Atomic Charge Distribution Research Articles

Molecular dynamics simulation for damping properties of PDMS composite enhanced by the last generation siloxane dendrimer alcohol with hydroxyl terminal groups

In this study, the damping properties of PDMS composite enhanced by last generation siloxane dendrimer alcohol with hydroxyl terminal groups G3-OH were evaluated by all atomic molecular dynamics simulation (AAMDS) method in terms of damping loss factors (DLFs) tanδ, compositional miscibility (|δi−δ0|), cohesive energy density (CED), binding energy (EB) and maximum free volume fraction (FFVmax). Based on the total atomic charge distribution, further, the potential damping mechanism in composite PDMS/G3-OH(100/47) was explored. The simulation results showed that the |δi−δ0| of composite PDMS/G3-OH(100/47) was 0.0939 (J/cm3)0.5, whose good compatibility between the two components laid a solid foundation for the excellent damping performance. As the argument, the tanδ, CED, EB and FFVmax of composite PDMS/G3-OH(100/47) were 0.8073, 1.668 (J/m3)×108, −19877.607 kcal/mol as well as 39.85 % respectively, which were better than 1.2439, 1.390 (J/m3)×108, −14539.327 kcal/mol and 40.71 % of pure PDMS matrix material PDMS/G3-OH(100/0). Furthermore, the multiple hydrogen bond mechanism can perfectly explain the structure-activity relationship between the internal structure and the excellent damping properties of composite PDMS/G3-OH(100/47). Specifically, a total of 19 α-type hydrogen bonds were formed in the composite PDMS/G3-OH(100/47). All in all, according to the evaluation of AAMDS method, the PDMS composite enhanced by 47-equivalent last generation siloxane dendrimer alcohol with hydroxyl terminal groups G3-OH had outstanding damping properties.

Spectroscopic characterization, quantum chemical and molecular docking investigations on methyl indole-3-carboxylate: A potent cervical cancer drug

Bioactive indole derivatives had great importance in recent years due to their numerous biological and pharmaceutical applications. In the present work, the vibrational, electronic, physicochemical, and inhibitory properties of the Methyl Indole-3-Carboxylate (MIC) molecule were predicted and analyzed. Initially, the molecular structure of the title molecule was optimized and its structural parameters were calculated, which were highly correlated with the previous reports. The simulated infrared and Raman spectra of the molecule were in good agreement with the FT-IR and FT-Raman spectra that were observed via the experiment. The observed UV–Visible spectrum validates the MIC molecule's π→π* electronic transition, which was also well matched with the simulated UV–Visible spectrum. The investigation of frontier molecular orbitals highlights intramolecular charge transfer across the molecule, establishing the bioactivity of the MIC molecule. The electron transport from the methyl group hydrogen atom H22 to the oxygen atom O11 is confirmed by Mulliken atomic charge distribution analysis and molecular electrostatic potential surface analysis. The calculated Fukui functions values validated the FMOs and Mulliken atomic charge distribution results. The natural bond orbital study further confirms the MIC molecule's intramolecular charge transfer and bioactivity. Molecular docking investigation results that the MIC molecule hinders the function of an enzyme known as Mitogen-activated protein kinase 14, which has been linked to cervical cancer. As a result, the present study provides the possibility towards the development of innovative to treat cervical cancer.

Comprehensive structural characterization and Quantum mechanical exploration of o-phenylenediamine Dihydrogenphosphate: An integrated theoretical and experimental approach

Inorganic-organic hybrid materials merge the best of both inorganic and organic properties, enabling enhanced performance in diverse applications. The present study elucidates the crystallographic attributes of O-Phenylenediamine Dihydrogenphosphate (OPDP; C6H11N2O4P), crystallized in an ethanol medium. Characterized by a triclinic lattice, the asymmetric unit contains a single molecule (Z'=0), while the unit cell is comprised of eight molecules (Z = 2). The overall architecture is connected by intermolecular NH···O hydrogen bonds, which give rise to a bi-dimensional supramolecular framework. To substantiate the experimental findings and to probe the molecule's particular attributes, Fourier Transform Infrared Spectroscopy was deployed, owing to its sensitivity to inter/intra-molecular interactions within crystal systems. Density Functional Theory (DFT) calculations were performed using B3LYB functional, yielding molecular structure optimization, vibrational frequencies, and molecular properties such as Mulliken atomic charge distribution and frontier molecular orbital. Functional groups were discerned using FTIR spectroscopy and compared with theoretical predictions. The molecule features fourteen HH and three OH bonds. Natural Bond Analysis (NBO) was conducted to evaluate stabilization energy in donor–acceptor transitions. Surface morphology was examined using Scanning Electron Microscopy (SEM) in conjunction with Energy-Dispersive X-ray Spectroscopy (EDX). This comprehensive study advances our understanding of the unique structural and molecular properties of OPDP, demonstrating its potential for multifaceted applications.

