News & Views in 2019

Intensified interest in the area of nickel catalysis has driven the quest for an air-stable and modular Ni(0) precatalyst. Now, an air-stable Ni(0)-olefin precatalyst allows for the convenient set-up of nickel-catalysed reactions on the benchtop.

Simple methods to incorporate deuterium into organic compounds are highly sought after as deuteration can enable mechanistic studies or improve the metabolic stability of pharmaceuticals. Now, a catalytic hydrogen–deuterium exchange reaction using deuterated water allows convenient access to deuterated aldehyde building blocks.

Because of the high strength of N≡N bonds, N₂ is often employed as an inert gas. Now it has been shown that it can partly react to yield surface nitrogen species that facilitate C–O hydrogenolysis reactions on supported Ru catalysts.

Enzymes require many, often hundreds, of amino acid residues arranged in a protein fold to promote catalysis. Now, self-assembly of a single amino acid — phenylalanine — in the presence of zinc is shown to form supramolecular structures that promote hydrolysis better than natural enzymes on a weight basis.

Bio-inspired by cellular respiration, the richness of oxygen redox chemistry is a cutting-edge field for building lithium batteries. While the Li–air battery uses external oxygen, a new lithium battery offers a high energy-density and long-term cycling stability just by confining oxygen and lithium between graphene oxides.

Imine reductases are promising catalysts, facilitating a direct stereoselective route to secondary amines. Now, protein engineering has created stable and efficient variants that allow their application in kilogram-scale synthesis.

Given the importance of enantioenriched β²- and β³-amino acids as building blocks, direct and versatile methods for their synthesis are highly coveted by organic chemists. Now, using easily accessible 1,3-oxazinane motifs, a regiodivergent and enantioselective C–H functionalization method permits their synthesis in a straightforward and practical fashion.

The design of heterogeneous catalysts with tunable activity and selectivity constitutes a remarkable challenge. Now, a synthetic approach towards producing nanocrystals encapsulated within polymer layers has been developed, unravelling the principles to achieve control of transition state and product diffusion using CO oxidation as a case study.

Transition metal-catalysed bioorthogonal reactions are severely hindered in biomedical applications, mainly due to a lack of target specificity. Now, research shows that a trojan exosome vesicle can deliver a palladium catalyst specifically to progenitor cells for bioorthogonal catalysis, allowing localized prodrug activation.

Fusion systems have been designed that link enzymes to cofactors and immobilization modules through appropriate synthetic spacers. These modular biocatalysts (assembling catalysis, cofactor provision/regeneration and assisted immobilization) are suited to heterogeneous biocatalysis systems and can be efficiently used in continuous flow reactors.

Conventional experiments for generating proteins with improved properties by directed evolution are iterative, lengthy and costly. Now, a label-free assay has been developed for ultrahigh-throughput microfluidic screening that can dramatically accelerate the discovery of superior biocatalysts from a single round of genetic randomization.

A strategy using pressure was devised to structurally identify conformational transitions in protein ensembles, allowing the rational prediction of mutations that induce pressure-driven enzyme activation. These results highlight the power of flexibility–function analyses in protein engineering design and applications.

S-adenosylmethionine (SAM)-dependent methyltransferase enzymes have significant synthetic potential, but their utility as biocatalysts has been limited by the availability of SAM. An elegant and simple method addressing this long-standing problem has now been developed using a halide methyltransferase (HMT) enzyme for SAM regeneration in vitro.

Understanding the nature of active sites in carbon electrocatalysis remains a subject of dispute and a great scientific challenge. Convincing new evidence supports the fact that, for oxygen reduction, defects present in carbon materials are more powerful catalytic sites than nitrogenated sites.

Tailoring platinum-based catalysts is of great research interest in the fields of electrochemical energy conversion and storage, as well as other applications. Now, an approach has been developed to boost the activity of platinum catalysts at the atomic scale.

Hydrogenases are very powerful biocatalysts for dihydrogen cleavage. Now, X-ray crystallography shows how [Fe]-hydrogenase requires ligand exchanges at the metal centre and significant molecular motions to open and close its active site to effectively transfer a hydride to an electrophilic organic substrate.

The biological functions of glycan motifs such as the Lewis blood antigens are often defined by their precise multivalent presentation on complex glycoconjugates, making synthesis particularly challenging. Access to a number of positionally defined Lewis motifs on natural polysaccharide scaffolds has now been achieved using bacterial glycosyltransferases.

A synthetic DNA enzyme catalyses the formation of a native phosphodiester bond between two RNA fragments, but the molecular details of the mechanism remained elusive. Research using computational and biochemical approaches now suggests that the DNA enzyme recruits two magnesium ions to assist in the catalysis of RNA ligation.

Given the fact that sodium is the most abundant alkali metal on Earth, the direct and indirect use of organosodium compounds in palladium-catalysed carbon–carbon bond forming reactions is an attractive alternative for sustainable organic synthesis.

Good durability and activity of single Ru atom catalysts is critical for their large-scale utilization in electrochemical water splitting. Now, both of these properties can be better controlled through compressive strain engineering.