DFT-based Descriptors Research Articles

A comprehensive analysis of the spectroscopic and drug-like properties of dimethyl 5-hydroxybenzene-1,3-dicarboxylate: insights from DFT and MD simulations

ABSTRACT An in-depth investigation was undertaken to explore the ground-state molecular and electronic structure of Dimethyl 5-hydroxybenzene-1,3-dicarboxylate (D5HD). The potential energy scan of D5HD at various dihedral angles identified the lowest energy conformer, which was re-optimised at the higher basis set. The recorded FT-Raman and FT-IR spectra were compared with corresponding theoretical spectra, demonstrating a high degree of coherence. A comprehensive Natural Bond Orbital analysis was done for D5HD to gain insights for the overall electronic distribution within the molecule. Additionally, nonlinear optical (NLO) properties along with various DFT-based descriptors were calculated. Molecular docking studies against human acetylcholinesterase enzyme (PDB 2JF0), D5HD displayed good binding affinity. The study revealed that hydrogen bonded as well as van der Waals interactions exist between D5HD and different residues in the binding cavity of the target protein. The 100 ns MD simulation confirms the conformational stability of protein (2JF0)–ligand (D5HD) complex. The binding energy and residue decomposition analysis performed using MM-GBSA approach showed positive results with binding energy of −17.76 kcal/mol. Furthermore, D5HD effectively passed all pharmacokinetic filters, establishing its potential as a promising candidate in the quest for novel acetylcholinesterase inhibitors. Highlights Systematic exploration of the structure and spectroscopic properties of D5HD. Molecular docking between D5HD and acetylcholinesterase (PDB 2JF0) reveals the establishment of hydrogen bonds and Van der Waals interactions. D5HD successfully complies with all relevant pharmacokinetic filters. MD simulation analysis on 2JF0–D5HD complex confirms the conformational stability. Energy and residue decomposition based on MMGBSA approach.

Synthesis, structural characterization, DFT and molecular dynamics simulations of dinuclear (μ-hydroxo)-bridged triethanolamine copper(II) complexes: efficient candidates towards visible light-mediated photo-Fenton degradation of organic dyes.

Multinuclear (di/tri) copper(II) complexes bridged through hydroxyl groups are very interesting coordination complexes owing to their potential applications in various fields. In this work, three novel dinuclear (μ-hydroxo)-bridged copper(II) complexes in the crystal form, namely, [Cu2(3,5-DIFLB)2(H2tea)2](H2O) (1), [Cu2(4-ClB)2(H2tea)2](H2O) (2), and [Cu2(4-ETHB)2(H2tea)2](H2O)2 (3) (where DIFLB = difluorobenzoate, CLB = chlorobenzoate, ETHB = ethoxybenzoate, and H3tea = triethanolamine), were isolated at room temperature using methanol and water in a 4 : 1 v/v ratio as a solvent. Furthermore, all three complexes (1-3) were characterised using spectroscopic (UV-vis, DRS, and FT-IR), electrochemical (CV) and single-crystal X-ray diffraction techniques. Structural insights gained by packing analysis revealed the role of steric constraints of substituents and various non-covalent interactions in lattice stabilization, which were indeed supported by theoretical and molecular electrostatic potential illustrations. Hirshfeld surface analysis provided quantitative verification about various non-covalent interactions (interatomic contacts) involved in the packing of molecules. Interestingly, as a potential application, complexes 1-3 all exhibited remarkable visible light-mediated photo-Fenton degradation of approximately 98% for 50 ppm concentration of organic dyes (fuchsin basic (FB) and methyl orange (MO)) in 90 minutes with the optimized conditions of 1 mg mL-1 of dye solution. In all the cases, dye degradation by these materials was ascribed to the symbiotic relations among the molecular structures of complexes 1-3, which were endowed with various electron-withdrawing and electron-releasing substituents and ionic strength, with respect to the structure, shape and interacting patterns of dye molecules. The adsorption mechanism indicates that various weak interactions between the donor and acceptor groups of complexes and dyes, such as electrostatic, hydrogen bonding, and direct coordination to metal sites, play a crucial role, which is confirmed by molecular dynamics (MD) simulations. Theoretical studies by DFT-based descriptors, molecular electrostatic potentials, and band gaps provided deep insights into various electronic and reactivity parameters. For subsequent processes of dye degradation, complexes 1-3 were stable and recoverable. The successful integration of experimental and theoretical approaches sheds light on copper-based dinuclear stable coordination complexes, showcasing a significant step towards the development of novel heterogeneous photo-Fenton catalysts.

