Chemistry - An Asian Journal最新文献

π-Electronic systems form various assemblies through noncovalent interactions and exhibit unique electronic and photophysical properties that arise from π-electronic states and molecular arrangements. Introducing charge into these π-electronic systems generates charged species capable of forming ion-pairing assemblies via ⁱπ–ⁱπ interactions, primarily governed by electrostatic and dispersion forces, resulting in novel functionalities derived from charged species. Typically, π-electronic ion pairs tend to form charge-by-charge assemblies, in which cations and anions alternately stack via electrostatic attractive forces. In contrast, forming charge-segregated assemblies that can exhibit semiconducting properties is challenging because a stacked arrangement of identically charged species is required to form columnar structures. Therefore, strategies to overcome electrostatic repulsion are highly desirable for the formation of such assemblies. Recent advances in molecular design have enabled the stacking of identically charged species by controlling assembly through charge delocalization, extending π-frameworks, and precise tuning of noncovalent interactions. This review summarizes recent progress in the design principles of charged π-electronic systems for charge-segregated assemblies and showcases their potential in modulating electronic, photophysical, and electric conductive properties.

Herein, a transfer hydrogenation of in situ generated imine intermediates from readily available isatin-hydrazones with 1,4-benzoquinones or aldehydes by Brønsted acid catalysis was established. This efficient, mild ambient, operationally simple and safe approach afforded stereospecific functionalized isatin-3-arylhydrazones and isatin-3-alkylhydrazones in excellent yields (up to 95%).

N-doped multi-shelled Ru-Co/Co₃O₄ graphene-coated nanospheres were synthesized from metal-organic frameworks (MOFs) using a hydrothermal method. The annealing process, conducted at temperatures of 250°C, 310°C, 380°C, 450°C, and 530°C with a heating rate of 2°C min⁻¹ in the presence of melamine under a nitrogen atmosphere, led to the formation of multi-shelled nanospheres. The annealing temperature played a crucial role in controlling the number of shells within the nanospheres and enhancing nitrogen incorporation into their structure. This study demonstrated that annealing at 530°C resulted in the formation of quintuple-shelled nanospheres with the highest nitrogen incorporation. The number of shells and nitrogen content emerged as key factors influencing the electrocatalytic performance of these materials in water splitting. The quintuple-shelled nanospheres demonstrated remarkable electrocatalytic efficiency, delivering the maximum current density with minimal overpotential for both hydrogen and oxygen evolution reactions (HER and OER) under acidic conditions. Conversely, reducing the number of shells led to a progressive decrease in the overall electrocatalytic performance.

A method for Ni-catalyzed coupling of thiophenols and thiols with aryl bromides is described. The reactions proceed under mild, base-free conditions and accommodate the coupling of tertiary alkyl thiols, aryl thiols, and cysteine derivatives with aryl electrophiles, yielding alkyl-aryl and diaryl thioethers in moderate to high yields.

Extensive molecular dynamics simulations were performed to investigate the structure, solvation, and transport behavior of LiTFSI in solvents; 1,3-dioxolane (DIO) and dimethyl-sulfoxide (DMS) in pure form and their binary mixtures with ethylene carbonate (EC) in the presence/absence of boron-based additives, B[C₂HBNS(NO₂)₂]₃ (CBSt) and boronic acid (BOH). In DIO-based electrolytes, although significant ion pairing is observed between Li⁺ and TFSI⁻, introduction of EC weakens these interactions, and further addition of CBSt disrupts Li⁺–TFSI⁻ coordination, indicating enhanced ion dissociation. Li⁺ shows well-defined solvation shells dominated by DIO, with EC playing a secondary role. In contrast, DMS-based electrolytes inherently exhibit weaker Li⁺–TFSI⁻ interactions, characterized by broader g(r) peaks, which promotes ion mobility. CBSt again mitigates the ion pairing effect. Interaction energy analysis confirms that Li⁺–TFSI⁻ pairing is strongest in pure DIO and weakest in DMS, with the inclusion of CBSt decreasing the interaction energy effectively. A similar trend in the solvation of Li⁺ was observed for DMS-based electrolytes. Interestingly, while DIO-based electrolytes were less effective in reducing ion-pair formation, the cation transport numbers were significantly good. In contrast, DMS-based electrolytes, in the presence of boron-based additives, improve cation transport and effectively decrease ion pairing, especially in the presence of EC and/or CBSt in the solution.

The enantiodivergent synthesis of R- and S-configured tetrahydroquinoxaline derivatives holds significant importance in pharmaceutical and bioorganic chemistry. In this work, we achieved precise control over the R/S selectivity in the ruthenium-catalyzed asymmetric hydrogenation of 2-alkyl-substituted quinoxalines by modulating the catalyst counteranion. Specifically, a chiral diamine–ruthenium complex bearing a BArF counteranion afforded the R-configured product. Remarkably, the product chirality was readily inverted by switching to racemic phosphate counteranion. Density functional theory (DFT) calculations identified various weak non-covalent interactions (such as CH/π and hydrogen bonding) between the counteranion, catalyst, and substrate, revealing the fundamental mechanism of enantioselectivity inversion.