Natural Bond Orbital Analysis Research Articles

FeC4H22+ Encompassing Planar Tetracoordinate Iron: Structure and Bonding Patterns

The singlet, triplet, and quintet electronic states of the FeC4H22+ system are theoretically explored using quantum chemical methods, and 39 isomers are identified in the singlet electronic state and 4 isomers in both triplet and quintet electronic states. A molecule with a planar tetracoordinate iron (ptFe) is found on the potential energy surface of singlet and triplet electronic states. The bonding features of ptFe in the singlet electronic state are analyzed with natural bond orbital (NBO) analysis, adaptive natural density partitioning (AdNDP), and molecular orbital analysis. The resultant data delineate that the ptFe is stabilized through electron delocalization in the ptFe system.

Investigations on the growth and antibacterial behaviour of bioactive creatininium hydrogen bromide (CRBr) single crystal

The major aim is to synthesize a creatininium hydrogen bromide (CRBr) single crystal through a slow evaporation technique, and its antibacterial activity. According to Single Crystal X-ray Diffraction (SXRD) analysis, the generated crystal belongs to monoclinic structure and centrosymmetric space group P21/n. The optimized structural parameters explain the structural stability with NH…O, CH…O, and OH…O interactions. To verify the existence of intermolecular interactions, Hirshfeld surface analysis of a grown-up single crystal was carried out and that shows the stable nature of the molecule. Intermolecular and intramolecular hydrogen bonding, intermolecular charge transfer and delocalization of electron density can all be studied effectively by Natural Bond Orbital (NBO) analysis. In addition to examining the functional groups, the vibrational analysis gives the absorption peaks and bands associated with the formed crystal. The generated crystal has thermal stability up to 200 °C according to TG/DTA analysis. The material's electronic transition was determined by analyzing the UV–visible absorbance spectrum, showing an optical band gap of 4.2 eV and a lower cut-off wavelength of 265 nm. The charge transfer within the molecule has been elucidated using frontier molecular orbital analysis that shows its antibacterial properties. Molecular electrostatic surface analysis shows that excellent ICT interactions exist in the crystal lattice, where the positive potential is scattered throughout the creatinine portion and the negative region is dispersed on the bromine atom. Molecular docking has been used to examine the compound's antibacterial properties. In addition, the generated compound is tested for its in vitro antibacterial activity against several bacterial strains, including Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Bacillus cereus, and Staphylococcus aureus. The above findings demonstrated the remarkable antibacterial effectiveness of the compound under study.

Exploring Unconventional σ-Hole Interactions: Computational Insights into the Interaction of XeO3 with Non-Aromatic Coordinating Solvents.

In order to control the explosiveness and shock sensitivity of XeO3 , we have investigated its plausible interaction with various non-aromatic coordinating solvents, serving as potential Lewis base donors, through density functional theory (DFT) calculations. Out of twenty six such solvents, the top ten were thus identified and then thoroughly examined by employing various computational tools such as the mapping of the electrostatic potential surface (MESP), Wiberg bond indices (WBIs), non-covalent interaction (NCI) plots, Bader's theory of atoms-in-molecules (AIM), natural bond orbital (NBO) analysis, and the energy decomposition analysis (EDA). The amphoteric nature of XeO3 was also explored by investigating the extent of back donation from the lone pair of Xe to the antibonding orbital of the donating atom/group of the solvent molecules. The C-H…O interactions were also found to be a contributing factor in the stabilization of these adducts. Although these aerogen-bonding interactions were found to be predominantly electrostatic, significant contributions from the orbital contributions, as well as dispersion interactions, were observed. The top three non-aromatic solvents (among the twenty six studied) which form the strongest adducts with XeO3 are proposed to be hexamethylphosphoramide (HMPA), N,N'-dimethylpropyleneurea (DMPU) and tetramethylethylenediamine (TMEDA).

