Chemistry - An Asian Journal最新文献

MXenes are a promising class of two-dimensional (2D) nanomaterials known for their exceptional metallic conductivity and adjustable surface chemistry. However, the current state-of-the-art synthesis methods rely on the chemical etching of MAX phase (e.g., Ti₃AlC₂) with HF or fluoride-based compounds, leading to fluorine-terminated MXenes. These MXenes suffer from poor stability in ambient conditions, restricting their applications, particularly in lithium-ion-based batteries and capacitors (LIBs and LICs). In this study, we present a two-step method to produce fluorine-free MXene, addressing the stability issues of MXene in aqueous dispersions and relatively improved performance in LICs. Specifically, an efficient etching process employing hydroiodic acid (HI) with vinegar is used for the selective removal of the A layer from the MAX phase, resulting in F-free exfoliated MXenes (HVM). The HVM shows an outstanding electrical conductivity of 388 S cm⁻¹, maintaining high stability in aqueous dispersions over two weeks. HVM as electrode shows significantly enhanced Li⁺ ion storage capabilities, delivering a discharge capacity of 295 mAh g⁻¹ over 500 cycles at 1 A g⁻¹, substantially outperforming MXenes derived from F-based etching approaches. Furthermore, the HI-vinegar etching mechanism introduces unique surface functionalities that provide HVM superior cycling stability and rate capability, enabling more stable, high-performance MXene-based energy storage devices.

Self-assembling cyclic peptides exhibit several advantages over their linear counterparts; however, the structural simplicity of monocyclic peptides (MCPs) limits their further development into assemblies with more elaborate and complex functions. Here, we demonstrate that bicyclic peptides (BCPs) offer significant potential for constructing peptide assemblies with enhanced controllability and proteolytic stability. Two types of amphiphilic BCPs were designed: one featuring a horizontal division of a monocycle into separate polar and nonpolar cycles (an 8-shaped bicycle), and the other involving a vertical division into two independent amphiphilic cycles (a ∞-shaped bicycle). This orientational orthogonality in bicyclization critically affects the molecular conformation and rigidity of BCPs, which in turn influence nanostructural features of the resulting assemblies, such as surface charge density. Notably, the BCPs exhibited nearly 100% proteolytic stability, despite being composed entirely of natural L-amino acids. In contrast, the corresponding MCP showed only 3% stability under the same experimental conditions. The enhanced functionality of BCPs, combined with the redox-responsive nature of our design, enables the construction of protease-resistant peptide nanoassemblies with high structural complexity and functions.

Photocatalytic CO₂ reduction represents a viable approach to achieving carbon neutrality through fuel production. Nonetheless, the practical deployment of photocatalysts is frequently hampered by the rapid recombination of photogenerated charge carriers. In this investigation, a one-pot solvothermal method was used to synthesize In-doped Bi₄O₅Br₂ photocatalysts. Comprehensive characterizations demonstrate that the electronic structure is effectively modulated by In³⁺ doping, resulting in a narrowed bandgap. Crucially, the recombination of photogenerated electron–hole pairs is suppressed through the introduction of dopant-induced energy levels. The 15In-Bi₄O₅Br₂ sample displays the optimal photocatalytic CO₂ reduction activity, producing CO at a rate of 4.67 µmol g⁻¹ h⁻¹, which is approximately 2.3 times higher than that of unmodified Bi₄O₅Br₂. This remarkable enhancement is attributed to the synergistic effects of an optimized band structure and improved charge separation efficiency induced by In doping. This work provides valuable insights into the rational design of bismuth-based materials for sustainable CO₂ conversion.

Cancer is a major disease that seriously threatens human health worldwide. The development of highly effective and low toxicity anticancer drugs has always been a research hotspot. Transition metal complexes, as antitumor drugs, offer multiple advantages, including the synergistic effect of targeting multiple sites, which reduces drug resistance, strong structural adjustability for optimizing the efficacy of the medicine, unique photodynamic/photothermal therapy capabilities, and the ability to integrate diagnosis and treatment. Early transition metals refer to the d-block metal elements from Group IIIB to Group VIIB in the periodic table. In recent years, antitumor complexes of early transition metals have received extensive attention due to their unique mechanisms of action and potential therapeutic effects. In this review, we summarize the latest advancements in the anticancer effects of metal complexes of Ti, V, Cr, Mn, Mo, Tc, and Re, which represent a new type of anticancer drug with multiple mechanisms, and are expected to provide more effective solutions for precise tumor treatment. With the deepening of research and the development of technology, early transition metal-based drugs may play a more important role in precision medicine.

