Quantum Chemical Parameters Research Articles

Elucidating the mechanisms of AV17 and BB41 dye degradation through combined computational and applied analyses

This study delved into the degradation efficiencies of Basic Blue 41 (BB41) and Acid Violet 17 (AV17) azo dyes employing various Fenton reactions, including Fenton (FP), photo-Fenton (P-FP), sono-Fenton (S-FP), and sono-photo-Fenton (S-P-FP) processes. The primary goal was to pinpoint the optimal degradation conditions by meticulously examining variables such as H2O2 and Fe2+ concentrations, reaction time, pH, and dye concentration. Density Functional Theory (DFT) calculations revealed the interaction between Fenton reagents and dye molecules, and crucial quantum chemical parameters reflecting the dye's reactivity were computed. The degradation efficiencies for AV17 in FP, P-FP, S-FP, and S-P-FP processes stood at 85 %, 92.6 %, 93.8 %, and 86.9 %, respectively. Meanwhile, for BB41, the corresponding efficiencies were 97.2 %, 98.1 %, 97.8 %, and 97.5 %. Notably, DFT-calculated data corroborated experimental observations, shedding light on the degradation mechanism. This study significantly advances existing research by demonstrating the efficacy and reliability of Fenton-like processes in degrading AV17 and BB41 dyes. The findings underscore the potential of these processes in addressing environmental concerns associated with azo dyes.

Inhibition of mild steel corrosion by 4-[(benzylidene)-amino]-antipyrine

The inhibition effect of 4-[(benzylidene)-amino]-antipyrine (BAAP) on corrosion behaviour of mild steel in 1 M HCl solution was studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. Polarization measurements indicate that BAAP acts as mixed type of inhibitor. The adsorption of BAAP on the mild steel surface follows Langmuir adsorption isotherm model. The thermodynamic parameters governing the adsorption process were determined and discussed. Also, quantum chemical parameters were calculated to provide further insight into the mechanism of inhibition action of BAAP.

Exploration of Choline Chloride Based Type II and Type III Deep Eutectic Solvents: A Computational and Experimental Approach

AbstractDeep eutectic solvents (DESs) of choline chloride with citric acid (CACC), Maleic acid (MACC) and Magnesium chloride hexahydrate (MAGCC) were synthesized in 1 : 1 molar ratio and investigated experimentally and computationally. For the computational study, density functional theory (DFT) calculation with B3LYP/6‐31 (+, +) G (d,p) level of theory for MACC and CACC and at B3LYP/SDD basis set for MAGCC was employed and the FT‐IR spectroscopy was used for experimental evaluation. For understanding the orientation of bonds and hydrogen bonding present in DESs geometrically optimized structures were used. Through frontier molecular orbital (FMO) theory and HOMO−LUMO values and various quantum chemical parameters, viz., ionization potential (IP), electron affinities (EA), electro negativity (χ), chemical potential (μ), global softness (σ) and hardness (η), electrophilicity index (ω) were calculated for all DESs. These computational values made it clear that MAGCC is the most stable among the three DESs due to the high value of global hardness (η) (3.291 eV) and HOMO−LUMO energy gap (Egap) (6.582 eV) and lowest value of softness (σ) (0.152 eV), CACC shows the moderate values (η=2.452, Egap=4.905 and σ=0.204 eV). While MACC is found to be the least stable and most reactive among three DESs with values of η, Egap and σ, 1.970, 3.940 and 0.254 eV, respectively. Furthermore, MESP analysis gives an idea about the electrophilic and nucleophilic surface region of DESs. This study will give valuable information for a better understanding of DESs and the applicability of computational calculations in the future.