Density functional theory calculations, vibrational spectral analysis and topological analysis of 1-acethyl-2(4-isopropoxy-3-methoxyphenyl) cyclopropane with docking studies

A systematic spectroscopic investigationof 1-acethyl-2(4-isopropoxy-3-methoxyphenyl) cyclopropanewasperformed by utilizing Density functional theory approaches at B3LYP level usingGaussian 09 W software package. The FT-IR and FT-Raman techniques were utilized to assign the spectral properties of the title compound. On the basis of Natural Bond Orbital (NBO) analysis,the transfer of second order perturbation energies and ElectronDensity (ED) from filled lone pairs of Lewis base to unfilled Lewis acid sites wereanalysed. The chemical stability,distribution of energy and energetic behaviour of the compound were calculated from the Highest Occupied and Lowest Unoccupied Molecular Orbital (HOMO-LUMO) Analysis. The nucleophilic and electrophilic locales of the moleculewas perceived by the Molecular electrostatic potential (MEP). NCI investigation gives data around the inter and intra non covalent interlinkages. By using the Multiwavefunction software the topological analysis of ELF and LOL were performed. The chemical reactivity sites were determined by means of the fukui function. The assignments of vibrational spectra were computed using thevibration energy distribution analysis (VEDA). Drug similarityfactors were intended to understand the biological aspects. Vadar software was used to generate the Ramachandran plot. The bioactivity of the title compound was confirmed fromthe molecular docking studies.

Novel cyano functional small molecule photosensitizers with amplified electron injection and photovoltaic attributes: molecular modelling towards efficient dye‐sensitized solar cells

AbstractBACKGROUNDThe exploration of novel photosensitizers with reverberant optoelectronic features for dye‐sensitized solar cells (DSSCs) is a frontline area of research. In this respect, attempts have been made to design a series of novel organic dyes (JFK‐1–JFK‐10) with D‐π‐A framework by π‐spacer modification strategy. The suitability of developed sensitizers for DSSCs applications is confirmed by executing natural bond orbital (NBO) analysis, transition density matrix (TDM) analysis, frontier molecular orbital (FMO) analysis, density of state (DOS) analysis, binding energy (Eb), electron regeneration energy (ΔGreg), free energy of injection (ΔGinject), electronic coupling constant (VRP), and intramolecular charge transfer (ICT) parameters qCT (e‐), DCT (Å), H index (Å), ∆(Å), t index (Å), μCT (D).RESULTSThe calculated results of these analyses show that replacing the thiophene (B0) π‐spacer with extended conjugated thiazole and thiophene as a π‐spacer (B1‐B10) results in significantly lowered FMO energy levels, broader λmax values, and ICT parameters respectively. All the proposed dyes could be used as excellent sensitizers for DSSCs; the B9 spacer in JFK‐9 makes JFK‐9 a highly efficient candidate for the high‐efficiency of DSSCs due to promising photovoltaic characteristics, like the reduced Egap (4.386 eV), longer λmax(427.989 nm), longer excited state lifetimes (1.483 ns), a lower ΔGreg (1.807 eV), a greater dipole moment of (9.475 D), and large qCT (0.546), LHE (0.981), and eVOC (1.729 eV).CONCLUSIONThe fabricated dyes’ (F1‐F9) photoelectronic and chemical transfer parameters near the titania‐electrolyte interface (dyes@TiO2) proved have better accumulation and recombination of dyes@TiO2 model. The adsorption energies calculated of all compounds provide a deep insight into adsorption and charge transfer to a semiconductor TiO2 conduction band. Hence, these modeled dyes (JFK‐1‐JFK‐10) could be used as efficient DSSCs and open new avenues for researchers to synthesize high‐performance DSSCs. © 2024 Society of Chemical Industry (SCI).

A theoretical study for the linear free energy relationship of CH bond activation and the role of the axial ligand in cytochrome P450 model complexes

AbstractHydrogen abstraction is essential for CH bond activation by Compound I in cytochrome P450 and is influenced by various factors, including spin states, bond dissociation energies of the CH and FeOH bonds, axial ligands, and quantum mechanical tunneling. The role of axial ligands has been extensively studied, but it is still not fully understood. To explore their role, we used density functional theory calculations to determine whether a linear free energy relationship is established for the hydrogen transfer reaction, according to changes in axial ligands. The B3LYP* functional exhibits a strong linear correlation, but the slopes are inconsistent with the characteristics of the transition state. Natural bond orbital analysis reveals no direct orbital interaction between axial ligands and the reaction center of hydrogen transfer. The electron‐donating orbitals of the axial ligands weaken the FeO bond, lowering the energy barrier, but they do not directly participate in the intrinsic hydrogen transfer. During the reaction, the FeO bond length increases significantly before the hydrogen transfer itself, generating an asynchronous shift in the bond orders, and most of the activation energy is used for the increase in the FeO bond rather than the hydrogen transfer itself. This study may explain why there is no apparent correlation between the rate constants and the FeO bond strength.

