Density Functional Theory Research Articles

QTAIM Analysis of a [2]Rotaxane Molecular Shuttle with a 2,2'-Bipyridyl Rigid Core.

Chemical contacts responsible for the supramolecular assembly of a rigid H-shaped [2]rotaxane molecular shuttle composed of a 24-crown-8(24C8) macrocycle on a molecular thread containing two benzimidazole (Bzi) recognition sites and a central 2,2'-bipyridyl (Bipy) rigid core are analytically addressed by combining the Quantum Theory of Atoms in Molecules (QTAIM) with density functional theory (DFT). In this respect, the available crystallographic structure-CCDC number 2248267-is taken as a reference condition for addressing the nature of the chemical interactions finely modulating the shuttling of the 24C8 between Bzi stations. Moreover, previous DFT computations (Chem. Sci., 2023, 14, 7215) are extended over a supercomputing environment to address the proposed ligand exchange mechanism involving DMF solvent molecules and promoting the observed shuttling process upon the addition of Zn(II) cations. To this end, converged DFT wavefunctions are fully analyzed by means of electron density ρ(r) and local electronic energy density-H(r)-descriptors; interestingly, the derived covalent versus noncovalent interaction patterns shed some light on the mutual position of the macrocycle along the axle following the coordination of Zn(II) ions in DMF solvent.

Dual-Active-Sites in Co-Doped Pd/Beta Catalyst for Robust Soot Oxidation.

The development of robust catalysts for soot oxidation is crucial for the emission control of diesel vehicles. Herein, a 0.5%Pd-1%Co/Beta catalyst with extraordinary soot oxidation activity is developed by doping Co into 0.5%Pd/Beta. Remarkably, doping with Co reduced the T50 of 0.5%Pd/Beta by 69 °C, surpassing even the activity of 1%Pd/Beta. Experiments and DFT (density functional theory) calculations identified that Co doping induces the formation of dual-active-sites in the Pd-Co/Beta catalyst (Pdδ+ (0 < δ <2) species and oxygen defects), which are beneficial for the adsorption/activation of reactants (O2 and NO) and dissociation of the intermediate (NO2), ultimately leading to more NO2 participating in soot oxidation. This study presents a strategy to enhance the soot oxidation activity of noble metal catalysts while simultaneously reducing the amount of noble metal used. The developed 0.5%Pd-1%Co/Beta catalyst is a promising candidate for soot control on diesel vehicles.

First principle studies of the lead-free all-inorganic halide double perovskites Cs3InX6 (X = Cl, Br and I)

The optoelectronic character, photovoltaic performance, structural and thermodynamic stability of halide double perovskites (HDPs) Cs3InX6 (X [Formula: see text] Cl/Br/I) are investigated using first-principles calculations based on density functional theory (DFT) for possible optoelectronic applications. In the structure composition of Cs3InX6 HDPs, eight Cs clusters occupy cubic octahedral cavities within the CsInI6 framework, where Cs[Formula: see text] and In[Formula: see text] formed corner-sharing CsX6 and InX6 octahedra. The thermodynamic stability of these materials is confirmed by their positive entropy change ([Formula: see text]S), as a positive [Formula: see text]S results in a negative change in Gibbs free energy. The specific heat capacity curves comply with the Dulong–Petit law and satisfy the equipartition theorem of classical mechanics. These HDPs exhibit a direct bandgap nature, with the conduction band (CB) and valence band (VB) edges located at the [Formula: see text] symmetry point. The spin–orbit coupling (SOC) effect typically shifts the CB and VB edges toward the Fermi level, leading to a reduction in the band gaps. The top of the VB is primarily composed of strongly hybridized p orbitals of In and X, which are crucial for carrier transport properties due to their role in facilitating valence electron excitation into the CB with minimal photon energy. The optical band gaps of Cs3InI6, Cs3InBr6 and Cs3InCl6 are 1.80, 3.05 and 4.10[Formula: see text]eV, respectively, which lie within the ultraviolet (UV) and visible regions of the optical spectrum. The calculated power conversion efficiency (PCE) of Cs3InI6 is 13.92%, with a quantum efficiency (QE) of [Formula: see text]90% in the UV energy range (50–250[Formula: see text]nm). The calculated optoelectronic properties and stability metrics of the studied HDPs offer valuable insights into their potential applications in photovoltaic and light-emitting devices due to their suitable band gap and higher quantum efficiency.

