Search Results (925)

Doping provides an effective means to tailor the chemical properties of clusters and construct novel functional materials. However, the specific effects of rare-earth doping on the structural evolution and electronic properties of semiconductor clusters remain unclear. To address this, we systematically investigated the structures, growth patterns, electronic properties, and spectroscopic characteristics of Ge_n⁻ and LaGe_n^0/− clusters (n = 10–20) using the ABCluster global search method combined with the mPW2PLYP double-hybrid density functional. Notably, the global minimum (GM) structures of Ge_n⁻ (n = 12–20), confirmed based on calculated energies and measured photoelectron spectroscopy data, differ from previously reported structures. Starting from n = 12, the GM structure of the Ge_n⁻ cluster can be considered as formed by attaching an additional Ge_(n–9) or Ge_(n–10) subcluster to a capped tetragonal antiprism Ge₉ (or dicapped tetragonal antiprism Ge₁₀) subunit. The evolution pattern of LaGe_n (n = 10–19) clusters can be viewed as substitutional structures, in which a La atom substitutes one Ge atom in the Ge_(n+1)⁻ cluster. At n = 20, a cage-like structure is formed. For LaGe_n⁻ (n = 10–19), when n = 10–12 and 18, the structures are linked configurations, where the La atom connects two Ge subclusters. For the remaining clusters, although their global minimum structures tend toward linked configurations, they are fundamentally substitutional in nature. The GM structure of LaGe₂₀⁻ is an encapsulated configuration, with the La atom encapsulated at the center of the Ge cage. The average binding energies, relative stabilities, and HOMO–LUMO energy gaps of the clusters were evaluated. The photoelectron spectra of LaGe_n⁻ (n = 10–20) and the UV–vis absorption spectrum of the LaGe₂₀⁻ cluster were simulated. The results demonstrate that the LaGe₂₀⁻ superatom cluster with high Ih symmetry exhibits favorable optical properties, along with excellent chemical and thermodynamic stability, suggesting its potential as a promising building block for further exploration in optoelectronic-related applications. Full article

Phenolic acids exhibit structure-dependent vibrational responses governed by aromatic substitution, π-conjugation, oxygenated functional groups, and molecular environment. In this work, p-coumaric, caffeic, trans-ferulic, and gallic acids were investigated through an integrated experimental Raman, density functional theory (DFT), and chemometric approach to establish molecular relationships between hydroxylation, methoxylation, conjugation, and Raman spectral behavior. Raman spectra were recorded in the solid state and in an ethanol/water (1:1, v/v) mixture. At the same time, DFT calculations were used to optimize the molecular structures, simulate Raman spectra, assign vibrational modes, and evaluate molecular electrostatic potential, frontier orbitals, electronic descriptors, and localized orbital locator maps. The solid-state Raman spectra provided the most resolved molecular fingerprints, with hydroxycinnamic acids exhibiting intense bands corresponding to aromatic and conjugated ν(C=C) modes. In contrast, gallic acid displayed a distinct hydroxybenzoic vibrational pattern dominated by phenolic C–O/O–H and carboxylic contributions. DFT-assisted assignments confirmed that the main spectral differences arise from coupled vibrations involving ν(C=C), ν(C=O), ν(C–O), δ(O–H), aromatic ring deformations, and methoxy-related modes. Molecular electrostatic potential (MEP) and localized orbital locator (LOL) analyses showed that oxygen-centered regions are the most electrostatically and electronically localized sites, thereby explaining the sensitivity of C–O, O–H, and C=O bands to solvent-mediated interactions. HOMO–LUMO analysis revealed extended frontier-orbital delocalization in hydroxycinnamic acids, in contrast to the more localized hydroxybenzoic electronic structure of gallic acid. Principal component analysis confirmed that solid-state Raman spectra provide stronger chemometric discrimination than solution spectra, with PC1 and PC2 explaining 79.0% of the total variance in the solid-state dataset. Overall, the results show that specific functional groups define the principal vibrational domains of the studied phenolic acids. In contrast, the exact band positions, relative intensities, and coupling patterns are additionally modulated by aromatic substitution, π-conjugation, electronic distribution, physical state, and molecular environment. Within the limitations of a single-conformer isolated-molecule model, the combined Raman–DFT–chemometric approach provides a comparative interpretation of the vibrational fingerprints of the four selected compounds. Full article