Computational study on the characteristics of the complexes resulting from the interaction of carbonyl selenide and hypohalous acids

This study computationally investigates the properties and competition of complexes formed by the interaction between hypohalous acids (HOX, where X = F, Cl, Br, and I) and carbonyl selenide (COSe) at the MP2/aug-cc-pVTZ computational level. Three distinct groups of complexes were obtained. The first group, consisting of complexes with a cyclic structure (HB-TB), exhibited the highest stability. remaining two groups formed less stable linear structures with different characteristics (ChB and XB). In the first group, the electronegativity of the halogen atom significantly influenced the stability of the complexes. Conversely, the stability of complexes in groups II and III was primarily determined by the acid and base strengths of the interacting monomers. To comprehensively evaluate the obtained results, various analyses were employed, including Molecular electrostatic potential (MEP), geometry Optimization, Spectroscopic, Interaction energy (SE), Natural bond orbital (NBO) analysis, Atoms in molecules (AIM) analysis, Non-covalent interaction (NCI) index, Energy decomposition analysis (EDA), and Electron density difference(EDD) analysis.

Exploration of nonlinear optical properties of 4-methyl-4H-1,2,4-triazol-3-yl)thio)-N-phenylpropanamide based derivatives: experimental and DFT approach

Triazoles, nitrogen-containing heterocycles, have gained attention for their applications in medicinal chemistry, drug discovery, agrochemicals, and material sciences. In the current study, we synthesized novel derivatives of N-substituted 2-((5-(3-bromophenyl)-4-methyl-4H-1,2,4-triazol-3-yl)thio)-N-phenylpropanamide and conducted a comprehensive investigation using density functional theory (DFT). These novel structural hybrids of 1,2,4-triazole were synthesized through the multi-step chemical modifications of 3-bromobenzoic acid (1). Initially, compound 1 was converted into its methyl-3-bromobenzoate (2) which was then transformed into 3-bromobenzohydrazide (3). The final step involved the cyclization of compound 3, producing its 1,2,4-triazole derivative (4). This intermediate was then coupled with different electrophiles, resulting in the formation of the final derivatives (7a–7c). Additionally, the characterization of these triazole-based compounds (7a, 7b, and 7c) were carried out using techniques such as IR, HNMR, and UV–visible spectroscopy to understand their structural and spectroscopic properties. The DFT study utilized M06/6-311G(d,p) functional to investigate geometrical parameters, HOMO–LUMO energies, natural bond orbital analyses, transition density matrix (TDM), density of states, and nonlinear optical (NLO) properties. The FMO analysis revealed that compound 7c exhibited the lowest band gap value (4.618 eV). Notably, compound 7c exhibited significant linear polarizability (4.195 > × 10–23) and first and second hyperpolarizabilities (6.317 > × 10–30, 4.314 × 10–35), signifying its potential for nonlinear optical applications. These NLO characteristics imply that each of our compounds, especially 7c, plays a crucial part in fabricating materials showing promising NLO properties for optoelectronic applications.

