)₂. Remarkably, two diastereomeric catalysts could be accessed selectively from a single diene precursor by simply varying the reaction temperature (see scheme). These catalysts exhibited excellent activity and selectivity in the hydrogenation of imines.

The co-doping of N and P on carbon produces great structural stability against SO_x, NO_x, and PO_x, leading to excellent resistance to poisoning during catalysis of the oxygen reduction reaction (O red, N blue, P green, S yellow).

Reversible intramolecular redox-interconversion in hydroquinone–quinone hybrid dihydrobenzofurans is the key to a dynamic four-state network. Peptide-mediated kinetic resolution via acylation allowed the interconversion pathways to be studied in detail and mechanistic insights to be obtained.

Weaker hydrogen bonds favour competing isomerism in neutral molecular clusters, as observed in five isomers of the aniline trimer and the hydrated aniline dimer.

Meet the methyl mark: Site-specific RNA-cleaving deoxyribozymes are reported that respond to the presence of N⁶-methyladenosine close to the cleavage site in RNA with enhanced or strongly diminished cleavage rates, and thereby directly reveal the presence of the epitranscriptomic m⁶A modification in the target RNA.

Sensitized micropatterning of photodegradable hydrogels by means of two-photon irradiation is possible. The efficiency of the photoscission of o-nitrobenzyl ester linkages is enhanced by the modular addition of a two-photon active small molecule to a preformed hyaluronic acid based hydrogel. Biocompatibility of the improved two-photon micropatterning process as well as the hydrogel is confirmed by cell culture studies.

The power of the Cloud was harnessed for pharmaceutical compound production. Servers in Japan autonomously optimized conditions for three active pharmaceutical ingredients synthesized in laboratories in the UK. A researcher in the USA controlled the process via an internet connection. The synthetic steps were optimized with minimal intervention from operators within hours for all examples.

The shape of water: The influence of methane on the structure of liquid water is elucidated using Raman hydration-shell vibrational spectroscopic measurements. Near ambient temperatures, methane's hydration-shell is found to be slightly more tetrahedral than pure water, and then at higher temperatures it undergoes a crossover to a more disordered structure.

Enantiospecific borylation: A highly enantiospecific borylation of configurationally stable α-N-Boc substituted tertiary organolithium species and HBpin has been developed to synthesize various α-amino tertiary boronic esters through the formation of a new C−B bond with excellet enantiopurity and complete retention of configuration.

“Mn” of action: A general and efficient dual-deoxygenative coupling of primary alcohols with 2-arylethanols, catalyzed by a well-defined manganese/PNP pincer complex, is reported. Mechanistic studies indicate that this transformation undergoes a reaction process involving catalytic dehydrogenation, aldol condensation, and base-promoted deformylation.

Take control: Double-stranded helices with clear and controllable handedness were constructed in a bulk block copolymer by using d- and l-tartaric acid (TA) as dopants. The helices showed clear handedness dependence on the configuration of the TA. These helical structures induced different achiral species, such as nanoparticles and organic molecules, to adopt a chiral arrangement (see picture; TPEOH=4-[2-(4-hydroxyphenyl)-1,2-diphenylethenyl]phenol).

Split personality: A divergent synthesis of polycyclic N-heteroaromatics and the corresponding N-oxides through electrochemical C−H functionalization of biaryl ketoximes has been developed. The choice of the cathode material controls product selectivity.

Two P rings in a line: The straightforward preparation of linearly fused systems containing two six-membered phosphorus heterocycles, diphosphahexaarenes, is presented (see structures). They are very stable towards air, moisture and light. Optoelectronic investigations revealed ambipolar redox behavior for all derivatives and high fluorescence quantum yields up to 0.85.

