Integrated Investigation on the Synthesis, Computational Analysis, Thermal Stability, and Performance of Eco-Friendly Chelating Agents for Calcium Ions

In this study, quantum chemical calculations and molecular dynamics simulations studies of a series of five nonionic surfactants namely: dimethyl alkyl phosphine oxide surfactants (C10-18PO) containing decyl, dodecyl-, tetradecyl-, hexadecyl-, and octadecyl alkyl chains were implemented using the density functional theory (DFT) method to interpret the correlation between the inhibition efficiency and the molecular structure of the different inhibitors in formation water. The global quantities including: highest occupied molecular orbital energy (HOMO), lowest unoccupied molecular orbital energy (LUMO), energy gap (ΔE), dipole moment (μ), total energy (TE), ionization potential (I), electron affinity (A), electronegativity (χ), chemical potential (π), global hardness (η), global softness (σ), global electrophilicity (ω), polarizabilities <α> and fraction of electrons transferred (ΔN) were calculated for the different inhibitors in formation water. The dependence of surface activities of the nonionic surfactants on the alkyl chain length was studied in distilled water. The surface activities and surface parameters of the studied surfactants were described using: surface tension and interfacial tension measurements. The determined surface parameters of the studied surfactants were surface tension, critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area at 25 °C. The thermodynamic evaluation of the surfactants was performed by calculating the standard free energies of micellization and adsorption. The structure-corrosion inhibition performance was estimated using potentiodynamic polarization, electrochemical impedance measurements and quantum chemical studies at 25 °C in true sample formation water.

Corrosion experiments and quantum chemical study on the basis of density functional theory (DFT) were done using some of the phytoconstituents of Araucaria heterophylla gum (AHG) for mild steel (MS) corrosion in acidic media. The inhibition performance of the certain phytoconstituents of AHG was explored with the aid of quantum chemical parameters. Quantum chemical descriptors that are allied with the inhibition efficiency such as the highest occupied molecular orbital energy (EHOMO−), lowest unoccupied molecular orbital energy (ELUMO−), energy gap (ΔE), dipole moment (μ), global hardness (ɳ), global softness (S), ionization potential (I), electron affinity (A), electronegativity (χ), the fraction of electrons transferred (∆N), electrophilicity index (ω), chemical potential and ΔEBack − donation were determined. These theoretical findings were used to understand the mechanism of inhibition.

Discovery of new molecular hybrid derivatives with coumarin scaffold bearing pyrazole/oxadiazole moieties: Molecular docking, POM analyses, in silico pharmacokinetics and in vitro antimicrobial evaluation with identification of potent antitumor pharmacophore sites

Computational study of some thiophene derivatives as aluminium corrosion inhibitors

This study utilizes the density functional theory (DFT) (B3LYP method and 6–31 + G* basis set)‐based method to theoretically investigate substituted 2‐amino‐3,5‐dicarbonitrile‐6‐thiopyridine derivatives within a prevalent multicomponent reaction involving aldehyde, malononitrile, and thiophenol. Various reactivity descriptors, including frontier molecular orbitals, dipole moment, polarizability, and molecular electrostatic potential, are computed to understand the variations in reactivity and stability of these compounds. The results demonstrate the reliability of DFT‐derived descriptors in predicting chemical reactivity and provide valuable insights for further research and practical applications in the field of chemical reactivity and reaction mechanisms. Geometric parameters, along with thermodynamic variables, such as standard enthalpies (Δ H ), entropies (Δ S ), Gibbs free energy (Δ G ), and global reactivity descriptors (ionization potential ( I ), electron affinity ( A ), chemical hardness ( η ), softness ( σ ), global softness ( S ), chemical potential ( μ ), global electrophilicity ( ω ), and nucleophilicity index ( N ), are calculated to gain insight into the dynamics of these interactions and variations in reactivity and stability.

Developing a descriptor to understand the reactivity of a catalyst is critical in achieving the rational design of heterogeneous catalysts. Ideally, the descriptor should be simple, predictive, as ...