Theoretical Evaluation of Eco-friendly Designed Nonionic Sugar-based Surfactants

Abstract: This study deals with the density functional theory calculations of eco-friendly designed nonionic sugar-based surfactants (SurfRing and SurfLinear). Then, it compares the results with the structural and electronic properties of a fatty alcohol surfactant (SurfFA). All geometry optimizations and energy calculations were performed using M06-2X functional and 6-31G(d,p) basis sets. The quantum chemistry reactivity parameters showed the effect of hydrophilic fragment structure on intramolecular interactions and conformational stability of surfactants. The results showed that SurfRing is more reactive than SurfFA. Based on Bader’s quantum theory of atoms in molecules (QTAIM), one intramolecular hydrogen bond (O43…H67―O57, EHB: -11.9 kcal.mol-1) is characterized for SurfRing, while two hydrogen bond interactions (O63…H60―O59 and O65…H64―O63 with EHB of -13.0, and -12.3 kcal.mol-1, respectively) form between the hydroxyl groups of SurfLinear. These intramolecular hydrogen bonds are partially covalent interactions. Natural bond orbital analysis reveals that the most prominent interaction energy is electron donation from the oxygen atom lone pair to the antibonding orbital of the O―H bond supporting the results obtained from the AIM calculations.

Superacidic Properties of Protonated PtFn (n = 1–6) and Their Ability to Form Supersalts: DFT Study

AbstractIn the present communication, this study has modeled protonated PtFn (n = 1–6), a new series of superacids. The calculated vertical de‐attachment energy (VDE) of PtFn (n = 1–6) reestablishes the superhalogenic behavior. The vibrational frequency, dissociation energy through the HF channel, and optimized geometries are utilized to discuss the stability of HPtFn (n = 1–6). The deprotonation energy of HPtFn is used to calculate the acidic strength of HPtFn (n = 1–6). The acidity of protonated PtFn (n = 1–6) is directly related to its counterpart superhalogen anions. The computed correlation factor (R2 = 0.9754) shows that VDE is directly associated with acidity. The mechanism of acidity of HPtFn (n = 1–6) is described by using natural bond orbital analysis charges on atoms. The electronic properties of HPtFn (n = 1–6) are calculated using the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy. The nature of chemical reactivity is also determined by the HOMO–LUMO plot of HPtFn (n = 1–6). It has formed the supersalts using superacids HPtFn (n = 1–6) and superbase (OLi3OH), and the nature of supersalts is compared with traditional salt LiF. The most stable conformers of supersalts PtFnOLi3 (n = 2–6) are analyzed for optoelectronic properties. It has computed the dissociation of supersalts through neutral and anions through superhalogns and superalkalis. The computed results show that PtF4OLi3 favors dissociation through anions as in traditional salts. The nonlinear optical parameters are calculated using dipole moment, mean polarizability, anisotropic polarizability, molar reflectivity (MR), order parameters, and hyperpolarizability of PtFnOLi3 (n = 2–4). The estimated nonlinear optical properties parameters are compared with corresponding parameters of traditional salt LiF by the same level theory.

Exploration of one-dimensional hydrogen bonding organic framework (1D-HOF) and charge transfer dynamics in N’-benzylbenzohydrazide: A comprehensive structural and quantum computational investigation

This study presents a comprehensive structural analysis of N’-benzylbenzohydrazide (NBBH) using experimental and computational techniques, shedding light on its non-covalent interactions and charge transfer dynamics. Single crystal X-ray diffraction studies confirm the three-dimensional molecular structure with high precision, revealing an orthorhombic crystal system and non-planarity of the NBBH molecule. Supramolecular interactions, including hydrogen bonds and short intermolecular interactions, are investigated, forming the basis for the assembly of molecular entities into extensive frameworks. Hirshfeld surface analysis provides insights into the intermolecular interactions in the crystal system, with the visualization of hydrogen bonds and short contacts. Energy framework analysis further explores pairwise interaction energies, emphasizing the role of dispersive forces in stabilizing the crystal lattice. Density functional theory studies, including molecular orbital analysis and global chemical reactivity descriptors, offer a deeper understanding of the electronic structure, redox potential, and charge transfer properties of NBBH. Natural bond orbital analysis reveals the charge transfer mechanism within the 1D Hydrogen-Bonded Organic chain, highlighting hyperconjugative interactions contributing to the stabilization of the molecule. Non-covalent interaction analysis using the Reduced Density Gradient method visualizes intra and intermolecular interactions, providing valuable insights into the formation and stability of the 1D network chain in the crystal structure of NBBH. Reorganization energy is discussed in the context of electron and hole transfer processes, emphasizing its importance in understanding the charge transfer dynamics within the molecular framework. The observed inverse relationship between reorganization energy and charge mobility contributes a key insight into the stability and conductivity of the material. The electron charge density distribution analysis, provides a detailed spatial distribution of electrons within the NBBH molecule. The findings have implications for understanding the molecular properties and potential applications of NBBH in various fields.

