Chemistry - A European Journal最新文献

Developing cost-effective oxygen evolution reaction (OER) catalysts for industrial current densities remains challenging, hindered by adsorbate evolution mechanism (AEM) scaling limitations and reconstruction instability. Here, we report a heterointerface-engineered Ni₃S₂/NiFeOOH catalyst formed via in-situ electrochemical reconstruction of Ni₃S₂/NiFe-LDH. Interfacial charge redistribution stabilizes high-valent Ni³⁺/Fe³⁺ species and generates coordinatively unsaturated lattice oxygen sites, thereby activating the lattice oxygen mechanism (LOM). Combined operando spectroscopy, pH-dependent kinetics, and isotope labeling confirm LOM dominance. Further theoretical analyses reveal that the heterointerface downshifts the metal d-band center and upshifts the O 2p-band center, optimized intermediate adsorption free energy. Benefiting from the compatible multi-mechanism, the reconstructed catalyst demonstrates outstanding OER performance, only requires overpotentials of 196/305 mV to drive current densities of 10/1000 mA cm^-2 in alkaline media, with robust stability for over 500 h. This work clarifies how interfacial electronic modulation connects pre-catalyst reconstruction to LOM activation, providing a scalable design strategy for high-current-density OER electrocatalysts.

Aromatic N-oxides have a rich photochemistry, but the primary steps have not been investigated in much detail. In this work pyridine N-oxide and pyridazine N-oxide are studied using steady-state and time-resolved X-ray absorption spectroscopy (XAS). Absorption changes at the nitrogen and oxygen K-edges following UV photoexcitation are recorded on a timescale of picoseconds to hundreds of nanoseconds. The spectral features are assigned to the presence of specific transient intermediates. Quantum chemical calculations indicate that the excited state dynamics in the S₁ state are characterized by a fast deplanarization. After reaching a minimum energy crossing point (MECP), evolution on the ground state surface leads to the starting materials and metastable products. The primary photoproduct of pyridine N-oxide, oxaziridine 3, is stable on the sub-microsecond timescale. In the photochemistry of pyridazine N-oxide, oxaziridine and oxadiazepine intermediates are not observed, and (Z)-4-diazobut-2-enal is formed within 100 ps. The mechanistic details of the two different N-oxides uncovered through characteristic features in the near-edge X-ray absorption fine structure (NEXAFS) region serve as an example of how time-resolved XAS enables the characterization of photochemical dynamics beyond those accessible to more traditional spectroscopies.

Living crystallization-driven self-assembly (CDSA), employing a seeded growth method, has emerged as a pivotal strategy for achieving precise control of anisotropic nanoparticles over the dimensions and structure, which enables the fabrication of 1D cylinders and 2D platelets with low dispersity. This versatile and robust approach, characterized by linearly tunable dimensions and programmability of structural sequences, has been widely applied in the construction of nanoparticles exhibiting uniform size and controlled architecture. A critical aspect of this technique lies in heteroepitaxial crystallization, which transcends the chemical composition constraints of conventional homoepitaxy and enables the design of segmented structures with spatially distinct core components. Building upon this foundation, we elucidate the key aspects of living CDSA seed growth, with a particular emphasis on exploring the mechanism of governing heteroepitaxial growth from crystalline seeds with distinctly chemical compositions. Elucidating the intricate mechanisms of heteroepitaxial crystallization allows access to broaden the design possibilities for segmented nanoparticles with spatially defined core compositions and functionalities. Moreover, the new developing methods for facile synthesis of uniform particles with high solid concentrations are also reviewed, which are promising for the real applications of these advanced nanomaterials.