Just Mannich enough: Despite their prevalence, 2- and 2,6-disubstituted piperidines are challenging to prepare enantioselectively, particularly when they possess β-functionalization. Two new approaches based on the use of cyclic nitrones provide the means to readily fashion an array of such materials, one of which proceeds with high enantioselectivity (up to 98 % ee) using a chiral thiourea promoter. Their sequential use has enabled 8-step total syntheses of both (−)-lobeline and (−)-sedinone from a common intermediate.

n-Type cubic GeSe has been stabilized at ambient conditions by entropy-driven formation of a solid solution with AgBiSe₂. It demonstrated promising thermoelectric properties with ultralow thermal conductivity. Upon increasing the AgBiSe₂ concentration in GeSe, the band gap of the system changes anomalously.

The linear piling of two (801 nm) or three (966 nm) photons via excited-state absorption (ESA) leading to upconverted visible emission was implemented at room temperature in a mononuclear molecular erbium complex possessing high-energy oscillators.

Keep it simple: The widely used, easily accessible, alkaline earth metal amides M(NR₂)₂ (M=Ca, Sr, Ba, R=SiMe₃) are highly active alkene hydrogenation catalysts. Alkene oligomerization is fully suppressed by trapping the reactive intermediate with R₂NH. A first example of Group 2 metal hydrogen transfer catalysis is given.

Record removal: A series of metal–organic frameworks with broad types of structures, pore sizes, and functionalities were used to identify UTSA-200 as the best separating agent for removal of trace C₃H₄ from C₃H₄/C₃H₆ mixtures. The efficiency is mainly attributed to the optimally dynamic pore size to efficiently block the larger C₃H₆ whilst retaining strong binding sites to selectively take up C₃H₄, thus producing high-purity C₃H₆ (99.9999 %).

Conjugated polymers have a higher ¹O₂ generation efficiency than their small molecular counterparts. Photosensitizers with A-D-A structures are better than D-A-D structures. Both in vitro and in vivo experiments show that the resulting materials can be used as photosensitizers in image-guided photodynamic anticancer therapy. D=donor, A=acceptor.

Herd instinct: A grouping effect is observed for single Ni−N₄ sites in a Ni catalyst supported by nitrogen-doped carbon (NC). A high 9.5 wt % Ni content was achieved with a ligand-stabilized polycondensation method. An enhanced electron density effect manifests at each single Ni−N₄ site, which decreases the binding energy of H radicals to Ni and promotes efficient coupling of benzyl alcohol and aniline to form N-benzylaniline.

Ice and solid H₂S look as different as pears and oranges, leading Pauling to conclude that H₂O has hydrogen bonds and H₂S has van der Waals interactions. Now it is shown that the H₂S dimer, like the H₂O dimer, is indeed hydrogen-bonded.

Opening up: A copper(II) acetate/(R)-DTBM-SEGPHOS-catalyzed ring opening of benzofurans and an enantioselective hydroamination cascade with dimethoxymethylsilane (DMMS) and hydroxylamine esters is described. Starting from readily available substituted benzofurans, a series of chiral N,N-dibenzylaminophenols, which are of high interest in pharmaceutical chemistry, were obtained with excellent enantioselectivity.

Core strength: The first total syntheses of the stemona alkaloids bisdehydroneostemoninine and bisdehydrostemoninine are reported. The synthesis features a novel palladium-catalyzed carbonylative spirolactonization to rapidly construct the oxaspirolactone moiety and a Lewis acid promoted tandem Friedel–Crafts cyclization and lactonization to form the 5-7-5 tricyclic core of the target alkaloids.

The Carbene Abides: Rhodium carbenes derived from substrates with no electron-withdrawing groups enable the highly selective syntheses of indolines and benzodihydrothiophenes. The reactions reported here represent the broadest level of functional-group tolerance yet demonstrated for enantioselective C−H insertion. A single catalyst/oxidant system is employed for all substrates and in most cases C−H insertion proceeds as a one-pot process from the hydrazone.

‘CuTi' pie: Cu/Zn and Cu/Ti dual metal systems have been devised to achieve the highly diastereo- and enantioselective propargylic substitution of 5H-thiazol-4-ones and 5H-oxazol-4-ones, respectively. These reactions demonstrate substantial substrate scope, giving terminal-alkyne-containing, functional-group-rich products in high yields.