New modified thieno[2,3-d]pyrimidine derivatives as VEGFR-2 inhibitors: Design, synthesis, in vitro anti-cancer evaluation and divers in silico studies

Angiogenesis is a critical regulatory mechanism for tumor development and metastasis. Tumor growth is closely related to the production of the vascular endothelial growth factor (VEGF), which is mediated by the cell-surface kinase VEGFR-2. Accordingly, blocking of VEGFR-2 is an important approach to find new treatments for malignancies. The aim of this research is the synthesis of new thieno[2,3-d]pyrimidine derivatives that could be potential anticancer leads inhibiting VEGFR-2. The prepared thieno[2,3-d]pyrimidine derivatives were tested in vitro for their inhibitory effects against the kinase activity of VEGFR-2. In addition, the synthesized compounds were assessed for their anti-proliferative activities against MCF-7 and HepG2 cell lines. Compound 4c displayed the strongest anti-VEGFR-2 potentiality with an IC50 value of 0.15 µM and exhibited good anti-proliferative effects against HepG2 and MCF-7 cells with IC50 of 17.14 and 11.56 µM, respectively. Compound 4c induced cell cycle arrest at the S phase and boosted early and late apoptosis in MCF-7 cells. Additionally, compound 4c increased BAX (4.5-fold), decreased Bcl-2 (3.5-fold), and demonstrated a notable increase in caspase-8 (2.9-fold) and caspase-9 (3.3-fold) levels. Furthermore, compound 4c significantly reduced TNF-α (3.6-fold) and IL-6 (3.2-fold) levels in MCF-7 cells. Molecular docking studies indicated good binding affinities as well as energies of the thieno[2,3-d]pyrimidine derivatives against the VEGFR-2. Molecular dynamics (MD) simulations were utilized to study the structural, energetic, and conformational changes of the VEGFR-2–4c complex, and the results indicated its stability. The MM-GBSA study of the VEGFR-2–4c complex showed a stable thermodynamic behavior with a binding free energy of -44 kcal/mol. The PLIP analysis identified the 3D interactions and binding conformation through the VEGFR-2–4c complex. Moreover, the DFT studies have been performed to study, Mullikan atomic charge distribution, FMO, ESP, the total density of state, and the QTAIM maps of compound 4c to theoretically verify its reactivity. Finally, computational ADMET and toxicity studies were conducted to assess the drug development potential of the thieno[2,3-d]pyrimidine derivatives.

Machine-learning-accelerated structure prediction of PtSnO nanoclusters under working conditions.

Credible property exploration or prediction can not be achieved without well-established compositions and structures of catalysts under working conditions. We construct surrogate models via combination of machine learning (ML), genetic algorithm (GA) and ab initio thermodynamics (AITD) to accelerate global optimization of PtSn binary metal oxides, which are typically used for CO2-assisted propane dehydrogenation to propylene. This challenging case illustrates that the subtle oxidized states of PtSnO clusters can be predicted in a large chemical space including a wide range of reaction conditions. The oxidation patterns, phase diagrams and atomic charge distributions of the PtSnO clusters have been discussed. The Sn decorating mechanism to Pt in PtSnO has been explained. These results also indicate that the oxidation of PtSn clusters is more feasible under working conditions, and that previous understanding obtained only with a fully reduced PtSn alloy may be incomplete.

Mechanistic studies of HF/BF3-catalyzed anthracene polymerization to prepare mesophase pitch.

