An intermediate look: N-heterocyclic carbene catalysis has emerged as a powerful strategy for enantioselective functionalizations at remote positions, and proceeds via azolium dienolate intermediates that are easily generated from various substrates. This Minireview highlights the development and the new advances of cycloaddition/annulation reactions involving azolium dienolate intermediates.

Formation and decomposition of Li₂CO₃: In lithium–air batteries, Li₂CO₃ is a major by-product that can lead to cell dry-out and early failure. Therefore, understanding the formation and decomposition mechanisms of Li₂CO₃ lays the basis for a better design of lithium–air batteries.

The tip of the iceberg? Functionalizing the tip of an atomic force microscope enabled atomic-resolution imaging of single molecules and offers unique applications in chemistry for the investigation of on-surface reactions and the characterization of elusive molecules and complex molecular mixtures. This Review covers the recent progress in high-resolution scanning probe microscopy with functionalized tips.

“Everything now” generation: An alkaline–acid Zn–H₂O fuel cell was developed for the simultaneous generation of electricity and H₂ (see picture). The cell delivered an open-circuit voltage of around 1.25 V with almost 100 % Faradic efficiency for H₂ production and reached a power density of 80 mW cm⁻² and an energy density of 934 Wh kg⁻¹.

MOF host S: The electrical conductivity of metal–organic frameworks (MOFs) was promoted by the construction of polymer–MOF composites. Using MOF-based sulfur hosts, the critical role of porosity at high charge–discharge rates in Li–S batteries was elucidated. MOFs with short ion transfer pathways and large pore apertures were identified as the most suitable for long-term cycling at extremely high rates.

Hybridization matters: Graphdiyne oxide (GDO), the oxidized form of graphdiyne (GDY), exhibits an ultrafast humidity response with an unprecedented response speed (ca. 7 ms), which is three times faster than that of graphene oxide (GO). The acetylenic bond of GDO is more electron-withdrawing than the ethylenic bond in GO and gives rise to a faster binding rate with water.

MOF-on-MOF: A series of core–shell MOFs with mismatching lattices has been synthesized under the guidance of nucleation kinetic analysis. Isoreticular expansion of microporous shells and orthogonal modification of the core was realized to produce multifunctional MOF composites, which act as size-selective catalysts for olefin epoxidation.

Metal centered: The cause for the large second-harmonic generation (SHG) of LiCs₂PO₄ is shown to be the metal-cation-centered CsO₆ and LiO₄ groups rather than the nonmetal-cation-centered PO₄ groups.

Afterglow, a cocktail: A semiconducting polymer nanococktail (SPN_CT) with temperature-correlated afterglow luminescence is designed for imaging-guided photothermal therapy. The afterglow intensity of the SPN_CT has a good linear correlation with temperature, allowing the photothermal temperature of the tumor to be monitored under NIR laser irradiation.

A new cathode material, layered calcium vanadium oxide bronze, was synthesized for aqueous zinc-ion battery applications. The calcium-based bronze shows promising performance for storage of Zn²⁺ ions from the aqueous electrolyte (see picture). The Zn cell delivers an energy density of 267 W h kg⁻¹ at a power density of 53.4 W kg⁻¹.

The fast and the sensitive: A hybrid strategy employing site-specific protein modification techniques produced a palette of fluorescent membrane voltage indicators with sub-millisecond response kinetics. These indicators enable the optical mapping of electrical communications among cells at high resolution.

Second is best: A significant increase in nitrite reductase activity is achieved by modification of the steric properties of the second coordination sphere of a type 2 copper center. The steric properties can be harnessed to control metal coordination and reactivity in a 3-stranded coiled coil TRI peptide scaffold (TRIW-H).

The surface functionalization of gold nanoclusters with quaternary ammonium salts provides an antibiotic agent that is active towards multidrug-resistant Gram-positive bacteria both in vitro and in vivo. These modified nanoclusters show no detectable toxicity and do not induce drug resistance.

The heat is on: A new cocrystal with NIR photothermal properties is prepared from two small molecules, wherein the strong charge-transfer interaction leads to active non-radiative pathways, as revealed by femtosecond transient absorption spectroscopy.