Structure and molecular interactions in 1‑ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ion pair conformers: abinitio DFT based study

Density functional theory (DFT) calculations with Grimme’s B97D functional including dispersion are employed to provide both structural and electronic insight into the multifold interactions occurring in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid [EMI][TFSI], which is currently being targeted for applications in next-generation Li-ion battery electrolytes. The geometric structure, interaction energy and natural bond orbital analysis of the ion-pair conformers of [EMI][TFSI] show differences from the conventional H-bonds. A total of six stable [EMI][TFSI] ion pair conformers were observed. Our results show that a doubly ionic H-bond exists between [EMI]+ and [TFSI]− ion pair conformers. The greater the number of multiple H-bond type interactions, the greater the absolute value of the interaction energy. Moreover, results from the NBO analysis show that, for [EMI][TFSI] ion pair conformers, charge transfer occurs mainly from the lone pairs of oxygen and nitrogen atom to the σ-type anti-bonding orbital of the C–H and π-type anti-bonding orbitals of N–C bonds. This was evident from the values of the stabilization energy E(2) associated with each electron delocalization from the donor to acceptor orbitals. There exist large numbers of multiple concomitant hydrogen bonds, but the values of the stabilization energy E(2) are generally small (E(2)n→\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ o$$\\end{document}σ* < 3 kcal/mol) for the individual H-bond interactions. The shorter the C–H···O and/or C–H···N bond is, the larger charge transfer, and the larger the stabilization energy E(2) associated with electron delocalization from donor to acceptor. Generally, the [EMI][TFSI] ion pair conformers tend to form multiple but bent H bonds, reducing the strength of the individual H bonds from a potential (linear) maximum.

A Quantum Chemical Investigation on Structural, Spectroscopic and Nonlinear Optical properties of an Organic Molecule Serotonin

Serotonin, a neurotransmitter known for promoting feelings of happiness and optimism, was the subject of theoretical studies conducted using Gaussian software. In these experiments, the 6-311++G/B3LYP basis set was employed. The finite-field-based B3LYP/6-311++G (d,p) approach was used to compute the first-order hyper polarizability and associated properties of this chemical system. Additionally, a Natural Bond Orbital (NBO) analysis was conducted to assess the molecule's stability, taking into account hyper conjugative interactions and charge delocalization. Additionally, HOMO-LUMO energy levels were computed to assess whether a chemical exhibits electrophilic or nucleophilic characteristic. TD-DFT simulations were conducted to examine the electrical and optical characteristics of the material, including absorption wavelengths and excitation energy. Subsequently, the chemical compound's electrophilic or nucleophilic nature was determined by calculating the molecular electrostatic potential (MEP).

Experimental and DFT Investigation of 6‐arylated‐pyridin‐3‐yl methanol Derivatives

AbstractAn investigation based on synthesis of 6‐arylated‐pyridine‐3‐yl)methanol derivatives: 6‐(2‐benzofuranyl)pyridin‐3‐yl)methanol (BFPM), (6‐([biphenyl]‐4‐yl)3‐pyridinyl methanol (BPPM), 6‐(3‐Flourophenyl)‐4‐pyridine‐methanol (FPPM), and 6‐(4‐Chlorophenyl)‐4‐pyridine‐methanol (CPPM) compounds is presented in this study. Furthermore, a comparison of experimental spectroscopic data (NMR, FTIR, UV‐Vis), structural factors, nonlinear optical characteristics with theoretical frontier molecular orbital analysis, natural population analysis, natural bond orbitals analysis of pyridine derivatives is drawn using density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) at the B3LYP/6‐311+G (2d,p) level of theory was used. Therefore, the DFT‐based findings and experimental data were in perfect accord. By using NBO analysis, it has been possible to understand how charge delocalization and HP interactions contribute to molecule stability. Moreover, the FMO energy levels were used to calculate global reaction characteristics, which showed that FPPM with the highest ▵ELUMO – HOMO of 4.91 eV, was less reactive and more stable than BFPM, BPPM, and CPPM. Compared to the prototype compound, NLO studies revealed that BFPM, BPPM, FPPM, and FPPM exhibit better characteristics, revealing their potential for use in photoelectric technology.