The mesophase pitch prepared by acid catalytic method typically had the advantages of low softening point and high solubility. To fully understand the mechanism of acid-catalyzed reactions and gain a deeper understanding of the microstructure of mesophase pitch, this article studied the mechanism of hydrofluoride/boron trifluoride (HF/BF3)-catalyzed anthracene using molecular simulation methods. The results showed that there might be two types of carbocations present in the system: classical and non-classical carbocations, and five reactions might occur, protonation reaction, chain elongation reaction, intramolecular cyclization reaction, deprotonation reaction, and dehydrogenation reaction. Classical carbocations acted as reactive intermediates in the chain elongation reaction and intramolecular cyclization reaction. When anthracene occurred chain elongation reactions with carbocations to form polymers, the generation of the tetramer required lager energy barriers than that of the dimer and trimer. The stiffness and flatness of molecules could be increased via intramolecular cyclization reactions. The polymers of anthracene might also occurred dehydrogenation reactions when the non-classical carbocations played the role of reactive intermediates. The dehydrogenation reactions required large energy barriers, which might be the reason for the product having a high aliphatic hydrogen content. The Materials Studio (MS) 2020 software was used to complete the simulation. The atomic charge distribution calculation and the structure optimization of molecules were carried out using the B3LYP functional and DNP basis. The DFT-D (TS) dispersion corrections were added to calculate the dispersion interaction between aromatic molecules. The complete LST/QST method was used to search the transition states and calculate the reaction energy barrier.

Exploration of 4-Chloro-3-nitrocoumarin: Spectroscopic Analysis, DFT Insights, Molecular Docking, Assessments of Antibacterial and In Vitro Anticancer Activities as a Potent Bioactive Agent

The detailed theoretical and experimental (FT-IR, FT-Raman, UV-visible) spectroscopy analyses of the 4-Chloro-3-nitrocoumarin (CNC) molecule were carried out. The CNC compound's pharmacological properties were also investigated utilizing antibacterial and anticancer activity investigations. Initially, the CNC molecule was optimized by the density functional theory B3LYP method with a cc-pVTZ basis set using the Gaussian 09W program. The optimized molecular structure provides the harmonic vibrational frequencies of the CNC molecule. The observed and computed vibrational wavenumbers were assigned and found to be well correlated. UV-Vis absorption spectrum analysis indicates that the molecule contains π→π* electronic transition. Frontier molecular orbitals (FMOs) analysis indicates that the LUMO of CNC molecule is mainly located over the nitro group, it indicates that the nitro group is particularly prone to accepting electrons from other molecules and participate in chemical reactions where acts as an electrophile. Mulliken atomic charge distribution analysis further confirms the FMOs results. The antibacterial test results validate that the CNC molecule exhibits a stronger inhibitory effect on Staphylococcus aureus compared to the other tested bacteria. In vitro anticancer cytotoxicity analysis clearly evidences that the CNC compound inhibits the growth of HeLa cervical cancer cell lines more than A549 lung cancer cell lines. In silico molecular docking study further validates that the CNC molecule inhibits the function of the p38a Mitogen-activated protein kinase 14, which has been associated with cervical cancer. As a result, the present study paves the way for the development of new drugs to treat cervical cancer.
 Keywords: 4-Chloro-3-nitrocoumarin; DFT; FT-IR; FT-Raman; Anticancer; Molecular docking; Cervical cancer drug.

1,10‐Phenanthroline‐Based Octahedra Induced by Protonation of a Nitrogen Atom: Structures and Emission Properties

AbstractAlthough a few metal‐free octahedral compounds based on nitrogen‐containing ligands are known, the realization of mixed ligand compounds remains difficult. To obtain an improved understanding of this class of compounds, two new octahedral compounds, [(tmphenH)(phen)]PF6, and [(tmphenH)(tmphen)]PF6 (where tmphen=3,4,7,8‐tetramethyl‐1,10‐phenanthroline and phen=1,10‐phenanthroline), were synthesized. The relationship between the emission properties, as evaluated using experimental measurements and theoretical calculations, and structures of the protonated compounds was studied. In addition, differences between the atomic charge distributions and geometries in the ground and singlet excited states were investigated using density functional theory calculations. Both [(tmphenH)(phen)]PF6 and [(tmphenH)(tmphen)]PF6 formed hydrogen‐bonded octahedrons in acetonitrile solution, even in the excited state. However, the hydrogen bonding in [(tmphenH)(phen)]PF6 was weak and thermal vibrations decreased the emission intensity. In contrast, the additional methyl substituents in [(tmphenH)(tmphen)]PF6 suppressed thermal vibrations, resulting in a higher emission intensity.