Contact electrification (CE), also referred to as triboelectrification, describes electron transfer occurring at the interface of dissimilar materials. Its microscopic mechanism remains unclarified due to the complex coupling of multiple physical fields, yet the rapid development of triboelectric nanogenerators (TENGs) has rendered CE a prominent research hotspot in tribology on account of its promising application prospects. Metal/polymer combinations have been widely employed for CE research due to their significant differences in electron gain and loss. Nevertheless, most existing studies focus solely on saturated polymers, and systematic comparative analyses between saturated and unsaturated molecular structures are rarely reported. Accordingly, the intrinsic microscopic origin of enhanced interfacial electrification performance induced by unsaturated groups has not been fully understood. In this work, first-principles calculations based on density functional theory (DFT) are implemented to establish interfacial models consisting of an Al substrate and three types of PTFE single chains: fully saturated-PTFE, PTFE with unsaturated bonds at the chain terminus, and PTFE with unsaturated bonds in the middle of the chain. The inherent mechanism governing the modulation of CE behaviors by unsaturated structures are comprehensively revealed from multiple perspectives, including charge transfer, electrostatic potential, and frontier orbital distribution. Computational results demonstrate that unsaturated groups drastically elevate local electrostatic potential and strengthen the electron-trapping capability of molecular chains, thereby substantially boosting CE performance. Moreover, this modulation effect exhibits remarkable position dependence, where unsaturated structures located in the middle of molecular chains deliver better performance improvement than terminal unsaturated moieties. The electron-donating and electron-accepting properties of materials are dominated by the energy level characteristics of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), respectively. This study elucidates the microscopic mechanism of CE at unsaturated polymer/metal interfaces at the molecular scale, and provides theoretical support for optimizing the output performance of TENGs through surface modification strategies. Full article

Silicone gel (SG) is an important soft encapsulation dielectric for high-voltage power modules, yet its limited insulation performance under high electric fields and elevated temperatures restricts its practical application. Herein, an ultralow loading of the organic molecular semiconductor anthrone (ET) was introduced into silicone gel to simultaneously improve dielectric properties and thermal stability. SG-ET_0.5 exhibited the best overall performance, with a breakdown strength of 29.14 kV/mm at 25 °C, 19.57% higher than that of pristine SG, and retained 22.86 kV/mm at 150 °C with only a 21.56% reduction. The relative permittivity increased to 3.16 and 2.85 at 25 °C and 200 °C, respectively. The partial discharge inception voltage increased from 3.1 to 4.8 kV, while both discharge frequency and amplitude were markedly reduced. Moreover, SG-ET_0.5 showed an increased 5% weight-loss temperature of 370 °C, together with slightly increased thermal conductivity and a reduced coefficient of thermal expansion. Mechanistic analysis suggests that the low-lying LUMO level and molecular characteristics of ET may contribute to the increased deep-trap density and enhanced electron-capturing tendency of the composites, thereby helping to suppress electron avalanche development and partial discharge. This work offers a molecular-level strategy for improving the electrical insulation performance of silicone gel dielectrics for high-voltage power modules. Full article

Three new isomeric pyridone fluorenone hydrazone-based boron complexes, 3-BrN to 5-BrN, with bromination at the 3-, 4-, or 5-position of the pyridone ring and their corresponding σ-platinum complexes trans-Pt(PEt₃)₂(n-N)X (n = 3, 4, or 5; X = Cl, Br, I) resulting from oxidative addition of the aryl-Br bond of n-BrN to Pt(PEt₃)₂ and, for X = Cl, I, subsequent substitution of the halogenide ligand, were synthesized and characterized by NMR, UV–Vis absorption, and photoluminescence spectroscopy. The molecular structures of dyes 3-BrN to 5-BrN and of seven complexes, including the cis-isomer of the bromo complex resulting from 3-BrN, were established by single X-ray diffraction. The nearly orthogonal orientation of the Pt coordination plane with respect to the plane of the dye ligand limits intermolecular π-stacking interactions in the crystalline state while giving rise to extensive C-H···halogen and C-H···π interactions, resulting in intricate packing patterns. Electronic absorption spectra of dyes 3-BrN to 5-BrN show a prominent HOMO-LUMO absorption band at ca. 520 nm, which is red-shifted and intensifies on platination. All compounds are dual fluorescence and phosphorescence emitters in the range of 520 to 670 nm, or at ca. 1000 nm, both at room temperature and at 77 K. The population of an excited triplet state and their photostability even towards continuous light irradiation renders these compounds efficient sensitizers for singlet oxygen generation and catalysts for the photo-oxidation of triphenylphosphine. Full article

