Chemphyschem最新文献

This study presents a comprehensive computational investigation of the adsorption and sensing potential of pristine and doped B₁₂N₁₂ nanocages B₁₂N₁₂, AlB₁₁N₁₂, and B₁₂N₁₁P toward cyanogen bromide (BrCN), a highly toxic gas. Equilibrium structures of the BrCN complexes are optimized at the ωB97XD/6-31 G (d, p) level, and adsorption energies, thermodynamic parameters (ΔH, ΔG), and electronic descriptors are calculated. Interaction analyses are performed using atoms in molecules, reduced density gradient, molecular electrostatic potential, and electron localization function approaches. The effects of solvents, nonlinear optical properties, and UV–visible spectra are examined under neutral conditions and external static electric fields (SEF, z + 0.01 to z + 0.04 au). Results reveal that BrCN adsorption is strongest on AlB₁₁N₁₂, exhibiting favorable thermodynamics in both gas and aqueous phases, highlighting its potential for realistic sensing applications. While increasing SEF generally reduces adsorption energies, the pristine B₁₂N₁₂ complex shows an exception. Reactivity and conductivity analyses indicate a superior electronic response for AlB₁₁N₁₂, with noncovalent interactions, primarily van der Waals forces, governing the binding. Overall, AlB₁₁N₁₂ is identified as a promising candidate for the design of selective and sensitive BrCN gas sensors.

In this study, carbon dots (C-dots) were synthesized from resorcinol and trisodium phosphate in ethylene glycol using a microwave-assisted method. The C-dots exhibited predominantly green photoluminescence when excited at 460 nm. Their absorption and emission spectra showed strong solvent-dependent variations, and the quantum yield varied between 45% and 62% depending on the solvent. Both absorption and emission maxima exhibited a noticeable red shift with increasing solvent polarity. Upon varying the excitation wavelength from 300 to 480 nm, two distinct emission bands blue and green emerged. However, no continuous spectral shift was observed in any solvent. Excitation spectra recorded at different emission wavelengths also revealed two well-defined excitation peaks. The blue emission originates from π→π* transitions within the CC sp² domains at the core of the C-dots, whereas the green emission arises from surface states associated with phenolic –OH and phosphate functional groups. The absence of continuous spectral shift in emission suggests the absence of heterogeneity in CC sp² domains in the structure. The pH-dependent study revealed two emissive states: a dark state at acidic pH due to protonation of surface groups, and a highly emissive state at higher pH due to their deprotonation. Time-resolved photoluminescence showed specific solvent effects on the emission originating from core and surface of the C-dots. These findings establish that the green emission is strongly governed by the surface functional groups, while the core-related blue emission remains distinct.

Developing high-performing photocatalysts and composites generate synergetic effects in modern photocatalysis. Zinc oxide (ZnO) is a promising photocatalyst; however, its wide bandgap and high charge carrier recombination rate significantly limit its visible-light activity and overall photocatalytic efficiency. To overcome these challenges, this study focuses on the synthesis of Cu–Ag codoped ZnO/graphene nanocomposites using both hydrothermal and sonochemical methods, aiming to regulate the interfacial interaction and enhance charge separation. The hydrothermally synthesized (CAZ/Gr)_H composite exhibited a lower bandgap, improved carrier transfer efficiency, and stronger Zn–O–C interfacial bonding compared to the sonochemically prepared (CAZ/Gr)_S sample. Density functional theory (DFT) calculations confirmed the reduced work function and enhanced electron mobility in the hydrothermal system. Under natural sunlight, the (CAZ/Gr)_H composite demonstrated superior photocatalytic degradation of organic dyes and excellent antibacterial activity against E. coli and S. aureus. These findings highlight the effectiveness of interface-regulated, green-synthesized ZnO-based nanocomposites in addressing the fundamental limitations of traditional ZnO photocatalysts.

