Analysis Of Electron Density Distribution Research Articles

Enhanced photodegradation of organic dyes using copper and zinc aluminate nanophotocatalysts

This study aims to enhance the photocatalytic efficiency of CuxZn1-xAl2O4 (x = 0.0, 0.2, 0.4, 0.6, and 0.8) nanophotocatalysts synthesized via a sol-gel self-combustion method. Rietveld analysis confirmed the formation of single-phase spinels with a face-centered cubic structure and Fd-3m space group symmetry, while electron density distribution analysis supported the ionic character of bonding within the material. Subsequent UV–visible spectroscopy revealed that the addition of Cu(II) reduced the band gap from 4.66 eV to 2.54 eV, facilitating enhanced light absorption. Consequently, the catalyst with x = 0.8 deteriorated 95 % of methyl orange (MO) and 93 % of rhodamine-B (RhB) in 120 min of visible light irradiation, following a pseudo-first-order kinetic model. The Cu0.8Zn0.2Al2O4 sample demonstrated significant reusability and stability, with degradation rates of 93–79 % for RhB and 95–81 % for MO after four cycles. Scavenging studies indicated that photoexcited holes (h), hydroxyl radicals (OH•), and superoxide radicals (O₂•⁻) were key factors in the degradation process. This study presents an improved approach for enhancing the photodegradation performance of the Cu0.8Zn0.2Al2O4 catalyst for pharmaceutical and wastewater treatment applications.

Ferrocene Appended D-π-A chromophores for Dye-Sensitized Solar Cells: Synthesis, Photophysical, Effect of Co-adsorbent on Photovoltaic Efficiencies and DFT studies

A new ferrocene conjugated donor–π–acceptor type of dyes 1 and 2 were synthesized and characterized using different spectroscopic techniques (FT-IR, NMR, and ESI-mass). The intramolecular charge transfer process of both the dyes were analysed using the solvatochromic method, which reveals positive solvatochromism due to its well stabilization in the excited states than in the ground states. The electrochemical behavior of the dyes 1 and 2 were carried out by the cyclic voltammetric technique, which shows quasi-reversible in nature, and the potentials were further utilized for the band gap calculation with UV–visible data [2.99 eV (1) and 2.88 eV (2)]. The photovoltaic attainments of the dyes 1 and 2 were studied through the dye-sensitized solar cells (DSSCs) in the presence and absence of co-adsorbent like chenodeoxycholic acid (CDCA), which act as an anti-dye aggregation material. The photovoltaic parameters like short circuit current density (Jsc) = 0.067 mA cm2, open circuit voltage (Voc) = 0.444 V, fill factor (FF) = 0.447, and the cell displayed an overall conversion efficiency of 0.013 % for dye 2. In contrast, the power conversion efficiency (PCE) was found to be enhanced to 0.177 % (Jsc = 0.389 mA/cm2, Voc = 0.577 V, FF =0.790), in the presence of chenodeoxycholic acid (CDCA) co-adsorbent. This enhancement in efficiency is due to reduced dye aggregation and increased electron injection in the presence of CDCA. In addition, chromophore 2 has 1.4 times higher efficiencies than 1, attributing to the presence of an additional phenyl group making an efficient intramolecular process of 2. Furthermore, the incident photon to current efficiency (IPCE) and electrochemical impedance spectroscopy (EIS) studies reveal the dye efficiencies were directly proportional to that of the power conversion efficiency (PCE), respectively. Moreover, the electronic structure and electron density distribution analysis were analysed for both dyes 1 and 2 to confirm the intramolecular charge transfer properties using density-functional theory (DFT) and time-dependent density-functional theory (TD-DFT) calculations using the B3LYP/ 6–31+G** level of theory.

Influence of surfactant on the structural, morphological and optical properties of SrWO4: Insights through electron density distribution analysis

Influence of surfactant on the structural, morphological and optical properties of SrWO4: Insights through electron density distribution analysis

Synthesis of (μ2,η3-allyl-η5-oxapentadienyl)diiron pentacarbonyl complexes, an unusual reaction product from η4-(vinylketene)Fe(CO)3 complexes: structure and electron density distribution analysis.