Present-day theoretical computation methods are quite effective at anticipating how corrosion inhibitors would behave on metal surfaces, conserving time and resources on laboratory testing. The present study aims to predict the inhibitory effectiveness of certain furan derivatives on surfaces of Fe (110) and Sn (111) in acidic media. To compare their fundamental attributes against corrosion as well as their behavior on iron (Fe) and tin (Sn) surfaces in an acid medium, six urea derivatives have been chosen for this purpose: Imidazolidin-2-one (Cpd A), 4-methylimidazolidine-2-one (Cpd B), Tetrahyropyrimidin-2(1H)-one (Cpd C), 1,3-dimethylimidazolidin-2-one (Cpd D), 1,1-diethylurea (Cpd E), 1,3-dimethylurea (Cpd F). The anti-corrosive characteristics of Cpds A - F were generally explored using Density Functional Theory and Monte Carlo simulations. The results indicate that the compounds had low energy gaps, the highest occupied molecular orbital energy, global hardness, as well as ionization energy and high Electron affinity, ELUMO, global softness, and number of transferred electrons, which explained their corrosion inhibition potentials. Electrostatic potential (ESP) and Fukui indices identified the reactive sites with the ability to accept and donate electrons via back-donation to the metal's d-orbital. The Monte Carlo simulation demonstrated a favorable contact between the Fe (110) and Sn (111) surfaces and inhibitory molecules in the acidic medium. In the industrial sectors, these compounds may be secured as corrosion protectors.

This work presents a multiscale theoretical investigation into the potential of quinoxaline derivatives (Q1–Q6) as corrosion inhibitors for various metals (Fe(110), Cu(111), and Al(110)). Employing a combined approach combining density functional theory (DFT) and Monte Carlo simulations, we explore the relationship between molecular structure, electronic properties, and adsorption behavior. Density functional theory (DFT) and molecular dynamics simulations (MDS) were used to investigate the electronic characteristics of diverse compounds. The study included key parameters including highest occupied molecular orbital energy ( E HOMO ), lowest unoccupied molecular orbital energy ( E LUMO ), energy gap ( E g ) between E LUMO and E HOMO , dipole moment, global hardness, softness ( σ ), ionization energy ( I ), electron affinity ( A ), electronegativity ( χ ), back-donation energy E b−d , global electrophilicity ( ω ), electron transfer, global nucleophilicity ( ε ), and total energy (sum of electronic and zero-point energies). These properties, alongside adsorption energies (following the trend Q6 > Q2 > Q3 > Q4 > Q5 > Q1), are used to identify promising inhibitor candidates and establish structure–property relationships governing their effectiveness. The results suggest that inhibitor efficiency increases with a decreasing energy gap between frontier orbitals. Notably, the protonated state of Q6 exhibits high reactivity, low stability, and strong adsorption, making it a potential candidate for further exploration. This comprehensive theoretical approach offers crucial insights for the conceptual development of new and powerful corrosion inhibitors.

The study reports a highly efficient, eco-friendly method using a novel reagent, N-pyridinium nosyl chloride ([DMAPNS]+Cl-), for the rapid synthesis of sulfonamides under mild conditions. Equimolar reactions of the reagent with various amines in dichloromethane at room temperature were completed within 15 minutes, affording isolated yields of up to 97% without the need for chromatographic purification. Density functional theory (DFT) calculations at the B3LYP/6-311G level were performed to examine the electronic structures and reactivity of the pyridinium salts. Key quantum chemical parameters such as EHOMO , ELUMO , energy gap (ΔE), electron affinity (EA), ionization potential (IP), global electrophilicity index (ω), dipole moment (µ), softness (S), chemical hardness (η), and absolute electronegativity (χ) were evaluated to interpret molecular stability and reactivity trends. Among these, compound 18 exhibited the highest ionisation potential (7.84 eV) and hardness (2.05 eV), indicating enhanced chemical stability. . Antibacterial screening against selected MTCC and NCIM strains showed that compounds 4, 8, 12, 16 and 18 displayed strong broad-spectrum activity, while compounds 14, 20, and 22 exhibited moderate effects. The integration of synthetic methodology, quantum chemical analysis, and biological evaluation highlights the potential of this nosylation approach for the design of future sulfonamide-based therapeutics.