Zinc-curcumin complexes: Design, synthesis, geometry optimization, and optical nonlinearity applications

This may be the first research to our knowledge that details the NLO characteristics of two zinc complexes with curcumin acting as a base ligand in solution form (viz. Zinc acetate-Curcumin (ZnAcCur) and Zinc acetate-Thiolene-Curcumin (ZnThCur)). The structural features of both complexes have been derived from various characterization techniques like UV–Vis, FT-IR, 1H NMR, 13C NMR, Elemental analysis and Mass spectrometry. The nature of ligand-to-metal interaction was validated by 1H NMR spectral studies along with DFT calculations. The result shows that the molecular system ZnAcCur is more stable with a HOMO-LUMO energy gap of 3.334 eV. The addition of an extra moiety in the form of thiolene decreased the stability and in turn the NLO properties. The computational study was extended to calculate various DFT-based descriptors. Nonlinear optical transmission was measured by a Z-scan technique with the implementation of nanosecond laser pulses at 532 nm, showed that both complexes can be prominently applied for optical limiting (OL) properties.

Bioactivity, molecular docking and anticancer behavior of pyrrolidine based Pt(II) complexes: Their kinetics, DNA and BSA binding study by spectroscopic methods

The complex [Pt(AEP)Cl2]; C-1 (where, AEP = 1-(2-Aminoethyl) pyrrolidine) and its hydrolyzed diaqua form cis-[Pt(AEP)(H2O)2]2+; C-2 were synthesized for their bioactivity and in vitro kinetic study with bioactive thiol group (-SH) containing ligands (like; L- cysteine and N-ac-L- cysteine) for their biological importance for 'drug reservoir' activity. The Thermal Gravimetric Analysis (TGA) was executed to confirm about the weight loss due to coordinated water molecules at high temperature range. At pH 4.0, the substitution behavior of C-2 with the thiols was studied in pseudo-first order reaction condition. The interaction mechanism of thiols with complex C-2 to their corresponding thiol substituted C-3 [Pt(AEP)(L-cys)] and C-4 [Pt(AEP)(N-ac-L-cys)] (where L-cys = L-cysteine and N-ac-L-cys = N-ac-L- cysteine) were proposed from their thermodynamical activation parameters (ΔH≠ and ΔS≠), which were obtained from Eyring equation. DNA and BSA binding activity of the complexes C-1 to C-4 were investigated by gel electrophoresis technique, spectroscopic titration and viscosity methods. The binding activity of the complexes with DNA and BSA was evaluated using a theoretical approach molecular docking study. The drug-like nature of the complexes is supported by the prediction of activity spectra for substance (PASS) from 2D structure of the Pt(II) complexes. Structural optimization, HOMO-LUMO energy calculation, Molecular electrostatic potential surface, NBO and TD-DFT calculation were executed by using density functional theory (DFT) with Gaussian 09 software package to pre-assessment of biological activity of the complexes. DFT-based descriptors were determined from the HOMO-LUMA energy to be related with the ability of binding affinity of Pt(II) complexes towards DNA and BSA to the formation of their corresponding adducts. The anticancer property of the design complexes were examined on HCT116 (colorectal carcinoma) cancer cell lines and as well as human normal cell NKE (Normal Kidney Epithelial) and compared with the recognised anticancer drug cisplatin. The Reactive Oxygen Species (ROS) production was assessed by DCFDA assay in presence of the Pt(II) complexes.