The synthesis of a series of ferrocenylvinylketenes as stable η4-[Fe(CO)3] complexes (3a-f) was successfully accomplished through the reaction of η2-[Fe(CO)4] complexes under mild carbonylation conditions. The reactivity of 3a-f under thermal conditions afforded the unexpected formation of a novel family of (μ2,η3-allyl-η5-oxapentadienyl)diiron pentacarbonyl complexes 5a-f proposed to be formed by a sequence metathesis-haptotropic rearrangement between the starting η4-vinylketene iron(0) complex 3 and a η4-vinylcarbene iron(0) complex trapped in situ after a reversible carbonylation process favored by the thermal conditions. An electron density distribution analysis (EDD) of 5e using high-resolution X-ray diffraction data in combination with the DFT framework was performed to understand the electronic communication between the two iron fragments.

Description of non-covalent interactions in benzyl chalcocyanate crystals from smoothed Cromer–Mann electron density distribution functions

A well-known method to characterize non-covalent interactions consists in the topological analysis of electron density distribution (EDD) functions, complemented by the search for minima in the reduced density gradient (RDG) distributions. Here, we characterize intermolecular interactions occurring in crystals of benzyl chalcocyanate compounds through bond critical points (BCP) of the promolecular electron density (ED) built from the crystallographic Cromer–Mann parameters, at several smoothing levels t. The trajectories formed by the t-dependent BCP locations are interpreted in terms of the intermolecular interactions occurring within the crystal arrangements. Chalcogen…nitro BCPs are clearly present in the unsmoothed EDDs but are annihilated as t increases, while chalcogen…chalcogen BCPs appear and are among the only BCPs left at the highest smoothing level. The chalcogen bonds are differentiated from the other chalcogen interactions through the linear chalcogen…BCP…nitro geometry at low smoothing level and their more negative Laplacian values. The annihilation of CPs can be followed by the apparition of a RDG minimum, associated with a very weak interaction. Along the BCP trajectories, the Laplacian shows a progressive concentration of the ED in the intermolecular space within the crystals and adopts the most negative values at the shortest atom…atom separations. At the termination point of a BCP trajectory, the drastic increase of the ellipticity value illustrates the flattening of the EDD.

Interactions and corrosion mitigation prospective of pyrazole derivative on mild steel in HCl environment

The effectiveness of 1H˗pyrazole˗3,5˗dicarboxylic acid 5˗benzyl ester 3˗phenyl ester (PCBPE) as a preventer for deterioration of IS 513 Gr. D steel in 1 M HCl medium is evaluated via weight loss, electrochemical impedance, and polarization techniques. Kinetic and thermodynamic parameters assessed the feasibility of the adsorption process at diverse temperatures. The inhibition action on mild steel has been enhanced with increasing PCBPE concentration. It is found from the polarization studies that PCBPE behaves as mixed type inhibitor in HCl medium. The adsorption process of PCBPE on mild steel surface from acid environment is favoured Langmuir adsorption isotherm. The shielding efficiency of PCBPE has been enhanced at elevated concentrations, and it has been diminished at amplified temperatures. The Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), and Energy Dispersive Spectrum (EDS) were used to establish a surface characterization of metal specimens. A quantum chemical analysis of electron density distributions in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) demonstrated how the inhibitor undergoes adsorption on mild steel in 1 M HCl. All experimental findings substantiate the corrosion mitigation performance of PCBPE on mild steel in acidic environments.

The Relevance of Experimental Charge Density Analysis in Unraveling Noncovalent Interactions in Molecular Crystals.

The work carried out by our research group over the last couple of decades in the context of quantitative crystal engineering involves the analysis of intermolecular interactions such as carbon (tetrel) bonding, pnicogen bonding, chalcogen bonding, and halogen bonding using experimental charge density methodology is reviewed. The focus is to extract electron density distribution in the intermolecular space and to obtain guidelines to evaluate the strength and directionality of such interactions towards the design of molecular crystals with desired properties. Following the early studies on halogen bonding interactions, several “sigma-hole” interaction types with similar electrostatic origins have been explored in recent times for their strength, origin, and structural consequences. These include interactions such as carbon (tetrel) bonding, pnicogen bonding, chalcogen bonding, and halogen bonding. Experimental X-ray charge density analysis has proved to be a powerful tool in unraveling the strength and electronic origin of such interactions, providing insights beyond the theoretical estimates from gas-phase molecular dimer calculations. In this mini-review, we outline some selected contributions from the X-ray charge density studies to the field of non-covalent interactions (NCIs) involving elements of the groups 14–17 of the periodic table. Quantitative insights into the nature of these interactions obtained from the experimental electron density distribution and subsequent topological analysis by the quantum theory of atoms in molecules (QTAIM) have been discussed. A few notable examples of weak interactions have been presented in terms of their experimental charge density features. These examples reveal not only the strength and beauty of X-ray charge density multipole modeling as an advanced structural chemistry tool but also its utility in providing experimental benchmarks for the theoretical studies of weak interactions in crystals.

