Photopolymerization is a promising method to generate advanced polymers. Particularly significant are photoactive species that form acids or bases upon irradiation by light to initiate polymerization of the monomers. This Minireview highlights the recent advances in the development of organic photobase and photoacid generators.

The rational design of peptide assemblies to achieve complex functions in a cellular environment has attracted increasing attention in recent years. In this Minireview, selected examples of peptide assemblies are highlighted, with a focus on instructed assembly for the spatiotemporal control of peptide assemblies in cells.

Taking charge: LiNiO₂ is one of the most heavily investigated layered oxides for use as the cathode active material of Li-ion batteries. This Review gives a comprehensive overview of this compound, almost 30 years after its introduction. The focus lies in the effect of Li off-stoichiometry, the key instability issues that plague the material and the strategies to overcome them, the open questions, and the most promising future research directions.

From simplicity, complexity: Modern arene hydrogenation methods provide direct access to complex saturated carbo- and heterocycles by controlling the diastereo-, enantio-, and chemoselectivity. The hydrogenation of multisubstituted arenes generally yields predominantly the cis isomer. Enantiocontrol may be imparted by chiral auxiliaries, Brønsted acids, or transition-metal catalysts. The chemoselectivity can often be controlled by optimization of the catalyst and reaction conditions.

Oxygen vacancies (OV) are native defects in transition metal oxides and their presence has a critical effect on the physicochemical properties of the oxide. Studies reveal that OV diffusion leads to their condensation along a specific lattice plane, resulting in the formation of lattice mismatches and microcracks in single-crystal cathode materials.

An Fe–N–C catalyst is analyzed using nuclear- and electron-resonance techniques. The results show that even after mild pyrolysis and acid leaching, it contains considerable fractions of α-iron and iron oxide. This raises the question how many FeN₄ sites, which are active centers in the oxygen reduction reaction, can be present in Fe–N–C catalysts prepared by pyrolysis at 900 °C and above.

An asymmetric allylic aromatization (AAAr) strategy employs readily accessible equivalents of benzylic nucleophiles in iridium-catalyzed allylic substitution reactions with the concomitant formation of aromatic rings. This strategy provides straightforward access to valuable heteroarenes, bearing a homobenzylic stereogenic center, in enantiopure form.

Born to run: A potassium–graphite battery with concentrated electrolyte exhibits an ultrastable performance for over 2000 cycles with negligible capacity decay, corresponding to a running time of over 17 months.

Colorimetric dermal sensors in the form of tattoos have been developed to measure pH, glucose, and albumin concentrations in an ex vivo porcine skin tissue model. The dermal sensors were injected into the dermis in an array format for multiplexed detection. Quantitative readouts were obtained with a smartphone camera.

Divide et impera: A general strategy to access both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic esters is based on an energy-transfer-mediated homolysis of unsymmetric σ-bonds. The independent aryl/alkyl radical generation step enables a series of key C−X and C−C bond-forming reactions by simply changing the radical trapping agent.

Cooperation then amination: A unified one-pot experimental procedure enables a versatile regio- and stereodivergent synthesis of homoallylic amines. Critical to the successful development of this method was the recognition that initial catalyzed C−C bond formation controls all aspects of regio- and stereoselectivity. Thereafter, in situ amination/Hofmann rearrangement results in stereospecific C−N bond formation.

Automatic transmission: An asymmetric hydrogen autotransfer reaction allows the practical synthesis of α-chiral amines by the alkylation of amines with alcohols. Under the co-catalysis of a ketone and NaOH, racemic secondary alcohols react with Ellman's chiral tert-butanesulfinamide, affording chiral amines with high diastereoselectivities (up to >99:1 d.r.). The reaction does not require a transition metal, can be run on a 10 gram scale, and can be used for accessing chiral deuterated compounds.

Growing aggregates on the fly: The largest isolated neutral peptide aggregates were grown by using laser desorption molecular beam techniques. Infrared action spectroscopy was employed to visualize their predominantly parallel β sheet type structures.

UFO-shaped supraparticles were synthesized for the dynamic monitoring of the cell membrane vesiculation process at the single-particle level.

A library of differentially fucosylated and sialylated oligosaccharides was produced starting from a single chemically synthesized tri-N-acetyllactosamine derivative. The resulting oligosaccharides were printed as a microarray that was probed by several glycan-binding proteins, which showed that complex patterns of fucosylation can modulate glycan recognition.

Cucurbituril-mediated microtubular aggregation was achieved by modifying an antimitotic peptide with a benzylimidazolium moiety, which could be encapsulated by cucurbituril. The exposed antimitotic peptide could bind microtubules, resulting in aggregation, leading to tumor-cell apoptosis in a mouse model.