Computational Catalyst Design for Dry Reforming of Methane: A Review

Because of the recent global warming environmental issues, dry reforming of methane (DRM)─which converts greenhouse gases (CO2 and CH4) into syngases (CO and H2)─is receiving significant attention. Recently, density functional theory (DFT) calculations have been effectively used to obtain fundamental information on DRM reactions. The DFT calculations can provide valuable theoretical knowledge in various heterogeneous catalyst systems, which is difficult to derive from experiments alone due to the complexity of reaction pathways. This work introduces theoretical studies concerning the most plausible reaction pathways, catalytic activities, and stabilities of Ni- and non-Ni-based metal catalysts. The review includes fundamental analyses of reaction mechanisms, catalytic activities, and several strategies to improve the catalytic properties of Ni- and non-Ni-based catalysts. Such strategies include doping, introducing promoters, forming bimetallics, and utilizing various catalyst supports. In addition, DFT-based descriptors provide guidelines for DRM catalyst design in terms of activity and stability. In conclusion, this review also suggests DFT-based analyses of catalysts based on morphological and compositional engineering, such as core–shell nanoparticles, single-atom catalysts, phosphides, and reduced solid solution catalysts. Finally, this review suggests a rational catalyst design for DRM by tuning catalytic properties based on engineered catalyst characteristics under a comprehensive understanding provided by DFT calculations and experiments.

Nonlinear optical and quantum chemical studies of Palladium benzimidazole Schiff base complex

This article presents the linear and nonlinear optics and density functional theory studies of a Palladium complex with a benzimidazole-based Schiff base. Linear absorption of the complex has been studied using a UV–Vis absorption spectrometer. Optical nonlinearity and thereby the optical limiting performance of the complex has been deliberated experimentally using a Z-scan method with a continuum wave laser of wavelength 532 nm. The NLO investigation of the complex demonstrated significant nonlinear absorption (βeff = 4.64–27.23 × 10−2 cm/W) with an imaginary part of nonlinear optical susceptibility of the third-order (Imχ(3) = 1.28–7.49 × 10−5 esu) and nonlinear refraction (n2 = 5.46–12.3 × 10−7 cm2/W) with real part of nonlinear optical susceptibility of the third-order (Reχ(3) = 3.55–8.00 × 10−5 esu). The large nonlinear absorption displayed superior optical power limiting characteristics with a threshold and clapping level of 115 W/cm2 and 35 W/cm2respectively. Theoretical studies are performed for Palladium benzimidazole Schiff base complex within Density Functional Theory (DFT) framework, using hybrid exchange-correlation B3LYP with basis set LANL2DZ. DFT-based descriptors are computed viz. energy gap between HOMO-LUMO, electronegativity, electrophilicity index, molecular hardness, and softness. Result reveals that the bond length between Pd–O is small as compared to Pd–Cl and Pd–N.

Binary quantitative activity-activity relationship (QAAR) studies to explore selective HDAC8 inhibitors: In light of mathematical models, DFT-based calculation and molecular dynamic simulation studies

Histone deacetylase 8 (HDAC8) selectivity over other HDACs is a major concern of interest, since HDAC8 has been implicated as a potential drug target of many diseases including haematological malignancy. Quantitative activity-activity relationship (QAAR) study is a good strategy to explore the possible features to design HDAC8 selective inhibitors. Here, a mathematical framework has been constructed to understand the important molecular fragments responsible for HDAC8 selectivity over HDAC1, 2 and 3. This study also deals with binary QAAR-based HDAC8 selectivity screening of some in-house molecules and understanding the toxicity of the in-house molecules using DFT-based descriptors. Further, this study explores the possible binding mechanism of in-house compounds with HDAC8 by molecular dynamic simulation. Hence, the comparative learning amongst the mathematical models, DFT-based calculation and molecular dynamic simulation methods will surely enrich the scientific community to design selective HDAC8 inhibitors in future.