First-principles insights into the mechanical, optoelectronic, thermophysical, and lattice dynamical properties of binary topological semimetal BaGa2

In the present study we have investigated the structural properties, electronic band dispersion, elastic constants, acoustic behavior, phonon spectrum, optical properties, and a number of thermophysical parameters of binary topological semimetal BaGa2 in details via first-principles calculations using the density functional theory (DFT) based formalisms. The electronic band structure and density of states calculations with spin–orbit coupling reveal semimetallic nature with clear topological signatures. The minimum thermal conductivities and anisotropies of the compound are calculated. The elastic constants and phonon dispersion calculations show that the compound under study is both mechanically and dynamically stable. Comprehensive study of elastic parameters shows that BaGa2 possesses fairly isotropic mechanical properties, reasonably good machinability, low Debye temperature and melting point. The chemical bonding in BaGa2 is interpreted via the electronic energy density of states, electron density distribution, elastic properties and Mulliken bond population analysis. The compound possesses both ionic and covalent bondings. The reflectivity spectra show strong anisotropy with respect to polarization of the incident electric field in the visible to mid-ultraviolet regions. High reflectivity over wide spectral range makes BaGa2 suitable as a reflecting material. BaGa2 is also an efficient absorber of ultraviolet radiation. Furthermore, the refractive index is quite high in the infrared to visible range. All the energy dependent optical parameters show metallic features and are in complete accord with the underlying bulk electronic density of states calculations. Most of the results presented in this study are novel and should serve as useful reference for future study.

Local structure and electron density distribution analysis of tin(II) sulfide using pair distribution function and maximum entropy method

Abstract Tin(II) sulfide (SnS) is a low symmetric orthorhombic double-layered dual bandgap semiconductor. It is low cost, toxic-free and highly abundant on Earth, with multifunctional optical, electronic, magnetic and light conversion applications when doped adequately with impurity. These physical properties can be understood only by the complete understanding of microstructural properties like average structure, electron density distribution inside the unit cell, bonding nature and local structure. In this work, the average and local structure, along with the electron density distribution of a nano crystallite sized single-phase sample of tin(II) sulfide is elucidated with the help of precise X-ray intensity data. The average structural information was extracted using Rietveld refinement analysis and the visual mapping of 3D, 2D and 1D electron density distribution inside the unit cell and its numerical contribution using maximum entropy method (MEM). The bonding between the first inter and intra bonding between Sn and S atoms is 2.65,105 Å and 3.2689 Å with mid bond electron density 0.907 e/Å3 and 0.1688 e/Å3 respectively. The inter-atomic correlations of 1st, 2nd and 3rd nearest neighbour atoms, their bond length, and the crystallite size are reported from pair distribution function (PDF) analysis using low Q-XRD data (Q ∼ 6.5 Å−1). The PDF analysis shows that the first and second nearest Sn–S bonding distance is 2.6064 Å and 3.4402 Å, first is between the Sn and S atoms of the same layer and the other between the Sn and S atoms of the adjacent layers respectively.

Ability of Boron to Act as a Nucleophile and an Electrophile in Boryl Shift Reactions Unveiled by Electron Density Distribution Analysis.