Final piece of the puzzle: The structures of amipurimycin and the miharamycins have been resolved using chemical synthesis and X-ray diffraction analysis. The stereochemistry of amipurimycin has been corrected. The miharamycins have a trans-fused dioxabicyclo[4.3.0]nonane sugar scaffold, which was previously assigned as being in the cis configuration.

The good ones go into the pot, the bad ones go into your crop: By exploiting the lower critical solution temperature (LCST) behavior of tailored thermoresponsive homopolymer layers, human induced pluripotent stem cells are selectively separated from unintentionally differentiated cells without any releasing reagent.

Responsive photocatalytic polymers: The inclusion of photocatalytic sites in a temperature-responsive polymer nanogel network created a dual-responsive polymer photocatalyst that can be utilised to selectively catalyse numerous reactions at specific temperatures.

Spaced-out dendrons: Step-growth “click” polymerization using well-defined linear polymeric and dendritic reactants has led to linear-dendritic copolymers in which the linear segments serve as uniform spacers between the dendrons. With alternating hydrophilic linear blocks and hydrophobic dendrons, the copolymers can spontaneously self-assemble into a unique type of microphase-segregated nanorod in water.

Tuneable surfaces: Surface micelles on silica particles are fabricated by the coassembly of polymer brushes and “free” block copolymer chains in a selective solvent. The surfaces of these modified silica particles present switchable properties upon treatment with water and with tetrahydrofuran (THF).

A treatment for lead poisoning, consisting of an Fe₃O₄ nanoparticle coated with amine-enriched hyperbranched poly(amidoamine)s, and an apparatus enabling the magnetic removal of nanoparticle-associated, lead-containing hemoglobin from the blood have been developed to treat lead poisoning in a safe and efficient way. This strategy enabled the removal of 75% of the lead from pig blood in vivo within 50 minutes.

A concise, scalable, and enantioselective synthetic route to ovatodiolides has been devised based on two tandem reactions, including ring-opening metathesis/ring-closing metathesis reactions (ROM/RCM). The butenolide ring and the α-methylene unit were found to be important for the biological activity of these compounds, which inhibit hepatic cancer stem cells and tumorsphere formation.

A–B–C easy as 1–2–3: High-performance batteries require tailored electrolyte cosolvents. The lithium-solvating ability of a series of hydrofluoroethers (HFEs), and the linear free-energy relationship between these solvents and lithium polysulfide (LiPS), are reported. HFE structures (A, B, and C) vary with respect to the location of fluoroalkyl groups and an ether oxygen atom. Key: lithium-solvating power (1), conductivity (2), LiPS dissolution (3).

Back to nature: In vitamin B₁-catalyzed umpolung, a Breslow intermediate (BI) is formed from an aromatic thiazolin-2-ylidene and the substrate aldehyde. The combination of a N-Dipp-substituted thiazolin-2-ylidene with pentafluorobenzaldehyde produced a BI, characterized by XRD. When trifluoroacetaldehyde was used, the first BI derived from a thiazolin-2-ylidene and an aliphatic aldehyde was generated, and characterized by NMR spectroscopy.

Destructive quantum interference has been demonstrated in charge transport through multicenter-bond-based single-molecule carborane junctions in which all three connectivities of the carborane framework show destructive quantum interference. The transmission channels in meta-connected carborane are comprehensively suppressed by destructive quantum interference, leading to highly insulating molecular junctions.

Natural fatty acids were readily loaded into a biocompatible nanocapsule through a well-defined hole in the wall for the controlled release of payloads in response to near-infrared laser irradiation or direct heating. The release profile depends on both the size of the hole and the duration of laser irradiation.

Sugar resistance: A diboronic acid, DBA2+, was prepared, which shows good affinity and selectivity toward glucose and changeable pK_a upon binding. DBA2+ was applied to the non-enzymatic, conductimetric monitoring of glucose. With negligible interference from other sugars, DBA2+ shows potential for selective, quantitative, and continuous glucose sensing.

Single chain cyclized/knotted polymer (SCKP) films, synthesized by reversible addition fragmentation chain transfer (RAFT) homopolymerization of multivinyl monomers (MVMs), followed by crosslinking by UV light, exhibit a higher resistance to bacterial attachment and biofilm formation than the corresponding non-SCKP films because of their altered surface morphology. SCKP films could be used to coat medical devices.

