Articles in 2024

Decarboxylative azidation is a valuable transformation in organic chemistry, but a biocatalytic equivalent remained elusive. Now merging photoredox with metalloenzymatic catalysis enables the enantioselective decarboxylative radical azidation and thiocyanation of N-hydroxyphthalimide esters.

Alkali cations in electrolytes are commonly considered chemically inert species, but their role has recently been called into question. Now, using in situ spectroscopy and molecular dynamics simulations, it is shown that alkali cations couple with intermediates in the oxygen reduction reaction, acting as cocatalysts.

The catalytic mechanism of [Fe]-hydrogenases is not well understood. Now a signal-enhanced nuclear magnetic resonance method based on parahydrogen is introduced to study [Fe]-hydrogenase under turnover conditions in situ, revealing intermediates of the catalytic cycle.

Compatibility issues often limit chemoenzymatic systems. Now it is shown that the proximity between catalytic polymers grafted from the membrane of microorganisms and intracellular heterologous enzymes enhances the reaction rates of a photoenzymatic system, while the coating increases the stability.

The development of catalytic systems for sequestering anthropogenic methane emissions from the atmosphere could potentially reduce global warming. Now, coupling the enzyme alcohol oxidase with an inorganic zeolite generates formaldehyde from methane under ambient conditions with 90% selectivity.

Despite the importance of difluoromethyl (CF₂H)-bearing centres for pharmaceuticals, there is currently no general strategy for the stereoselective introduction of a CF₂H group at chiral centres. Here the authors describe an enantioconvergent difluoromethylation method for racemic alkyl halides to construct such stereocentres.

Electrifying energy-intensive processes is a promising approach for decarbonization. Now, 1,3-butadiene is electrochemically produced from acetylene on I⁻−induced Cu^δ+–Cu⁰ sites with a Faradaic efficiency of over 90% at −0.85 V_SHE and a partial current density of −75 mA cm⁻² at −1.0 V_SHE.

Obtaining high-purity CO requires energy-intensive purification processes. Here metastable fluorite ZrO₂ is prepared that can catalyse thermal and photothermal formic acid dehydration to CO while completely shutting off the impurity-generating dehydrogenation pathway.

Catalysts used for steam methane reforming frequently suffer from deactivation by coking and oxidation. Here an active Cu–Rh plasmonic antenna–reactor photocatalyst is selective and stable under illumination but deactivates under purely thermal conditions. The thermally deactivated catalyst can then be regenerated under illumination.

Anion-exchange membrane water electrolysers have the potential to rival more costly acidic proton-exchange membrane electrolysers, but their performance and efficiency commonly still fall short. Now an anion-exchange membrane water electrolyser is prepared with a NiFe layered double hydroxide catalyst-coated membrane that achieves high current densities above 2 A cm⁻² at 1.8 V and operando X-ray absorption spectroscopy is used to track the formation of the catalytically active γ-LDH phase.

Catalytic conversion of alkenes into carbanion equivalents usually requires stoichiometric reductants. Now an alternative strategy to access alkyl carbanion equivalents from abundant alkenes with the help of visible light photocatalysis is reported and used in four distinct C–C bond-forming reactions.

Heteroatom-substituted C(sp³)-rich polycyclic hydrocarbon rings, isosteric to heterocyclic rings, are not common due to the challenging synthesis. Now a photoredox-catalysed strategy to insert amidyl radicals into bicyclo[1.1.0]butanes is presented, providing direct access to 2-oxa-4-azabicyclo[3.1.1]hept-3-enes.

The replacement of palladium with other metal catalysts in C–C bond-forming reactions is attractive in terms of costs and sustainability. Now an iron-based catalyst is successfully employed in the Suzuki cross-coupling of aryl chlorides with aryl boronic esters activated with tert-butyl lithium.

Achieving atomic control during the synthesis of heterogeneous catalysts remains challenging. Here the authors tackle this challenge by applying a liquid-phase atomic layer deposition approach to the synthesis of Cu/ZrO_x clusters on MgO as efficient catalysts for CO₂ hydrogenation to methanol.

Fe-exchanged zeolite catalysts are known for their ability to remediate NO_x and N₂O emissions, but their reactivity in mixed streams of NO and N₂O remains unclear. Now a suite of operando spectroscopies reveals the active Fe species involved in the process and their synergistic effect during the simultaneous conversion of these pollutants.

The catalytic activation of alkyl amines as α-nitrogen carbanions is challenging. Now the activation of N-arylidene-protected alkyl amines as carbanions by chiral ammonium organocatalysis for asymmetric conjugate addition and the Mannich reaction is reported, affording chiral α,α-dialkyl amines.

The catalytic power of DNA polymerases for artificial genetic polymer (XNA) synthesis remains underdeveloped. Now, the evolution and structure of an α-l-threofuranosyl nucleic acid polymerase is described that achieves XNA synthesis with ∼1 nt s⁻¹ and >99% template-copying fidelity.

The electrocatalytic activity of metal catalysts commonly exhibits a positive linear correlation with the presence of steps, but this dependency breaks down for Pt catalysts with high step densities. Now, using in situ electrochemical scanning tunnelling microscopy, it is shown that this is due to the bunching of closely spaced steps, forming double and triple steps.

The mechanism of electrocatalytic CO/CO₂ reduction on Cu surfaces is complex and its various mechanisms remain under debate, including the important role of cations in the electrolyte. Here the authors quantitatively determine the impact of alkali cations on the thermodynamics of CO adsorption under electrochemical conditions and the activation parameters of the rate-determining step.

Heterologous expression of an active, metallocentre-containing nitrogenase in a non-diazotrophic host is challenging. Now, the heterologous biosynthetic pathway of Mo-nitrogenase is pieced together in Escherichia coli using genes from Azotobacter vinelandii and Methanosarcina acetivorans.