Articles in 2019

A set of enantioprobes—photoreactive, clickable fragment pairs differing only in absolute stereochemistry—have been used to provide a robust and streamlined chemical proteomic map of small-molecule/protein interactions in human cells. More than 170 stereoselective fragment–protein interactions were discovered and shown to occur at functional sites on proteins from diverse classes.

Ring-opening metathesis polymerization of norbornene-based (macro)monomers produces macromolecules with diverse compositions and complex architectures that cannot be degraded easily. Now, it has been shown that a class of eight-membered cyclic bifunctional silyl ether-based monomers copolymerize efficiently with norbornene-based (macro)monomers, providing a range of copolymers with tunable degradability under mildly acidic aqueous conditions.

Although transporting a starship crewmember onto the surface of an alien planet is clearly science fiction, quantum state teleportation is not, and has been observed in various systems over the last few decades. Now, electron-spin teleportation has been observed in a carefully designed molecular system, paving the way for such behaviour to be tailored through molecular engineering.

The in situ, nanoscale positioning of a single molecule below the diffraction limit remains a challenge for chemists. Now, two approaches show how this can be accomplished through a combination of super-resolution microscopy and photo-inducible crosslinking chemistry.

Understanding the effects of adding a simple salt to an aqueous solution of a protein is far from simple — and Bruce C. Gibb explains why.

Tuning the selectivity for [2+2] photocycloadditions remains challenging. Now, triplet–triplet energy transfer from CdSe quantum dots enables the homo- and heterocouplings of 4-vinylbenzoic acid derivatives via [2+2] photocycloaddition. Preorganization of substrates on the quantum dots reverses intrinsic stereoelectronic preferences to yield cyclobutane products with unprecedented diastereo- and regioselectivity.

Asymmetric Sonogashira C(sp³)–C(sp) couplings provide complementary approaches to established C(sp³)–C(sp²/sp³) couplings for chiral C–C bond formation; however, relatively few reactions have been developed. Now, a versatile, enantioconvergent Sonogashira coupling via a radical intermediate has been developed. The approach uses a copper catalyst featuring a multidentate electron-rich cinchona alkaloid-derived ligand.

The oxidation of water remains the kinetic bottleneck of solar-to-fuel synthesis. Now, spectroelectrochemical evidence together with density functional theory calculations show that charge accumulation determines the reaction mechanism on metal–oxide photoanodes. These insights reveal features that are common to the mechanisms of water oxidation carried out by other inorganic and biological systems.

Generating stable single-atom catalysts is far from straightforward and can involve complicated preparation procedures. Now, mononuclear gold oxo-clusters formed in alkaline solutions through a facile one-pot synthesis are shown to catalyse the heterogeneous methanol self-coupling reaction to methyl formate and hydrogen. The intrinsic activity is the same for both supported and unsupported gold catalysts.

The isoelectronic series of alanes [R₃Al] and silylium cations [R₃Si]⁺ has now been extended with the synthesis and characterization of two phosphorandiylium dications ([R₃P]²⁺), which are trigonal planar Lewis superacids. The electrophilicity at the phosphorus atom is governed by the π-electron-donating ability of the attached N-heterocyclic imine substituents.

A flavin-dependent halogenase with a remarkable preference for iodination has now been discovered. The halogenase (VirX1) was discovered using a bioinformatics-based approach and comes from a cyanophage. Structural characterization and kinetic studies show that VirX1 possesses broad substrate tolerance, making it an attractive tool for synthesis.

The four-coordinate iron sites of typical iron–sulfur clusters rarely react with small molecules, implicating three-coordinate iron in many catalytic cycles. Now, a [4Fe-3S] cluster featuring three-coordinate iron sulfide that resembles the proposed substrate binding site has been synthesized. This cluster shows biomimetic reactivity with a low-spin electronic configuration.

Stereoselective functionalization of C(sp³)–H bonds could greatly simplify the construction of complex molecular scaffolds. Now, a series of enzyme catalysts derived from a cytochrome P450 have been developed using directed evolution. The catalysts enable the enantioselective amination of primary, secondary and tertiary C(sp³)–H bonds.

Nucleophiles directly substitute alcohols in the Mitsunobu reaction, but the process uses hazardous materials and generates an excessive amount of toxic waste. More than 50 years on from its initial discovery, chemists report a new catalytic version of the reaction, with water as the only by-product.

Phase-forming conversion chemistry, like that observed in Li–S and Li–O₂ batteries, shows great promise, but these systems suffer some drawbacks, such as practically low cathode areal capacities and electrolyte decomposition. Now, high-energy conversion battery chemistry—based on nitrate/nitrite redox where one of the products is soluble—has been enabled by using nanoparticulate Ni/NiO electrocatalysts.

The electronic structures of the metal cofactors of nitrogenase are key to biological nitrogen fixation; however, the [Fe₈S₇] P-cluster and FeMo cofactor have eluded detailed electronic characterization. Now, the electronic structure of the P-cluster of nitrogenase has been revealed at the many-electron level through exhaustive quantum wavefunction simulations.

To celebrate the centenary of the International Union of Pure and Applied Chemistry in July 2019, the 47th IUPAC World Chemistry Congress took place in Paris. Its programme reflected how chemistry can help to address today and tomorrow’s most challenging issues, in particular, those relevant to human well-being and sustainable development.