Molecularly imprinted polymers (nanoMIPs) are used to inhibit the growth of HER2-positive breast cancer. NanoMIPs, imprinted using HER2 glycans, can bind to these glycans, preventing HER2 heterodimerization. This blocks HER2-dependent signaling pathways and leads to the inhibition of HER2-positive breast cancer growth.

Highly crystalline nanoporous hexagonal boron nitride nanosheets (h-BNNS) were prepared using amorphous h-BN precursors through a dissolution–precipitation/crystallization process in the presence of magnesium. The crystalline h-BNNS is a catalyst for the dehydrogenation of dodecahydro-N-ethylcarbazole.

A blessing in disguise: Conjugating a diglycine (GG) to an antibiotic prodrug (chloramphenicol succinate) increases the rate of prodrug activation by increasing the rate of ester-bond hydrolysis catalyzed by bacterial esterases. Dipeptide conjugation to antibiotic prodrugs can increase antibiotic efficacy and reduce adverse drug effects.

This cavity doesn′t hurt: The solvolysis reaction of para-nitrophenyl acetate is accelerated by an order of magnitude through cooperative vibrational strong coupling of the reactant and solvent molecules at room temperature. The reaction mixture is injected into a Fabry–Perot (FP) cavity and the cavity mode is tuned to the carbonyl stretching mode of both the reactant and solvent molecules together to achieve strong coupling.

Regioselective hydrogen-atom abstraction: A combined experimental and computational study gives evidence of electrophilic reactivity of a side-on manganese(III)–peroxo complex. Furthermore, isotopic substitution of the substrate changes the regioselectivity of the reaction and the product distributions.

A low-cost Ni/NiO/C catalyst with abundant Ni/NiO interfacial sites as a competent HOR electrocatalyst was designed. It exhibits better stability and CO tolerance than commercial Pt/C in alkaline media.

Better than PAH: A highly regioselective bistriflyloxylation of a polycyclic aromatic hydrocarbon (PAH) occurs during its cyclopentannulation under Scholl-type conditions. OTf moieties undergo palladium-catalyzed cross-coupling reactions, allowing simple access to larger and more complex PAHs.

Ringing the Changes: The inorganic phosph(III)azane [{P(μ-N^tBu)}₂NH]₅ macrocycle provides a unique H-bonding host environment for N−H⋅⋅⋅π bonding to alkynes, nitriles, and the PCO⁻ anion. Oxidation of the P^III periphery with sulfur kinetically entraps halide ion guests, which cannot be abstracted even with powerful methylating agents.

A photodynamic therapy system has been developed using hemoglobin-linked conjugated polymer nanoparticles that can luminesce and supply oxygen. This system does not require an external light source and circumvents the problem of low molecular oxygen levels found in hypoxic tissue. This system could also be used for the controlled release of an anticancer prodrug, combining PDT and chemotherapy.

Core–shell structured plate-like LaKNaTaO₅/LaTaON₂ containing LaTaON₂ shells exposing (010) facets and having a low defect density on the lattice-matched LaKNaTaO₅ cores was obtained by a brief nitridation process. When modified with a Rh co-catalyst, LaKNaTaO₅/LaTaON₂ exhibited photocatalytic H₂ evolution activity four times greater than that obtained from conventional LaTaON₂ powders with uncontrolled facets.

Pore patrol: A series of heterogenous catalysts based on iridium complexes bound inside porous polycarbazoles was prepared for the selective monoborylation of methane. Catalysts with high efficiency and good chemoselectivity can be developed through tuning the pore size distribution of the porous polycarbazole.

Thanks to the links: A copper phthalocyanine-based 2D conjugated MOF with square-planar cobalt bis(dihydroxy) units (Co-O4) as linkages serves as an electrocatalyst for the oxygen reduction reaction with high catalytic activity (E_1/2=0.83 V vs. RHE). The linking Co centers with optimized electronic structure (e_g=1) are identified as the active sites.

Increasing molecular “CO”mplexity: Carbonylation of 1,3-diynes provides a general approach to a variety of synthetically useful conjugated dienes in excellent yields and high chemo-, regio-, and stereoselectivities. The key to the reaction is the bidentate ligand with a built-in pyridine base.

Cool down: Using the refrigerant HFO-1234yf together with [RhH(PEt₃)₃], a C−F bond activation occurs to produce a rhodium fluorido complex. This reaction is followed by a C−H bond activation mediated by the fluorosilane and a subsequent 1,2-fluorine shift.

Cutting with air: C(sp³)−C(sp³) single bonds in amines can be cleaved using homogeneous copper-based catalysts in the presence of air. The utility of this novel methodology is demonstrated for C_α−C_β bond scission in >70 amines with excellent functional group tolerance.