Quantum chemical and molecular docking studies of some phenothiazine derivatives

Phenothiazines are synthetic antipsychotics with a wide range of biological effects. Their properties are determined by the structure and variety of substituents in the heterocyclic system. It is known that various quantum chemical properties have a significant influence on drug behavior in biological systems. Because of the diversity in the chemical structure of phenothiazines and other drugs that include heterocyclic systems, quantum chemical calculations provide useful methods for predicting their effects. This study made an attempt to describe the physicochemical properties and the molecular docking simulation of phenothiazine derivatives. To predict the reactivity of phenothiazine derivatives, DFT-based descriptors including certain highest occupied molecular orbital and lowest unoccupied molecular orbital, energy gap, electronic chemical potential, chemical hardness, nucleophilicity, and electrophilicity were performed by using B3LYP / 6311 ++ G (d, p) level. The most and least active compounds were docked to the protein proteins glycosylphosphatidylinositol phospholipase D inhibitor (1GYM), anaphylatoxin receptor antagonist (6C1Q), arylacetonitrilase inhibitor (3UGC) and aspulvinone dimethylallyl transferase inhibitor (3RIX) to confirm the observations of DFT models and elucidate the mode of binding between this type of compound and the corresponding protein.

Quantitative structure-activity relationship study of skin sensitization of Michael acceptors based on quantum chemical descriptors

The skin sensitization potential has been scrutinized using density functional theory (DFT) based descriptors within the structural-activity relationship (SAR) parlance. These are the most recurrently used chemical reactivity descriptors to explore the various molecular reactivity studies. For this, a model system consisting of 30 different Michael acceptors whose activity is depicted in terms of pEC3 was taken into account. The usefulness of these descriptors in Quantitative Structure-Activity Relationship (QSAR) research is demonstrated by a good correlation. The statistical results showed that using global softness as a quantum chemical descriptor, the sensitization potential can be adequately explained. It can be concluded from the results that the DFT-based descriptors may be suitable to enlighten effectively the skin sensitization potential of Michael acceptor molecules.

Modeling the Liquid-Phase Adsorption of Cephalexin onto Coated Iron Nanoparticles Using Response Surface and Molecular Modeling

In order to assess the interactions between process factors, the experiments involving the liquid-phase adsorption of cephalexin (CEX) onto silicon-coated iron nanoparticles (Fe3O4@SIO2) were designed using the Box-Behnken Design-Response surface methodology (BBD-RSM). Optimal circumstances were used to investigate the synergistic influence on the process’s efficiency. In addition, the data was used to test and fit an artificial neural network (ANN) model. Molecular-level DFT calculations on the CEX molecule were carried out. The PW6B95D3/Def2-TZVP level of theory was used to build DFT-based descriptors for the CEX molecule. At 25°C, pH 5.83, 37.67 min, a dosage of 0.8 g Fe3O4@SIO2 and 118.01 mg/L CEX, the removal efficiency achieved a maximum of 99.01 percent. For example, we found that OH --- O, NH --- O, CH --- O hydrogen bonds, NH --- π, OH --- π, CH --- π interactions as well as dipole-dipole interactions between CEX and the nanoparticles could all be used to connect the CEX and the nanoparticles. There is a strong correlation between the output and target values acquired by BBD-RSM and ANN fits. Fe3O4@SIO2 proved to be an excellent tool for eliminating CEX.

Chemical Reactivity and Skin Sensitization Studies on a Series of Chloro- and Fluoropyrroles—A Computational Approach

Global density functional descriptors analysis on a series of chloro- and fluoropyrroles provide vital data concerning their overall biochemical activities. In this study, a comprehensive investigation is presented for a series of chloro- and fluoropyrroles using DFT-based descriptors to elucidate physicochemical properties and their relevance to reactivity, charge transfer, site selectivity, and toxicity. Electrophilicity-based charge transfer (ECT) descriptor reveals the fact that chloro- and fluoropyrroles act as electron donors during their interaction with DNA bases. The local descriptor, namely, multiphilic descriptor conveys the activeness of specific sites in chloro- and fluoropyrroles. Further, Toxicity Prediction Komputer Assisted Technology (TOPKAT) studies on carcinogenicity bioassays using four rodent models provide the interesting fact that chloro- and fluoropyrroles exhibit a strong skin sensitization effect in these species.

