Volume 15 Issue 5, May 2023

Systems that feature long-range order but no translational periodicity are intriguing. Now, a T-shaped molecule consisting of three non-miscible components has been devised that self-assembles into a columnar liquid quasicrystal.

Monomeric stibine oxide has remained elusive due to the large antimony orbitals coupled with a high electronegativity difference with oxygen. Now, a free tris(2,6-diisopropylphenyl)stibine oxide has been isolated that can act as oxo-transfer reagent.

The chemistry of polynitrogens has been enriched by a new isomer of N₆ through the synthesis, in a laser-heated diamond anvil cell, of a charged aromatic [N₆]^4– ring that is recoverable at ambient temperature under high pressure.

Enantioenriched β-amino acid derivatives are attractive synthetic targets, considering the significance of these motifs in medicinal and material chemistry. Now, using ambiphilic ynamides as two-carbon synthons in a four-component reaction, three classes of β-amino amides with well-defined stereocentres can be accessed.

The ability to detect and quantify a given analyte at the molecular level is a long-lasting goal for analytical and bioanalytical chemistry. This Review highlights how single-molecule junctions (SMJs) have been used for analytical purposes, from the detection of isomers and reaction intermediates to the detection of proteins and nucleic acids. Different SMJ approaches are discussed, along with their advantages and limitations over bulk analytical techniques.

Stereogenic sp³-hybridized carbon centres are the principal building blocks of chiral organic molecules. Usually, these centres are configurationally fixed. Now, low-energy pericyclic rearrangements have been used to create rigid cage molecules with fluxional sp³-stereochemistry, influencing chiral information transfer. The sp³-carbon stereochemistry of the cages is inverted through strain-assisted Cope rearrangements.

Quasicrystals are intriguing structures that exhibit long-range positional correlations but no periodicity in real space. Now, T-shaped amphiphilic molecules featuring rigid cores have been found to self-assemble into a columnar liquid quasicrystal with dodecagonal symmetry. The honeycomb structure observed arises from a strictly quasiperiodic tessellation of square, triangular and trapezoidal tiles, rather than from random tiling.

In contrast to phosphine and arsine oxides, stibine oxides have been challenging to isolate in monomeric forms as they tend to polymerize. Now, such a SbO moiety has been kinetically stabilized using sterically bulky protecting groups, and its reactivity found to be substantially different to that of its lighter pnictogen counterparts.

Aromatic polynitrogen units can display both high stability and high energy content. A hexazine anion has now been identified in a complex compound, K₉N₅₆, which is formed at high pressures and temperatures under laser-heating in a diamond anvil cell. The [N₆]⁴⁻ ring is planar and proposed to be aromatic.

β-Amino acids are broadly found in biomimetic drugs and therapeutics, but the general synthesis of chiral β-amino amides remains limited. An organocatalytic four-component reaction has now been developed for their asymmetric synthesis with notable efficiency, chemoselectivity and stereoselectivity. This protocol shows broad product scope and provides a shortcut to other important structures.

The molybdenum nitrogenase catalytic cofactor is composed of seven high-spin Fe sites making it difficult to study spectroscopically. Now it has been shown that ⁵⁷Fe can be incorporated into a single site and that such site-selectively labelled samples provide insights into the cofactor’s electronic structure and the mechanism of biological nitrogen fixation.

The controlled functionalization of multihydrosilanes is challenging. Now, using a hydrogen-atom-transfer photocatalyst based on neutral eosin Y, a method for the diverse functionalization of hydrosilanes has been developed, enabling the stepwise on-demand decoration of silicon atoms. This approach is distinguished by its atom-, step-, redox- and catalyst-economy, metal-free nature, its versatility (>150 examples), modularity, selectivity and scalability.

Crystals of hexachlorobenzene have now been shown to support the autonomous motion of water and particulate matter over their surface. Parallel microchannels present at the surface of the crystal gradually widen by sublimation, propelling droplets of condensed ambient water that can also transport microscopic amounts of material such as silver microparticles.

Borylated bicyclopentanes and bicyclohexanes are valuable compounds in drug research but are difficult to prepare. Now, an iridium-catalysed method has been developed for the borylation of the bridgehead tertiary C–H bonds in bicyclopentanes and bicyclohexanes, providing access to a variety of highly decorated bicyclic cores.

Techniques to specifically modulate protein activity are needed to interrogate spatial effects in cellular processes. A genetically encoded method for site-specific protein–protein conjugation based on a photoclick chemical reaction has now been developed. This method permits rapid and irreversible reassembly of bioactive proteins from non-functional split fragment pairs with full spatiotemporal control in solution, biomaterials and living mammalian cells.

The electrochemical reduction of carbon dioxide to propylene requires multiple C–C coupling steps and the transfer of 18 electrons, posing kinetic and thermodynamic barriers. Now the electrosynthesis of propylene from carbon dioxide using copper nanocrystals has been demonstrated, with analysis revealing that the key step for its formation is probably the coupling between carbon dioxide or carboxyl with intermediates involved in the ethylene pathway.

Catalytic enantioselective approaches to access chiral organophosphorus compounds are rare. A two-stage catalytic strategy for the synthesis of diverse enantioenriched P(V) compounds has now been developed: a bifunctional iminophosphorane superbase enables enantioselective nucleophilic desymmetrization, followed by downstream enantiospecific diversification of the resulting intermediate by substitution with medicinally relevant O-, N- and S-based nucleophiles.

Californium is difficult to prepare in its divalent state. Now, crystals of a Cf(II) crown–ether complex have been synthesized by reduction of a Cf(III) precursor with an Al/Hg amalgam. They exhibit 5f→6d transitions in the visible region and near-infrared emission that are highly sensitive to changes in the coordination environment.

Water-soluble, cell-permeable, inert fluorescent tags called OregonFluors have been developed to withstand environmental changes while resistant towards non-specific binding with subcellular structures. These tags enable quantitative imaging of drug target availability in cells and tissues, providing a route for the future assessment of personalized therapies.

Organisms that glow are perhaps eerie. Vadim Viviani ponders on the luciferin–luciferase systems responsible for their intriguing bioluminescence.