Theoretical Study of Khellin Derivatives as Corrosion Inhibitors Based on Density Functional Theory (DFT)

Theoretical studies of Khellin in the presence of electron donor and electron with-drawing groups as a corrosion inhibitor are investigated using the B3LYP/6-31G (d, p) theory level with Gaussian software. This research focuses on the correlation between corrosion inhibition efficiency (EI%) and quantum chemical parameters such as EHOMO (Highest Occupied Molecular Orbital Energy), ELUMO (Lowest Unoccupied Molecular Orbital Energy), energy gap (∆E), dipole moment (µ), absolute hardness (η), absolute softness (σ), the absolute electronegativity (χ), the fractions of electrons transferred from the inhibitor molecule to the metallic atom (∆N), the electrophilicity index (ω), total energy (ET) and theoretical corrosion inhibition efficiency (EI %). The generated results show that the electron-donating groups increase the corrosion inhibition efficiency of Khellin in the sequence -NH2> -SH> -H> -NCH2> -NO2. The highest corrosion inhibition efficiency obtained about 98.40% proves that NH2-Khellin is the best corrosion inhibitor of iron.

Synthesis, molecular structure, experimental and computational studies, nonlinear optical properties of amaranth dye doped L-lysine sulphate (ALLS) semiorganic crystal

A polycrystals of amaranth dye-doped L-lysine sulphate (ALLS) was synthesized and fabricated as a single crystal utilizing the solution-based growth approach and confirmed the orthorhombic structure through XRay diffraction anlaysis. The ALLS molecule was optimized in Gaussian 09 W utilizing the density functional theory (LANL2DZ/DFT) basis. Along with PED, the Fourier transform infrared (FTIR) spectroscopy helps vibrational assignments of ALLS were both theoretically and experimentally suited to one another. The FMO energies of ALLS molecules are used to derive quantum chemical parameters. To study the properties of charges existing at the molecular structure level, DOS, MESP, and MULLIKEN studies were performed. To figure out the compound's NLO activity, hyperpolarisability values are calculated. ELF, LOL, and RDG topological studies were carried out through which the localization and delocalization of electrons were found. MEP gives the relative polarity and the UV absorption gives maximum absorption at 414 nm were recorded. Additionally, ALLS's thermodynamic parameters were calculated. The NLO behaviour of the LLS complex was improved by amaranth dye, and ALLS has been suggested as a suitable compound for the fabrication of NLO devices as an outcome of both experimental and computational results.

Development of tripodal imine metal chelates: Synthesis, physicochemical inspection, theoretical studies and biomedical evaluation

Direct condensation of 2-acetylferrocene with tris(2-aminoethyl)amine resulted in a novel tripodal imine ligand (L). Treatment of the metals’ chlorides (Fe3+, Cr3+, Co2+, Ni2+, Cu2+, Mn2+, Cd2+, and Zn2+) with equimolar ratio of the tripodal imine ligand led to cleaned production of the equivalent mononuclear complexes. They are well characterized by different physicochemical analyzing tools such as CHN, FT-IR as well as electronic spectroscopy, mass spectrometry and TGA analyses. Furthermore, scanning electron microscope (SEM) study for the tested ligand as well as Cd(II) chelate proved that it was nanosized. The stoichiometry of the prepared metal chelates in solution confirm M:L is 1:1 ratio. The DFT calculations demonstrated that all metal complexes possess octahedral geometry in accordance with the experimentally deduced geometry. The MEP surface indicated the reactive regions of the compounds for electrophilic and nucleophilic attack. HOMO-LUMO analysis implies charge transfer interaction during complex formation. Quantum chemical reactivity parameters showed that the complexes are stable and the decomposition process into constituent elements does not occur. Morover, anti-pathogenic and anticancer activities were studied against different bacterial, fungal strains and selected cancer cell lines. The metal chelates show potent anti-microbial and anti-cancer activity than its tripodal imine ligand. Furthermore, MOE-docking of the title ligand, Cu(II) as well as Cd(II) chelate was studied with crystal structure of the antimalarial drug Amediaquine (3AOU), colon cancer antigen10 (2HQ6), breast cancer (3HB5) and gastrointestinal cancer (4IJO).