A theoretical study of radical scavenging antioxidant activity of 3-styrylchromone derivatives using DFT based on quantum chemical descriptors

Chromone (4H-chromen-4-one, 4H-1-benzopyran-4-one) heterocyclic compound has been widely used in traditional medicine, which has anti-allergy, anti-inflammation, anti-diabetes, anti-tumor, antibacterial and other pharmacological effects. To estimate the scavenging activity on free radical of 3-styrylchromone derivatives, we considered the physical and chemical properties of the molecule structure, orbital, and thermodynamics. The antioxidant activity of 3-styrylchromone derivatives was studied by density functional theory (DFT) in gas and water. A series of quantum chemical parameters were calculated to describe molecular properties and clarify the radical scavenging mechanism. Our study suggests that the antioxidant activity of scavenging free radicals is largely affected by molecular structure, especially the number of hydroxyl groups, hydrogen bonds, and conjugation effects. 3-styrylchromone derivatives containing pyrogallol structure may have potential antioxidant activity. The antioxidant ability of catechol structure is greater than pyrogallol structure. 1,4-pyrrole also has a positive effect on free radical scavenging, but the scavenging effect of 2-OH and 5-OH introduced by antioxidants was not obvious. The excellent correlations between the structure and the mentioned DFT-based descriptors lead us to predict good antioxidants.

Drug repurposing: Fusidic acid as a potential inhibitor of M. tuberculosis FtsZ polymerization – Insight from DFT calculations, molecular docking and molecular dynamics simulations

Filamentous Temperature Sensitive Mutant Z (FtsZ), an important cell division protein in bacteria, has been validated as a potential target for antibiotics development. Citric acid has been found to inhibit the polymerization of Mycobacterium tuberculosis (MTB) FtsZ and several other drugs have been predicted as potential inhibitors through a gene ontology-based drug repurposing approach. An in-depth study on four of the predicted drugs; Fusidic acid (FusA), l-tryptophan, Carbamic acid, and 2-(3-guanidinophenyl)-3-mercaptopropanoic acid, as potential inhibitors of MTB-FtsZ polymerization was conducted using Citric acid as reference compound. The applied in silico methods involve DFT calculations, molecular docking and molecular dynamics simulations. DFT approach was applied to evaluate selectivity and stability properties of the predicted drugs. Calculated parameters including non-linear optical properties, charge distribution and electrostatic potential analyses enabled selectivity prediction of these potential drugs. DFT-based descriptors revealed FusA as the most potent compound, even more reactive than the referenced compound, Citric acid, which is also supported from the molecular docking study. Parameters including MM/PBSA binding free energies, RMSD, RMSF, RoG and hydrogen bond analysis also support FusA as the best potential MTB-FtsZ polymerization inhibitor, that forms a stable complex with the protein and impose greatest level of rigidity to the protein.

DFT-based reactivity and combined QSAR, molecular docking of 1,2,4,5-Tetrazine derivatives as inhibitors of Pim-1 kinase

In the present work we have calculated several DFT reactivity descriptors for 1,2,4,5-Tetrazine at the B3LYP/6–311++G(d,p) level of theory in order to analyze its reactivity in vacuum and solvent phases. Whereas, the influence of the solvent was taken into account employing the PCM model. DFT-based descriptors such as (electronic chemical potential, electrophilicity, condensed Fukui function….) have been determined to predict the reactivity of 1,2,4,5-Tetrazine. A series of eighteen 1,2,4,5-Tetrazine derivatives was studied by using two computational techniques, namely, quantitative structure activity relationship (QSAR) and molecular docking. QSAR models of the antitumor activity of some 1,2,4,5-Tetrazine derivatives were established in gas and solvent phases which exhibited good statistical values for both cases. Whereas, multiple linear regression (MLR) procedure was used to obtain the best QSAR models and the leave-one-out (LOO) method to estimate the predictivity of our models. The most and the least active compounds were docked with the protein (3C4E) to confirm those obtained results from QSAR models and elucidate the binding mode between this type of compounds and corresponding protein.