The Bs needs: Boron-graphdiyne (BGDY) is prepared through a bottom-up chemical strategy. BGDY has a unique structure with molecular pores decorated with boron atoms. The pure sp-hybridized-carbon skeleton and boron heteroatoms can stabilize the metal atoms intercalated in the BGDY framework. As a result of this unique structure, BGDY shows remarkable electrochemical performance in sodium-ion half cells.

The barium carbonyl complexes [Ba(CO)]⁺ and [Ba(CO)]⁻ have been spectroscopically characterized and show a highly unusual bonding situation. The alkaline-earth metal barium behaves like a transition metal.

Two become one: Many prevailing methods for cis-olefination are complicated by the presence of multiple unsaturated units or electrophilic functional groups. In this study, Z-olefins are delivered through selective reduction of activated dienes using formic acid. The reaction proceeds with high regio- and stereoselectivity (typically >90:10 and >95:5, respectively) and preserves other alkenyl, alkynyl, protic, and electrophilic groups.

Crystal packing on a rugged surface: non-planar molecular building blocks restrict the interlayer slippage and modulate dispersion interactions for the formation of 2D G-quadruplex organic frameworks. Charge-transfer complexes can be obtained when size-matched building blocks of similar nonplanarity are co-crystallized.

Unprecedented inversion: The first catalytic inverse hydroboration of imines with N-heterocyclic carbene boranes has been realized by means of cooperative organocatalysis and photocatalysis. The nature of the thiol is vital for inverse hydroboration. This procedure represents an important step forward to enhancing α-amino organoboron libraries.

A semiconducting polymer nanoenzyme with photothermic activity is designed. Upon near-infrared (NIR) irradiation, the nanoenzyme can be activated to efficiently digest collagen in the tumor extracellular matrix (ECM), thereby leading to enhanced photothermal therapy.

In vivo sensing of H₂S: A luminescent probe, Ru-MDB, was developed for phosphorescence and time-gated luminescence quantification of H₂S using a responsive luminescence-masking moiety. Monitoring and visualization of H₂S in cell lysosomes, D. magna, zebrafish, organs, mice, and human sera, is possible. Key: electron transfer (ET), emission (Em), excitation (Ex).

A healthy glow: Ultralong phosphorescence was observed from hydrogen-bonded organic aromatic frameworks (HOAFs) with different pore sizes that were constructed under different conditions from the same aromatic precursor containing three carbazole units. Intralayer π–π interactions and interlayer hydrogen bonds endowed the HOAFs with high thermal stability and phosphorescence lifetimes of up to 79.8 ms (see picture).

Electrocatalytic oxidation of a luminophore at single Au, Pt, and Au-Pt Janus nanoparticles was studied using electrogenerated chemiluminescence (ECL) microscopy. Compared to the monometal nanoparticles, the Janus particle structure exhibited enhanced ECL intensity and stability, indicating better catalytic efficiency.

Protein modification: The pyroglutamate-histidine dipeptide sequence exhibits remarkably fast and efficient copper-catalyzed N−H coupling with boronic acids, allowing specific and bioorthogonal functionalization at a natural posttranslational modification.

Down to the wire: Colloidal Fe-doped NiSe₂ ultrathin nanowires (UNWs) down to 1.7 nm in diameter were synthesized by a binary soft-template strategy. These UNWs yield surface-confined electrochemical oxidation, enabling efficient and robust oxygen evolution catalysis owing to their favorable electronic structures and unsaturated local coordination environments.

Styling gel: Supramolecular hydrogels that have distinct crystalline and amorphous networks are obtained by balancing the rigidity and flexibility of the inorganic–organic co-assemblies. Using polyoxometalates (POMs) and zwitterionic amphiphiles, the transition morphologies between kinetically and thermodynamically controlled gelation process are evidenced as ordered wormlike micelles.

Criss-cross: Incorporation of a phenanthrene moiety into a hexaphyrin(1.1.1.1.1.0) core resulted in an intramolecular ring fusion to give two chiral helicenophyrins. These molecules comprise helicene and porphyrin units.

Tribromomethyl-substituted arenes were directly converted into C−C triple-bonded structural motifs by on-surface dehalogenative homocoupling reactions, as confirmed by a combination of high-resolution scanning tunneling microscopy, non-contact atomic force microscopy, and density functional theory calculations. Concurrently, sp³-hybridized carbon atoms state are converted into sp-hybridized ones.