Polyoxometalates (POMs) are anionic metal oxide nanoclusters with rich redox chemistry, making them promising candidates for photocatalysis. However, their strong UV-light absorption and rapid charge recombination hinder visible-light applications. This review focuses on covalent organic–inorganic hybridization as a modular strategy to engineer POMs for visible-light photoactivation. By grafting chromophoric ligands, metalloporphyrins, or organometallic complexes onto POM surfaces via robust covalent bonds (e.g., Si–C, P–C, C–C), two key photochemical pathways are enabled: (i) direct visible-light excitation of organic sensitizers followed by intramolecular charge transfer to/from POMs and (ii) modified ligand-to-metal charge transfer (LMCT) transitions in POMs via ligand-induced electronic structure perturbation. We discuss how organic ligands regulate POM frontier orbital energy levels (HOMO/LUMO), redox potentials, and photoresponse range, supported by experimental and density-functional theory (DFT) studies. We also review hybrid systems with organic photosensitizers (e.g., pyrene, boron dipyrromethene (BODIPY)), metalloporphyrins, and organometallic complexes (e.g., Ru(II), Ir(III)), emphasizing structure–activity relationships in electron-transfer efficiency, charge-separation lifetime, and catalytic performance (e.g., hydrogen evolution, selective oxidation). Finally, we outline current challenges and prospects for designing multifunctional POM hybrids with tailored visible-light photocatalytic properties. Full article

With the rapid advancement of the IoT society and growing awareness of environmental issues, thermoelectric conversion technology—which directly converts waste heat into electricity—is gaining attention as a self-powered, autonomous power source capable of driving countless devices. While currently mainstream metal-based inorganic thermoelectric materials demonstrate high performance, their high rigidity and brittleness, as well as their frequent inclusion of toxic heavy metals, have limited their application in biological systems and on curved surfaces. As a next-generation alternative, single-walled carbon nanotubes (SWCNTs)—which possess excellent flexibility, electrical conductivity, and mechanical strength while being low in toxicity—are garnering significant attention. However, n-type SWCNT materials, which are essential for thermoelectric module fabrication, have faced two major barriers to practical application: low atmospheric stability (they easily revert to p-type upon exposure to atmospheric oxygen and moisture) and thermoelectric performance that falls short of inorganic materials. This review comprehensively outlines the latest composite approaches designed to overcome these critical challenges and achieve both extreme atmospheric stability and high thermoelectric performance in n-type SWCNT materials, along with the flexibility required to withstand severe deformation. Three main strategies are discussed. The first is the organic/polymer approach, which involves doping with organic small molecules that control the LUMO level or bicyclic organic superbases with strong electron-donating properties, as well as polymer coating, to achieve long-term stable n-type characteristics and high power output even in air or under severe high-temperature conditions. The second is the inorganic hybrid strategy, which involves nanoscale compositing with inorganic materials such as Bi₂Te₃ and Cu₂O; this reduces thermal conductivity through phonon scattering via interface control, while the inorganic layer physically blocks oxygen to ensure long-term atmospheric stability. The third approach involves ultra-long-term stabilization techniques, such as bulk encapsulation using cationic or gemini surfactants, and environmentally friendly aqueous processes utilizing natural amino acids. Furthermore, we discuss the latest developments in imparting practical-level toughness (flexibility) capable of withstanding thousands of bending cycles and high tensile stress through the introduction of dynamic covalent network polymers and elastomers. The conformal flexible thermoelectric power generation modules created through the integration of composite optimization, low-environmental-impact processes, and doping techniques will serve as a crucial foundational technology for realizing a sustainable next-generation electronics society, including future wearable devices, artificial skin, and smart sensor networks. Full article