BackgroundCorrosion is a threat to material strength and durability. Electron-rich organic inhibitor may offer good corrosion mitigation potentials. In this work, anti-corrosion potentials of nine derivatives of 1H-indene-1,3-dione have been investigated using density functional theory (DFT) approach and molecular dynamics (MD) simulation. Chemical reactivity descriptors like energies of lowest unoccupied molecular orbital (ELUMO), highest occupied molecular orbital (EHOMO), electron affinity (A), ionization potential (I), energy gap (ΔEgap), global hardness (η), global softness (σ), electronegativity (χ), electrophilicity (ω), number of transferred electrons (ΔN) and back-donation (ΔEback-donation) were computed at DFT/B3LYP/6-31G(d) theoretical level. The local reactive sites and the charge partitioning on the compounds were studied using Fukui indices and molecular electrostatic potential (MEP) surface analysis. The adsorption behavior and the binding energy of the inhibitors on Fe (110) surface in hydrochloric acid solution were investigated using MD simulation.ResultsThe high chemical reactivity, kinetic instability and good corrosion inhibition potentials demonstrated by the inhibitors are rationalized based on their high EHOMO, A, σ, ΔN, ΔEback-donation, and low ΔEgap, ELUMO, I and η. A wide difference of approximately 2.4–3.2 eV between the electronegativities of iron and the 1H-inden-1,3-diones suggests good charge transfer tendency from the latter to the low-lying vacant d-orbitals of iron. The heteroatoms (O and N) and the aromatic moieties are the nucleophilic sites on the inhibitors for effective adsorption on the metal surface as shown by condensed Fukui dual functions and MEP analysis. The MD simulation shows good interaction and strong binding energy between the inhibitor and Fe (110) surface.ConclusionsEffective surface coverage and displacement of H3O+, Cl− and water molecules from Fe (110) surface by the inhibitors indicate good corrosion inhibition properties of the inden-1,3-diones. 2-((4,7-dimethylnaphthalen-1-yl)methylene)-1H-indene-1,3(2H)-dione display low energy gap, strongest binding interaction and most stabilized iron-inhibitor configuration, hence, the best anti-corrosion potential.Graphical abstract

Theoretical approach for the performance of 4-mercapto-1-alkylpyridin-1-ium bromide as corrosion inhibitors using DFT

Numerous synthetic routes have been established for the synthesis of organotin (IV) derivatives of carboxylates, thiocarbamates, thiols, alcohols, amines, Schiff bases, etc. However, no synthetic path has been still developed for the synthesis of organotin (IV) aldehydes. We have synthesized four O,S‐coordinated organotin (IV) aldehydes (1–4) of the general formulas LSn(S)(Cl)R2 (where R2 = Me2, n‐Bu2, Ph2 for 1–3, respectively) and LSn(S)Ph3 (4) by reaction of 4‐(dimethylamino)benzaldehyde (L) with KOH, CS2, and R2SnCl2/Ph3SnCl in methanol. The synthesized products were characterized by microanalysis (CHN), FT‐IR analysis, UV–visible spectroscopy, NMR spectroscopy (1H and 13C), thermogravimetric analysis (TGA), computational studies, and single‐crystal XRD. Elemental analysis data were agreed well with the molecular composition of the products. FT‐IR spectroscopy has shown a significant lowering of C=O vibrational frequency after ligand–metal coordination. The electronic spectroscopy of complexes 1–4 demonstrated the π–π* (342–343 nm) and n–π* (279–296 nm) transitions, with the band gap values of 3.15–3.38 eV. 1H NMR spectra displayed distinct signals for the ligand skeleton and organotin (IV) moieties. 13C NMR spectroscopy exhibited an upfield shift of carbonyl oxygen after ligand–metal coordination. The thermogravimetric analysis revealed the thermal stabilities of complexes up to a temperature of 190 to 320°C. Single‐crystal XRD analysis of product 4 has shown a distorted trigonal bipyramidal geometry around Sn (IV), in which the three phenyl groups were positioned equatorially while the carbonyl oxygen (from the aldehyde) and the sulfur atom occupied the apical positions. Employing the 6‐31G(d,p) basis set and the CAM‐B3LYP functional, time‐dependent density functional theory (TD‐DFT) computations were performed for the calculation of absorbance maxima, oscillator strength (f), and matching molecular designations. MEP maps and HOMO–LUMO energy gaps were predicated on the CAM‐B3LYP/6‐31+g(d,p) level of theory and were used to resolve GRD, including chemical potential (μ), global hardness (η), global softness (S), electronegativity (χ), electrophilicity (ω), ionization potential (IP), and electron affinity (EA). The phenyltin (IV) derivatives (3 and 4) have shown a fantastic biofilm inhibition of Escherichia coli, which was even higher as compared with that of the reference drug ciprofloxacin. The bioactivity of 2 against Bacillus subtilis was equivalent to that of the ciprofloxacin. The products 2 and 3 have shown very little (less than 10%) toxic hemolytic effects demonstrating their possible safe use for the human beings.

