ChemistryEurope最新文献

Ammonia is vital for global agriculture, yet its conventional synthesis via the Haber–Bosch process is energy-intensive and environmentally burdensome, contributing ∼2% of global CO₂ emissions. Simultaneously, excessive use of ammonia-based fertilizers has led to nitrate pollution in water systems. Electrochemical nitrate reduction (E-NO₃RR) offers a dual solution: mitigating nitrate contamination while enabling decentralized, sustainable ammonia production. Here, we explore nickel oxide (NiO) nanoparticles as efficient, low-cost electrocatalysts for E-NO₃RR, capitalizing on their earth abundance and inherent ability to suppress competing hydrogen evolution. NiO is synthesized via a scalable precipitation method using different ethanol/water solvent ratios to modulate defect density, porosity, and crystallinity. Materials-related differences are probed by thermal, structural, and spectroscopy methods. Electrochemical tests reveal that increasing ethanol content during synthesis enhances defectiveness, correlating with improved Faradaic efficiency and ammonia production rates. This work underscores the critical role of synthetic parameters in tailoring catalytic performance and positions defect-engineered NiO as a promising platform for green ammonia generation via nitrate reduction.

The Cover Feature shows an octopus in an underwater lab holding marine-derived rubrolides A, D, P, T, U, and a rubrolide U analog as well as two building blocks in its tentacles. The ceiling displays a biofilm control to emphasize the compounds’ outstanding antibiofilm activity. Behind the window, one can see the beautiful underwater world where these natural products are produced. More information can be found in the Research Article by I. Alio, N. Schuetzenmeister and co-workers (DOI: 10.1002/ceur.202500298).

In the pursuit of advanced functional materials, π-extended porphyrin derivatives, particularly β,β-benzannulated tetrapyrroles, have garnered significant attention due to their unique structural and electronic properties. This study refines existing methodologies for the selective synthesis of opp-A₂B₂-symmetric benzoporphyrins based on 4,7-dihydro-4,7-ethano-2H-isoindole or [3,4]epipyrroloanthracene building blocks. By condensation of preformed biscarbinols, this approach overcomes regioselectivity challenges in traditional condensation methods, which typically favor other isomers over the desired opp-A₂B₂ regio derivative. The analysis of the resulting C_2v-symmetric tetrapyrroles exhibit distinct optoelectronic, electrochemical, and structural properties compared to their fully symmetrical A₄ counterparts, underscoring their potential in organic optoelectronics applications.

The Cover Feature highlights gallium-based liquid metals, where the formation of a gallium oxide interfacial layer gives rise to both a “bright” side and a “showdown” side. Acting as a double-edged sword, these interfaces endow the material with enhanced properties and expanded functionalities, while simultaneously introducing potential risks and limitations. More information can be found in the Perspective by X. Hou and co-workers (DOI: 10.1002/ceur.202500295).

The Front Cover portrays a phosphinine-borane adduct that promotes a new mode of C─N σ─bond activation reaction that finally results in the P-functionalization of the aromatic phosphorus heterocycle. More information can be found in the Research Article by Z. Benkő, C. Müller and co-workers (DOI: 10.1002/ceur.202500280) Artwork by Linus Lohs, Samantha Frank and Christian Müller.

The dehydrocoupling of terminal alkynes and hydrosilanes catalyzed by alkaline-earth complexes: calcium, strontium and, most prominently, barium, is reported. [Ba{N(SiMe₃)₂}₂.(thf)₂] (1) is a convenient precatalyst, affording conversions in the range 75–95+% and good chemoselectivity for substrates bearing aromatic substituents, e.g., with the benchmark phenylacetylene and phenyldimethylhydrosilane. Over 20 different combinations of substrates were coupled, typically over 12–24 h at 90 °C with a 5 mol-% loading of 1. Reaction rates increase upon descending group 2, according to Ca < Sr < Ba. Kinetic analysis performed for the coupling of our benchmark substrates catalyzed by 1 in pyridine-d₅ allows for the determination of the rate law r = k.[barium]¹.[PhMe₂SiH]¹, with ΔH^‡ = 12.7(1) kcal mol^–1 and ΔS^‡= –42.8(1) cal mol^–1K^–1 consistent with a kinetically affordable, albeit relatively slow, reaction. DFT calculations conducted on the system 1/pyridine indicate the mono-solvated [Ba{N(SiMe₃)₂}₂.pyridine] to be the prevailing catalyst, with a rate-determining step consisting of the protonolysis between a [Ba]-hydride intermediate and floating HN(SiMe₃)₂. Compared to Ca and Sr, the greater efficiency of Ba precatalysts stems from the greater ability of barium to lose precoordinated pyridine and, thus, to generate the catalytically competent mono-solvated species.