Spectroscopic Characterization, Quantum Chemical, Molecular Docking, Antibacterial and Anticancer Studies on Ethyl Coumarin-3-Carboxylate: an Antibacterial and Lung Cancer Agent

The detailed theoretical and experimental (FT-IR, FT-Raman, UV-visible) spectroscopy analyses of the Ethyl Coumarin-3-Carboxylate (ECC) molecule were carried out. The ECC compound’s pharmacological properties were also investigated, utilizing antibacterial and anticancer activity investigations. Initially, the ECC molecule was optimized by the density functional theory B3LYP method with a 6-311 G++ (d,p) basis set using the Gaussian 09 W program. The optimized molecular structure provides the harmonic vibrational frequencies of the ECC molecule. The observed and computed vibrational wavenumbers were assigned and found to be well correlated. UV-Vis absorption spectrum analysis indicates that the molecule contains π →π* and n → π* electronic transitions. The Frontier molecular orbital analysis confirmed the molecular reactivity and bioactivity of ECC, while the Mulliken atomic charge distribution analysis pinpointed the molecule’s reactive sites. Antibacterial testing demonstrated the ECC compound’s inhibitory effect on various bacterial strains, with a particular impact on Klebsiella pneumonia. In vitro, anticancer assessments showcased ECC's stronger inhibitory effects on A549 lung cancer cell lines compared to HeLa cervical cancer cell lines. Additionally, in silico molecular docking investigations provided further validation that the ECC compound can inhibit the function of the epidermal growth factor receptor, a factor associated with lung cancer. As a result, this study lays the foundation for the development of novel drugs for lung cancer treatment.

COMPUTATIONAL MODELLING OF THE ACTIVATION PARAMETERS OF DIELS ALDER REACTION OF QUINOFLAVONOID AND 2, 3 DIMETHYLBUTA-1, 3-DIENE

Kinetics and thermodynamics of Diels alder reaction of quinoflavoniod and 2, 3 dimethylbuta-1,3-diene was studied using ab-initio method with Hartree Fock at 6-311G* basis set in spartan, Conformational search was carried out on the molecules to obtain the structures that has the lowest energy, an indication of the stability of the structure. Reaction path calculation was done on the most stable structure using C26 – C15 and C27 – C14 as reaction coordinate in 20 iterations, this was done to ascertain the reaction mechanism. Geometric calculation was carried out on the structures of the reactant, transition state and products to obtain the bond length, bond angle, dihedral angle and atomic charge distributions. Kinetics and thermodynamic parameters was calculated at 3480C. The reaction proceeded through a concerted asynchronous six-membered cyclic transition state. True saddle point was characterized and verified by the presence of only one imaginary vibrational frequency which smoothly connect the reactant, the transition state and the product. Negative values obtained for ?H* (-66.65kJ/mol shows that the reaction is exothermic and according to literature this may be as a result of conversion of two of the ?-bonds to two new ?-bonds). Values obtained for energy of formation (-1329.974 hatrees, -1329.911 hatrees, and 1330.023 hatrees for GS, TS and PRD respectively) according to Hammond’s postulate, confirms the exothermicity of the reaction. ?Greaction (-60.16kJ/mol, shows that the reaction is favourable, Negative ?S* (-11.29J/mol.K) suggests the spontaneity of the reaction and Ea (-63.76kJ/mol) suggests that the reaction involves transfer of electrons. It was also observed that rate constants decrease with increase in temperature, although very uncommon but suggested a complex reaction mechanism.

A COMPUTATIONAL DENSITY FUNCTIONAL THEORY INVESTIGATION OF THE INTERACTION OF BORON NITRIDE NANOSHEETS WITH MULTIPLE MOLECULAR HYDROGENS