In molecular spintronics, achieving precise control over the spin polarization direction of transported electrons at the single-molecule level remains a great challenge. This study addresses this challenge by leveraging the unique electronic structure of bipolar magnetic molecules (BMMs). By performing density functional theory (DFT) calculations, we designed and screened a series of transition metal complexes, identifying Cr(II)(BBM)₂ (where BBM is the 2,2′-bibenzoimidazole anion) as a promising BMM candidate. Combining DFT with the non-equilibrium Green's function (NEGF) formalism, spin-polarized quantum transport calculations were carried out on a molecular junction where Cr(II)(BBM)₂ was coupled to graphite electrodes. Our results demonstrate that the application of an external gate voltage enables reversible switching of the spin transport direction. A gate voltage of −5 V yields a 100% spin-polarized current in the spin-up channel. Conversely, a small positive gate voltage of +0.05 V results in a completely polarized spin-down current. This gate-controlled spin channel switching, achieved through rational molecular design, underscores the potential of BMMs as fundamental components for future ultra-dense, low-power spintronic devices.

Machine learning (ML)-enabled high-throughput screening to predict potential electrocatalysts for the CO₂ reduction reaction (CO₂RR) offers new insights for energy conversion and environmental remediation. In this work, for the first time, we established a comprehensive electrocatalytic database containing ≈400 entries of CO₂RR catalysts. Through decision tree analysis, correlation heatmaps, and feature importance ranking, we systematically decoded structure-property relationships. Among the tested algorithms, the nonlinear tree-ensemble method Random Forest Regression demonstrated superior predictive performance for CO₂RR systems. Subsequent screening of 500 000 catalyst configurations generated by the the sequential model-based algorithm configuration method, using Expected Improvement as the evaluation metric, identified promising multinary alloy catalysts for C1 molecule production. Notably, BiSb-based alloys emerged as high-potential candidates for CO₂RR applications. This ML-driven paradigm highlights the growing significance of artificial intelligence in materials discovery, synergistically combining screening efficiency, prediction accuracy, and proficiency in big data processing.

The TaN_n⁺ cationic clusters were generated via laser ablation and analyzed using time-of-flight (TOF) mass spectrometry. The mass spectrometry experiment identified the TaN₁₂⁺ cluster as the dominant TaN compound, exhibiting the most intense peak. Photodissociation experiments on the TaN₁₂⁺ clusters with 266 nm (4.66 eV) photons revealed that the photodissociation fragment ion TaN₄⁺ was dominant in the spectrum. Density functional theory calculations revealed that TaN₁₂⁺ has an octahedral D_4h geometry symmetry with six N₂ ligands. The cluster features two distinct TaN bond lengths of 2.16 and 2.22 Å. Orbital analysis uncovers the origin of this asymmetry: the four coplanar N₂ ligands are strongly σ-bound and activated, whereas the two axial ones engage via weaker π-interactions. Photodissociation pathway analysis established a reversible relationship between TaN_2n⁺ (n = 1 − 6) clusters growth-dissociation processes. Quantitative Hirshfeld charge and charge transfer analyses confirm Ta as a Lewis acid center with N₂ ligands functioning as Lewis bases. The spin-density population indicates the presence of antiparallel coupling within the TaN₁₂⁺ cluster, leading to ferrimagnetism. Interaction region indicator analysis confirms the presence of well-defined coordination bonds between the Ta atom and its ligands.