Most water splitting studies have been investigated in acidic or alkaline electrolytes, while achieving efficient water splitting in safer and lower-cost neutral electrolytes remains challenging. The oxygen evolution reaction (OER) mechanism in neutral electrolytes is still nearly blank and elusive. We investigate the complete water splitting in neutral electrolytes on the semiconductor MoSiGeN₄ monolayer. For OER, Gibbs free energy calculations revealed the highest catalytic activity (η = 0.64 V) at a biaxial strain of 4%. For the hydrogen evolution reaction (HER), ΔG_H* is calculated in the existence of pre-adsorbed OH*, the Ge–N layer has the highest catalytic activity (ΔG_H* = −0.03 eV) at biaxial strain of 2%. The OH*-reservoir mechanism for OER and HER is summarized for the first time, since OH* is stored on the Ge sites when OH* is not required for HER, and OH* is released when OH* is required to be involved in each step of intermediates (OH*, O*, and OOH*) formation for OER. The involvement of OH* effectively reduces the energy barrier for the intermediates formation of neutral water splitting, resulting in an optimal reaction pathway. This work provides a promising strategy to promote the splitting of abundant neutral water, which can be utilized in the field of clean and sustainable energy.

Nitric oxide (NO) is a key signaling molecule in human physiology, and its controlled delivery from small-molecule prodrugs remains a major challenge. 4-Nitronaphthalimides (4-NNs) have recently been identified as glutathione (GSH)-mediated nitrite (NO2⁻) donor prodrugs, with accelerated release observed in cellular compared to cell-free environments. We hypothesized that confined reaction spaces play a crucial role in this reactivity. Here we show that micelles, as cellular confinement mimics, markedly influence the thiol-mediated nitrite release from 4-NNs. Systematic studies under micellar and non-micellar conditions, with varied surfactants, thiols, and pH, reveal that confined microenvironments and the nature of micellar assemblies critically control reaction rates. Confocal fluorescence and lifetime imaging visualized micelle localization and reactivity differences, while DOSY-NMR, DLS, and zeta potential measurements established that 4-NNs reside in the palisade layer of cationic micelles, rendering them accessible to thiol nucleophiles. Moreover, 4-NN analogues with cationic-surfactant-like structures exhibited further enhanced nitrite release, underscoring the catalytic role of micellar confinement. These findings highlight confined environments as powerful modulators of NO-prodrug activation.

Incorporation of electronegative fluorine atoms into the polymer backbone is an effective strategy to lower the highest occupied molecular orbital (HOMO) energy levels and to enhance backbone coplanarity through nonbonding intramolecular interactions, which are essential for improving the performance of the organic photovoltaic cells (OPVs). In this work, we synthesized a series of new naphtobisthiadiazole (NTz)-based semiconducting polymers by incorporating a bithiophene-phenyl-bithiophene unit bearing zero, two, or four fluorine atoms on the phenyl ring, namely, PNT4TB, PNT4TB-F2, and PNT4TB-F4, respectively, for application in nonfullerene acceptor (NFA) OPVs. Fluorination effectively lowered the HOMO energy levels of the polymers, leading to increased open-circuit voltages in the order PNT4TB < PNT4TB-F2 < PNT4TB-F4. In addition, fluorination enhanced backbone coplanarity; however, excessive aggregation was observed in the NFA blend films. As a result, the cells based on PNT4TB-F2, which achieved a favorable balance of HOMO energy level, backbone coplanarity, and thin film morphology, exhibited the highest power conversion efficiency of up to 11%, compared with those based on PNT4TB (9.2%) and PNT4TB-F4 (2.4%). This simple yet effective molecular design strategy provides useful guidelines for developing versatile p-type semiconducting polymers for high-performance OPVs.

A β-vinylated tri(1-adamantyl)phosphine was synthesized from tri(1-adamantyl)phosphine through a photocatalytic cycloaddition/base-induced elimination sequence. The electronic and steric properties of the new phosphine were examined through structural characterization of its chalcogenides and gold complex. The gold complex catalyzed hydroamination of alkynes, demonstrating its potential in transition metal catalysis.

A copper-catalyzed enantioselective hydroboration of cyclic dienes, which afford enantioenriched allylboronates, is disclosed. This reaction is catalyzed by a chiral bisphosphine–Cu complex in combination with commercially available pinacolborane as the hydroborane source. The method is applicable to 1-aryl-cyclohexadienes and 1,2-dihydropyridine derivatives, affording allylboronate products in high regio- and enantioselectivity. The obtained allylboronates serve as versatile intermediates for the synthesis of diverse chiral compounds.