Interactions of Acetylene-Derived Thioester Collectors with Gold Surfaces: A First-Principles Study

The high reactivity of the acetylene group enables the formation of strong chemical bonds with active sites on mineral surfaces, thereby improving the flotation performance of gold minerals. This study utilized density functional theory (DFT) to analyze the quantum chemical parameters of structure, Mulliken population, and the frontier orbitals of a thioester collector containing an acetylene group, PDEC (prop-2-yn-1-yl diethylcarbamodithioate). PDEC was compared with analogous thioester collectors Z-200 and Al-DECDT. The interaction mechanism of PDEC on the Au(1 1 1) surface was simulated, followed by empirical validation through adsorption experiments. The findings indicate that the S atom of PDEC in the carbon–sulfur group exhibits shorter covalent bond lengths, and has reduced carbon–sulfur double bonds and Mulliken population, resulting in enhanced electron localization. This confers greater selectivity to PDEC during its adsorption on mineral surfaces. Frontier orbital analysis shows that the electrons of the acetylene group possess a notable electron-accepting capacity, significantly influencing the frontier orbital energy of PDEC and playing a pivotal role in the bonding interaction with mineral surfaces. Both the S atom in the carbon–sulfur group and its acetylene group establish stable adsorption structures with the A(111) surface in a single coordination mode. The adsorption energy sequence is PDEC > Al-DECDT > Z-200. Partial density of states demonstrates that the S 3p orbit of the carbon–sulfur group hybridizes with the Au 5d orbit, while the C 2p orbit of the acetylene group engages in weaker back-donation bonding with the Au 5d orbit. This is corroborated by the electron density difference and post-adsorption Mulliken population analyses, revealing that the S atom of the carbon–sulfur group in PDEC donates electrons to the Au atom, forming dominant positive coordination bonds, whereas the acetylene group accepts partial electrons from the Au atom, resulting in weaker back-donation bonds. The adsorption experiments align with the DFT adsorption energy results.

Photocatalytic activity of ZnMn2O4/TiO2 heterostructure under solar light irradiation: Experimental and theoretical study

This study focuses on the application of the hetero-junction ZnMn2O4/TiO2 as an efficient photocatalyst for the degradation of Rhodamine B (RhB), a cationic dye. ZnMn2O4 was synthesized by sol-gel auto-combustion, employing citric acid as fuel. The photocatalysts underwent characterization by X-ray diffraction, Fourier Transform infrared spectroscopy, Scanning Electronic Microscopy with integrated EDX and UV–Vis Diffuse Reflectance. Creating a p-n heterojunction could significantly boost photocatalytic efficiency. In this work, we use TiO2 as a n-type co-catalyst to enhance electron transfer efficiency. The ZnMn2O4 spinel exhibits direct optical transition at 1.97 eV, while TiO2 displays an indirectly allowed transition at 3.24 eV. Mott-Schottky plots revealed flat band potentials of -0.121 and +0.3 V/SCE for ZnMn2O4 and TiO2, respectively. Kinetic data of RhB adsorption were fitted using the pseudo-second order model. The heterojunction p-ZnMn2O4/n-TiO2 demonstrates a significant pollutant degradation rate, with 95% removal within 180 min under sunlight irradiation, surpassing the effectiveness of ZnMn2O4. To validate the experimental results, a theoretical investigation was conducted using density functional theory (DFT) and molecular dynamics (MD) simulations. Geometry optimization of the Rhodamine B molecule was studied in both gas and liquid phases, and various quantum chemical parameters were computed. Molecular dynamics simulations were additionally employed to examine the dynamic behavior of Rhodamine B adsorption on ZnMn2O4 (211) and TiO2 (101) surfaces in an aqueous environment.