One to three: Phosphine-catalyzed activation of alkylidenecyclopropanes (ACPs) generates allylic phosphonium intermediates that resemble the well-studied phosphine-allene adducts but exhibit distinct properties. These intermediates facilitate three types of rearrangements to form polysubstituted furans and dienones.

Golden capture: A σ-gold allenyl intermediate was isolated and characterized during the study of a novel gold-catalyzed propargylation reaction. Propargylsilanes serve as very effective reagents for the propargylation reaction of carbonyl compounds. The reaction can be directed toward formation of either homopropargyl silyl ethers or the in situ synthesis of 2-silyl-4,5-dihydrofurans. TBS=tert-butyldimethylsilyl, TMS=trimethylsilyl.

Make stable: BN-embedment is demonstrated to play an important role in stabilizing a pentacene derivative by tuning the orbital distribution and lowering the HOMO energy level. This study provides an effective strategy to attain stable acenes without changing the molecular configuration or intermolecular packing structure, and thus improves the potential application of large acenes in electronic devices.

Some like it hot: A composite of Au nanorods/CoFe-MOF nanosheets (Au/CoFe-MOFNs) was used as an electrocatalyst for the hydrogen evolution reaction (HER). Au/CoFe-MOFNs give a four-fold increase of current density and a much reduced activation energy upon light irradiation as a result of hot-electron injection from plasmonic Au to CoFe-MOFNs.

Less is more: The 20-membered marine macrodiolide clavosolide A is prepared in 7 steps (LLS) in the absence of protecting groups or chiral auxiliaries via enantioselective alcohol-mediated carbonyl addition. In nine prior total syntheses, 11–34 steps (LLS) were required.

New kid on the block: Silicon Grignard reagents can be used in a new enantioselective copper-catalyzed reaction. With the assistance of BF₃⋅OEt₂, a Cu^I-josiphos complex promotes the highly regioselective addition of silicon Grignard reagents to alkenyl-substituted heteroarenes (see scheme). The new method expands the scope of “conjugate addition” type reactions forming C(sp³)−Si bonds.

Double activation required: Latent nucleophiles enlarge substrate scopes and improve selectivities in Lewis base catalysis. N-Silyl pyrroles, indoles, and carbazoles serve as latent N-centered nucleophiles in highly selective enantioselective Lewis base catalyzed substitutions of allylic fluorides.

Keeping it flat: Morphology-engineered TiO₂-{100} and TiO₂-{101} nanocrystal supports can stabilize flat Ru nanoparticles, resulting in a very stable activity of the Ru/TiO₂ catalysts for the selective CO methanation. Weaker metal–support interactions on the TiO₂-{001} nanocrystals result in a shape change of the Ru nanoparticles, from flat to hemispherical, together with continuous deactivation.

So long! Poly(propylene oxide) with exceptionally high molar mass can be prepared with a catalytic setup consisting of a nucleophilic N-heterocyclic olefin and a magnesium-based Lewis acid. The magnesium species activates the monomer for attack by the olefin, resulting in a rapid, Lewis pair type polymerization via zwitterionic species.

Covalent effects compensate for photo-induced charge variations within a charge-transfer excited transition-metal dye. Using time-resolved X-ray absorption spectroscopy and DFT calculations, the underlying mechanism is found to uphold local charge densities at the photo-oxidized transition-metal center, while transferring spin density to peripheral parts of the molecule.

Not lost in translation: A new strategy to guide sequence design for accessing functional precision polymers is described. The direct translation of side-chain functionality sequences into nonpeptidic backbones leads to macromolecules that mimic or improve on the properties of the parent peptide. As an example, the approach was applied to a peptide-based formulation additive to solubilize a photosensitizer drug.

Oligo(deoxy)nucleotide ligands are effective tools for the manipulation, detection, and study of biological phenomena. A receptor-guided design strategy based on the hydrophobic molecule (−)-Δ⁹-tetrahydrocannabinol (THC) was used to generate a modified DNA library capable of identifying clickmers (modified aptamers).

Hydrogenobyric acid, the metal-free corrin ligand of the natural B₁₂ derivatives, has been prepared via an engineered biosynthesis. Its structure revealed a uniquely ring-contracted and strongly helical ligand cavity. It binds cobalt ions tightly in an entatic state strained by coordinative misfit. This activates the B₁₂ cofactors for homolytic and reductive cleavage of their organometallic Co−C bond, which is key for catalysis by B₁₂-dependent enzyme reactions.