Bioorthogonal chemistry has emerged as a transformative strategy for detecting and quantifying biomolecules in complex biological systems. This review highlights recent advances in catalyst-free bioorthogonal reactions specifically applied to semi-quantitative and quantitative biomolecular analysis. We exclude reactions that require toxic or complex catalysts and focus on four reactions: Staudinger ligation, strain-promoted azide-alkyne cycloaddition, inverse electron-demand Diels-Alder reaction, and 2-cyanobenzothiazole-cysteine condensation. For each, we discuss reaction kinetics and strategies for representative applications in biomolecular quantification. The scope of target biomolecules varies by reaction, including proteins, nucleic acids, glycans, and small molecules. Quantification techniques such as fluorescence spectroscopy, luminescence spectroscopy, and mass spectrometry are examined, with reported limits of detection typically ranging from nanomolar to micromolar, and a few advanced techniques reaching femtomolar or attomolar sensitivity. Each reaction is discussed in terms of kinetics, molecular compatibility, and analytical sensitivity. Finally, we outline key challenges and future opportunities, emphasizing the need for faster reaction kinetics, improved probe design, enhanced integration with advanced analytical platforms, and standardized methods to improve reproducibility and cross-study comparability in biomolecular quantification.

A catalyst screening for six different α-alkylation reactions of methyl sulfides with unsaturated substrates performed in hermetically sealable and inexpensive 42-well aluminum reactor blocks is described. As a result, a new titanium-catalyzed hydrothiomethylation reaction of alkenes, which takes place under C─H bond activation at the α-carbon atom of simple methyl sulfides, is presented. The best catalyst is prepared in situ from the readily available titanium catalyst precursor Ti(CH₂SiMe₃)₄, a formamidinato ligand precursor, and the Lewis acid [Ph₃C][B(C₆F₅)₄]. Although selected 1,2-disubstituted alkenes, for example, cyclohexene and cyclopentene, undergo successful hydrothiomethylation reactions, the best results are obtained with monosubstituted 1-alkenes. In these cases, the reactions take place with excellent regioselectivity and give branched hydrothiomethylation products exclusively (23 examples). When dimethyl sulfide is used as a substrate, either the monohydrothiomethylation product or the dihydrothiomethylation product can be obtained with very good selectivity.

Macrocycles and molecular cages possess enzyme-like cavities whose size, shape, and functionality can be precisely engineered. Helicenes, characterized by rigid π-conjugated backbones and inherent helical chirality, serve as exceptional scaffolds for constructing highly distorted chiral macrocycles and cages. These supramolecular architectures demonstrate enhanced circularly polarized luminescence (CPL), enantioselective recognition, and efficient guest adsorption. This minireview provides a comprehensive overview of recent advances in helicene-based coordination and covalent strategies, highlighting synthetic methodologies, chiroptical modulation, and emerging applications. Key challenges-including fluorescence quenching in metallacages, synthetic complexity, and limited structural diversity-are critically discussed. We also highlight potential opportunities involving high-emission linkages, dynamic covalent strategies, and stimuli-responsive designs. Collectively, these insights establish a framework for the rational design of helicene-derived macrocycles and three-dimensional cages, paving the way toward the development of advanced chiral functional materials.

Ammonia is one of the most important industrial products. The Haber-Bosch process has enabled large-scale ammonia production but also results in substantial carbon emissions. Amid growing environmental concerns, there is an urgent need to transform this highly energy-intensive process and develop ammonia synthesis technologies under mild conditions. Covalent organic frameworks (COFs), as one of the most prominent emerging materials in recent years, have demonstrated exceptional application potential and advantages in various fields such as photocatalysis and electrocatalysis. The modular structural design of COFs allows for tunable band gaps according to practical requirements, their permanent porosity endows the materials with excellent adsorption capabilities for reactants, and the abundant heteroatoms provide numerous reactive sites. Currently, COFs-based catalysts have achieved high performance in various photocatalytic applications, and sustainable ammonia synthesis is highly likely to become the next research focus. This review summarizes the fundamental principles of photocatalytic ammonia synthesis, methods for ammonia detection, and the research progress in COFs-based materials for ammonia synthesis. Finally, it analyzes and discusses the future challenges and prospects of this emerging field of sustainable ammonia synthesis using COFs.