Designing, DFT, biological, & molecular docking analysis of new Iron(III) & copper(II) complexes incorporating 1-{[-(2-Hydroxyphenyl)methylene]amino}−5,5-diphenylimidazolidine-2,4-dione (PHNS)

The exploration encompassed the synthesis and characterization of two innovative complexes, namely FePHNS and CuPHNS, employing a diverse array of analytical techniques such as elemental analysis, infrared and ultraviolet-visible spectroscopy, mass spectrometry, molar conductivity measurements, magnetic susceptibility assessments, and thermal analysis (TGA). In the spectral domain, infrared spectroscopy substantiated the tridentate ONS coordination of the PHNS ligand to the central metal atom. Thermal analysis offered valuable insights into the distribution and content of water molecules within the complexes. Density functional theory (DFT) calculations were harnessed to validate the molecular structures of both the PHNS ligand and its complex entities, providing an intricate comprehension of their quantum chemical parameters. The investigation extended to an evaluation of the in vitro antibacterial, antifungal, and antioxidant efficacy of the PHNS ligand and its complexes, revealing heightened biological activities for the complexes in comparison to the free PHNS ligand, notably with the CuPHNS complex demonstrating the highest activity, while the PHNS ligand exhibited the lowest. To delve into potential physiological activities, molecular docking studies were conducted, predicting the binding affinity of the compounds to proteins 2vf5 (Glucosamine-6-phosphate synthase in complex with glucosamine-6-phosphate) from Escherichia coli, 3cku (rate oxidase from Aspergillus flavus complexed with its inhibitor 8-azaxanthin and chloride) from Aspergillus flavus, and 5IJT (Crystal structure of Human Peroxiredoxin 2 Oxidized). The ensuing analysis of protein-ligand interactions and binding energies underscored the promising physiological activities of the investigated compounds, warranting further exploration for their potential in novel drug development.

Experimental and density functional theory studies on some metal oxides and the derived nanoclusters: a comparative effects on human ferritin

A comprehensive investigation into the green synthesis of metal oxide nanoparticles (NPs) has garnered significant attention due to its commendable reliability, sustainability, and environmentally friendly attributes. Green synthesis methods play a crucial role in mitigating the adverse effects associated with conventional approaches employed for nanostructure preparation. This research endeavors to examine the impact of ginger plant extract-assisted green synthesis of metal oxides NPs on the serum ferritin levels of anemic diabetic patients in vitro, focusing specifically on α-Fe2O3 and ZnO NPs. Sixty diabetic volunteers with anemia (35–50 years) and thirty healthy volunteers were enrolled as controls. The assessment was conducted using the VIDAS Ferritin (FER) assay. Photoluminescence (PL) spectroscopy measurements were performed to elucidate the intrinsic and extrinsic transitions of these NPs, affirming the successful formation of α-structured iron oxide. Density functional theory (DFT) calculations were carried out at the B3LYP/6-311++G(d,2p) level of theory to investigate the geometry optimization and molecular electrostatic potential maps of the NPs. Furthermore, TD-DFT calculations were employed to explore their frontier molecular orbitals and various quantum chemical parameters. The binding affinity and interaction types of ZnO and α-Fe2O3 NPs to the active site of the human H-Chain Ferritin (PDB ID: 2FHA) target were determined with the help of molecular docking. Results unveiled the crystalline structure of ZnO and the α-structure of α-Fe2O3. Analysis of the frontier molecular orbitals and dipole moment values demonstrated that ZnO (total dipole moment (D) = 5.80 µ) exhibited superior chemical reactivity, biological activity, and stronger molecular interactions with diverse force fields compared to α-Fe2O3 (D = 2.65 µ). Molecular docking of the metal oxides NPs with human H-chain ferritin provided evidence of robust hydrogen bond interactions and metal-acceptor bonds between the metal oxides and the target protein. This finding could have a great impact on using metal oxides NPs-ferritin as a therapeutic protein, however, further studies on their toxicity are required.Graphical abstract

Inhibition performances of new pyrazole derivatives against the corrosion of C38 steel in acidic medium: Computational study