In this study, the adsorption of molecular hydrogens (H2) on boron nitride (BN) frameworks was investigated using the density functional theory (DFT) technique. The results of optimized geometric structures revealed that molecular hydrogens were favourably adsorbed on top of nitrogen atoms in the BN monolayers. In addition, the optimized equilibrium geometries were utilized to calculate the electronic structures, including binding energies, energies of the highest and lowest occupied molecular orbitals (HOMO and LUMO), molecular electrostatic potentials (MEPs), and Mulliken atomic charges (MACs). The binding energy values were calculated to be approximately 0.01 eV per molecular hydrogen based on the results. As the number of molecular hydrogens increased in the BN framework, a slight increase was observed in the binding energy value per hydrogen molecule. Furthermore, the HOMO–LUMO gaps were determined with the corresponding energy values of about 6 eV. Regarding the Frontier molecular orbitals (FMOs) diagrams, the electron densities for the HOMOs of the studied systems were primarily focused on the N-edges. Conversely, for the LUMO, the electron density distribution was localized in the B-edges of titled systems. In the context of hydrogen adsorption on BN nanosheets, the MEP maps indicated that hydrogen atoms at the N-edges of the studied systems exhibited the most positive electrostatic potentials in this research. In contrast, surfaces with negative electrostatic potential surfaces were situated in the region close to B-edges. The computed results are consistent with the corresponding Mulliken atomic charge distributions. From the analyses of the Mulliken scheme, all nitrogen atoms displayed negative charge values, and positive charges were found on the boron atoms. The DFT results obtained in this report may serve as the foundation for developing hydrogen storage materials

Structural Study of a La(III) Complex of a 1,2,3-Triazole Ligand with Antioxidant Activity.

The 1,2,3-triazole derivative 2-(4-chlorophenyl)-5-(pyrrolidin-1-yl)-2H-1,2,3-triazole-4-carboxylic acid with potential anticancer activity was used as a ligand in complex formation with the lanthanum(III) ion. The molecular structure and vibrational spectra of the complex were optimized at three DFT levels, and the scaled IR and Raman spectra were compared to the experimental ones. Several scaling procedures were used. Through a detailed analysis, the structure predicted for the newly synthetized La(III) complex was confirmed by the good accordance of the calculated/experimental IR and Raman spectra. The best DFT method appeared to be M06-2X with the Lanl2mb basis set, followed closely by Lanl2dz. The effect of the lanthanide atom on the molecular structure and atomic charge distribution of the triazole ring was evaluated. The potential free radical scavenging activity of both the ligand and the complex was investigated in several radical-generating model systems. The potential mechanisms of antioxidant action (hydrogen atom transfer (HAT) and single-electron transfer (SET)) were elucidated.

Swarm Smart Meta-Estimator for 2D/2D Heterostructure Design.

Two-dimensional (2D) semiconductors are central to many scientific fields. The combination of two semiconductors (heterostructure) is a good way to lift many technological deadlocks. Although ab initio calculations are useful to study physical properties of these composites, their application is limited to few heterostructure samples. Herein, we use machine learning to predict key characteristics of 2D materials to select relevant candidates for heterostructure building. First, a label space is created with engineered labels relating to atomic charge and ion spatial distribution. Then, a meta-estimator is designed to predict label values of heterostructure samples having a defined band alignment (descriptor). To this end, independently trained k-nearest neighbors (KNN) regression models are combined to boost the regression. Then, swarm intelligence principles are used, along with the boosted estimator's results, to further refine the regression. This new "swarm smart" algorithm is a powerful and versatile tool to select, among experimentally existing, computationally studied, and not yet discovered van der Waals heterostructures, the most likely candidate materials to face the scientific challenges ahead.

Spectroscopic, Quantum Chemical and Molecular Docking Studies on N-(9H-Purin-6-yl) Benzamide: A Potent Antimalarial Agent

This study presents a comprehensive analysis of N-(9H-purin-6-yl) Benzamide (NPB) using a combination of Density Functional Theory (DFT) calculations and experimental techniques. The molecular configuration of NPB was optimized using DFT/B3LYP method employing the 6-311++G (d,p) basis set. The fundamental frequencies were calculated and assigned, which agree well with the experimental results. The UV-Vis spectroscopic analyses, HOMO-LUMO energy gap assessment, Molecular Electrostatic Potential calculation, and Mulliken charge analysis, Fukui function calculation and Natural bond orbital analysis were performed for the NPB molecule. The UV-Visible spectral analysis, which predicts the transition of bonding and anti-bonding π-electrons from the purine ring to the aromatic ring of the NPB molecule. A smaller energy gap in the HOMO-LUMO analysis reveals that the NPB molecule is more reactive and Mulliken atomic charge distribution analysis indicates that the carbon atoms are highly influenced by their substituents. Natural Bond Orbital (NBO) analysis was employed to investigate the bonding within the NPB molecule. The Fukui function analysis indicates that the biological activity of the NPB molecule. In order to analyze the structure of NPB molecule, the thermodynamic properties in the temperature range 100–1000 K were obtained by thermodynamic analysis software SHERMO calculator. The molecular docking analysis was carried out for antimalarial proteins (5ZNC, 2BMA, 7E27, 7E26) using auto-docking simulations. This computational method confirms the bioactivity and drug-likeness parameters of the NPB molecule. The molecular docking results predicts the formation of hydrogen bonds between the ligand (NPB) and the protein receptors. Based on these findings, this study establishes that the distinctive methodology applied to identify NPB molecule as a potential candidate for an antimalarial drug designing, which is suitable for in vivo and in vitro investigations.