3D Precise Structure Determination of Single-Atom Cu Species on TiO2 Using Polarization-Dependent Total Reflection Fluorescent X-ray Absorption Fine Structure Empowered by Chemically Constrained Micro Reverse Monte Carlo and Density Functional Theory

3D Precise Structure Determination of Single-Atom Cu Species on TiO₂ Using Polarization-Dependent Total Reflection Fluorescent X-ray Absorption Fine Structure Empowered by Chemically Constrained Micro Reverse Monte Carlo and Density Functional Theory

Effect of Trivalent Metal Cations in Layered Double Perovskites on Highly Selective CO2 Photoreduction to CO.

Trivalent metal cation engineering in vacancy-ordered layered double perovskites (LDP) is a useful strategy to tune photocatalytic activity. However, the regulatory mechanism of cation composition on photocatalytic performance still lacks in-depth understanding. This study explores vacancy-ordered LDP with the formula Cs4CdX2Cl12 (X = Bi, Sb) for photocatalytic CO2 reduction. The catalytic performance is fine-tuned by regulating the composition of M(III)-site metal ions. The yields of CO and CH4 from Cs4CdSb2Cl12 MCs were measured at 23.81 and 2.68 μmol g-1, resulting in a CO selectivity of 89.9%. Cs4CdBi2Cl12 demonstrated higher yields, with CO and CH4 produced at 90.77 and 2.53 μmol g-1, achieving a CO selectivity of 97.2%. In addition, in situ diffuse reflectance infrared Fourier transform spectra reveal that the modulation of metal ions at the M(III)-position can enhance the photocatalytic activity of Cs4CdX2Cl12 (X = Bi, Sb) MCs. Density functional theory (DFT) analysis suggests that Bi displays a lower energy barrier than Sb for the rate-determining step, thus facilitating the effective photocatalytic reduction of CO2 to CO. These findings highlight the influence of metal cation selection on structural properties and catalytic performance.

A Direct Route to Habiterpenol Synthesis Using Anticopalic Acid as a Chiral Pool Template.

The concise total synthesis of habiterpenol utilizing the highly abundant natural product, anticopalic acid, as a chiral pool starting material is presented in this work. The key synthetic transformations involved the acid-induced cyclization of the bicyclic anticopalic acid to directly construct the C-ring of the habiterpenol framework and the aromatic Nazarov cyclization to afford the pentacyclic ring-fused indane core structure. The synthesis was completed in 10 steps with an overall yield of 17.3%. All carbon atoms present in anticopalic acid were incorporated into the habiterpenol structure, highlighting the atom economy of this synthesis. Density functional theory (DFT) calculations were performed to gain insight into and explain specific reaction outcomes. Additionally, various assays were conducted to evaluate the chemopreventive properties of habiterpenol and related pentacyclic derivatives, providing new biological insights into these compounds. This study demonstrates the effectiveness of the chiral pool approach, using a high-abundance natural product as a starting material to access a low-abundance natural product valuable for biological activity exploration. The potential application of this strategy to the total synthesis of similar terpenoid scaffolds offers valuable opportunities for medicinal chemistry and drug development.

Elastic properties of the W0.75Re0.25 alloy at high pressure up to 183 GPa

The high pressure equation of state for the W0.75Re0.25 alloy is experimentally determined up to 183 GPa with synchrotron angle-dispersive powder x-ray diffraction in the diamond-anvil cell and to ∼925 GPa with density-functional theory. W-Re alloys are used in many industrial high-temperature applications and as a confining gasket material in high-pressure diamond-anvil cell research. The inclusion of 25 wt. % Re achieves the highest performance in terms of strength and ductility while also maintaining the body-centered-cubic (bcc) crystal structure, yet to date there has been no investigation into its elastic behavior at high pressure. We present the experimentally and theoretically determined volumetric and elastic pressure response and systematically compare these results to other W-Re alloys, finding that the bulk modulus of W-Re alloys varies nonlinearly with Re content and W0.75Re0.25 becomes less incompressible than W at 85 GPa. Published by the American Physical Society 2025

3‐arylcoumarins as the potential neuroprotective agents for the treatment of Alzheimer's disease by targeting monoamine oxidase: Molecular docking, 3D QSAR, and molecular dynamics simulations

