Chemistry - An Asian Journal最新文献

An asymmetric synthesis of C-N atropisomers with pyrrole, oxindole and succinimide moities was developed via organocatalytic desymmetric Michael addition of 3-pyrrolyloxindole with prochiral N-aryl maleimides. The C-N atropisomers were obtained in acceptable yields with high diastero- and enantioselectivities (>20:1 dr, up to >99% ee). C-N Rotational energy barrier has also been determined.

We present a highly sensitive and selective fluorescence "turn-on" sensor for L-histidine (His) detection in aqueous solutions utilizing a 1-Cu2+ complex. This sensing platform employs a fluorescence-based ligand displacement approach, featuring a meso-(N'-acetyl-hydrizide)-based BODIPY derivative (1) complexed with Cu2+. Initially highly fluorescent, the emission of 1 is selectively quenched by Cu2+ ions, forming the 1-Cu2+ complex. The high affinity between His and Cu2+ effectively displaces 1 from the complex, restoring fluorescence. The system exhibits rapid response (within 5 minutes), excellent sensitivity (detection limit of 78 nM), operational simplicity, and a large fluorescence "turn-on" signal. It demonstrates remarkable selectivity for His over other amino acids, with maleimide masking cysteine interference. Notably stable in complex biological matrices, the sensor has successfully quantified His in artificial urine samples. Its practical applicability extends to paper-based test strips, offering portability and potential for real-time His monitoring in clinical diagnostics and biological systems.

Herein, we have reported a series of cationic aggregation-induced emission (AIE) active iridium(III) complexes (Ir1-Ir5) of the type [Ir(C^N)2(N^N)]Cl, wherein C^N is a cyclometalating 2-phenylbenzimidazole ligand with varying alkyl chain lengths and N^N is a 2,2'-bipyridine ligand attached to bis-polyethylene glycol chains, for the treatment of bacterial infections. The AIE phenomenon of the complexes leveraged for detecting bacteria by fluorescence microscopy imaging that displayed a strong red emission in Gram-positive bacteria. The antibacterial activity of the complexes assessed against Gram-positive methicillin-sensitive S. aureus, methicillin-resistant S. aureus, E.faecium and E.faecalis and Gram-negative E. coli and P.aeruginosa bacteria of clinical interest. The complexes Ir2-Ir4 exerted potent antibacterial activity towards Gram-positive strains with low minimum inhibitory concentrations (MICs) values in the range of 1-9 μM, which is comparable to clinically approved antibiotic vancomycin. In contrast, these complexes were found to be inactive towards Gram-negative bacterial strains (MICs > 100 µM). The mechanism of antibacterial activity of the complexes implies that ROS generation, membrane depolarization and rupture are responsible for bacterial cell death. Further, the complexes Ir1-Ir3 were found to be low-toxic against human red blood cells and human embryonic kidney (HEK293) cells, indicating their potential for use as antibacterial agents.

A simple and efficient strategy for the synthesis of structurally diverse β,β-diarylmethine substituted isoxazoline derivatives have been developed. This approach employs a manganese-promoted oxidative cyclization coupled with a 1,6-conjugate addition of unsaturated oximes to p-quinone methides. The key features of this study include the formation of C-O and C-C bonds through intramolecular and intermolecular interactions, facilitated by in situ generated iminoxyl radicals. β,β-diarylmethine substituted isoxazolines, bearing a wide range of functional groups, were isolated in high yields.

It has been found that various heavy metals can initiate different types of regulated cell deaths. Among these metals, copper, an essential trace micronutrient that plays a major role in a lot of physiological processes, also can initiate cell death. It can act as a constituent of metalloenzymes, and can act as a mediator for signaling pathways to regulate proliferation and metastasis of tumor. It is also an integral part of some metal-based anticancer drugs. Recent studies have revealed that excessive intracellular copper accumulation leads to the aggregation of mitochondrial lipoylated proteins, causing proteotoxic stress and ultimately resulting in cell death. This newly discovered copper-induced cell death is termed as cuproptosis. In the last few, a lot of research has been done to understand the mechanism of copper-mediated cell death, and attempts have also been made to identify the relationship between cuproptosis and the development of cancer. In this review, we provide a comprehensive overview on the significance of copper, its regulation inside the body, the possible mechanism of cuproptosis, and how this cuproptosis can be employed as a therapeutic tool for cancer ablation.

