Angewandte Chemie International Edition最新文献

Herein, we present the first catalytic asymmetric nucleophilic addition of diarylphosphines to 2H-azirines, facilitated by a chiral Mn(I) complex. This method not only provides access to novel class of derivatives of the aziridine core-a structural motif recognized for its antitumor and antibacterial properties-but also introduces a phosphine moiety alongside the generation of an NH moiety within a strained three-membered ring. The discovery of this new Mn(I) complex that both enables the reaction and induces stereoselectivity is pivotal, as it underscores the significant potential of this earth-abundant metal in advancing asymmetric catalysis.

Herein, we report the synthesis and properties of triptycene-based C3v- and Cs-symmetric stable radical trimers. SQUID magnetometry showed the propeller-shaped trimers were both an antiferromagnetic equilateral triangle spin system with small spin-spin interaction J/kB ~ -120 K and -106 K, leading to ca. 4/6 coexistence of the doublet/quartet states in thermal equilibrium at room temperature. The trimers exhibited characteristic NIR absorption bands reaching 1000 nm, which was solely ascribed to the triradical in the doublet state by variable-temperature spectroscopic studies and quantum chemical calculations. Taking advantage of the spin-specific absorption feature, we found that the triradicals in the low-spin state undergo symmetry-breaking charge transfer, while those in the high-spin state fall into a monomer-like excited state.

The active sites of metalloenzymes involved in small molecules activation often contain pendant bases that act as proton relay promoting proton-coupled electron-transfer processes. Here we focus on hydrogenases and on the reactions they catalyze, i. e. the hydrogen evolution and oxidation reactions. After a short description of these enzymes, we review some of the various biomimetic and bioinspired molecular systems that contain proton relays. We then provide the formal electrochemical framework required to decipher the key role of such proton relay to enhance catalysis in a single direction and discuss the few systems active for H₂ evolution for which quantitative kinetic data are available. We finally highlight key parameters required to reach bidirectional catalysis (both hydrogen evolution and hydrogen oxidation catalyzed) and then transition to reversible catalysis (both reactions catalyzed in a narrow potential range) as well as illustrate these features on few systems from the literature.

Owing to their well-defined crystalline pore structures and ordered functional ionic groups along the skeleton, ionic covalent organic frameworks (iCOFs) exhibit excellent performance and have significant potential for use in energy storage and conversion devices. Herein, we for the first time developed cationic phosphonium COFs with high hydroxide conduction even with low ion exchange capacity (IEC). Specifically, we synthesized COFs containing quaternary phosphonium groups as excellent ion transport moieties. Then, we fabricated freestanding phosphonium membranes through a vapor-assisted method, which exhibited high hydroxide conductivity of 126 mS cm-1 at 80 °C from a minimal IEC of 1.17 mmol g-1. The resulting film was successfully applied to zinc-air batteries, demonstrating energy density of 96.1 mW cm-2, specific capacity of 95.0 mAh cm-2, and stable operation over 2,300 min. Overall, in addition to investigating a novel cationic functional group, we demonstrated a freestanding film formation method of COF-based materials. The findings can provide a solid foundation for advancing the field of iCOFs to ion transport and promoting electrochemical applications.

Developing pure organic materials with ultralong lifetimes and balanced quantum efficiency is attractive but challenging. In this study, we propose a novel strategy to investigate external heavy atoms by linking molecular emitters with halogen through a flexible alkyl chain. X-ray crystal analysis clearly reveal the halogen C-X-π interactions, which can be tuned by halogen donors, as well as the distance and geometry between them. Impressively, DOPTZ-C3Cl featuring a chloride atom as donor, exhibits a balanced long phosphorescence lifetime of 1351 ms and a phosphorescence quantum yield of 10.1%. We also first demonstrate that Cl can induce more positive effect than heavier halogens (Br and I) on prolonging the lifetime. We envisage that the present study will expedite new molecular design to manipulate the room temperature phosphorescence via external heavy atom effect, and highlight a special C-Cl··π interaction for the development of ultralong phosphorescent materials.

Numerous reactions within metabolic pathways have been reported to occur nonenzymatically, supporting the hypothesis that life arose upon a primitive nonenzymatic precursor to metabolism. However, most of those studies reproduce individual transformations or segments of pathways without providing a common set of conditions for classes of reactions that span multiple pathways. In this study, we search across pathways for common nonenzymatic conditions for a recurring chemical transformation in metabolism: alkene hydration. The mild conditions that we identify (Fe oxides such as green rust) apply to all hydration reactions of the rTCA cycle and gluconeogenesis, including the hydration of phosphoenolpyruvate (PEP) to 2-phosphoglycerate (2PGA), which had not previously been reported under nonenzymatic conditions. Mechanistic insights were obtained by studying analogous substrates and through anoxic and radical trapping experiments. Searching for nonenzymatic conditions across pathways provides a complementary strategy to triangulate conditions conducive to the nonenzymatic emergence of a protometabolism.

With the increasing sales of electric vehicles, lots of spent lithium-ion batteries (LIBs) assembled with LiFePO4 (LFP) cathodes will retire in the next few years, posing a significant challenge for their effective and environmentally-friendly recycling. The main reason why spent LFP cathodes fail to re-utilize lies in the lattice defects caused by lithium loss and structural defects resulting from stress accumulation. In this work, we propose an in-situ granule reconstruction strategy to directly regenerate spent LFP black mass (S-BM) using glycerol in industry settings. The hydroxyl groups abundant in glycerol serves as electron donor that help reduce Fe (III) and repair Fe-Li antisite defects (FeLi). Additionally, the chelating properties of glycerol intervene with structurally disintegrated particles, inhibiting Oswald ripening effect and promoting bonding of grain boundaries to generate lamellar microcrystals with homogeneous grain size, recover their morphology and crystal structure after a facile annealing procedure. Furthermore, the regenerated LFP restores Fe-O bonds which further inhibits structural distortion and improve Li+ migration kinetics. As a result, the regenerated industrial LFP black mass (R-BM) exhibits superior lithium storage performance with a discharge capacity of 123.2 mA h g-1 after 500 cycles at 5.0 C (a capacity retention rate of 93.1%).

Herein, a copper(I)-catalyzed asymmetric 1,4-hydroarsination of β-substituted α,β-unsaturated esters is achieved in moderate to excellent yields with high to excellent enantioselectivity, based on the proposed nucleophilic [Cu]-AsPh2 species. As for α-substituted α,β-unsaturated esters, a 1,4-hydroarsination/enantioselective protonation event occurs smoothly in satisfying results. Furthermore, β-substituted α,β-unsaturated ketone, α,β-unsaturated amide, and α,β-unsaturated phosphine sulfide are well applied in the present catalytic system. Finally, some control experiments show that HAsPh2 is activated through coordination with the copper(I) catalyst and HAsPh2 exhibits inferior soft Lewis basicity to HPPh2 in the presence of a copper(I)-bisphosphine complex.