AbstractMAO‐A and MAO‐B have gathered pharmacological importance in Alzheimer's and Parkinsons disease, owing to their function in the monoamine neurotransmitters metabolism. The development of potent inhibitors of MAO‐A and MAO‐B is the need of the hour. This research was aimed to determine the 3‐arylcoumarin scaffold's as enzyme inhibitor based on protein ligand interaction. The density functional theory data confirmed that the most of the compounds' derivatives were stable, validating the compounds' properties. Molecular docking revealed potential molecular interaction between selected compounds and targeted protein among which compound SC was found to be a potent inhibitor of MAO‐B. The results of the investigation were supported by MD simulations and ADMET characteristics, which demonstrated that the synthesized compounds have drug‐like qualities. Future research could be conducted to determine the significance of the SC derivatives in the field of medicine.

Exploring the role of hydrodynamic interactions in spherically confined drying colloidal suspensions.

We study the distribution of colloidal particles confined in drying spherical freestanding droplets using both dynamic density functional theory (DDFT) and particle-based simulations. In particular, we focus on the advection-dominated regime typical of aqueous droplets drying at room temperature and systematically investigate the role of hydrodynamic interactions (HIs) during this nonequilibrium process. In general, drying produces transient particle concentration gradients within the droplet in this regime, with a considerable accumulation of particles at the droplet's liquid-vapor interface. We find that these gradients become significantly larger with pairwise HIs between colloidal particles instead of a free-draining hydrodynamic approximation; however, the solvent's boundary conditions at the droplet's interface (unbounded, slip, or no-slip) do not have a significant effect on the particle distribution. DDFT calculations leveraging the radial symmetry of the drying droplet are in excellent agreement with particle-based simulations for free-draining hydrodynamics, but DDFT unexpectedly fails for pairwise HIs after the particle concentration increases during drying, manifesting as an ejection of particles from the droplet. We hypothesize that this unphysical behavior originates from an inaccurate approximation of the two-body density correlations based on the bulk pair correlation function, which we support by measuring the confined equilibrium two-body density correlations using particle-based simulations. We identify some potential strategies for addressing this issue in DDFT.

Twisted Molecular Core Conjugated Oxo-Ether as a Fluorescent Probe for Lipid-Droplets Bioimaging and Live Cancer Cell Discrimination.

In quest of a new working design for a photostable lipid-droplets (LDs) bioimaging probe, we herein unveil and demonstrate a twisted donor(naphthalene)-π-acceptor(dicyano) architecture linked with oxo/thioether functionality, where the probes' emission, hydrophobicity, cytotoxicity, and cell permeability are altered by replacing the present chalcogen/s. In this class of molecules, an "oxanthrene"-based compound, "OXNCN", was realized as the noncytotoxic and cell-permeable probe, displaying intense fluorescence in a nonpolar solvent, aggregates, and viscous medium. Time-dependent density functional theory (TD-DFT) investigations revealed that OXNCN holds a favorable extent of excited-state planarity to bring out considerable emission only in a nonpolar solvent, resulting in polarity-dependent emission. Outcomes of the concentration- and time-dependent colocalization investigations, cholesterol depletion/repletion studies, and oleic acid treatment-based experiments validated its LD specificity. Strong twisted intramolecular charge transfer (TICT) culminated in weak emission in the polar medium, which helped the probe reduce the cytoplasmic signal. Moreover, the results of time-dependent kinetic acquisitional photophysical studies, fluorescence recovery after photobleaching (FRAP), and intracellular emission investigations testified to the probe's photostability. Assiduous analysis and quantification of confocal laser scanning microscopy (CLSM) images by two-way analysis of variance (ANOVA), followed by Sidak's multiple comparison statistics, could provide insights into the probe's better performance in robust cancer cells (FaDu) than in normal ones (HEK-293). A precise discrimination between oral and normal cancer cells could be established by quantifying the deposited lipid droplets from the CLSM-captured cellular images and applying Student's t test with the quantified values.

Golden Single-Atom Alloys Selectively Boosting Oxygen Reduction and Methanol Oxidation.