Density Functional Theory (DFT) calculations were applied at the B3LYP/6-311G+(d,p) level to examine how nitrogen (N) and boron (B) and combined nitrogen/boron doping (N/B) affected the electronic properties and chemical behavior of graphene oxide (GrO). The work aimed to measure how global reactivity descriptors, including ionization potential, chemical hardness, and electrophilicity, changed when dopants entered the system while evaluating their prediction accuracy for gas sensing performance against NH₃ and H₂O and CO₂. The results show that undoped GrO exhibits a HOMO/LUMO gap value of 2.9059 eV while the introduction of dopants increases reactivity through gap reduction because N-doping decreased the gap to 1.3622 eV, B-doping reduced it to 1.3388 eV, and co-doping (GrO-NB) led to a gap of 1.9897 eV. The TDM analysis and the gas interaction energy gap results show that GrO-NB-H₂O exhibits the strongest interaction which results in chemical reactivity through its lowest ΔE of 1.9565 eV, establishing itself as a highly sensitive water vapor sensor when compared with NH₃ and CO₂. With adsorption energies of −0.1986, −0.1742, and −0.0735 eV for NH₃, H₂O, and CO₂, respectively, the N/B co-doped graphene oxide demonstrated favorable and reversible physisorption, underscoring its potential for gas sensing applications. The results offer an essential understanding of how N/B co-doping influences the electronic and adsorption characteristics of graphene oxide, thereby supporting its potential use in graphene-based sensing technologies. Full article

The development of multi-targeted therapeutic agents is increasingly recognized as essential for treating multifactorial diseases. Butyrolactone I and butyrolactone III, γ-butyrolactone derivatives isolated from the marine fungus Aspergillus terreus, represent structurally related natural products with largely unexplored polypharmacological potential. This study employed a comprehensive in silico approach combining ADMET profiling, quantum chemical calculations, molecular docking, and molecular dynamics simulations to evaluate their therapeutic potential across multiple pharmacological targets. Physicochemical analysis revealed favorable drug-like properties for both compounds, with complete compliance with Lipinski’s Rule of Five, high predicted gastrointestinal absorption (>80%), and acceptable toxicity profiles (toxicity class 4, LD₅₀ = 2000 mg/kg). Neither compound showed hepatotoxic, neurotoxic, cardiotoxic, carcinogenic, or mutagenic liabilities. Frontier molecular orbital analysis (DFT/B3LYP/6-31G(d,p)) revealed comparable HOMO energies (−6.054 and −6.059 eV), with butyrolactone III exhibiting enhanced kinetic stability based on a larger HOMO–LUMO gap (4.662 eV vs. 4.443 eV) and higher chemical hardness (η = 2.331 eV vs. 2.222 eV). Molecular docking against four therapeutic targets revealed target-selective binding profiles: butyrolactone III demonstrated binding affinity toward acetylcholinesterase exceeding donepezil (−9.0 vs. −8.3 kcal/mol), while butyrolactone I exhibited MDM2 binding affinity slightly exceeding nutlin-3a (−7.8 kcal/mol). Both compounds showed moderate interactions with COX-2 and topoisomerase IV. Molecular dynamics simulations validated the stability of AChE complexes (RMSD < 2.0 Å) and the MDM2–butyrolactone I complex (RMSD: 0.69 ± 0.09 Å), while the MDM2–butyrolactone III complex exhibited significant instability (RMSD up to 3.55 Å), highlighting the critical role of the prenyl group in MDM2 recognition. These findings, consistent with, though not a direct experimental validation of, previously published in vitro data, support the evaluation of butyrolactone III as a scaffold for neuroprotective agents and butyrolactone I as a p53 pathway modulator for cancer therapy, illustrating the potential value of fungal metabolites in multi-target drug discovery and the role of integrated computational approaches in prioritizing candidates for subsequent experimental testing. Full article

