Building bridges: Chalcogen bonds are noncovalent interactions similar to hydrogen bonds that are based on electrophilic chalcogen substituents. This Minireview provides an overview on the origin and features of chalcogen bonding as well as its applications in the solid state and in solution. A certain focus will be on the latter and particularly on the recent introduction of chalcogen bonding in noncovalent organocatalysis. LB=Lewis base.

Energy-consuming thermal separation processes such as distillation will eventually be replaced by low energy-consuming processes like membrane filtration. This change has already occurred for desalination of seawater. Major challenges, however, remain with respect to increasing selectivity and permeation flux and controlling mass transport. New predictive models are needed that account for all “three legs”—selectivity, capacity and transport of mass and momentum.

Phenolics on the rise: Recent advances in the preparation of functional materials, namely thin films, particles, and bulk materials, based on phenolic building blocks and their diverse applications, ranging from biomedicine to catalysis, are highlighted. This Review will help integrate various disciplines that use phenols and serve as a guide for the development of future materials.

Radiochemistry in a flash: A photochemical conjugation and radiolabelling approach enables the rapid, one-pot synthesis of radiolabelled monoclonal antibodies (and other proteins/peptides) for use in immuno-positron emission tomography (immuno-PET) and targeted radioimmunotherapy.

Color change: The origin of the spectral shift from a red- to a green-absorbing form in the cyanobacteriochrome Slr1393g3 was identified by combined quantum mechanics/molecular mechanics simulations and wave function analysis. The calculations reveal that the effective conjugation length in the chromophore becomes shorter upon conversion from the red to the green form.

The smallest cyclic Si=P species: A phosphorus(I) cation was used as a precursor for the synthesis of the first three-membered cyclic phosphasilene. The highly strained ring compound can be coordinated to a transition metal through the ylidic phosphorus center or “clicked” with itself to give two cluster-like Si₄P₂ isomers.

Which way to go? The monoterpene l-menthone was incorporated into the backbone of a photochromic diarylethene. Chirality transfer upon photocyclization leads to preferred formation of one major stereoisomer. Complete reversal of the diastereomeric outcome was achieved by altering either the chemical environment or the irradiation wavelength, resulting in selective formation of the minor isomer.

Group therapy: Employing easy-to-handle trichloroisocyanuric acid, potassium fluoride, and catalytic amounts of acid allows simple, mild and direct access to aryl-SF₄Cl intermediates that have either not been or cannot be prepared using other methods. The approach also provides access to aryl-SF₃ and aryl-SeF₃ compounds, which extend the applications of this chemistry beyond arene SF₅-functionalization.

Who is faster? The reactivity of donor–acceptor cyclopropanes was investigated in (3+n) cycloaddition reactions with an aldehyde, a nitrone, and an isobenzofuran by NMR and in operando IR spectroscopy. The obtained reaction rates were compared with the structural and electronic properties of the donor–acceptor cyclopropanes.

Sequence coins function: Sequences that bind m-THPC are selected from a library of thiolactone (Tla)/Michael oligomers by single-bead readout with MALDI-TOF MS/MS. The corresponding Tla/Michael-PEG conjugates make m-THPC available in solution and allow drug payload as well as drug release kinetics to be fine-tuned by sequence variation in the precision segment.

Host–guest complexes of bidentate boron Lewis acids with small nitrogen bases differ in their stability. Molecular recognition of some guest compounds in the binding pocket of the receptor is illustrated by selective exchange reactions.

Matchmaker: The commercially available precatalyst system MesCu/(R,R)-Ph-BPE couples Ph₃SiH with the fast-reacting enantiomer of racemic mixtures of tertiary propargylic alcohols. This non-enzymatic kinetic resolution provides access to synthetically valuable and versatile enantiomerically enriched tertiary propargylic alcohols and the corresponding silyl ethers (see scheme).

Like puffed rice! Metal–organic frameworks (MOFs) composed of high-energy ligands (1H-1,2,3-triazole) and volatile zinc nodes decompose/evaporate upon pyrolysis. The carbon networks foam, while the pre-imbedded Fe and Co ions are transformed into active atomically doped metal sites (ADMSs). These ADMS-decorated carbon networks with hierarchical pores are highly active catalysts for the oxygen reduction reaction.

Metal–carbene reaction: A novel rhodium-catalyzed dearomatization of O-substituted pyridines provides N-substituted 2-pyridones. A computational study suggests a mechanism involving the formation of a pyridinium ylide followed by 1,4-acyl migratory rearrangement from O to C. When chiral dirhodium complexes serve as the catalyst, the asymmetric variant proceeds with excellent enantioselective control.

π-Electrons were rapidly and efficiently incorporated into the g-C₃N₄ by copolymerizing π-electron-rich barbituric acid with melamine via a microwave-assisted heating process. The as-produced g-C₃N₄ shows a near 20-fold enhancement in H₂ generation upon exposure to visible light, representing a rate of 25.0 μmol h⁻¹ over 1.3 μmol h⁻¹ from g-C₃N₄ produced by conventional heating in an electric furnace.