Engineering electrocatalysts at a single-atomic site can enable unprecedented atomic utilization and catalytic activity, yet it remains challenging in multimetallic active centers to simultaneously achieve high catalytic selectivity and stability. Herein, the atomic design and control of golden single-atom alloys (PdAu1 and PtAu1 SAAs) based on fully ordered PdBi and PtBi matrixes is presented, serving as highly selective, active, and stable cathode and anode electrocatalysts, respectively, to trigger direct methanol fuel cell (DMFC). The octahedral PdAu1 SAA exhibits ultrahigh mass-activity of 5.37 A mgPd + Au -1 without noticeable decay for 120000 cycles toward oxygen reduction. While PdAu1 SAA is inactive for methanol oxidation, PtAu1 SAA exhibits an ultrahigh mass-activity of 28.59 A mgPt + Au -1. The selective electrocatalysts drive a practical DMFC with a high-power density of 155.0mW cm-2. Density functional theory calculations reveal the desired regulation of selectivity via reducing the energy barrier for potential-determining steps (PDS) of *OH to H2O and *HCOO to CO2. This work provides a general strategy to engineer multimetallic alloys at the atomic level, advancing the development of high-performance electrocatalysts.

Three-dimensional MXene coupled CoFe nanoalloys as sulfur host for long-life room-temperature sodium-sulfur batteries

Room-temperature sodium-sulfur (RT Na-S) batteries are potential candidates for next-generation energy storage systems because of low-cost resources, high theoretical capacity, and high energy density. However, their commercialization is hindered by the inherent shuttle effect, insulation of sulfur, and slow catalytic conversion. This study proposes a novel approach involving the design of a C/CoFe alloy catalyst coupled with Ti3C2Tx MXene substrate (C/CoFe-MXene) as a three-dimensional porous conductive sulfur host. Polysulfide adsorption/catalytic experiments and density functional theory calculation confirmed the excellent affinity and strong catalytic conversion ability of the C/CoFe-MXene composite for polysulfides. The heterostructure formed between the CoFe alloy and the MXene substrate promotes Na+ transport and accelerates reaction kinetics of sulfur species. Consequently, the assembled RT Na-S batteries with a C/CoFe-MXene sulfur host (2.0 mg cm-2) deliver a high initial specific capacity of 572 mAh g-1 at 1 C. Even at 5 C, the battery achieves ultralong-term cycling over 5,400 cycles with a capacity retention rate of 61.9%, corresponding to a slow capacity fading rate of 0.0089% per cycle, demonstrating outstanding high-rate tolerance. This work provides new insights into the preparation of three-dimensional porous sulfur cathodes with high specific surface area and excellent catalytic activity using catalysts loaded on MXene substrates in RT Na-S batteries.

Imine-Linked Covalent Organic Frameworks Tuned by Quaternary-Ammonium-Alkyl for Highly Effective and Selective Adsorption of Perchlorate from Water.

Perchlorate (ClO4 -) contamination in surface water is an escalating issue for drinking water safety. Herein, an imine-linked covalent organic framework (COF) tuned by quaternary ammonium alkyls (R4N+) is developed for ClO4 - adsorption. The hydrophobic and cationic COF adsorbent achieves a record-breaking adsorption capacity of ClO4 - at 912.7mg g-1, demonstrating remarkable selectivity for ClO4 - over other environmentally relevant anions and exhibiting rapid adsorption kinetics. Furthermore, the adsorbent maintains excellent recycling performance (removal efficiency ≥ 80% after 10 cycles) using tetrachloroferrate for regeneration. In dynamic flow-through experiments with real water samples, the adsorbent effectively treats ≈3200-bed volumes of feed streams (≈500µg L-1), with an enrichment factor of 15.2. The hydrophobicity of the COF adsorbent is identified as a premise for its interaction with ClO4 -. Molecular dynamic simulations and density functional theory calculations reveal that R4N+ anchored in COF cores enriches ClO4 - via electrostatic attraction and bonds with ClO4 - via unconventional hydrogen bonds (C─H─O). These key insights pave the way for future design and optimization of adsorbents for removing oxo-anion from water, especially for ClO4 -.

Utilization of a Chelating Bis[(dialkylamino)cyclopropenimine] to Isolate a Series of Heavier Zero-Valent Group 14 Tetracarbonyl Iron Complexes.