The behavior of the tetracoordinate boron of N-methyliminodiacetic acid (MIDA) boronates as a nucleophile and an electrophile during the 1,2-boryl migration promoted by a Lewis acid and the 1,4-boryl migration promoted by a neighboring atom, respectively, have been investigated using density functional theory and the quantum theory of atoms in molecules. We found that when boron acts as a nucleophile, the electron density of the B-N interaction of the BMIDA moiety maintains the charge concentration over the boron atom, facilitating its transport toward the electron-deficient center. In this process, the BMIDA remains as a tetracoordinate. On the other hand, the B-N weakening generates a charge depletion region over the boron, allowing it to interact with the electron-rich center of O1, developing the boron atom, a pentacoordinate form. Then, the B-N bond breaking triggers a series of changes in the electronic structure of the boron atom. Our results explain the role of the MIDA ligand upon the remarkable susceptibility of the boron atom for switching its structural and electronic characteristics in the migration processes. In addition, the dichotomous behavior was evaluated with a different scenario, considering tricoordinate pinacol boronate as a boryl migrating group.

Rietveld Refinement and X-ray Absorption Study on the Bonding States of Lanthanum-Based Perovskite-Type Oxides La1−xCexCoO3

Metal-oxygen bonding of the Ce-doped LaCoO3 system remains largely unexplored despite extensive studies on its magnetic properties. Here, we investigate the structure and local structure of nanoscale La1−xCexCoO3, with x = 0, 0.2, and 0.4, using the Rietveld refinement and synchrotron X-ray absorption techniques, complemented by topological analysis of experimental electron density and electron energy distribution. The Rietveld refinement results show that LaCoO3 subject to Ce addition is best interpretable by a model of cubic symmetry in contrast to the pristine LaCoO3, conventionally described by either a monoclinic model or a rhombohedral model. Ce4+/Co2+ are more evidently compatible dopants than Ce3+ for insertion into the main lattice. X-ray absorption data evidence the partially filled La 5d-band of the pristine LaCoO3 in accordance with the presence of La–O bonds with the shared-type atomic interaction. With increasing x, the increased Ce spectroscopic valence and enhanced La–O ionic bonding are noticeable. Characterization of the local structures around Co species also provides evidence to support the findings of the Rietveld refinement analysis.

Three dimensional atomistic-scale electron density distribution analysis of ZnWO4: Sm phosphors

In this work, we demonstrate a study of three-dimensional atomic-scale electron density distribution analysis for Sm3+ doped ZnWO4 phosphors. The rare-earth element Sm3+ doped ZnWO4 with various concentrations synthesized via chemical precipitation technique were studied for understanding their photoluminescence properties and bonding characteristics. The density of the electrons along the bond path was determined and the parameters of electron density distribution analysis were correlated with the photoluminescence behavior of the synthesized materials. The present work paves a promising path to get efficient phosphor material for display and lighting applications.

Flower decorated rod-like Pd @ MnO2 nanocomposite: Focus on photocatalysis, Rietveld refinement analysis and electron density distribution analysis

In this scenario, the Pd doped MnO2nanocatalysts were constructed by hydrothermal route. As-synthesized Pd loaded α-MnO2 nanocomposites were systematically characterized by various characterization techniques, respectively. The FESEM and TEM results reveal the surface morphology, the rose flower-like Pd was evenly decorated on the MnO2 surface. The elemental compositions of the presenting elements Pd, Mn and O are confirmed by XPS spectroscopic analysis. The photocatalytic activity of 2% Pd loaded α-MnO2 for crystal violet (CV) degradation was very high compared to immaculate α-MnO2 under visible light embellishment. Moreover, the radical trapping experiment substantiates that O2•− and •OH plays a vital role in CV abatements. This work will provide new in-depth insights into other photocatalytic nanomaterials with potential applications in the field of environmental compensation. Besides, the electron density distributions analysis was carried out for this catalyst to explain the bond length value between the atoms.

Thermal transport in planar [formula omitted]-hybridized carbon allotropes: A comparative study of biphenylene network, pentaheptite and graphene

The biphenylene network with periodically arranged four-, six-, and eight-membered rings has been successfully synthesized in very recent experiments. This novel two-dimensional (2D) carbon allotrope has potentials in applications of lithium storage and carbon-based circuitry. Understanding the thermal transport properties of biphenylene network is of critical importance for the performance and reliability of its practical applications. To this end, the thermal transport in biphenylene network is comprehensively investigated in this paper with the aid of molecular dynamics simulations together with first-principles calculations. For the sake of comparison, the thermal conductivities of other 2D sp2-hybridized carbon allotropes including graphene and pentaheptite are also investigated using the same method. It is found that the thermal conductivities of biphenylene network and pentaheptite are, respectively, only about one-thirteenth and one-eighth of graphene. Through the analysis of phonon property, mechanical property and electron density distribution, it is demonstrated that the great reduction in the thermal conductivity of biphenylene network and pentaheptite arises from the decline in their structural symmetry, which leads to the decrease of phonon group velocity and the reduction of phonon mean free path.