Structure, Frontier Molecular Orbitals, MEP, Charge Analysis, and NLO Study of 2,4-, 2,5-, and 2,6-Dimethylanilines Using DFT

This study includes the evaluation of most stable structure, frontier molecular orbitals, molecular electrostatic potential (MEP), and nonlinear optical (NLO) parameters of 2,4-dimethylaniline (2,4DMA), 2,5-dimethylaniline (2,5DMA), and 2,6-dimethylaniline (2,6DMA) using density functional theory (DFT) employing B3LYP functional with 6-311++G(d,p) basis set. HOMO-LUMO energies, band gap energies, and global reactivity descriptors were obtained from the optimized structures. The band gap energy was determined as 3.7865, 3.9348, and 3.9443 eV for 2,4DMA, 25DMA, and 2,6DMA, respectively. The reactive sites of the molecules were obtained from the molecular electrostatic potential energy. The NLO parameters such as dipole moment, polarizability, and hyperpolarizability have been investigated for the title molecules. The investigated dipole moment and first-order hyperpolarizability values are higher than the prototypical value of urea and show good NLO behavior. The NMR chemical shifts, electronic absorption spectra, and charge distribution of atoms were calculated theoretically. Furthermore, thermodynamic and rotational constants were also calculated.

Insight with Crystallization, Quantum Computation, Hirshfeld, ELF/LOL and Molecular Docking of Syringic Acid Nicotinamide Cocrystal as Potent Mycobacterium Tuberculosis Inhibitor

Tuberculosis (TB) is a recurring and progressive illness with a high global death rate. MycobacteriumTB drug resistance is a serious impediment to allelopathy therapy. Contemplating combinatorial drug delivery (pharmaceutical cocrystal) as anti-TB medicines targeting Mycobacterium tuberculosis’s active site can be an alternative strategy. The syringic acid nicotinamide (SYNI) cocrystal was synthesized in this work through slow evaporation technique and was examined based on quantum chemical calculations, Hirshfeld analysis, electron localization analysis and molecular docking. The intended vibrational wavenumbers were allocated a PED value and related with experimental frequencies. The UV–Visible absorption spectra of the cocrystal in the liquid phase (ethanol) were revealed as [Formula: see text]* electronic transitions. The HOMO–LUMO values, band gap, molecular electrostatic potential and Mulliken atomic charge distribution of the molecule were evaluated to estimate its stability and molecular reactivity. The molecule’s second-order perturbation energy [Formula: see text] standards were determined by means of natural bond orbital analysis, and potential reactive site was assessed using local reactivity descriptors. Hirshfeld analysis revealed that H…H (44.9%), O…H/H…O (39.3%), C…H/H…C (6.1%), N…H/H…N (5.3%) and C…C (2.4%) have the major percentage contributions from the most significant interactions. The topological features of the SYNI cocrystal were assessed through electron localization function based on color gradient. The binding ability of SYNI cocrystal with the Mycobacterium tuberculosis associated proteins was evaluated through docking and their binding scores fall between the range of −9.1 kcal/mol and −10.8 kcal/mol, which confirms the better binding ability and makes SYNI cocrystal a potent medication against TB.

Peculiarities of the Spatial and Electronic Structure of 2-Aryl-1,2,3-Triazol-5-Carboxylic Acids and Their Salts on the Basis of Spectral Studies and DFT Calculations.