Corrosion inhibition performances of two new pyrazole derivatives, namely 5-(4-dimethylamino)phenyl)-3-(4-dimethylamino)styryl)-4,5-dihydro-1H-pyrazole-1-carbothio amide (P1) and 5-(4-dimethylamino)phenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-carbothio amide (P2) against the corrosion of carbon steel in acidic medium are theoretically investigated by combination of the density functional theory with the molecular dynamics approach. Additionally, the toxicity and solubility of the aforementioned molecules were investigated. Quantum chemical parameters of considered molecules (calculated energy levels of HOMO and LUMO molecular orbitals as well as the gap between them, hardness, softness, chemical potential, electronegativity, electrophilicity index, nucleophilicity, electro donating power, electro accepting power, polarizability, dipole moment, metal-inhibitor interaction energy, the fraction of electrons transferred from inhibitors to metal surface, back-donation energy, Fukui indices) were calculated at B3LYP/SVP, CAM-B3lyp/TZVP and ωB97XD/Def2-TZVP levels of theory. Comparative calculations were performed in the gaseous phase and in the aqueous solutions. The adsorption behavior of the mentioned molecules on the Fe (110) surface was investigated with the molecular dynamics. Both considered molecules demonstrates high adsorption energies on steel surface, low toxicity and high solubility. P1 is found to be more efficient in hydrochloric acid, whereas P2 molecule is found to be more efficient in sulfuric acid.

Designing of novel nano-sized coordination compounds based on Spinacia oleracea extract: Synthesis, structural characterization, molecular docking, computational calculations, and biomedical applications

A novel series of nano-sized metal chelates of 1-((E)-(2-mercaptophenylimino)methyl)naphthalen-2-ol (H2L) Azo-methine ligand with Fe(III), Ni(II) and Ag(II) were prepared and investigated for antitumor activities. The structures of all the synthesized compounds have been analyzed using various physicochemical techniques. The results showed a distorted square-planar geometry for Ni2L2 and AgL, whereas the geometry around the FeL complex is octahedral. The nano-sized Fe and Ag complexes were prepared in an easy, rapid andeco-friendly way using Spinacia oleracea (SO) extract in EtOH. X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV.Vis. spectra were used to assess the structural characteristics and particle size of the newly produced nano-sized Fe and Ag complexes. Furthermore, from TGA, we investigated the impact of heat on the particle size of newly prepared compounds. The geometry optimization of the prepared complexes and various quantum chemical parameters were computed by Gaussian 09 softwares. The results showed that all of the metal complexes studied are more stable than the free ligand H2L, with the Ni2L2 complex being the most stable. All micro- and nano-complexes were tested for in vitro anticancer activities, and the results revealed inhibition of cancer cell activity, although the smaller size is better than the larger size. The liver cancer and COVID‑19 were screened using molecular docking to determine the possible binding energy of inhibitors.

Understanding the hydrogen bonding preferences and dynamics of prontosil in water and methanol

Solvation energy, defined as the Gibbs energy change accompanying the transfer of a molecule or an atom from vacuum to the solution, plays a crucial role in understanding molecular interactions. In this study, we explore the interaction of prontosil, an important sulfa drug and the first developed antibiotic capable of combating gram-positive cocci bacteria with two common solvents, methanol and water. To investigate these interactions, we employed the DFT/M06–2X/cc-pVDZ level of theory for the geometry optimization of each system. Considering prontosil's six electronegative sites that offers numerous possibilities for interactions, we observed prominent interactions between the drug prontosil and the solvents water and methanol at various sites. The prontosil-water and prontosil-methanol complexes most stable sites were used for additional research. The NBO analysis provided insights into the delocalization phenomena present in prontosil under vacuum and in the presence of solvents. The non-covalent interactions (NCI) and reduced density gradient (RDG) plot aided in the interpretation of the steric interactions, strong and weak hydrogen bonds, as well as intra and intermolecular interactions within prontosil and its complexes. In the NBO analysis, the hydrogen and electronegative atoms of the most stable site of the prontosil-methanol complex showed the highest transmittance energy and in the case of the NCI plot, the same region displayed a blue colour which denotes a strong hydrogen bond. After calculating the quantum chemical parameters of reactivity, it was observed that the prontosil-methanol complex had a lower electrophilicity and is hence more stable. Quantum theory of atoms in molecules (QTAIM) analysis revealed the existence of non-covalent interactions at all the bond critical points (BCP) under consideration in the prontosil molecule and its complexes formed with the solvents. Further investigation of several QTAIM parameters revealed that the prontosil-methanol complex exhibited the lowest binding energy, indicating the most stable interactions among the investigated bond critical points. Additionally, we employed local energy decomposition (LED) and ab initio molecular dynamics (AIMD) simulations based on the M06–2X/cc-pVDZ method, with LED analysis performed using DLPNOCCSD(T). The LED analysis demonstrated that prontosil exhibits more pronounced interactions with methanol than water, and we explored how energy distributions contribute to the total binding energy. Prontosil-methanol complex showed the lowest energy (-14.50 kcal/mol) than the prontosil-water complex (-14.32 kcal/mol). The LED analysis provided insights into why the total binding energy is attractive and predominates the repulsive nature. AIMD simulations of prontosil-methanol complexes yielded favourable results when compared to prontosil-water complexes.

