News & Views in 2018

Nanoscale texture of electrocatalysts, enabled by the tools of nanoscience, is emerging as an important lever for the control of electrochemical reaction pathways.

A crucial malonic acid moiety in the antibiotic malonomycin has been shown to be installed by a bacterial vitamin K-dependent (VKD) carboxylase orthologue.

The biosynthesis of the pharmacophoric tetrahydropyran of the clinically important antibiotic mupirocin remained enigmatic for a long time. Now, research shows that this ring is formed by a unique epoxidation–epoxide-opening cascade starting from a non-activated alkane.

Single-atom catalysts recently attracted considerable research interest for heterogeneous electrocatalysis, including the oxygen reduction reaction. Now, an intriguing two-step approach towards a less explored atomic nitrogen-coordinated manganese with a high loading density has been developed.

Indirect methods are generally adopted to elucidate complicated mechanisms of transition metal catalysis. Now, a way to directly observe transient manganese species and monitor key reaction steps has been established by using time-resolved multiple-probe spectroscopy.

Despite being used as a water-oxidation catalyst in alkaline electrolysis for over a century, the details of how Ni–Fe (oxy)hydroxide catalysts function remains unclear. Now, using a nanoparticle model system, the intrinsic activity and underlying catalytic mechanism is probed.

The mechanism of methanol coupling to methyl formate over single-crystal gold catalysts has been firmly established but barely reconciled with experiments performed under practical conditions. Now, a method to close this gap has been reported, which enables the prediction of the reaction´s selectivity for a broad range of experimental conditions.

The electroreduction of CO represents a promising approach toward artificial hydrocarbon synthesis, but its rate is limited by the sluggish transport of CO in aqueous electrolytes. Recent work shows how the issue can be circumvented by using gas diffusion electrodes.

Development of an earth-abundant and inexpensive copper-based catalyst is desirable for CO₂ hydrogenation. Now, the combined application of a stable copper hydride and a Lewis pair is shown to effect activation of CO₂ as well as heterolysis of H₂, achieving significant turnover numbers.

Heterogeneous photocatalysts are rarely employed in industry for the synthesis of commodity chemicals due to efficiency problems. Now, a photochromic Bi₂WO_6–x/amorphous-BiOCl composite is reported, which features a remarkable activity for the photocatalytic oxidation of toluene into benzaldehyde and benzoic acid.

Artificial metalloenzymes generally consist of a synthetic (organo)metallic catalyst incorporated into a protein. Asymmetric catalysis by such metalloenzymes could result by virtue of the chiral protein environment. Now, redox-sensitive anchoring enables reversible incorporation of an iridium catalyst for transfer hydrogenation.

Typically, catalysts are discovered through trial and error coupled with chemical intuition. Now, an automatic machine-learning framework has been developed that can guide itself to find intermetallic surfaces with desired catalytic properties.

The chemical synthesis of natural products, such as sesquiterpenes, is a daunting task due to their complexity and precise functionalization, and multiple synthetic and purification steps that reduce overall yields are usually required. Now, a highly efficient alternative approach using supramolecular chemistry has been proposed by Tiefenbacher and co-workers.

Metalloprotein activity can be tuned by altering first- and second-sphere interactions with the metal ion or ions. Here, a non-canonical haem axial ligand is introduced into a myoglobin variant, modulating both. The resulting enhancement of cyclopropanation activity illustrates the utility of expanding the suite of available amino acids for biocatalyst engineering.

How the first metabolic network was organized to power a cell remains an enigma. Now, simple iron–sulfur peptides have been used to generate a pH-gradient across a protocell membrane by catalysing hydrogen peroxide reduction. This indicates that short peptides could have fulfilled the role of redox active metalloproteins in early life.

The identification of organic structure-directing agents capable of tailoring the physicochemical properties of microporous materials has remained a challenge. Now, a unique methodology to design organic mimics of reaction intermediates provides a route to optimize the selectivity of zeolite catalysts.

Control over the length and composition of polymers is key to controlling their properties. Now, a photoswitchable catalyst is shown to allow external control over reaction rates, chain lengths and even polymer composition in ring-opening polymerizations.

Pairing electrosynthetic anode and cathode processes (either convergent or divergent) is essential to maximize energy usage/sustainability and to minimize waste. New approaches to pairing in electrosynthesis are needed and the use of a palladium film membrane by Berlinguette and co-workers represents an effective paired reactor prototype that couples electrosynthesis with chemical catalysis.

Although the replacement of palladium with iron in metal-catalysed cross-couplings continues apace, the Suzuki synthesis of biaryls — arguably the most widely used class of such C–C bond formations — has remained elusive. Now, by use of a π-coordinating directing group, another step has been taken toward iron-catalysed Suzuki reactions.

Iron–sulfur metalloproteins are widespread and efficient catalysts for multielectron reduction of small molecules. Now, research shows that simple Fe₄S₄ cofactors and related complexes can perform effective reductive chemistry producing small hydrocarbons from CO₂ and CO.