Angewandte Chemie最新文献

Herein, two Cu-based model electrocatalysts, Cu nanosheets modified with Cd single atoms (Cd-SACs@Cu NS) and unmodified Cu nanosheets (Cu NS), were rationally designed to investigate the C–C coupling to C₂₊ alcohols mechanisms in CORR. Compared to Cu NS, Cd-SACs@Cu NS exhibits a significantly enhanced Faradaic efficiency (FE) for C₂₊ alcohols of nearly 70% at an unprecedented current density of 1100 mA cm⁻² and maintains a higher FE (>50%) over a broad range of current densities (100–2100 mA cm⁻²) under alkaline conditions in a flow cell. In situ characterizations and theoretical studies reveal that the enhanced selectivity toward C₂₊ alcohols on Cd-SACs@Cu NS is attributed to the improved H₂O dissociation at atomically dispersed Cd sites and enhanced CO adsorption on the paired Cu atoms adjacent to single Cd atoms. These effects synergistically facilitate the spillover of hydrogen atoms from Cd to Cu sites, thereby promoting the protonation at the β-carbon of *CH₂CHO, which leads to the selective formation of C₂₊ alcohols. In contrast, the unmodified Cu NS is prone to promoting the cleavage of the C─O bond, thereby facilitating the generation of C₂H₄.

Self-assembly has proven to be a robust strategy for constructing intricate hierarchical structures. The construction of chiral or toroidal nanostructures has attracted considerable attention. However, hierarchical nanostructures involving both chiral and toroidal features are rarely reported and related mechanism is less understood. Herein, we report a discovery of toroids with controllable helical senses from the one-pot self-assembly of polypeptides. Through the addition of selective solvent to polypeptide solution and the followed dialysis, uniform toroids with left-handed helical structures are formed. Mechanism analysis revealed that the polypeptides are initially assembled into spherical aggregates, then the spheres perforated into toroids during the dialysis process. Simultaneously, chain rearrangement occurs, resulting in an ordered packing of polypeptides within the toroids and the formation of helical structures. The formation of helical toroids can be well controlled by the assembly conditions, and its chirality was found to be dependent on the polypeptide backbone chirality. This is a pioneering example of one-pot self-assembly of hierarchical structures containing multiple topological features, providing a straightforward efficient strategy for constructing complicated nanostructures with chiral and toroidal features.

Chromanes are frequently encountered as chiral structure elements in active pharmaceutical ingredients (APIs). We have now discovered an access to enantiopure chromanes, which employs a 1:1 mixture of their enantiomers (racemate) in a photochemical deracemization reaction (21 examples, 71%–90% yield, 80%–99% ee). A chiral photocatalyst (10 mol%) acts by selective hydrogen abstraction at one chromane enantiomer and establishes a photostationary state in which the other enantiomer prevails. A thiol additive (20 mol%) was found to improve the enantioselectivity of the process. The mechanism of the reaction was investigated by experimental and quantum-chemical studies. The oxygen atom of the chromane locks the rotation around the exocyclic C─C bond to the amide by forming an intramolecular hydrogen bond. Forward hydrogen atom transfer (HAT) occurs exclusively in one diastereomeric complex via a readily accessible transition state. Reasonable pathways for back HAT were identified which are in line with deuterium labeling experiments. The method was applied to the concise preparation of five chromane-containing drugs (Doxazosin, Fidarestat, Nebivolol, Repinotan, Sarizotan) as single enantiomers.