Design, synthesis and antibacterial activity of new Isatin-based Schiff base derivatives: Molecular docking, POM analysis, in silico pharmacokinetics and identification of antitumor pharmacophore sites

A novel organic nonlinear optical (NLO) material, 4-dimethylaminopyridinium picrate (4DMAPP) with molecular formula (C7H11N2)+.(C6H2N3O7)- has been synthesized. The single crystals have been grown from synthesized material by slow evaporation technique. The NLO behavior of the 4DMAPP has been investigated using the quantum chemical calculations with 6-311++G(d,p) basis set. The bond lengths, bond angles, and torsional angle of optimized structure of 4DMAPP are in good agreement with the X-ray diffraction experimental data. The global softness, electron affinity, global hardness, Ionization potential, electronegativity, global electrophilicity, and chemical potential have been estimated. The Meyer index is found to be 2.51 and the nature of the 4DMAPP NLO material is identified as soft. Thermodynamics and molecular parameters of 4DMAPP have been carried out with zero-point vibrational energy 186.191 and 171.908 kcal/mol using Hartree–Fock (HF) and density functional theory (DFT) methods, respectively. In optical absorption spectrum, the material 4DMAPP shows the lower cut off wavelength of 325 nm. The narrow energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) facilitates the intramolecular charge transfer (ICT) which makes the material to be NLO active.

5-Diethylamino-2-{[4-(3-methyl-3-phenyl-cyclobutyl)-thiazol-2-yl]-hydrazonomethyl}-phenol single crystal was synthesized and by using FT-IR, NMR and UV-Vis spectral techniques and X‒ray diffraction method were characterized. It has adopted an enol-imine tautomeric form with a strong intramolecular O‒H···N and intermolecular N‒H···N hydrogen bond interaction. The compound has a photochromic property and is not planar. NMR chemical shift values, FT-IR and UV-Vis spectra of the title compound were theoretically calculated using density functional theory (DFT) and the spatial magnetic property known as visual ICSS employing the NICS concept was calculated. Using the TD‒DFT method, the electronic absorption spectrum was calculated and determined to be in good agreement with the experimental UV‒Vis values. It has been found that the title compound may have two tautomer structures (enol-imine and keto-amine). Tautomeric structures of the title compound were used to investigate corrosion inhibition effect on Cu and Fe metal atoms. Some quantum chemical parameters such as HOMO and LUMO orbital energies, electron affinity (IE), ionization potential (EA), electronegativity (χ), global hardness (η) and global softness (S) were calculated. Using these parameters, the fraction of electrons (δ) transfer from inhibitor to metal was calculated to investigate the corrosion inhibition effects of Cu and Fe metals of the two tautomer structures. The corrosion inhibition effects of these structures were compared with the help of calculated quantum chemical parameters, and the relationships between quantum chemical parameters and the corrosion inhibition mechanism were analyzed. Electrophilic and nucleophilic attack sites of these tautomers also were examined using Fukui functions. In addition, optimized structure of the title compound in the solid phase was obtained using Quantum ESPRESSO under periodic boundary conditions (PBC).