Developing efficient, stable and low-cost electrocatalysts is a viable approach to solve the current energy crisis. It is found that increasing the surface area of the electrodes can effectively promote the electrocatalytic efficiency. Herein, the atmospheric plasma spraying (APS) technology was used to prepare FeCoNi-Ni3C alloy coating by adding Ni3C powder to FeCoNi powder with an equal molar ratio. The atomic ratios of Ni3C in the powder are 25 %, 50 %, and 75 %, respectively. The results prove that the pores on the surface of the coating have increased after Ni3C doping, which can provide more active sites in the electrocatalytic process to promote the electrocatalytic reaction. By controlling the proportion of Ni3C, the porosity of the coating surface can be effectively regulated. In 1.0 M KOH electrolyte and 10 mA cm-2, the 50 at.% Ni3C coating shows an overpotential of 105 mV and 212 mV for HER and OER, respectively. It is worth noting that the 50 at.% Ni3C coating has a low Tafel slope of 45.78 mV dec-1 (HER) and 44 mV dec-1 (OER).  Furthermore, the 50 %at. Ni3C coating catalyst has a low potential of 1.664 V at 10 mA cm-2 in a water-splitting system.

Two different types of novel nonaromatic acenaphthene fused macrocycles such as acenaphthene fused dithiaporphyrin(3.1.1.1)s and acenaphthene fused N-fused triphyrin(3.1.1)s were synthesized in one pot condensation reaction using 5,6-dibromoacenaphthene as a key precursor. The X-ray analysis revealed the oval core-shaped structure for dithiaporphyrin(3.1.1.1)s and intramolecular ring fusion in N-Fused triphyrin(3.1.1)s. The NMR, absorption and DFT studies suggested the non-aromatic nature of both macrocycles which absorb strongly in visible-NIR region.  Both macrocycles were stable under electrochemical conditions and showed their electron-rich nature.

Heterogeneous catalysis currently stands as a foundational area in materials synthesis and applied chemistry. In this context, emphasizing the significance of heterogeneous catalysis in expediting chemical reactions and controlling the formation of desired products using porous materials represents an intriguing approach in the current technological landscape. This work delves into the synthesis and design of a variety of porous materials, encompassing microporous, mesoporous and macroporous materials (e.g. carbonaceous materials, metal oxides, MOFs, zeolites and functionalized analogues), alongside their properties and characteristics pivotal in heterogeneous catalysis. among others, and their subsequent modification, underscoring the significance of tailoring porous materials for specific catalytic applications.

A novel strategy to catalyze alkylation reactions through chalcogen bond interaction using a supramolecular structure is presented herein. Utilizing just 1.0 mol% of selenoxide-pillar[5]arene (P[5]SeO) as the catalyst we achieved efficient catalysis in the cyanation of benzyl bromide in water. Our approach demonstrated high efficiency and effectiveness, with the results supported by designed control experiments and theoretical models, highlighting the catalytic effect of the pillar[5]arene through noncovalent interactions. Quantum-chemical calculations (ωB97X-D/def2-TZVP@SMD) pointed out that the catalyzed cyanation reaction followed an SN2-like mechanism, with energy barriers (ΔH‡) ranging from 16.7 to 18.2 kcal mol-1, exhibiting dissociative character depending on the para-substituent. 1H NMR analysis revealed that P[5]SeO acted as a catalyst through inclusion complex formation, facilitating the transfer of the electrophilic substrate to the aqueous solution for nucleophilic displacement. Our reaction protocol proved applicable to various substrates, including aromatic and alpha-carbonyl derivatives. The use of sodium azide as the nucleophile was also feasible. Importantly, our method allowed scalability, and the catalyst P[5]SeO could be recovered and reused effectively for multiple reaction cycles, showcasing sustainability.

The time-dependent mechanism underlying the formation of Co0.8Fe0.2(OH)x-t nanomesh (nanomesh having 80% Co and 20% Fe, "t" represents materials synthesis time) has been identified towards the development of a highly effective catalyst for the OER. Utilizing 2-ethyl imidazole as an etching reagent and the Ostwald ripening process enabled the evolution of nanomesh formation with a precise pore size of inkbottle shape. Material characterization confirmed the evolution of pore structure from layered double hydroxide-like structure to hierarchical slit-pores to uniform ink-bottle pores after 24 h of synthesis with limited pore shrinkage attributable to iron redeposition at the pore entrances. AFM showed a gradual reduction in nanomesh thickness with an increase in synthesis time up to 24 h, indicative of successful exfoliation. The best catalyst (Co0.8Fe0.2(OH)x-24h) was developed after 24 h of synthesis, having 3.8 nm ink-bottle-shaped pores on the basal plane of nanosheets with only 3-4 layers. Co0.8Fe0.2(OH)x-24h exhibited the best catalytic performance, characterized by a 330 mV overpotential, a mass activity of 309.1 A/g, and a turnover frequency of 2.28 s-1. An increased electrochemical surface area (70.74 cm²) and a high roughness factor of approximately 1010 underlined the importance of narrow mesopores in facilitating catalyst-electrolyte interactions and improving mass transport.