Awaking the force of materials for specific efficacy by precise electronic modulation remains a fundamental challenge in catalysis. Herein, we transform ordinary NiFe-layered double hydroxide (NiFe-LDH) into a high-performance NO₃⁻-to-NH₃ electrocatalyst via cathodic electrochemical restructuring, which effectively induces oxygen vacancy (O_v) clusters preferentially localized around low-valence Ni sites. The resultant restructured NiFe-LDH (NiFe-LDH-R) demonstrates excellent concentration-universal NH₃ electrosynthesis activity in 1 M KOH, notably sustaining high Faradaic efficiencies (FEs, 88.5%–95%) across a broad potential range and attaining an ampere-level current density (−1.46 A cm⁻²) together with a remarkable yield rate of 104.1 mg_NH3 h⁻¹ cm⁻². In situ spectroscopic analyses reveal boosted hydrogenation kinetics and a thermodynamically favorable NOH pathway for NiFe-LDH-R, which is further decoded by theoretical calculations indicating that synergized O_v/Fe and low-valence Ni sites, respectively enhance NO₃⁻ adsorption and directional active hydrogen (*H) supply, thus streamlining overall energy barriers. Moreover, a new-style membrane-free bipolar electrosynthesis system is established, which enables unprecedent NH₃ FEs exceeding 100% and scalable NH₃ valorization into 4.1 g of methenamine. This study rekindles power of electrochemical restructuring in catalyst advance and pioneers a new paradigm for energy-efficient electrochemical NH₃ production and fixation.

Aqueous Zn||MnO₂ batteries offer a compelling solution for large-scale, low-cost, and safe energy storage, yet their cycle life remains inadequate for practical applications. This instability stems from intertwined H⁺/OH⁻ interfacial reactions and the intrinsically low conductivity of MnO₂, leading to poor redox reversibility and electrode passivation. Here, we report a MoS₂–MnO₂–electrolyte triple-interface design that enables interfacial charge orchestration to reshape interfacial chemistry and charge transport dynamics. MoS₂ catalyzes H₂O dissociation to facilitate efficient H⁺-redox, while Mo sites stabilize the interfacial pH via OH⁻ adsorption. Concurrently, the MoS₂–MnO₂ heterojunction accelerates electron transfer through synergistic chemical-electrochemical pathways. The resulting Zn||MoS₂–MnO₂ cells deliver extraordinary durability, maintaining 92.7% capacity after 10,000 cycles at 20 C, and pouch-scale devices with 5.2 mAh cm⁻² high areal capacity exhibit stable cycling. This work establishes a cross-scale strategy in which ordered interfacial charge orchestration couples microenvironment regulation with multi-step transport control, advancing aqueous Zn batteries toward grid-level application.

The development of single-component photocatalysts that can achieve highly efficient photocatalytic CO₂ overall reactions (PCOR) to generate multielectron products remains a crucial challenge. Here, we present, for the first time, a novel strategy of constructing asymmetric “intramolecular electron compartments” (IEC) in single metal–organic frameworks (MOFs) that enables efficient PCOR to multielectron products. The resulting Cu-MOF-NK1(BF₄⁻) achieves a remarkable CH₃OH production rate of 115.8 µmol g⁻¹ h⁻¹ (92.0% selectivity) without using any sacrificial agents and cocatalysts, making it one of the top-performing single-component PCOR catalysts reported to date. Notably, under simulating flue gas condition (15% CO₂), it remains the remarkable performance of 110.2 µmol g⁻¹ h⁻¹ with corresponding total electron assumption rate of 661.2 µmol g⁻¹ h⁻¹, the highest value reported to date, setting a benchmark for low-concentration CO₂ photocatalysts in overall reaction. Combined experimental and theoretical studies reveal new insights that the presence of asymmetric IEC within MOFs accounts for the enhanced accumulation of photogenerated electrons, thereby promoting the production of multielectron products. Our work not only develops a promising photocatalyst for converting CO₂ and H₂O to methanol, but also establishes a universal design principle for constructing single-component PCOR catalysts that enable multielectron reduction products.

Single-walled carbon nanotubes (SWCNTs) consist of a carbon monolayer and fluoresce in the near-infrared (NIR, 800–2500 nm) region. Introduction of sp³ quantum defects (QDs) creates novel NIR emission features, which promise huge potential for (bio)photonics. However, so far defect chemistry based on diazonium salts is mainly limited to benzene derivatives. The reaction side products also quench SWCNT fluorescence and impair additional surface chemistry. Here, we introduce a photochemical strategy based on arylazo sulfonates to a) create more complex aromatic QDs and b) avoid side products that adsorb and quench. We show that this way coumarin and other QDs are incorporated, which increases overall NIR emission by more than 90% without purification. These materials can be non-covalently modified with biocompatible polymers (polyethyleneglycoles, DNA) without a change in photophysical properties and we demonstrate mechanical (viscosity) and chemical (neurotransmitter dopamine) sensing. This one-pot approach creates QDs in SWCNTs and provides access to advanced hybrid materials for photonic applications.