Synthesis, crystal structure, spectroscopic and computational studies of NLO active 2-methylimdazolium 4-nitrobenzoic acid single crystal

In this report, we have presented the theoretical and experimental investigation of 2-Methylimdazolium 4-Nitrobenzoic Acid (2MI4NB) – an organic crystal. The good quality 2MI4NB single crystal was grown by slow evaporation technique. Both single and powder X-ray diffraction (XRD) analysis confirmed that the grown crystal structure is Triclinic with the P1 space group. The vibrational modes present in the chemical were validated through Fourier transform infrared (FT-IR) spectrum investigations. Density functional theory (DFT), a quantum chemical approach, has emerged as a potential or an effective tool for studying molecular structure and NLO properties and is being used frequently in applications involving NLO systems. HOMO-LUMO analysis and reactivity parameters were calculated. Molecular Electrostatic Potential (MEP), Natural Bond Orbital (NBO) analysis and first order hyper polarizability were studied by B3LYP theoretical level with 6-311++G(d,p) basic set. In addition, the Mulliken Atomic Charge was calculated with the same basic set. The thermal properties of the 2MI4NB crystal was analysed by TG-DTA studies. It shows that the two endothermic peaks were observed. The optical absorption spectrum shows that there is no absorption in the region of 430–1200 nm. The Z-scan analysis gives the third order NLO properties like refractive index and third-order NLO susceptibility of 2MI4NB crystals.

Solvation effects, structural, vibrational analysis, chemical reactivity, nanocages, ELF, LOL, docking and MD simulation on Sitagliptin

Sitagliptin is a medication used to manage type-2 diabetes. The present study investigates the experimental and theoretical results of Sitagliptin (SG). Density functional theory (DFT) calculations were used to determine optimized parameters at the B3LYP functional /6-31++G(d,p) basis set. In addition Time-dependent DFT is used to compute excited states of SG and SG-Ag6 and predict UV spectra. The electronic properties of silver nano cages containing SG have exhibited a notable enhancement. Natural bond orbital (NBO) analysis was also used to determine charge transfer within the molecule and stabilization energy. Electronic properties such as molecular electrostatic potential (MEP), frontier molecular orbital (FMO) analysis of SG and SG-Ag6 were investigated. The chemical significance of SG has been discussed using electron localization function (ELF) and local orbital locator functions (LOL) with contour images. Sitagliptin appears to have promise as a treatment for the chosen inhibitors, according to the docking binding affinities and the formation of a significant amount of hydrogen bonds. The molecular dynamics simulations were also performed using Gromacs 5.1.3 and discussed.

Single-and double transition metal atoms anchored C2N as a high-activity catalyst for CO oxidation: A first-principles study

The oxidation of CO has attracted great interest in recent years due to its important role in enhancing the catalyst durability in fuel cells and solving the growing environmental problems caused by CO emissions. Consequently, the catalytic oxidation of CO at double non-noble metal atoms anchored C2N is investigated using density functional theory (DFT) computations. All the screened Ti@C2N and Ti2@C2N are thermodynamically stable based on their binding energy calculations. The electronic characteristics, the natural bond orbital analyses (NBO), Frontier orbital, statistical thermodynamics, projected densities of states (PDOS) characteristics, non-covalent interactions (NCI), and quantum theory of atoms in molecules (QTAIM) descriptors of these systems have been examined to analyze the interaction process. Our comparative study suggested that the newly predicted double-atom catalyst (Ti2@C2N) is highly active for CO oxidation, which is a useful guideline for further development. The calculated static first-order hyperpolarizability (βo) illustrated that the double-atom catalyst under investigation can be considered a potential candidate for non-linear optical behavior and could be used for NLO applications. CO oxidation on Ti2@C2N along the Eley–Rideal (ER) mechanism with a low energy barrier of 0.16 eV, which is smaller than the maximum energy barrier (0.73 eV) of CO oxidation along the Langmuir–Hinshelwood (LH) mechanism. Consequently, the ER mechanism is more favorable both thermodynamically and dynamically. This work can provide useful insights and guidelines for future theoretical and experimental investigations to promote the design and development of highly effective and low-cost non-precious-metal Ti2@C2N nanocatalysts towards CO oxidation at ambient temperature.