Weapon of choice: Penicillin-binding proteins and serine β-lactamases, which employ nucleophilic serines, hydrolyze β-lactam antibiotics. However, the l,d-transpeptidases, which employ nucleophilic cysteines, also fragment some β-lactams. Serine β-lactamases where the nucleophilic serine is substituted with cysteine also catalyze β-lactam fragmentation, consistent with a mechanism involving the formation of thioester-enolate intermediates.

Not a ferryl flip: Water converts the nonheme [Fe^IV(O_syn)(TMC)(NCMe)]²⁺ complex, where the oxo ligand is on the same face of the macrocycle as all four methyl groups (2), into its anti isomer (1), where the oxo ligand is on the opposite face. This conversion occurs not by a ferryl flip, but by the binding of water trans to the oxo atom, with two subsequent consecutive proton transfers to place the oxo atom in the thermodynamically favored anti position.

Multiple weak synergetic interactions enable the generation of photooxidase-mimicking nanovesicles that contain an amphiphilic amino acid as a simplified protein host and phthalocyanine as a chlorophyll active site model. These vesicles catalyze the oxidation of dopamine into leucodopaminechrome under aerobic conditions.

Synergy in hybrid: A hybrid platform has been developed based on a hapten-labeled bispecific peptide and an anti-hapten antibody to overcome the short plasma half-life of most peptide therapeutics.

The ties that bind: Spectroscopic evidence of a rare example of a Au⋅⋅⋅H⁺−N hydrogen bond is reported. Computational investigations confirm the nature of the hydrogen bond to gold(I).

Two for the price of one: A multifunctional nanoagent based on Gd₂(WO₄)₃:Tb@MC540 nanoparticles with capabilities for dual-modal CT/MRI-guided synergistic radio-/X-ray inducible photodynamic therapy of tumors was developed. This type of therapy exhibits a higher tumor growth inhibition efficiency than radiotherapy alone, indicating a promising prospect of nanoscintillators for cancer theranostics.

Cumulene or alkyne? The reduction of a [3]cumulene using Na and K in the presence of 18-crown-6 gives the mono- and doubly reduced cumulenes as solvent-separated ion pairs. The analogous reduction with Cs affords a contact-ion complex. Crystallographic analysis of all the species shows dramatically increased bond-length alternation upon reduction, while the cumulenic framework remains essentially planar in all cases.

Zincing out loud: A method is proposed that uses zinc, a low-cost and moderately active metal, to generate sulfur vacancies and realize zinc doping on MoS₂ basal planes simultaneously.

Introducing strong antiaromaticity: Reported here is a modular and efficient synthesis of a series of dinaphthobenzo[1,2:4,5]dicyclobutadienes with strong antiaromaticity, orthogonally tunable electronics and molecular packing, and high charge mobility. These features allow the application of the structures in organic electronics. CANAL=catalytic arene-(oxa)norbornene annulation.

A cycloarylene cylinder serves as a pliable host for C₇₀ to dynamically cover the ellipsoidal guest through unbiased rotational motions.

An identical probe complementation system was developed by flopped fusion of charge-engineered fluorescent protein fragments. The probe was applied for the reliable and robust visualization of the homo-oligomerization of diverse receptors (GPCR, EGFR, DAI) in live cells with extremely low background signals.

Ray of light: An in vivo, reactive oxygen species (ROS)-responsive, cross-linking strategy was developed utilizing glutathione-modified, sub-10 nm, ultra-small nanoprobes to improve NIR-II bioimaging and excretion properties.

The metastable bct phase was only observed in ultrathin cerium oxide nanoplates. Thermodynamic energy analysis confirmed that the surface energy of the ultrathin nanoplates is the cause of the remarkable stabilization of the metastable bct phase. The mechanism of surface energy regulation can be expanded to other metallic oxides, thus providing a means for manipulating and stabilizing such materials under ambient conditions.

Iron in: An inexpensive and earth-abundant electrocatalyst, an iron-based oxygen-deficient perovskite, shows unprecedented oxygen-evolution activity. Using it, systematic correlations between electrocatalytic activity, composition, defect-order and electrical conductivity are demonstrated.

Base motive: A base-promoted defluorosilylation of unactivated C(sp²)−F and C(sp³)−F bonds, obviating the need for transition-metal catalysis, specialized ligands, or harsh reaction conditions, has been developed. The salient features of this method are the mild reaction conditions, ease of execution, and wide substrate scope, even within the context of late-stage functionalization of advanced fluorinated building blocks, thus offering a complementary reactivity mode to existing silylation technologies.

Nanophosphors on display: Mesoporous silica nanoparticles were used as nanocarriers to form the nanophosphor ZnGa₂O₄:Cr³⁺,Sn⁴⁺ (ZGOCS) in the mesoporous structure after sintering. Good dispersity and morphology can be observed. Good packing density and light conversion efficiency were achieved for a mini-light emitting diode.