This study explores the surface interaction mechanism of phytic acid (PA) on Fe, Cu, and Al metals and its applicability in green anticorrosion surface treatment through a combination of quantum chemical calculations, molecular dynamics (MD) simulations, and electrochemical measurements. Quantum chemical calculations identified the nucleophilic/electrophilic active sites of PA via HOMO-LUMO and Fukui functions. MD simulations then constructed solution-metal interface models, calculating adsorption energies, radial distribution functions, and the diffusion behavior of H₂O and Cl⁻ to elucidate PA’s adsorption configurations and its inhibition of corrosive species diffusion. Based on these theoretical insights, PA conversion coatings were in situ constructed on Fe, Cu, and Al substrates. Potentiodynamic polarization tests confirmed that these coatings effectively enhanced the corrosion resistance of the metals in a 3.5 wt% NaCl solution, achieving inhibition efficiencies of 92% for Fe, 86.5% for Al, and 26% for Cu. This work provides a comprehensive mechanistic interpretation from molecular adsorption to surface film formation, offering theoretical and experimental support for PA—based green surface treatment technologies. Full article

Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the two main neurodegenerative diseases and cause disability and death in patients worldwide. Neurodegeneration is characterized by a progressive loss of neuronal function and structure, causing enormous impairment in cognitive–motor function. Magnolol and honokiol are isomeric biphenyl neolignans and have exhibited neuroprotective activity in previous studies. Hence, we assessed and compared honokiol, magnolol, and mixtures of honokiol and magnolol in honokiol/magnolol molar ratios of 1:3, 1:1, and 3:1 in terms of their neurotoxicity, using the cell counting kit-8 (CCK-8) assay, and of their neuroprotective effect on intracellular reactive oxygen species (iROS) against amyloid-beta (Aβ)- and 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced neurotoxicity in SH-SY5Y cells, using the 2′,7′-dichlorodihydrofluorescein diacetate (H₂DCF-DA) assay. The results showed that honokiol (H) and magnolol (M) at 0.1 μM and the mixtures of honokiol and magnolol in H/M ratios of 1:3, 1:1, and 3:1 at 0.0001 μM exhibited a significant neuroprotective effect of reducing iROS in SH-SY5Y cells where neurotoxicity was induced by Aβ- and MPP⁺ (p-value with respect to Aβ-treated cells < 0.005 and p-value with respect to MPP⁺-treated cells < 0.0001). Moreover, magnolol and honokiol possess antioxidant properties according to computational molecular analysis with Highest Occupied Molecular Orbital (HOMO)- Lowest Unoccupied Molecular Orbital (LUMO) prediction, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Ferric Reducing Antioxidant Power (FRAP) assays. The mixtures of honokiol and magnolol exerted synergistic neuroprotective ability at all ratios while showing better antioxidation ability than that of pure magnolol alone but comparable to that of pure honokiol alone. Drug-likeness, Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) prediction, and toxicity profiles showed that both compounds are promising neuroprotective agents and that one of the possible targeting mechanisms is the ROS-mediated oxidative stress pathway. Additional neuronal cell lines and in vivo models are required to determine similar effects or other protective mechanisms involving the neuroprotective ability of honokiol and magnolol. Full article

NAD⁺ depletion is a defining feature of the aging cell, driven by a progressive decline in nicotinamide phosphoribosyltransferase (NAMPT) activity, the rate-limiting enzyme of the NAD⁺ salvage pathway. Pyrroloquinoline quinone (PQQ), a plant-derived redox-active quinone cofactor, elevates intracellular NAD⁺ by a mechanism that remains incompletely understood. We employed an integrated in silico approach combining molecular docking, density functional theory (DFT), and 100 ns molecular dynamics (MD) simulation to evaluate whether PQQ directly targets NAMPT. Docking against the NAMPT crystal structure (PDB: 7ENQ) yielded a binding free energy of −9.4 kcal/mol, with PQQ positioned in the allosteric activation site and forming hydrogen bonds at His191, Asp219, and Val242 together with π–π stacking at Tyr188, extending a known synthetic activator pharmacophore to a dietary ligand class. MM-GBSA analysis yielded binding free energy = −31.2 kcal/mol, confirming dominant electrostatic and van der Waals stabilization. In silico alanine mutagenesis of Tyr188 and Val242 reduced binding affinity to −7.2 and −7.0 kcal/mol respectively, with complete loss of allosteric-site contacts, validating the proposed mechanism computationally. DFT analysis revealed a HOMO–LUMO gap of 3.20 eV and electrophilicity index ω = 8.91 eV, consistent with non-covalent binding to nucleophilic residues. MD simulation confirmed retention of PQQ within the allosteric site over 100 ns. These data provide a structural and electronic framework for the NAD⁺-boosting activity of PQQ and a rationale for experimental validation. Full article