We report on the utilization of the ethylene-bridged bis[(dialkylamino)cyclopropenimine] (bisCPI) ligand, LCPI, to give access to new main-group E(II) halide complexes (E = Ge, Sn, Pb; 1, 2, 3). Subsequent reduction with Collman's reagent (Na2Fe(CO)4•dioxane) enables the isolation of a series of zero-valent tetrylone-tetracarbonyl iron complexes, (LCPI)E(Fe(CO)4 (E = Ge (4), Sn (5), Pb (6)). Compounds 4 - 6 were reacted further with iron pentacarbonyl to yield the bis-tetracarbonyl iron complexes (LCPI)E[(Fe(CO)4]2 (E = Ge (7), Sn (8), Pb (9)). The electronic structure of these complexes was studied by 57Fe Mössbauer spectroscopy and computationally by density functional theory calculations.

First-principles study of defect energetics and magnetic properties of Cr, Ru and Rh doped AlN

Abstract Spintronics offers more efficient data storage and quantum computing. Dilute magnetic semiconductors (DMS) are viewed as a sustainable means of achieving practical spintronics. Incorporating transition metal ions into a semiconductor lattice and creating ferromagnetic material is an important aspect of DMS research. This work explores the magnetic properties of Cr, Ru, and Rh doped w-AlN through spin-polarized density functional theory calculations of the electronic structure using supercell models. Formation energies of the point defects computed as a function of Fermi level predict that Cr4+, Ru4+ and Rh3+ are the most probable charge states for dopant Cr, Ru and Rh atoms, respectively, substituted for Al in w-AlN. Cr-doped AlN with Cr in Cr4+ charge state is found to be stable in the ferromagnetic state rather than in the antiferromagnetic state for all the concentrations of Cr considered (1.85 to 16.67% of Al). Whereas Ru and Rh doped AlN with Ru and Rh in Ru4+ and Rh3+ charge states are unstable in the ferromagnetic state. The electronic density of states (DOS) of Cr-doped AlN in the ferromagnetic state shows that the system remains an insulator, with Fermi level placed directly above the valence band maximum (VBM) for Cr less than 5.56%. With Cr between 7.40 and 12.96%, the system exhibits a half-metal state with Fermi level located on the Cr 3d spin-up peaks occurring on the shoulder of VBM. The DOS transforms to normal metal state at 16.67% Cr with the Fermi level placed on both the spin-up and spin-down Cr 3d DOS. The half metal feature is absent in the DOS of energy-favored antiferromagnetic models of Ru and Rh doped systems. With changes in dopant concentration, the Fermi level falls nonsequentially between the DOS peaks or on the spin-up and spin-down DOS peaks originating from gap states of 4d electrons.

A graph-based statistical model for carbon nanostructures.

Energy degeneracy in physical systems may be induced by symmetries of the Hamiltonian, and the resonance of degeneracy states in carbon nanostructures can effectively enhance the stability of the system. Combining the octet rule, we introduce a statistical model to determine the physical properties by lifting the energy degeneracy in carbon nanostructures. This model offers a direct path to accurately ascertain electron density distributions in quantum systems, akin to how charge density is used in density functional theory to deduce system properties. Our methodology diverges from traditional quantum mechanics, focusing instead on this unique statistical model by maximizing bonding entropy to determine the fundamental properties of materials. Applied to carbon nanoclusters and graphynes, our model not only precisely predicts bonding energies and electron density without relying on external parameters but also enhances the prediction of electronic structures through bond occupancy numbers, which act as effective hopping integrals. This innovation offers insights into the structural properties and quantum behavior of electrons across various dimensions.

Revisiting the Half-and-Half Functional.

Hybrid density functionals typically provide significantly better accuracy than semilocal functionals. Conventional wisdom holds that incorporating more than 20-25% exact exchange is deleterious to thermochemical properties and should only be used as a last resort, for problems that are dominated by self-interaction error. In such cases, the Becke-Lee-Yang-Parr "half-and-half" functional (BH&H-LYP) has emerged as a go-to choice, especially in time-dependent density functional theory calculations for excitation energies. Here, we examine the assumption that 50% Hartree-Fock exchange sacrifices thermochemical accuracy. Using a sequence of functionals B(α)LYP, with different percentages of exact exchange (0 ≤ α ≤ 100), we find that BH&H-LYP (with α = 50) is nearly optimal and affords accuracy similar to B3LYP for thermochemistry, barrier heights, and excitation energies. Although BH&H-LYP is significantly less accurate than B3LYP for atomization energies, this emerges as the sole rationale for the taboo against values α > 25. Overall, BH&H-LYP is a reasonable choice for problems that are dominated by self-interaction error, including charge-transfer complexes and core-level excitation energies. While B3LYP remains more accurate for valence excitation energies, the use of 50% exact exchange appears to be an acceptable compromise, and BH&H-LYP can be used without undue concern over its diminished accuracy for ground-state properties.