Influence of steric and electronic effect of carrier ligand on kinetics & mechanism of Pt(II) complexes with l-cysteine and its substituted derivatives: Their experimental and DFT-based theoretical study

The present research work focuses on influences of steric and electronic effect on the kinetic and mechanistic investigation of the cytotoxic Pt(II) complexes with sulfur containing bio-molecules, which is relevant in order to understand the drug-reservoir activity of the complexes. To evaluate the steric and electronic effect of carrier ligand on substitution kinetics of Pt(II) complexes, 2° and 3° bidentate amine (DMEEDA) have been considered. Pt(II)-dichloro complex [Pt(DMEEDA)Cl2], 1 and its hydrolysed form [Pt(DMEEDA)(H2O)2](ClO4)2, 2 have been synthesised and characterised, wherein DMEEDA stands for N,N-Dimethyl-N′-ethylethylenediamine, a bidentate carrier ligand with different alkyl substituents. The diaqua platinum complex 2 has been considered for detailed kinetic investigation with biologically important intercellular thiol l-cysteine (l-cys) and its derivative N-acetyl-l-cysteine (N-ac-l-cys) under pseudo first order condition at pH 4.0 in aqueous medium. The product complexes [Pt(DMEEDA)(l-cys)](ClO4), 3 and [Pt(DMEEDA)(N-ac-l-cys)], 4 have been isolated and characterised. The activation parameters (ΔHǂ and ΔSǂ) for both the steps underlying the thiol assisted substitution reactions have been calculated. Theoretical Density Functional Theory (DFT) has been undertaken to optimise the complexes for HOMO-LUMO energy calculation, TD-DFT and natural bond orbital (NBO) analysis to strengthen the experimental findings. Various electronic properties of the complexes, called DFT-based descriptors have been calculated from frontier molecular orbital energies to predict their adduct formation ability with DNA. TD-DFT study has been undertaken to generate both the simulated spectra of UV–Vis and IR to compare with the corresponding experimental spectral results. To justify the chelation via (S,O), not through other possible modes, NBO analysis has been considered for the complex 3 and 4, which is also supported by spectroscopic observation.

Cationic dyes adsorption by Na-Montmorillonite Nano Clay: Experimental study combined with a theoretical investigation using DFT-based descriptors and molecular dynamics simulations

In this work, adsorption kinetics, isotherms and mechanisms of two cationic dyes, Toluidine Blue (TB) and Crystal Violet (CV), on a Na-Montmorillonite Nano Clay (Na-MNC) have been experimentally and theoretically determined. The structure and the morphology of the Na-MNC were characterized by XRD, FTIR, SEM, EDAX and BET. High adsorption capacity was observed for both dyes (5.80 mmol/g for TB and 5.40 mmol/g for CV). Maximum removal of both dyes was observed at pH 11.0. Equilibrium was attained after the contact time of 30 min for CV dye and 50 min for TB dye. The adsorption isotherms were described by Langmuir isotherm model suggesting that the dyes were adsorbed homogenously over a monolayer surface of the Na-MNC. The adsorption kinetics was well fitted to pseudo-second-order kinetic model (R2 > 0.98). The theoretical investigation carried out on the CV and TB dyes structures using the quantum molecular descriptors derived from density functional theory (DFT) calculations have proved that the TB cations are more electrophilic, reactive and have the ability to accept electrons allow to adsorb strongly on the adsorbent surface compared to the CV ones. Molecular dynamic (MD) simulations were performed to obtain information on molecular arrangements and to predict interaction energies of studied dyes with the Na-MNC surface. These simulations show that the adsorption of the studied dyes can result in a variety of configurations, including single layers parallel to the basal surface, tilted and random piles.