Combination analgesic therapy is commonly used to improve pain control, yet conventional molecular docking approaches typically evaluate individual ligands and provide limited insight into potential intermolecular associations between co-administered drugs. In this study, paracetamol, codeine, and their proposed 1:1 and 2:1 non-covalent assemblies were investigated using lipophilicity analysis, molecular docking, short molecular dynamics relaxation, electrostatic potential surface mapping, and HOMO–LUMO analysis. Docking simulations were performed against cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), and the μ-opioid receptor (MOR). The proposed assemblies produced docking scores that differed from those of the individual compounds, with the most pronounced differences observed for the cyclooxygenase targets. The 2:1 assemblies generally exhibited the most favorable docking scores, whereas the predicted interaction profiles at MOR appeared to be more dependent on molecular orientation. Molecular dynamics relaxation and electronic structure analyses further revealed differences in the energetic and electronic characteristics of the investigated configurations. These findings support the theoretical feasibility of distinct interaction patterns among the proposed paracetamol–codeine assemblies within the applied computational framework. However, the reported docking scores represent relative computational values rather than experimentally validated binding affinities, and the short-timescale molecular dynamics simulations provide only preliminary information regarding conformational stability. Furthermore, the existence and biological relevance of the proposed assemblies under physiological conditions remain to be established. This study provides a computational basis for future investigations of intermolecular associations in multicomponent drug systems. Full article

In this work, the structural, optical, vibrational, and stability properties of a series of Al_xAs_x nanostructures are systematically investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Starting from the fundamental cubic-like Al₄As₄ building block, progressively larger nanostructures were constructed through directional elongation and structural rearrangements, allowing for the exploration of one-dimensional chains, two-dimensional planar structures, and several exotic geometries. The calculated UV–visible absorption spectra reveal that structural dimensionality and topology strongly influence the electronic transitions of the nanostructures, with elongated and distorted configurations exhibiting broader absorption features and richer spectral distribution. Vibrational analysis shows that increasing structural complexity and reducing symmetry lead to a higher density of IR-active modes and more complex infrared spectra. The stability of the nanostructures is evaluated through binding energy calculations, which indicate a clear size-dependent stabilization trend, with the Al₂₄As₂₄-L1 configuration exhibiting the highest stability among the examined systems. In addition, the calculated HOMO-LUMO gaps reveal the semiconducting character of the clusters and demonstrate their sensitivity to geometric topology. The present results establish clear structure–property relationships between dimensional growth and the optical response of AlAs nanoparticles and provide theoretical reference data for future experimental investigations of III-V semiconductor nanostructures. Full article

This study employs a multiscale theoretical approach to systematically investigate the thermal stability, phase transition characteristics, and pyrolysis product distributions of four long-chain n-alkanes ranging from n-dodecane to n-pentadecane (C12–C15). At the electronic structure level, density functional theory calculations reveal that with increasing chain length, the HOMO–LUMO gap narrows monotonically from 8.87 eV to 8.77 eV and global softness increases, indicating enhanced electronic responsiveness to thermal perturbation. Molecular electrostatic potential analysis shows decreasing surface potential variance and 100% nonpolar surface area across all species, confirming that intermolecular interactions are exclusively governed by London dispersion forces. At the condensed-phase level, semiempirical quantum-based molecular dynamics (xTB-MD) simulations at 3500 K over 6 ps trajectories reveal qualitative chain-length-dependent initial bond-breaking patterns: C2 species appear prominently among early fragments for C12–C15 systems, with medium-sized fragments (C3, C4) becoming increasingly prevalent and C1 species relatively less prominent as chain length grows. This work provides an integrated “electronic structure-condensed phase transition-pyrolysis kinetics” perspective, offering precise theoretical insights and critical benchmark data for the pyrolysis mechanisms of long-chain n-alkanes. Full article