Computational Investigation of Corrosion Inhibition Properties of Hydrazine and Its Derived Molecules for Mild Steel

Corrosion of mild steel has gained a lot of attention by many industries and academia. This study was aimed to find the corrosion inhibition properties of hydrazine and its 11 derived molecules for mild steel using computational method, namely, the density functional theory with Beck 3‐parameter Lee Yang and Parr functional along with the 6‐311++G (d, p) basis set using simple quantum chemical parameters. The main quantum chemical parameters were energies of highest occupied and lowest unoccupied molecular orbitals and their energy gap, dipole moment, hardness, softness, electrophilicity index, the fractions of electrons transmitted, the change energy back‐donation, electron‐donating power, electron‐accepting power, molecular electrostatic potential, and Fukui function as well as polarizability. The results indicated that hydrazine derivatives have good anticorrosion nature which is consistent with the experimental findings. Out of the 12 target inhibitor molecules, N′‐(3‐nitrobenzylidene) hydrazine carbodithioic acid (NBHCA) and N′‐(4‐dimethylaminobenzylidene) hydrazine carbodithioic acid (DABHCA) are the most effective inhibitors. According to the value of the quantum chemical parameters, EHOMO, ΔEgap, Χ, η, σ, ε, ΔN, α, and ΔEb-d DABHCA showed the top effective anticorrosion inhibitor, and by the value of the quantum chemical parameters, ELUMO, TE, ω−, and ω+ NBHCA showed an effective anticorrosion inhibitor. The quantum chemical parameter data showed that NBHCA and DABHCA are nearly equivalent in their values, which is consistent with experimental values. Furthermore, a multiple‐linear regression equation was proposed as a quantitative structural activity relationship model to relate the calculated molecular descriptors of hydrazine derivatives to their experimental inhibition efficiencies obtained from literature. As a result, this model showed an excellent accuracy with an R‐squared of 0.924 and this uses to predict inhibition efficiencies of another molecules.

Molecular structure, HOMO–LUMO, and NLO studies of some quinoxaline 1,4-dioxide derivatives: Computational (HF and DFT) analysis

The theoretical investigation results of quinoxaline-1, 4-dioxide (I), and some of its derivatives (II-VII) were reported in this paper. Quantum chemical calculations were performed on seven molecules at ab initio/RHF/6–311++G (d, p) and DFT/B3LYP/6–311++G (d, p) levels of theory. Calculated optimized molecular structures, dipole moments, polarizabilities, and first order hyperpolarizabilities for all molecules were dedicated. Also, the frontier molecular orbitals (FMOs), EHOMO (the highest occupied molecular orbital energy), ELUMO (the lowest unoccupied molecular orbital energy), HOMO-LUMO energy gap (ΔE), quantum chemical parameters such as chemical potential (Pi), absolute electronegativity (χ), chemical hardness (η), global softness (S), and global electrophilicity (ω) are investigated. 1HNMR spectrum for quinoxaline-1, 4-dioxide (I) was calculated and compared with experimental data. The results of two theoretical methods have been analyzed using the Excel program in the linear regression method.