Double duty: The combination of B(C₆F₅)₃ and an organic base, such as triethylenediamine (DABCO), serve as an excellent catalytic system for the C(sp)−H silylation of terminal alkynes with hydrosilanes. DABCO plays two crucial roles (Lewis base and Brønsted base) as revealed by experimental and DFT studies.

N to B: A mild catalytic system was developed for the preparation of alkyl potassium trifluoroborate salts by C−N bond cleavage. This method has good functional-group compatibility and can serve as a powerful synthetic tool for late-stage borylative cleavage of C−N bonds in complex compounds. dtbpy=4,4′-di-tert-butyl-2,2′-bipyridine.

I make(s) spirocycles: Iodospirocyclization of tryptamine-derived isocyanides affords highly substituted spiroindolenine imidoyl iodides. The imine functionality can undergo a variety of diastereoselective addition reactions, including in situ reduction, while the imidoyl iodide functionality is remarkable stable. The utility of the method was demonstrated by the formal total synthesis of (±)-aspidofractinine.

When two become one: The first tetragonal intermetallic cobalt stannide electrocatalyst, produced through diffusion of Co and Sn, acts as a superiorly active material for the electrocatalytic oxygen evolution and hydrogen evolution reaction as well as for overall water-splitting in strongly alkaline media. The self-supporting structural and electronic factors of Co and Sn enable enhanced net catalytic activities and long-lasting stability.

Flexible, stable, potent: Inhibitors of kinesin spindle protein (KSP) have been developed as a novel payload class in antibody–drug conjugates (ADCs) with the goal to increase the therapeutic window. Flexibility in linker attachment and tuning of the profile of active metabolites matching the KSPi mode of action as well as high linker stability provide potent ADCs against different targets.

Catch desired couplings: The non-directed cross-dehydrogenative coupling of allylic C(sp³)−H bonds with (hetero)arene C(sp²)−H bonds is enabled by C−H activation and employs abundant chemical feedstocks: olefins and (hetero)arenes. A particular highlight of this mild reaction is the applicability in late-stage functionalization reactions.

The metal-free reduction of phosphane oxides with H₂ using oxalyl chloride as activating agent was achieved. H₂ is activated by the in situ formed electrophilic phosphonium cation and phosphane oxide. The reaction is also catalyzed by B(2,6-F₂C₆H₃)₃ and 2,6-lutidine or phosphane oxide as Lewis base.

The nucleotides have turned: Using photolithography, phosphoramidite chemistry and a new set of base-sensitive monomers, mixed-base RNA microarrays can now be synthesized in situ. RNA arrays fabricated at high-density can accommodate up to about 780 000 different sequences inside a small, approximately 1.5 cm² wide synthesis area. The concept is illustrated with the synthesis of all possible 9-nt long sequence permutations.

Three techniques combined: Capturing local and global dynamics from one to hundreds of nanoseconds in the intrinsically disordered protein (IDP) α-synuclein: the combination of three experimental techniques, which are sensitive to motions on different length and timescales, with long molecular dynamics simulations is a powerful strategy to determine residue-specific protein dynamics in IDPs.

An electron against frustration! Silylium ions accept an electron from sterically hindered triarylphosphanes, regardless of whether these Lewis acids form a frustrated or a classical Lewis pair with the phosphane Lewis base. The thus-generated phosphoniumyl radical cations were characterized by EPR and UV/Vis absorption spectroscopy and single-crystal X-ray diffraction (see picture).

The parent trap: Successive reductions of a cyclic (alkyl)(amino)carbene (CAAC)-supported (bromo)dihydroborane yield a hydride-shift isomer of the corresponding tetrahydrodiborane and the first stable dihydroboryl anion, which acts as a powerful boron nucleophile.

Live and let dienes: Sterically unhindered diborenes based on a chelating benzylphosphine group undergo Diels–Alder cycloaddition reactions with dienes to generate 4,5-diboracyclohexenes.