Valley-Selective Optical Absorption and Giant Exciton Binding Energy of Breathing Kagome Semiconductor with Nearly Flat Band.

Endowed with topological flat band and dispersive Dirac cones, layered Kagome materials, which are expected to exhibit distinctive electronic and optical properties, have garnered significant attention in the forefrontier research of condensed matter physics. Using density functional theory and many-body perturbation theory, here we study the optical and excitonic properties of tunable two-dimensional (2D) breathing Kagome material Ta3SBr7 with topologically nontrivial flat band. Originated from the bulk counterpart, two thermodynamically stable structures are proposed, suggesting a new geometric degree of freedom for controlling the electronic and optical properties of the breathing Kagome lattice. Both Ta3SBr7 monolayers exhibit momentum selective optical absorption, whose mechanism is unveiled from the detailed analysis of the dispersion, symmetry, and valley-contrasting Berry physics of electronic band structure. Because of the existence of characteristic nearly flat bands, the ground-state excitons of both Kagome structures possess exceptionally large binding energies up to 1.1 eV. Moreover, this geometric degree of freedom also results in significant differences in the optical activity and exciton radiative lifetimes for ground-state excitons in these two structures. Our results showcase the potential of Kagome semiconductors not only in the manipulation of excitonic behaviors but also in fundamental physics, such as fractional Chern insulators at zero applied magnetic field.

Heterophyllin B: Combining Isotropic and Anisotropic NMR for the Conformational Analysis of a Natural Occurring Cyclic Peptide.

Heterophyllin B is a natural occurring cyclic peptide with diverse attributed bioactivities. NMR-based conformational analysis of cyclic peptides often poses a challenge due to limited isotropic solution-state NMR data. In this study, we combined isotropic and anisotropic NMR observables including J-coupling, NOEs, amide proton temperature coefficients, and residual dipolar couplings (RDCs), which enabled the determination of a minimal conformational ensemble of heterophyllin B in methanol at density functional theory (DFT) accuracy. For conformational sampling of a cyclic peptide with a high degree of conformational freedom, we proposed a computational strategy that combines the Conformer-Rotamer Ensemble Sampling Tool (CREST) with the Commandline Energetic SOrting (CENSO). This combined computational and NMR-based approach offers a robust framework for the conformational analysis of cyclic peptides.

Electrocatalytic Reduction of CO2 to Long-Chain Hydrocarbons on (FeCoNiCu)3O4 Medium Entropy Oxide Nanoparticles.

Electrocatalytic CO2 reduction reaction (CO2RR) to valuable multicarbon (C2+) fuels and chemicals presents a promising strategy to mitigate atmospheric CO2 accumulation and promote the closure of the carbon cycle. However, significant challenges persist in achieving both high product selectivity and sustained stability in the CO2RR. In this study, the catalytic performance of (Fe,Co,Ni,Cu)3O4 medium entropy oxide (MEO) nanoparticles anchored on reduced graphene oxide (rGO) was evaluated for the CO2RR. The MEO-rGO catalyst exhibited remarkable activity, achieving a cathodic current density of -0.5 A cm-2 at -1.7 V, significantly outperforming bare nickel foam (-0.15 A cm-2). Additionally, the catalyst demonstrated a high total Faradaic efficiency (FE) of 60.3% for C2+ products, comprising 30.6% C5H12O and 29.7% C5H10O. This exceptional selectivity toward long-chain hydrocarbons is attributed to the enhanced C-C coupling on the MEO-rGO surface, facilitated by reduced energy barriers. Density functional theory (DFT) calculations further revealed that the adsorption and reduction of CO2 on the (Fe,Co,Ni,Cu)3O4 MEO surface are energetically favorable processes.