We present a method for the rapid assembly of highly substituted 1,4-benzodiazepin-2-ones by the addition of unsymmetrical imides to arynes, the subsequent deprotection of a protected amino functionality followed by immediate ring closure. An optimized procedure for the synthesis of diversely substituted unsymmetrical imides was developed, granting access to a large pallet of benzodiazepine precursors. This allows for the application of this protocol in a modular fashion, which is demonstrated for both the unsymmetrical imides and the benzodiazepines. Ultimately, we thereby reveal rapid access to a large variety of densely functionalized benzodiazepine cores.

The Cover Feature depicts the interaction of linearly and circularly polarized light with a series of oligoamide foldamers bearing different lateral electron-donating groups. Using advanced quantum chemistry methods, this work provides the first computational chemistry investigation of their linear and nonlinear (chir)optical responses. More information can be found in the Research Article by B. Champagne and co-workers (DOI: 10.1002/ceur.202500404).

Cleavage by γ-secretase within the transmembrane domain (TMD) of amyloid precursor protein (APP) generates Aβ peptides that can accumulate in amyloid plaques in Alzheimer's disease pathogenesis. How γ-secretase selects its substrates has been an enigma as they do not have a consensus sequence. In our previous study, we discussed a dynamic signature that controls internal bending/kinking and orientation of the two halves of the TMD. The extent, however, had remained ambiguous due to limitations of NOE-based NMR structure determination. To solve this question, we measured residual dipolar couplings (RDCs) of APP-TMD, using a polyethylene glycol gel-based alignment medium with TFE/water mixtures. Using ¹H¹⁵N RDCs, we analyzed the conformations of APP-TMD and two mutants, G38L and G38P, which previously had differed significantly in bend and orientation and cleavage efficiency by γ-secretase. By fitting snapshots from a molecular dynamics trajectory, we analyzed how well structures matched the measured RDC values. This indicated that G38L retained mainly its relatively straight conformation, whereas bent and—in the case of G38P—locally unfolded structures likewise contribute dynamically to the other two. The RDC selected structures thus reproduce the features of the NOE-derived structures, but show that all three TMDs retain some conformational adaptability.

High-entropy alloy (HEA) nanoparticles (NPs) have been subject to increasing interest as prospective catalyst materials. However, highly controllable synthesis methods for HEA NPs remain scarce. To address this issue, we present a systematic study of the synthesis parameter space in a simple colloidal synthesis approach where IrPdPtRuRh NPs were synthesised in triethylene glycol. We show that ultra-small (1–3 nm), single-phase HEA NPs can be synthesised through a hot-injection synthesis approach. In contrast, multiple phases are observed when a one-pot synthesis is carried out. We also show that the particle sizes and morphologies are affected by the choice of metal precursor counterion, and further investigate the dependence of metal reduction on the reaction temperature. Additionally, we present the synthesis of mixed noble/non-noble-metal IrPdPtRuNi and IrPdPtRuCo HEA NPs. By carrying out reduction kinetics experiments, we relate phase separation and compositional gradients of some of the synthesised samples to large differences in the reduction rates of the reacting metals. The individual metal reduction rates are found to vary depending on which other elements are present during particle formation. These results emphasise the importance of understanding the chemical landscape during reaction for the controlled synthesis of HEA NPs.