A data-guided approach for the evaluation of zeolites for hydrogen storage with the aid of molecular simulations.

This study employs a data-guided approach to evaluate zeolites for hydrogen storage, utilizing molecular simulations. The development of efficient and practical hydrogen storage materials is crucial for advancing clean energy technologies. Zeolites have shown promise as potential candidates due to their unique porous structure and tunable properties. However, the selection and design of suitable zeolites for hydrogen storage remain challenging. Therefore, this work aims to address this materials science question by utilizing molecular simulations and data-guided approaches to evaluate zeolites' performance for hydrogen storage. The results obtained from this study provide valuable insights into the evaluation of zeolites for hydrogen storage. Through molecular simulations, we analyze the adsorption behavior of hydrogen molecules in various zeolite structures. The performance of different zeolite frameworks in terms of hydrogen storage capacity, adsorption energy, and diffusion properties is assessed. Linde type A zeolite (LTA) had the highest capacity with a hydrogen capacity of 4.8wt% out of the 233 investigated zeolites. Furthermore, we investigate the influence of different factors such as mass (M), density (D), helium void fraction (HVF), accessible pore volume (APV), gravimetric surface area (GSA), and largest overall cavity diameter (Di) on the hydrogen storage performance of zeolites. The results show that Di, D, and M have a negative effect on the percentage weight capacity, while GSA and VSA have the highest positive contribution to the percentage weight. This study, therefore, provides new insights into the factors that affect their hydrogen storage capacity by exhibiting the importance of considering multiple factors when evaluating the performance of zeolites and demonstrates the potential of combining different computational methods to provide a more comprehensive understanding of materials. The current study contributes to the understanding of zeolite-based materials for hydrogen storage applications, aiding in the development of more efficient and practical hydrogen storage systems. Computational techniques were employed to investigate the hydrogen storage properties of zeolites. Molecular simulations were performed using classical force fields and molecular dynamics methods. The calculations were carried out at a force field level of theory with the GGA functional. To accurately capture the thermodynamics and kinetics of hydrogen adsorption, enhanced sampling techniques such as Monte Carlo simulations and molecular dynamics with metadynamics were utilized. We employed Grand Canonical Monte Carlo (GCMC) simulations to model hydrogen adsorption in zeolite structures for hydrogen storage. Our approach involved performing a substantial number of Monte Carlo steps (10,000) to ensure system equilibration and precise results. We defined a cutoff distance for particle interactions as 12.5 Ǻ and considered 0.000e framework charge per cell and 0.000e sorbate charge in energy calculations. The choice of an appropriate simulation cell size (50 × 50 × 50) Ǻ was crucial, mirroring real-world conditions. We specified lower and upper fugacity values (1 to 10atm) to capture the range of gas pressures in the simulations. These methodical steps collectively enabled us to accurately model hydrogen adsorption within zeolites, forming the core of our hydrogen storage evaluation. In this research, we utilized DFT calculations to thoroughly investigate the interactions between zeolites and hydrogen. We employed pseudopotentials to describe electron behavior in zeolite systems, choosing them in line with DFT norms and basis set compatibility. Our simulation cell design replicated zeolite periodicity and eliminated boundary effects. Pre-geometry optimization was performed with HyperChem29, ensuring stable conformations with strict convergence criteria. We utilized 6-31 + G(d) and LanL2DZ basis sets for light and heavy atoms, aligning with field standards for computational efficiency and precision. A machine learning algorithm was used to rank the importance of various structural features such as mass (M), density (D), helium void fraction (HVF), accessible pore volume (APV), gravimetric surface area (GSA), and largest overall cavity diameter (Di) and how they affect the capacity of the zeolites. Machine learning analysis was performed with the Scikit-learn library, an open-source Python tool. We employed a range of machine learning models, including SVMs, random forests, and neural networks, primarily for data analysis and feature extraction. Pearson correlation analysis, a classical statistical technique, was used to evaluate linear relationships between variables and assess the strength and direction of these relationships. It served as a complementary tool to understand the interplay of variables in our dataset, distinguishing it from machine learning algorithms. Further quantum chemical calculations were also performed to calculate the adsorption energy, global reactivity electronic descriptors, and natural bond orbital analysis in order to provide insights into the interaction of the zeolites with hydrogen. The simulations and data analysis were performed using BIOVIA material studio software, Gaussian, and Origin Pro software.