Developing efficient and durable oxygen reduction reaction (ORR) electrocatalysts from earth-abundant elements is of great significance for the advancement of sustainable energy technologies such as rechargeable zinc-air batteries. Herein, we present a 3D honeycomb-like nitrogen-doped carbon matrix decorated to in-situ form Fe nanoparticles (denoted as Fe-NPs@N-HC) via an ice-templating method. Theoretical calculations and experimental analyses collectively reveal that the work function mismatch between metallic Fe and the N-doped carbon host drives spontaneous charge transfer, establishing a built-in electric field at the heterointerface to form the rectifying contact. This interfacial effect fine tunes electronic structure and optimizes the adsorption of oxygen intermediates, thereby accelerating the ORR kinetics. Benefiting from these synergistic effects, Fe-NPs@N-HC achieves a half-wave potential of 0.86 V, superior tolerance to methanol, and excellent long-term durability in alkaline media. When integrated into a liquid zinc-air battery, Fe-NPs@N-HC also delivers a high peak power density of 126.4 mW cm^-2 and outstanding cycling stability exceeding 482 cycles, surpassing the benchmark Pt/C-based system. This work demonstrates that tailoring the electronic structure through interfacial engineering, coupled with rational 3D framework design, provides a promising strategy for the development of next-generation nonprecious metal catalysts for practical energy conversion applications.

Endoplasmic reticulum (ER) micro-polarity, with its spatial heterogeneity and dynamic changes, regulates key physiological processes like protein folding and lipid metabolism. Its abnormal alterations under pathological conditions, such as oxidative stress are closely linked to metabolic diseases and tumors. Capturing these subtle dynamics to reveal connections with organelle dysfunction remains a critical challenge. Existing traditional physical approaches are complex and cannot achieve real-time spatial imaging. Fluorescent probes for polarity sensing could provide spatiotemporal resolution, nevertheless, suffer from unstable signals due to nonfixed dual channels, narrow response ranges, interference from viscosity, and nonlinear responses, hindering quantitative monitoring. We designed an ER-targeted probe MBDP via hybridizing coumarin and BODIPY fluorophores, by introducing a benzene to reduce dihedral angles and a methyl group to inhibit intramolecular rotation, enabling specific polarity response. It shows a broad linear response, strong anti-interference ability, which quantifies ER micro-polarity via dual-channel and lambda mode imaging. It captures ER micro-polarity changes under stress and hippocampal regional differences. Moreover, the remarkable lifetime variations upon polarity change endow MBDP capability under fluorescence lifetime imaging microscope (FLIM). This probe provides a powerful tool with ratiometric imaging and FLIM dual-modal monitoring for ER micro-polarity, aiding in revealing ER-related physiological/pathological mechanisms and disease research.

Multilevel computational approaches based on electronic structure methods currently enable the accurate structural and thermodynamic characterization of medium to large-sized host-guest systems, but have been scarcely used to systematically study their kinetics. Here, we show how this type of protocol can be easily applied for the task, using the well-known complexation reaction between the cucurbit[6]uril host and alkylammonium cations as a test case. To this end, the recently reported aISS docking workflow is used for the fast exploration of the coconformational space of a set of nine host-guest aggregates, at the robust and fast semiempirical GFN2-xTB(ALPB) level of theory. After identification of appropriate intermediates and reaction products, those can be in turn efficiently connected by the Nudged Elastic Band method, enabling fast screening of different potential reaction mechanisms, and the identification of the corresponding transition states. Further refinement of the equilibrium geometries and a better energetic description of the stationary points is nevertheless mandatory, for instance with the state of the art and efficient ωB97X-3c(COSMO-RS)//r²SCAN-3c(CPCM) density functional-based protocol, which not only accurately reproduces the experimental reference values of the free energy of association (MAE = 1.4 kcal/mol), but also the kinetic in/out barriers reported for the processes (MAE = 2.0 and 2.9 kcal/mol, respectively). Overall, this work presents a robust and cost-effective multilevel workflow for the routine kinetic profiling of supramolecular association processes.