Theoretical Studies of the Zeolite-Y Encapsulated Chlorine-Substituted Copper(II)phthalocyanine Complex on the Formation Glycidol from Allyl Alcohol.

Density functional theory (DFT) used to study the encapsulation of copper(II)phthalocyanine and chlorine-substituted copper(II)phthalocyanine to a zeolite-Y framework. Changes occurring in the redox properties, as well as the red shift of the time-dependent DFT (TD-DFT) spectra, point out the influence of encapsulation on the geometric parameters of the complexes. Also, the TD-DFT calculations show good agreement with the energy changes occurred in the highest occupied molecular orbital and lowest unoccupied molecular orbital. DFT-based descriptors are used for scrutinizing the reactivity of the encapsulated complexes and a mechanism of the glycidol formation is proposed based on the energetics involved in the transformation.

Adsorption of basic dyes onto activated carbon: Experimental and theoretical investigation of chemical reactivity of basic dyes using DFT-based descriptors

Adsorption of basic dyes, basic blue 26 (BB26), basic green 1 (BG1), basic yellow 2 (BY2) and basic red 1 (BR1) onto activated carbon surfaces were investigated. Activated carbons (ACs) were produced by thermal treatment at 800 °C, oxidation with HNO3 6 M and chemical activation with H3PO4 at 450 °C and açaí seeds (Euterpe oleracea) and Brazil nut shells (Bertholletia excelsa) were used as precursors. ACs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), analysis (TGA/DTA), N2-adsorption at 77 K, mercury intrusion porosimetry, evaluation of acidity/basicity, and determination of the point of zero charge (pHpzc). The molecular chemical reactivity of the dye molecules was investigated using the DFT-based reactivity descriptors, electrophilicity index (ɷ), chemical potential (μ) and chemical hardness (η), values were approximated in terms of the frontier molecular orbital energies, HOMO and LUMO. ACs produced by activation with H3PO4 were more effectives to remover the dyes tested, performances attributed to their pore structure and surface functional groups. The experimental and theoretical results of chemical reactivity show that BG1 and BB26 dyes are more reactive than BR1 and BY2 dyes.

Local Lewis Acidity of (TiO2)n (n = 7–10) Nanoparticles Characterized by DFT-Based Descriptors: Tools for Catalyst Design

Transition metal oxide nanoparticles are common materials in a multitude of applications including heterogeneous catalysis, solar energy harvesting, and energy storage. Understanding the particles’ interplay with their surroundings is key to their efficient usage and design. Herein two DFT-based descriptors are used to study local reactivity on (TiO2)n (n = 7–10) nanoparticles. The local electron attraction energy [E(r)] and the electrostatic potential [V(r)], evaluated on isodensity surfaces, are able to identify and rank Lewis acidic sites on the particles with high accuracy when compared to the interaction energies of the Lewis bases H2O, H2S, NH3, and CO. These interactions are characterized as mainly electrostatically controlled. Given the local character, low computational cost, and excellent performance of the ES(r) and VS(r) descriptors, they are anticipated to find widespread use in nanoparticle research and development.

Computational Investigation of Cationic, Anionic and Neutral Ag2AuN (N = 1–7) Nanoalloy Clusters

AbstractThe study of bimetallic nanoalloy clusters is of immense importance due to their diverse applications in the field of science and engineering. A deep theoretical insight is required to explain the physico-chemical properties of such compounds. Among such nanoalloy clusters, the compound formed between Ag and Au has received a lot of attention because of their marked electronic, catalytic, optical and magnetic properties. Density Functional Theory (DFT) is one of the most successful approaches of quantum mechanics to study the electronic properties of materials. Conceptual DFT-based descriptors have turned to be indispensable tools for analysing and correlating the experimental properties of compounds. In this report, we have investigated the ground state configurations and physico-chemical properties of Ag2AuNλ(N= 1–7,λ=±1, 0) nanoalloy clusters invoking DFT methodology. Our computed data exhibits interesting odd-even oscillation behaviour. A close agreement between experimental and our computed bond length supports our theoretical analysis.