Theoretical investigations on electronic structure and optoelectronic properties of vinyl fused monomeric and oligomeric benzimidazole derivatives using DFT and TDDFT techniques.

The present work encompasses the theoretical investigation of 14 benzimidazole-based (seven vinyl fused monomeric benzimidazole (VFMBI) and seven vinyl fused oligomeric benzimidazole (VFOBI)) derivatives using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) techniques. The effects of electron donor and acceptor groups on the electronic structure such as HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies, HOMO-LUMO energy gap, ionization potentials (IPs), electron affinities (EAs), internal reorganization energies of holes and electrons (λh/e), and excited state properties have been explored in the present work. In addition, natural bond orbital (NBO) analysis of these compounds has been investigated to reveal the typical stabilization interactions in these molecules. Hence, the aim of the present work is to explore the electronic structures and optoelectronic properties of the title molecules on the basis of the DFT quantum chemical calculations and to make an idea on the parameters influencing the optoelectronic efficiency toward a better understanding of the structure-property relationships. Moreover, the calculated results reveal the suitable optoelectronic properties of benzimidazole oligomer derivatives using theoretical techniques. Of the investigated molecules, 4_MABIMCY and 4_MABIOCY show potential optoelectronic properties and can be used as a potential charge transport material due to their narrow band gap, high hyperpolarizability, low ionization potential, and high electron affinity. The larger λab and λem values favor the system to be used as a potential optoelectronic material with better optical properties. All quantum chemical calculations were carried out using Gaussian09 theoretical chemistry code. Ground state calculations were made using the B3LYP/6-31+G(d,p) method. All excited state calculations had been computed using TDB3P86/6-311++(d,p). The initial structure for excited state calculations was optimized using the AM1 semi-empirical method.

Detection of C6H6, CO2, and H2S gases on arsenic (As) and cobalt (Co) doped quantum dots (QDs) nanostructured materials

Abstract Gas sensors exhibit significant potential due to their widespread use in various applications, such as food packaging, indoor air quality assessment, and real-time monitoring of man-made gas emissions to mitigate global warming. The utilization of nanostructured materials for sensor and adsorbent surfaces has seen remarkable growth over time, though substantial efforts are still needed to develop more efficient adsorbents. Consequently, this study investigates the viability of metal-doped quantum dots (QDs) as prospective gas-sensing and adsorption materials. Density functional theory (DFT) calculations employing the 6-311 + G(d,p) basis set and three functionals (B3LYP, B3LYP-GD3(BJ), and ɷB97XD) were utilized for this investigation. Three environmentally and health-significant gases (C6H6, CO2, and H2S) were chosen as adsorbates on arsenic (As) and cobalt (Co) functionalized QDs to assess the performance and sensing capabilities of resulting QD surfaces. The analysis encompassed computation of adsorption energy, thermodynamic properties, non-covalent interactions, natural bond orbital analysis, and other topological aspects for both the surfaces and gases. The outcomes indicate that the GP_As functionalized surface exhibits a lower energy gap, rendering it more reactive and sensitive toward the respective gases (C6H6, CO2, and H2S). Moreover, the calculated adsorption energies of the investigated systems indicate thermodynamic favorability and spontaneity. Notably, our findings suggest that QD_As surfaces possess superior adsorption potential for H2S compared to the other gases examined; nonetheless, all studied QD surfaces demonstrate significant adsorption capacities for C6H6, CO2, and H2S gases.