Journal of Chemical Sciences最新文献

A comparative analysis between the procedure originally followed to establish the local hardness concept and a recent one based on a local chemical potential, defined within the grand canonical ensemble formalism, is done to get a better understanding of the main aspects involved in both procedures and to show that the local and non-local counterparts of global reactivity descriptors recently developed, constitute an excellent complement to analyze chemical reactivity within the framework of conceptual density functional theory.

Graphical abstract

A comparative analysis between the procedure originally followed to establish the local hardness and the hardness kernel concepts and a recent one based on a local chemical potential, defined within the grand canonical ensemble formalism, is done. The original local softness and softness kernel remain unchanged.

This work emphasizes the potential of (benzo)chalcogenadiazole in recognizing anions via chalcogen bonding as a key interaction. We employed various theoretical tools to analyse the binding affinity and selectivity of substituted (benzo)thiadiazole for fluoride. The molecular electrostatic potential surface provided qualitative insights into the influence of substituents on electronic properties and the (sigma ) hole of the sulfur atom in directing the interaction strength with the anionic counterpart. Quantitative evaluations using symmetry-adapted perturbation theory, natural bond orbital analysis and topological descriptors at bond critical points confirmed the interaction mechanisms. Notably, the study revealed that the S···F^- bond strength was moderately enhanced for bis(trifluoromethyl)thiadiazole compared to tetrafluorobenzothiadiazole. Finally, the significant S···F^- bond was found to exhibit a partial covalent character, which has important implications for the design of novel chalcogenadiazole-derived anion receptors and sensors, contributing to the advancement of anion recognition.

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Anionic redox chemistry has emerged as a promising strategy to enhance the capacity of sodium-ion battery (SIB) cathode materials by leveraging both cationic and anionic redox processes. While anionic redox offers the potential for higher capacities, its practical implementation is often limited by challenges such as irreversibility, molecular oxygen release, and structural degradation at elevated voltages. In this study, we examine a series of hypothetical prototype cathode materials such as NaAlO₂, Na₂TiO₃, Na₂NiO₃, and Na₂MnO₃, using a funnel-based screening approach. Machine learning interatomic potentials are employed to efficiently pre-screen a wide range of structures with different vacancy orderings, enabling the identification of low-energy configurations. These candidate structures are subsequently refined through first-principles calculations based on density functional theory (DFT). To probe the underlying anionic redox mechanisms, we apply both the PBE and SCAN meta-GGA functionals, capturing the behaviour in iono-covalent and strongly covalent Na-ion systems. We define and evaluate key descriptors to quantitatively characterize oxygen redox activity, including changes in the occupancy of metal-d and oxygen-p orbitals, the number of holes generated in these states, and shifts in average net atomic charges. Additionally, we calculate the electronic structure, integrated Crystal Orbital Hamilton Population (COHP) and average operating voltage, using the SCAN functional. This comprehensive investigation offers valuable insights into tuning metal-oxygen bonding to achieve reversible anionic redox, facilitating the rational design of next-generation, high-capacity sodium-ion cathodes.

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An efficient and environmentally benign cyclocondensation of anthranilamide, aldehyde, and Anderson-type hexamolybdochromate (III) is described for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones analog (DHQs) through a one-pot two-component reaction at room temperature. This method offers mild reaction conditions, simple purification without column chromatography, and moderate to good yields for constructing 2-substituted-2,3-dihydroquinazolin-4(1H)-one derivative. Various spectroscopic investigations are used to establish the structures of the target molecules.

Graphical abstract

The present work reports the environmentally benign synthesis of 2-substituted-2,3-dihydroquinazolin-4(1H)-one analogs (2,3-DHQs) via the cyclocondenzation of 2-aminobenzamide and aldehydes at room temperature in an aqueous medium, using sodium hexamolybdochromate (III) as a catalyst. This methodology is efficient and simple, providing better product yield and reduced reaction time.

Halide double perovskites have been considered as the most competitive alternative of lead-based perovskite for various optoelectronic applications. With the aim of understanding the intricacies of electronic diversity in halide double perovskites, this work reports a comparative theoretical investigation of Cs₂NaEuCl₆ and Cs₂NaBiCl₆ using Density Functional Theory with the PBE and HSE06 functionals. In electronic structure, the distribution of states on the energy scale is found to vary with the functional, and the extent of variance is greater for Cs₂NaEuCl₆. In the case of Cs₂NaEuCl₆, Eu-4f states emerge as isolated states within the mid gap region, and the extent of isolation was found to be greater for the HSE06 functional. In contrast, Bi-6p states in Cs₂NaBiCl₆ have been found to significantly mingle with anion states. The isolation and mingling of Eu's and Bi's valence electrons, respectively, in the two HDPs, have been confirmed by B3LYP calculation on the corresponding molecular analogue under the LCAO-MO approach. Since the facets of perovskite are important for its chemical reactivity, the electron localization function has been plotted along the [010], [110] and [111] directions and a greater extent of localization of electrons around the anion is observed for Cs₂NaEuCl₆ in contrast to Cs₂NaBiCl_6.

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The transport of water at the nanoscale is fundamental to advancements in nanofluidics, membrane technology, and biological systems. While numerous studies have investigated the one-dimensional diffusion of water in carbon nanotubes (CNTs), its viscosity remains underreported. Experimental measurements of viscosity at this scale are challenging, but molecular dynamics simulations offer a viable alternative for predicting the viscosity of cylindrically confined water. Various methods have been employed for this purpose; however, their limitations raise questions about the accuracy of the predicted values. Our group has developed a novel approach, the Jump-corrected confined Stokes–Einstein (JCSE) method, based on the confined Stokes–Einstein equation, to estimate the viscosity of water within cylindrical nanopores. This technique is particularly promising because it accounts for the breakdown of the Stokes–Einstein relation in both confined and supercooled water, enhancing the reliability of viscosity predictions. In this short perspective, we introduce the JC-CSE method and its application to supercooled water confined in hydrophobic and superhydrophobic CNTs. Additionally, we rationalize viscosity trends using hydrogen-bond analysis. Finally, we provide a brief outlook on the broader applicability of this method to other confined liquids.

Graphical abstract

This figure illustrates approaches to determining the viscosity under confinement. Traditional Green–Kubo relations are often inadequate, while the confined Stokes–Einstein relation offers alternatives. The Jump-corrected Confined Stokes–Einstein (JCSE) equation introduces corrections for molecular jumps and confinement effects, relating viscosity to diffusion, temperature, and confinement length scale, improving accuracy in nanoscale systems.