Corrosion inhibition ability of L-tryptophan and 5-hydroxy-L-tryptophan for mild steel: a combination of experimental and theoretical methods.

An investigation into the corrosion inhibition properties of L-tryptophan (TP) and 5-hydroxy-L-tryptophan (5-OH-TP) for mild steel in a 1.0 M HCl acidic medium was conducted using experimental and theoretical methods. Results obtained from polarization curve measurements reveal that TP and 5-OH-TP are effective mixed-type inhibitors, exhibiting the highest inhibition efficiencies of 91.22% and 94.05%, respectively, at a temperature of 293 K and a concentration of 10-2 M. However, their inhibition efficiencies gradually decline with increasing temperature, reaching the lowest values of 70.65% for TP and 73.55% for 5-OH-TP at a concentration of 10-4 M and a temperature of 323 K. The adsorption of TP and 5-OH-TP on the steel surface follows the Langmuir isotherm, suggesting monolayer adsorption. Electrochemical impedance spectroscopy analysis indicates that the adsorbed inhibitors form a protective film, effectively shielding the steel from corrosive agents in the solution. Notably, 5-OH-TP consistently exhibits superior inhibition efficiency compared to TP, attributed to the presence of polar OH groups that facilitate stronger bonding of the inhibitor molecule with the metal surface. Quantum chemical parameters and molecular dynamics simulations further confirm the superior corrosion inhibition ability of 5-OH-TP over TP in acidic environments. In particular, the binding energies of protonated TP at the N3 position and 5-OH-TP at the N4 position are 556.40 and 579.27 kJ mol-1, respectively.

Изучение возможности применения фульвовой кислоты для флотационного извлечения ванадия на основе расчёта молекулярных дескрипторов

The relevance of the work lies in the need to process acidic productive solutions containing the valuable component vanadium in the form of vanadyl cations. The object of study in this work is fulvic acid (FulvAc), and the subject is the possibility of its use as a flotation reagent-collector of vanadyl cations. The purpose of the work is to study the possibility of flotation extraction of vanadium from acidic productive solutions. To achieve the goal, the following tasks are set: selection of a selectively acting collecting reagent in relation to a valuable component based on the "structure-property / activity-property" principle; carrying out molecular calculations, including structural, physicochemical and quantum chemical parameters of a new reagent of natural origin - fulvic acids; application of a software package for modeling and visualization of "substrate-reagent" systems; studying the mechanism of interaction between FulvAc molecules and the substrate [VO(H2O)4]2+; implementation of laboratory flotation testing of the collecting reagent. The following special research methods are used in the work: chemical modeling and analysis using The Cambridge Crystallographic Data Center (CCDC) and Avogadro software systems. Calculations of molecular descriptors of flotation activity of a new organic reagent FulvAc in relation to the extractable valuable component vanadium (metal substrate), which quantitatively allow to evaluate the possibility of using FulvAc for flotation extraction of vanadium substrate from solutions based on the principle of "structure-property/activity-property", are presented. The calculation of molecular descriptors carried out in this work has showed that FulvAc due to phenolic, hydroxyl, carbonyl and carboxyl groups are able to form chelate complexes with vanadium cations, oxygen heteroatoms cause chemisorption centers. Vanadium in acidic productive solutions is in the form of vanadyl cations (VO)2+ and aquavanadylcations [VO(H2O)4]2+, which show the properties of complexing agents. Modeling of flotosystems "substrate-reagent" formation with the use of The Cambridge Crystallographic Data Center software is carried out. The possibility of formation of stable substrate-reagent flotation system "(VO)2+ / [VO(H2O)4]2+– FulvAc" by charge-controlled mechanism has been proved.