The molecular structure and vibrational spectra of six 1,2,3-triazoles-containing molecules with possible anticancer activity were investigated. For two of them, the optimized geometry was determined in the monomer, cyclic dimer and stacking forms using the B3LYP, M06-2X and MP2 methods implemented in the GAUSSIAN-16 program package. The effect of the para-substitution on the aryl ring was evaluated based on changes in the molecular structure and atomic charge distribution of the triazole ring. An increment in the positive N4 charge was linearly related to a decrease in both the aryl ring and the carboxylic group rotation, with respect to the triazole ring, and by contrast, to an increment in the pyrrolidine ring rotation. Anionic formation had a larger effect on the triazole ring structure than the electronic nature of the different substituents on the aryl ring. Several relationships were obtained that could facilitate the selection of substituents on the triazole ring for their further synthesis. The observed IR and Raman bands in the solid state of two of these compounds were accurately assigned according to monomer and dimer form calculations, together with the polynomic scaling equation procedure (PSE). The large red-shift of the C=O stretching mode indicates that strong H-bonds in the dimer form appear in the solid state through this group.

Sensor response and electron distribution in the systems of In2O3 nanoparticles decorated with CeO2 nanoclusters

The charge distribution and spillover of oxygen atoms in nanostructured CeO2-In2O3 systems have been studied. The interaction of nanoobjects (nanoparticles or nanoclusters) i.e. the spillover of oxygen atoms from catalytically active CeO2 nanoclusters to In2O3 nanoparticles, results in an increase in the inhomogeneity of the radial electron density distribution in the nanoparticles. This in turn increases the resistance of the CeO2-In2O3 system in air relative to pure In2O3. It is shown here that the spillover of oxygen atoms in the two-component system (CeO2-In2O3) causes a shift of the maximum in the temperature dependence of the sensor response to hydrogen towards lower temperatures and a significant enhancement of the sensor response compared to one-component system (In2O3). The theoretical model developed agrees well with the published experimental data on the sensor response in In2O3 and CeO2-In2O3 systems.

A Reactive Molecular Dynamics Investigation of Nanoparticle Interactions in Hydrocarbon Combustion

ABSTRACT The use of energetic nanoparticles to tailor the properties of a base liquid fuel has attracted attention due to the possibility of decreasing fuel consumption and increasing control over the combustion process. In this study, the role of nanomaterials in the consumption of hydrocarbon fuel vapor is investigated using reactive molecular dynamics. Simulations are performed with aluminum and iron nanoparticles inside an n-heptane and oxygen gas mixture. The role of atomic charges on the dynamics of nanoparticle-hydrocarbon interactions is also investigated using different charge equilibration methods. Results show that both nanomaterials act as catalysts and enhance fuel decomposition. The decomposition of fuel molecules is initiated by dehydrogenation at the particle’s surface. This reaction path occurs significantly faster than the oxidation and pyrolysis paths observed for n-heptane in absence of nanoparticles. The oxidation in the presence of aluminum is characterized by more rapid particle heating and fragmentation compared to iron. Metal fragments further enhance the reactivity of the system due to a higher surface area available for reactions. The atomic charge distribution was found to affect the kinetics and reactivity of the system, showing that the non-bonded interactions influence the oxidation process. This study confirms that the use of nanomaterials is beneficial to accelerate the decomposition of fuel and that the combustion behavior of the selected hydrocarbon is strongly dependent on the type of nanomaterial used in combination with the base fuel.

Spectroscopic, Biological, and Topological Insights on Lemonol as a Potential Anticancer Agent.

A monoterpene alcohol known as lemonol was investigated experimentally as well as theoretically in order to gain insights into its geometrical structure, vibrational frequencies, solvent effects on electronic properties, molecular electrostatic potential, Mulliken atomic charge distribution, natural bond orbital, and Nonlinear Optical properties. The frontier molecular orbital energy gap values of 5.9084 eV (gas), 5.9261 eV (ethanol), 5.9185 eV (chloroform), 5.9253 eV (acetone), and 5.9176 eV (diethyl ether) were predicted, and it shows the kinetic stability and chemical reactivity of lemonol. Topological studies were conducted using Multiwfn software to understand the binding sites and weak interactions in lemonol. The antiproliferative effect of lemonol against the breast cancer cell line Michigan Cancer Foundation (MCF-7) was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, while nuclear damage, condensation, and reactive oxygen species generation were identified using acridine orange/ethidium bromide, propidium iodide, and dichlorodihydrofluorescein diacetate staining. The theoretical and experimental findings are highly correlated, confirming the structure, and the results of in vitro studies suggest that lemonol acts as a potent inhibitor against the human breast cancer cell line MCF-7, highlighting its strong antiproliferative activity.