A Z-scheme heterojunction of 2D/2D black phosphorus/monolayer Bi₂WO₆ was fabricated with enhanced photocatalytic performance under visible light irradiation. The highest NO removal ratio was up to 67 % and the H₂ evolution ratio 21 042 μmol g⁻¹. The black phosphorus nanosheets can be used for photocatalytic degradation of exhaust gases in air.

More than a ligand: A rhodium catalytic system has been established for the direct and ortho-selective borylation of commercially available arylphosphines by P^III-directed C−H activation. A series of ortho-boronated phosphines with different steric and electronic properties were obtained in high yields.

Designer enzyme: The directed evolution of a designer enzyme featuring a uniquely reactive aniline side chain as catalytic residue (in red) is reported. Multiple beneficial mutations were identified (blue), which when combined increase the turnover frequency (k_cat) of the designer enzyme by more than 90 times.

Successful iteration: Donor rhodium(II) carbenes are generated by retro-Buchner reaction (decarbenation) of 7-substituted 1,3,5-cycloheptatrienes, leading to broad-scope synthesis of allylsilanes by Si−H insertion and a new method for the iterative vinylogation of aldehydes.

3D copper anchored with an artificial solid–electrolyte interface (SEI) layer is proposed for Li-plating. The anchoring construction of 3D copper and SEI layer can lower current density, provide buffer space, reduce lithium/electrolyte contact, and endure Li-deposition-induced volume change, leading to high-performance lithium anode with long lifespan, high rate, high area capacity, and high efficiency.

Trading places: Two new nonlinear optical materials, α- and β-Ba₂[GaF₄(IO₃)₂](IO₃) (1 and 2), were designed via three-site aliovalent substitution of VO₄F₂ in α- and β-Ba₂[VO₂F₂(IO₃)₂](IO₃) by GaO₂F₄. The new materials display large second-harmonic generation responses (≈6×KH₂PO₄ (KDP)), wide energy band gaps (4.61 and 4.35 eV), and high laser damage thresholds (29.7× and 28.3× relative to that of AgGaS₂).

Directly fused metalloporphyrin tapes were simultaneously synthesized and deposited in a thin film form by scalable and substrate-independent chemical vapor deposition (CVD). Patterned and conductive (3.6×10⁻² S cm⁻¹) conjugated poly(porphyrin) thin films are formed. Mass spectrometry provides insight into the oxidative polymerization reaction and two side reactions (metalloporphyrin chlorination and π extension via intramolecular ring fusion).

Cold as ice: Freezing DNA oligonucleotides stretches and aligns random coils, as confirmed using fluorescence resonance energy transfer, thiazole-orange staining, and surface-enhanced Raman spectroscopy. This will have interesting implications for biointerface science, biosensors, and DNA nanotechnology.

Dual gold catalysis: A synthesis of unconjugated (E)-enediynes from allenyl amino alcohols is reported and their gold-catalyzed cascade cycloaromatization to a broad range of enantioenriched substituted isoindolinones has been developed.

The hydroformylation of propene to give predominantly iso-butanal has been achieved; class-leading selectivity is possible even at higher temperatures that deliver fast conversion. Racemic rhodium complexes of bidentate phospholane phosphites derived from tropos-biphenols and unusual solvent systems are the key to the selectivity observed.

Homogeneous catalysis of electrochemical reactions often involves proton-coupled electron-transfer. The conditions that make installing proton relays inside the catalyst molecule lead to a considerable boosting of catalysis instead of being a zero-sum game are analyzed in detail, showing why the proton is such a uniquely appropriate agent for this task.

C−N coupling: A new electrophilic amination of boronic acids with simple and inexpensive nitro compounds has been developed allowing the preparation of a variety of highly substituted and functionalized aromatic secondary amines. The process employs affordable PPh₃ as reducing agent, in the presence of an easily available and highly stable dioxomolybdenum(VI) complex as catalyst.

Worth protecting: Pd^II-catalyzed enantioselective C(sp³)−H cross-coupling of free carboxylic acids with organoborons has been realized using either mono-protected amino acid (MPAA) ligands or mono-protected aminoethyl amine (MPAAM) ligands. A diverse range of aryl- and vinyl-boron reagents can be used as coupling partners to provide chiral carboxylic acids.

Be selective: δ-Azido, δ-cyano, and δ-thiocyanato alcohols were obtained in high yields from N-alkoxypyridinium salts under mild dual photoredox/copper catalysis. A catalytic enantioselective δ-cyanation protocol in the presence of a chiral bisoxazoline ligand was also developed.

A straightforward method for indenone synthesis was achieved by Pd/NBE-catalyzed annulation between simple aryl iodides and unsaturated carboxylic acid anhydrides. This method enabled streamlined syntheses of pauciflorol F and acredinone A.

An asymmetric C−H/C−H cross-coupling reaction of ferrocenes with azoles such as oxazoles and thiazoles is presented. Palladium(II)/monoprotected amino acid (MPAA) catalytic system exhibits excellent reactivity and regioselectivity for oxazoles and thiazoles. This method offers a powerful strategy for constructing planar chiral ferrocenes.