0.2 M Low Concentration Electrolytes (LCEs) for lithium-based batteries formed from lithium salts with very weakly coordinating anions, i.e., the aluminate Li[Al{OC(CF₃)₃}₄] and the gallate Li[Ga(C₂F₅)₄] in ortho-difluorobenzene (o-DFB), showed competitive conductivity to classical electrolytes of up to 5.0 mS cm⁻¹ at 25 °C combined with electrochemical stability at least up to 4.5 V vs. Li/Li⁺. Given that a stoichiometric amount of 2 equivalents dimethoxyethane (DME) per lithium ion (as Li⁺ complexing agent) and 2 wt.% fluoroethylene carbonate (as solid electrolyte interphase (SEI) former) were present in the LCEs, half and full-cell measurements confirmed stable LCE cycling over 300 cycles in Lithium-Ion-Batteries. Even at high currents (5C), the discharge retained two thirds of the practical 1C capacities of NMC622. By contrast, a LCE made from 0.2 M LiPF₆ in EC/EMC 3:7 solution already led at a 2C rate to cell death, while a simple switch of the conducting salt to 0.2 M Li[Al{OC(CF₃)₃}₄] led to stable cycling including rate tests for over 300 cycles and approached closely the values of the standard 1.0 M LiPF₆ electrolyte in EC/EMC 3:7 – attributed to the anions’ stability. The performance of the aluminate LCE was further evaluated in symmetrical Li-Li cells and Lithium-Metal-Batteries containing 48 µm thin Lithium-Metal-Anodes (LMAs): LCEs improved the cell's lifetime by a factor of 3–6 at a current density of 1 mA cm⁻². Scanning electron microscope/energy-dispersive X-ray and potentiostatic electrochemical impedance spectroscopy measurements confirmed the exceptional stabilization of the LMAs by the aluminate LCE throughout the cycling, especially when combined with an artificial, adaptive and self-healing SEI based on Li[PO₂(OCH₂CF₃)₂]. The solvation structure of standard and LCEs was investigated by NMR spectroscopic diffusion measurements and quantum chemical calculations. A three-to-fourfold increased Li ion mobility was found in LCEs compared to the system with 0.2 M LiPF₆ in standard carbonate solution. The presence of stable and compact Li(DME)₂⁺ structures as moving ions was shown and the relevance of Li⁺ ions solvated with fluoro-ethylene carbonate or o-DFB for SEI-formation is discussed.

Preparing artificial assemblies that can achieve multi-stimuli-responsive and multi-level transformations remains a huge challenge. Here, a pair of dynamic metal-organic tube isomers was prepared from a ligand with multiple coordination modes and flexible conformations. They can undergo multi-level transformations in response to different types of stimuli, including conformational isomerization driven by physical factors (e.g., concentration, temperature, and polarity), adaptive deformations driven by neutral guests, adaptive reconstructions induced by anionic templates. Notably, the guest-driven deformed tubes can continue to undergo reconstruction induced by the PF₆⁻ template, and DMSO can simultaneously serve as a physical factor and a chemical template to continuously regulate isomerization and reconstruction of the dynamic tube. The dynamic tube can be used to regulate the stacking modes of encapsulated 1-formylpyrene and 1-acetylpyrene through adaptive deformations, thereby generating stable guest radicals, enhancing guest fluorescence and achieving white light emission.

In the Research Article (e17420), Yi Shen and co-workers turned the attention to the often-ignored “Interstitial electrons” in CuZn alloy clusters. These interstitial electrons were found to be pivotal regulators, actively participating in stabilizing reaction intermediates and steering the CO₂ conversion pathway with high efficiency and selectivity. The cover image depicts the interstitial electrons within the CuZn alloy-functionalized covalent organic framework promote the reduction of CO₂ to C₂H₄.