This study investigates the Bi(III) ions electroreduction in aqueous chlorate(VII) and aqueous-ethanolic chlorate(VII)-supporting electrolytes (SE) in the presence of the anionic surfactant sodium 1-octanesulfonate (1OSASS) over a range of temperatures. Electrochemical techniques, including direct current (DC) polarography, cyclic voltammetry (CV), and square-wave voltammetry (SWV), were used to evaluate both kinetic and thermodynamic parameters. Increasing ethanol concentration led to a decrease in the standard heterogeneous electron transfer rate constant (k_s), despite an increase in the diffusion coefficient of the oxidised species (D_ox). Rising temperature and surfactant concentration caused a shift in the formal potential (E_f⁰) and an increase in redox peak separation (ΔE), indicating reduced process reversibility. Activation parameters, including activation energy (E_a), enthalpy (ΔH⁰), entropy (ΔS⁰), and Gibbs free energy (ΔG⁰), were determined using the Arrhenius and Eyring equations. The results confirm that 1OSASS exhibits a ‘cap-pair’ effect, likely due to competitive adsorption and complexation, significantly affecting redox kinetics. Overall, the study highlights the complex influence of the solvent–surfactant system on the structure of the electrical double layer (EDL) and on the kinetics and mechanism of the Bi(III) ions electroreduction process.

The N-terminal domain of the Drosophila melanogaster Escargot transcription factor (Esg) is an intrinsically disordered region (IDR) that complements the DNA-binding activity of its C-terminal zinc fingers. Within this IDR, the S2 segment (residues 120–152) is predicted to form an α-helical molecular recognition feature, a transient structural element implicated in protein–protein interactions. We examined the conformational equilibrium of the S2 peptide in water and in helix-promoting 2,2,2-trifluoroethanol (TFE)/water solutions using replica exchange with solute tempering 2 (REST2) simulations and circular dichroism measurements. We show that the peptide can display substantial ellipticity, with TFE nearly doubling the helix population at 40% v/v compared to pure water. Minimum-distance distribution functions and the Kirkwood–Buff theory of solvation show that TFE preferentially accumulates on the peptide domain. This effect primarily arises from nonspecific contacts between TFE and uncharged polar and nonpolar side chains of the peptide. These findings support the view that the S2 region's structural plasticity is critical for modulating the function of Esg and provide further insights into TFE-induced helix stabilization.

The function and properties of a transmembrane (TM) protein depend on the membrane composition. Consequently, the membrane adaptation to the inserted protein can also be influenced by the said membrane composition. This work examines the impact of cholesterol (Chol) composition on the Gramicidin A (gA)-induced membrane curvature and order parameter (|S_CD|) of the lipids present in the membrane. The magnitude of the curvature was found to be dependent on the Chol concentration present in the membrane leaflet and resulted in countering the hydrophobic mismatch at the gA-membrane interface. Additionally, a minor reduction of the number of water molecules present in the channel and the formation of the previously proposed gA–Chol complex were noted. Using a four-region annular model, it was demonstrated that the bilayer thickness and |S_CD| around the gA were affected by the Chol concentration in a distance-dependent manner. The paralipidome was enhanced in Chol and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids, which may have resulted in the reduction of energy cost associated with forming the gA conduction channel and removing the hydrophobic mismatch between the membrane and the gA dimer. This work will help better understand the role of Chol in the membrane adaptation in the presence of TM proteins.

Nonplanar hydrocarbon structures, such as corannulene and sumanene, are of particular interest due to their bowl-shaped structures. These molecules can be conceptualized as truncated versions of a bucky-ball C₆₀, where the curvature is reduced and the boundary is hydrogenated. The ability to catalyze the inversion of these bowl-shaped structures using 2D materials like graphene has stimulated significant research into the interaction of these structures with graphene and the catalytic effect of graphene, reducing the energy barrier for bowl-to-bowl inversion. While it has been observed in simulations that the interaction with nonplanar structures can generate a dimple-shaped deformation in graphene sheet, no mathematical model has been formulated to determine such deformation profile. As such, this article proposes a model based on calculus of variational approach to study a dimple-shaped deformation in the graphene sheet induced by fullerenes and bowl-shaped structures. The dimple shapes are shown to depend on the orientations and configurations of fullerene, corannulene, and sumanene when facing graphene sheet. The results indicate that fullerene produces the deepest dimple profile in graphene, followed by corannulene and sumanene, respectively. These results are also consistent with findings found using density functional theory.