Strong backbone: A class of chiral 1,3,2-diazaphospholenes with rigidified backbones has been developed. In first benchmark experiments, they are shown to behave as catalytic molecular hydrides for enantioselective 1,4-reductions.

Low thermal conduction: Soft phonon modes and optical-acoustic phonon coupling cause an ultralow lattice thermal conductivity in the room-temperature hexagonal phase of AgCuTe, while the dynamic disorder of Ag/Cu cations leads to reduced phonon frequencies and mean free paths in the high-temperature rocksalt phase. A high thermoelectric figure of merit (zT) of 1.6 is achieved in the p-type AgCuTe at around 670 K.

A matter of solvent: Alkynyl and monofluoroalkenyl isoindolinones were generated with good enantioselectivities from N-methoxy benzamides and α,α-difluoromethylene alkynes by C−H activation with a chiral CpRh^III catalyst. Remarkably, the product formation is solvent-dependent; whereas alkynyl isoindolinones are formed in methanol, monofluoroalkenyl isoindolinones are generated in isobutyronitrile.

A four-component coupling of 2-lithioindoles, boronic esters, donor–acceptor cyclopropanes, and alkyl halides in the presence of the Lewis acid catalyst Sc(OTf)₃ provided indolines with three contiguous stereocenters, including a quaternary center, with complete diastereoselectivity and stereospecificity (see scheme). The valuable boronic ester moiety remaining in the products allows for subsequent functionalization.

The synergistic combination of chain walking, a process involving repeated migratory insertions and β-H eliminations, and cross-coupling chemistry led to the development of a mild, efficient NiH-catalyzed process for the remote hydroalkylation of alkenes. Unfunctionalized C(sp³)−C(sp³) bonds were constructed from two simple feedstock chemicals, namely olefins and alkyl halides.

Go with the flow: Reported is the electrophilic amination of organolithium intermediates using optimized amine reagents under mild reaction conditions within flow microreactors. Flow reactions are suitable for fast and mild amination using unstable organolithium compounds. Also notable is the fact that additional reagents and catalysts were not necessary. FG=functional group, R¹ and R²=alkyl groups.

Balance of power: The incorporation of aromatic groups onto POM clusters introduces strong cation–π interaction during the their self-assembly and changes the trend of the assembly size. A small difference between two aromatic groups is amplified after the incorporation, initiating self-recognition phenomenon between two highly similar macroanions.

Homogeneous catalysis: Trifluoromethyl arenes have been obtained by Pd-catalyzed decarbonylative functionalization of acid fluorides. The key Pd^II-F intermediate forms through intramolecular redistribution to Pd, allowing direct transmetalation to occur. Computational and experimental mechanistic studies reveal that transmetalation occurs prior to decarbonylation.

Good clean functionalization: A mild and selective C(sp³)−H oxidation promoted by an inexpensive decatungstate photocatalyst was significantly improved by a microflow reactor, which enabled the safe use of oxygen and enhanced irradiation of the reaction mixture. Both activated and unactivated C−H bonds could be oxidized by this sustainable method, including those in natural scaffolds, such as (−)-ambroxide and artemisinin.

Color filter: A continuous, high-quality two-dimensional imine-linked COF membrane with ordered and tunable pore channels was prepared on tubular alumina supports. The COF-LZU1 membrane shows excellent water permeance and high rejection rates for various water-soluble dyes, as well as high stability during water purification.

First step into a novel field in Ge chemistry: The subhalide cluster Ge₁₄Br₈(PEt₃)₄ was obtained by heating a metastable solution of Ge^IBr to room temperature and then structurally characterized. This cluster can be seen as the first trapped intermediate of the disproportionation reaction of Ge^IBr en route to elemental germanium. DFT calculations indicate that classical bonding is realized within the cluster.

Small change, big difference: Local investigation of the hydrogen evolution reaction (HER) on a single crystal of iron nickel sulfide, one of the most active non-noble-metal HER catalysts, was carried out using scanning electrochemical cell microscopy (SECCM). Small variations in the Ni/Fe ratio at the surface induce tremendous changes in the catalytic HER activity.

Unsymmetrical diborenes were prepared through reduction of cyclic diboranes(4) containing a benzylphosphine bridge. A doubly phosphine-stabilized diborene underwent an unprecedented, thermally induced rearrangement to form a borylborylene.