Research articles

Aβ42 oligomers are key toxic species associated with protein aggregation; however, the molecular pathways determining the dynamics of oligomer populations have remained unknown. Now, direct measurements of oligomer populations, coupled to theory and computer simulations, define and quantify the dynamics of Aβ42 oligomers formed during amyloid aggregation.

Metal-mediated self-assembly in solution typically leads to small two- and three-dimensional architectures on scales smaller than 10 nm, but now a series of large, discrete, two-dimensional supramolecular hexagonal grids have been prepared through a combination of intra- and intermolecular coordination interactions. These 20-nm-wide grids have been imaged at submolecular resolution using scanning tunnelling microscopy.

Au/C single-site catalysts have been validated commercially for acetylene hydrochlorination, but they have previously been prepared using highly oxidizing acidic solvents or additional ligands. It has now been shown that they can be made by impregnation of a metal salt from an acetone solution—generating catalysts with comparable activity to those synthesized by the other methods.

Single-molecule nanopore measurements have revealed ligand-induced conformational changes in the catalytic cycle of dihydrofolate reductase, and showed that the enzyme adopts distinctive conformers, which have different affinities for substrates and products. Crossing the transition state facilitates conformer exchange, suggesting that the chemical step catalyses the switch between conformers to obtain a more efficient product release.

The preparation of unprotected alicyclic amines containing variable substituents in multiple ring positions typically requires multistep synthetic sequences. Now, an advance in C–H bond functionalization methodology that enables the convenient preparation of elusive endocyclic 1-azaallyl anions allows the introduction of up to three substituents in a single operation.

Inverting the order of nature’s two-phase biosynthesis of terpenes offers a strategy by which the synthesis of these compounds can be simplified. The key reaction is a palladium-catalysed polyenyne cycloisomerization that not only tolerates the presence of all of the oxygen functionalities but also is facilitated by them.

The copolymerization of CO₂ with epoxides is an attractive approach for valorizing waste products and improving sustainability in polymer manufacturing. Now, a heterodinuclear Mg(ii)Co(ii) complex has been shown to act as a highly active and selective catalyst for this reaction at low CO₂ pressure. The synergy between the two metals was investigated using polymerization kinetics.

Responsive hydrogels are of interest for a range of potential applications, including microscale soft robotic and biomedical devices. Now, a versatile fabrication approach has been developed to prepare patterned, multi-material and multi-responsive hydrogels. Pre-gel droplets are connected through lipid bilayers in predetermined architectures and photopolymerized to yield continuous hydrogel structures that respond to a variety of stimuli.

The discovery of amplifying autocatalysis in a pyridine-3-carbaldehyde system facilitates a mechanistic deconstruction of the Soai reaction. A tetrameric autocatalyst, assembled by a combination of steric effects and nitrogen–zinc coordination, activates the substrate by two-point binding. This is followed by intra-complex isopropyl group transfer that generates the product alkoxide with high homochiral fidelity.

ortho-Quinone methides are highly reactive transient intermediates found in some organic syntheses and biological processes. The generation of these species often requires pre-functionalized substrates and/or metal oxidants, but now the chemoselective oxidative generation of ortho-quinone methides from ortho-alkylarenols has been achieved using hypoiodite catalysis under nearly neutral conditions.

Despite the importance of trifluoromethylated compounds, direct catalytic methods for the conversion of C(sp³)–H bonds into the corresponding C(sp³)–CF₃ analogues have remained elusive. This transformation has now been achieved by the merger of copper catalysis with decatungstate photocatalysis, enabling the C(sp³)–H trifluoromethylation of abundant feedstocks, natural products and pharmaceuticals.

A material based on a three-dimensional –Fe–N≡C–Mo– anionic framework that hosts a Cs⁺ cation in every other pore has been shown to exhibit superionic conductivity, despite its polar crystal structure. It also exhibits second harmonic generation (SHG)—usually observed in insulators—and its ionic conductivity was reversibly altered under light irradiation.

Understanding the photophysical properties of transition-metal complexes is paramount to advances in photocatalysis, solar energy conversion and light-emitting diodes. Now, long-lived emission via thermally activated delayed fluorescence has been demonstrated from an air- and water-stable zirconium complex featuring excited states with significant ligand-to-metal charge transfer character.

A catalytic para-selective alkylation reaction connects C–H functionalization and decarboxylative coupling strategies using simple bases to trap a previously hidden intermediate. This reaction exploits an ‘inverted sequence’ that forms the C–C bond prior to C–H bond cleavage and provides a new entry into C–H functionalization reactions.

A programmable polymer library that responds to external and internal stimuli has been developed and used to fabricate a series of nanocarriers for drug release. The carriers respond to disease biomarkers, triggering self-immolative motifs and leading to the site-specific release of therapeutics both in vitro and in vivo.

Even- and odd-numbered homologues of some hydrocarbons are known to exhibit different trends in solid-state properties. Now, experimental and computational investigations on a homologous series of a stereochemically well-defined hydrocarbon have revealed an odd–even effect in conformational behaviour in solution that is caused by a single gauche interaction.

Distinguishing remote C–H bonds on adjacent carbon atoms is a fundamental challenge because of a lack of electronic or steric bias. Now, differentiation of distal C–H bonds that are adjacent to each other has been achieved by combining selective remote C–H activation—based on distance and geometry—with a norbornene-assisted palladium migration.

Controlling single-molecule magnets (SMMs) with ultrashort laser pulses could be key to future data storage devices, however, the photophysics of SMMs is complex. Now, using a monomer model system, it has been shown that optical excitation of Mn(iii)-SMMs leads to a modulation of the Jahn–Teller distortion, which is important for its magnetic anisotropy.

Generating high-energy triplet excitons from singlet fission without excess energy loss is a critical goal for potential applications. Now it is shown that molecular chromophores that are connected covalently can harbour multiple long-lived and high-energy triplets—created from one photon—only if more than two chromophoric units are present and they have sufficient flexibility to isolate the excitations upon torsional motion.

A method to fabricate heterotrimeric three-stranded coiled-coil peptide structures has now been developed using coordination around a Pb(ii) centre. The heterotrimeric structures require only three cysteines that bind to Pb(ii) to form a trigonal pyramidal structure, and the formation of an adjacent cavity in which water can hydrogen bond to the cysteine sulfur atoms.