Red emitting Eu3+ induced SrWO4 materials: synthesis, structural, morphological and photoluminescence analysis

Rare-earth doped phosphors have occupied significant percentage in the field of luminescence applications. In order to get the optimized intensity of PL spectra, the dopant selection, dopant concentration and preparation technique plays a major role. In this work, SrWO4 and Eu3+ doped SrWO4 were successfully synthesized via fuel assisted solid state reaction technique at a temperature of 900 °C. The effect of Eu concentration on SrWO4 was analyzed by X-ray diffraction, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and PL spectroscopy. All the diffraction peaks of prepared SrWO4 and Sr1−xEuxWO4 (x = 0.01, 0.02, 0.03, 0.04 and 0.05) were well-matched with the standard tetragonal phase of SrWO4. In the PL study, SrWO4:Eu3+ shows the characteristics emission peaks at 5D0 → 7FJ (J = 1, 2, 3, 4) transitions for Eu3+. 5D0 → 7F2 (615 nm) is predominant at 394 nm excitation wavelength. The PL emission intensity at 615 nm gradually increases upto 4% of Eu3+ and then decreases. Using XPS, the chemical state analysis was carried out in Sr1−xEuxWO4 (x = 0.04) and Eu dopant is in 3 + oxidation state. The electron density distribution analysis in the unit cell was carried using the maximum entropy method (MEM) and their charge derived properties were correlated with the PL analysis. Based on the different characterization analysis, Eu3+ doped SrWO4 act as an efficient red-emitting phosphor for Near UV (394 nm excitation), blue LED (450 nm excitation) based white LED and FED applications.

Molecular-Level Insight into the Interfacial Reactivity and Ionic Conductivity of a Li-Argyrodite Li6PS5Cl Solid Electrolyte at Bare and Coated Li-Metal Anodes.

Sulfide glasses, with high room-temperature Li-ion conductivities, are a promising class of solid-state electrolytes for all-solid-state batteries. Yet, when in contact with Li metal, our current understanding of important interfacial phenomena such as electrolyte reduction and Li-ion transport is still quite limited, especially at the atomic scale. Here, using first-principles molecular dynamics simulations, we tackle these open questions head-on and examine key interfacial properties of Li-argyrodite Li6PS5Cl electrolyte at bare and coated Li-metal anodes. Specifically, we investigate the role of the interfacial composition and morphology in a number of Li-metal surfaces, including surfaces coated with thin films of Li2Sn5, MoS2, LiF, and Li3P. Our materials models are designed to gain insights into the early stages of interface formation and structural evolution. In addition, by employing a novel topological analysis of procrystal electron density distribution as applied to interfacial solid-state ionics, we thoroughly assess Li-ion conductivity through the investigated interfaces. Our results provide evidence of progressive breaking of P-S bonds in PS43- groups and eventual P-P recombination of intermediate species as the main reaction mechanisms of Li6PS5Cl reduction by Li metal. We also predict Li2Sn5 as the most suitable coating to partially prevent the electrolyte degradation while keeping a relatively low interfacial resistance. These findings shed light on the interface chemistry of sulfide-based electrolytes in contact with Li metal and pave the way for rationalizing further computational and experimental studies in the field.

