Volume 13 Issue 10, October 2021

Charged nanoparticles can behave as large ions or as small colloids. Their interaction with multivalent ions has now been shown to reflect this dichotomy, providing new paths to large, self-assembled nanoparticle superstructures.

Transition metal complexes with metal-to-ligand charge transfer (MLCT) luminescence and photoactivity typically rely on precious metals such as ruthenium or iridium. Now, two complexes of the Earth-abundant 3d manganese have displayed room-temperature MLCT luminescence in solution and a unique excited-state reactivity.

Methods for the synthesis of bicyclo[1.1.1]pentanes (BCPs) typically rely on the release of strain energy, but these routes cannot easily introduce substituents on the BCP bridges. Now, an intramolecular coupling gives access to multi-substituted BCPs, through the synthesis of bridge-substituted bicycloalkyl boronic esters.

Finding alternative fates for plastics that would otherwise end up in landfills requires innovative chemistry. Now, poly(acrylic acid) from diaper waste has been converted into valuable pressure-sensitive adhesives through an open-loop recycling method that is cost-effective and environmentally competitive.

Porous materials are promising candidates for the cost- and energy-efficient separation of ethylene and ethane from gas mixtures: an important but challenging industrial process. Now, a hydrogen-bonded organic framework has been reported that is stable under harsh conditions and can take up ethylene at practical temperatures—with very high selectivity over ethane—through a gating mechanism.

Coulombic interactions can be used to assemble charged nanoparticles into higher-order structures, but this process typically requires similarly sized oppositely charged partners. Now, small anions or cations with as few as three charges have been shown to induce attractive interactions between oppositely charged nanoparticles in water, guiding the assembly of colloidal crystals.

Bicyclic hydrocarbons, and bicyclo[1.1.1]pentanes in particular, are playing an emerging role as saturated bioisosteres in pharmaceutical, agrochemical and materials intramolecular coupling approach has been developed for the modular construction of underexplored multisubstituted strained bicyclic hydrocarbons, ranging from [1.1.1] to [3.2.1] scaffolds.

Manganese(i) is isoelectronic to iron(ii) but has typically been overlooked as a cheap Earth-abundant metal for the development of 3d⁶ metal-to-ligand charge transfer (MLCT) emitters and photosensitizers. Now, using chelating isocyanide ligands, air-stable manganese(i) complexes have been obtained that exhibit MLCT luminescence, as well as energy- and electron-transfer photoreactivity.

The opening mechanism of the SARS-CoV-2 spike protein has been studied by integrating computational and experimental data. Combining weighted ensemble molecular dynamics simulations, biolayer interferometry and ManifoldEM analysis of cryo-EM data revealed that the glycan at N343 plays a gating role in the opening mechanism of the SARS-CoV-2 spike protein.

The formation of weak chemical bonds at or near thermodynamic potential is a challenge in chemical synthesis and catalysis. A bifunctional iridium hydride catalyst has now been discovered that absorbs visible light and promotes proton-coupled electron transfer to a range of substrates—creating element–hydrogen bonds—using dihydrogen as the terminal reductant.

As the number of atoms involved in a reaction increases, so do the experimental and theoretical challenges faced when studying their dynamics. Now, using ion-imaging experiments and quasi-classical trajectory simulations, the dynamics of the polyatomic reaction F^– + CH₃CH₂Cl have been studied and the competition between bimolecular nucleophilic substitution and base-induced elimination has been disentangled.

Although organocatalysis has emerged as a powerful catalysis platform, its application for the selective transformation of inactive arenes remains challenging. Now, an organocatalyst-controlled site-selective C–H functionalization of arenes has been developed, with wide substrate generality and applicability, offering a general strategy for arene transformation.

Machine learning has now been shown to enable the de novo design of abiotic nuclear-targeting miniproteins. To achieve this, high-throughput experimentation was combined with a directed evolution-inspired deep-learning approach in which the molecular structures of natural and unnatural residues are represented as topological fingerprints. The designed miniproteins, called Mach proteins, are non-toxic and can efficiently deliver antisense cargo in mice.

Molecules with 4n π electrons should display Baird aromaticity in the triplet state, but isolation of ring systems with this electronic ground state is stymied by structural distortion. Now, a benzene diradical dianion has been stabilized by being held rigid in a binucleating ligand as well as through magnetic exchange; single-crystal X-ray diffraction data and NICS calculations support its ground-state Baird aromaticity.

Using synergistic bimetallic catalysis, a general ring expansion strategy has been developed for cross-dimerization between three-membered aza heterocycles and three- and four-membered-ring ketones. This method provides a straightforward and broadly applicable route for the assembly of 3-benzazepinones, dihydropyridinones and uracils, which are versatile units in numerous drugs and biologically active compounds.

Computationally designed enzymes can be substantially improved by directed evolution. Now, it has been shown that evolution can introduce a dynamic network that selectively tightens the transition-state ensemble, giving rise to a negative activation heat capacity. Targeting such transition state conformational dynamics may expedite de novo enzyme creation.