Synthesis, characterization and theoretical exploration of pyrene based Schiff base molecules as corrosion inhibitor

Synthesis of highly efficient organic molecules to be used for corrosion inhibition is the prime importance to minimize the degradation of metal substrates from the corrosive solutions. In this regards, the theoretical exploration of the corrosion inhibitor before its application is very important. Herein, pyrene based two novel Schiff bases, viz., 4-((pyren-3-yl)methyleneamino)phenol (PMP) and 2-(2,4-dinitrophenyl)-1-((pyren-3-yl)methylene)hydrazine (DPH) were synthesized and characterized. The incorporation of pyrene unit (fused aromatic rings) and contribution of hydroxyl or nitro functional groups in the Schiff base skeleton might make these molecules work as efficient corrosion inhibitors. The atomic-level insight of the electronic properties, the presence of local reactive sites and the adsorption behaviours of these molecules were investigated meticulously. Subsequently, it's probable use as corrosion inhibiting molecule was predicted based on computational outcomes obtained from density functional theory (DFT), Fukui indices (FIs) analysis and molecular dynamics (MD) simulation approaches, simultaneously. The optimization of the geometries of molecules, analysis of electron density distribution within frontier molecular orbitals obtained from DFT outcomes; and FIs analysis of each atom of these synthesized molecules were carried out to investigate the plausible mode of interactions of these designed molecules with metal's atoms. Furthermore, the crystal morphology study was performed using “Morphology” module in Material Studio software to explore the growth characteristics as well as to find out the exceptionally stable surface present in α-Fe crystal. In doing so, the Wulff construction plot was used to analyse α-Fe crystal morphology. Afterwards, the MD simulation technique was employed to envisage interaction spontaneity and adsorption of the synthesized molecules with equilibrium configuration onto the metal surface atoms imitating the actual corrosion inhibiting processes that occurs in actual corrosive environments.

Fabrication of pebble stone-like PbMoO4 nanostructure: Focus on photocatalysis, photoluminescence and electron density distribution analysis

In this work, the PbMoO4 nanocatalyst is synthesized by the hydrothermal way. The as-prepared PbMoO4 nanomaterial was confirmed by powder X-ray diffraction (P-XRD), UV–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL), scanning electron microscopy (SEM) and Transmission electron microscopy techniques (TEM). The scanning Electron Microscope result indicates the pebble stone morphology structure of PbMoO4 nanomaterials. The catalytic performance for as-synthesized PbMoO4 nanomaterial was analyzed by the ciprofloxacin (CIP) degradation process. More interestingly, the as-prepared PbMoO4 material is having higher catalytic performance compared to the other previous PbMoO4 nanoparticles reports with an efficiency of above 92%. A photodegradation mechanism and the reaction kinetics of PbMoO4 nanomaterial were also investigated. The aforesaid results are strong enough to suggest the PbMoO4 nanomaterial may be an effective catalyst for environmental application. In addition, the electron density distributions studies were carried out for this PbMoO4 nanomaterial to explain the bond length value between the atoms.

Pnictogen effects on the electronic interactions in the Lewis pair complexes Ph3EB(C6F5)3 (E = P, As, Sb)

Lewis pair complexes bearing a BR3 acid and a R’3E base (E = P, As, Sb; R, R’ – organic ligands) play key roles in modern chemistry and technology, their properties being strongly relevant to catalysis and material science. The donor acceptor complexes Ph3EB(C6F5)3 attract special interest due to the elongated E-B bond that shifts the molecular parameters towards those of a frustrated Lewis pair. In depth theoretical and experimental studies of the Ph3EB(C6F5)3 systems presented in this work provide new insights into the nature of intramolecular electronic interactions in these molecules. A missing X-ray structure of Ph3AsB(C6F5)3 is described. Analyses of molecular structures, orbitals, dissociation energies and electron density distributions reveal crucial influence of non-covalent interactions on the Ph3EB(C6F5)3 stability.

Effect of preparation techniques on BaWO4: structural, morphological, optical and electron density distribution analysis

The scheelite BaWO4 materials were prepared by co-precipitation and molten salt method. The crystallographic structure, optical behavior, morphology, and electronic charge distributions of the prepared BaWO4 were studied by various spectroscopic techniques such as X-ray power diffraction, photoluminescence spectroscopy, UV–Visible absorption spectroscopy, scanning electron microscopy and electron density distribution analysis, respectively. The micron-sized rock-like structured BaWO4 particles were obtained in the surface morphology. These structured BaWO4 exhibited intense blue emission peak at 430 nm when excited at 375 nm. The synthesized material revealed the high intense blue emission which attributed to the intrinsic transitions of [WO4]2− tetrahedrons.