SON KULLANMA TARİHİ GEÇMİŞ BİR İLACIN İNHİBİSYON ETKİNLİĞİ ÜZERİNE PROTONASYONUNUN DEĞERLENDİRİLMESİNE YÖNELİK TEORİK BİR YAKLAŞIM

The quantum theoretical calculations were performed to elucidate the corrosion inhibition efficiency of an expired drug. For this purpose, molecular orbital analysis, which is used in the analysis of chemical interactions and gives detailed data about the electronic structure of molecules, was used to gain insight into the electronic properties of the selected drug molecule in neutral and aqueous form. The calculations were carried out at the (B3LYP) 6-311G**(d,p) basis set level utilizing density functional theory (DFT) to examine the relationship between the molecular structure and inhibition efficiency of the corresponding drug molecule. Various quantum chemical descriptors such as highest occupied molecular orbital energy (HOMO), lowest unoccupied molecular orbital energy (LUMO), energy gap (ΔE), dipole moment (μ), ionization potential (I), electron affinity (A), electronegativity (χ), hardness (η), softness (σ), back donation (ΔEback- donation) and fraction of electrons transferred (ΔN) were calculated and correlated to the inhibition efficiency. The most probable nucleophilic and electrophilic reactive sites of studied drug molecule were analyzed through computed Fukui indices. Overall, obtained theoretical data indicate that the quantum chemical parameters correlate well with the inhibition performance.

Impacts of pyridinium gemini surfactants on corrosion inhibition of carbon steel

Pyridinium gemini surfactants (PGS-n) are an important class of amphiphiles with antibacterial properties and hence, are usually preferred in industrial and medicinal applications. In this work, three PGS-n with different alkyl chain lengths having two amide spacers, 3,3′-(Malonylbis(azanediyl))bis(1-dodecylpyridin-1-ium) dibromide (PGS-12), 3,3′-(Malonylbis(azanediyl))bis(1-tetradecylpyridin-1-ium) dibromide (PGS-14), and 3,3′-(Malonylbis(azanediyl))bis(1-octadecylpyridin-1-ium) dibromide (PGS-18), were synthesized, characterized and tested as corrosion inhibitor on carbon steel in HCl for the first time. The corrosion inhibition efficiency was examined by weight loss measurement, electrochemical impedance spectroscopy (EIS), and potentiodynamic measurements at 30 °C. Furthermore, micellization parameters such as critical micelle concentration (cmc), degree of counter ion dissociation, and Gibb's energy of micellization of these PGS-n were determined. The inhibition efficiency of the studied PGS-n was found to be maximum near their cmc values and found to follow the order: PGS-18 > PGS-14 > PGS-12. The PGS-n with the longest alkyl chain could achieve a maximum inhibition efficiency of 99.2 %. The adsorption of PGS-n on the surface of carbon steel was found to follow the Langmuir adsorption isotherm. The results obtained from EIS measurements agreed well with those of polarization and weight loss studies. Field emission scanning electron microscopic analysis revealed that the corrosion of the carbon steel surface is not severe, especially in the presence of PGS -18. Density functional theory was employed to calculate various quantum chemical parameters of the PGS-n. The results suggest PGS-n as an effective inhibitor for corrosion inhibition of carbon steel.

Effects of solvents on structure and energy of 6-amino-2-mercapto-3H-pyrimidin-4-one: A computational study

6-amino-2-mercapto-3H-pyrimidin-4-one (AMP) is a π-conjugated organic molecule extensively used as a semiconductor in many optoelectronic devices. The computational hybrid meta-generalized gradient Minnesota M06-2x, ωB97XD, and B3LYP functionals in conjunction with the correlation consistent polarized valence triplet zeta (cc-pVTZ) basis set and the moderate composite CBS-QB3 procedure were used with the aid of the Gaussian 09 program and the kinetic and statistical thermodynamical package (KiSThelP) in the temperature range 250–400 K to investigate the behavior of AMP in the gas phase, and in different polar (water, ethanol), and non-polar (dimethyl sulfoxide (DMSO), acetone)) solvents. Non-linear optical (NLO) characteristics and quantum chemical parameters were examined. Natural bond orbital analysis (NBO) was used to characterize the charge transfer of the electron density in the investigated compounds. The quality of the methods used was inspected and compared to give accurate results. The stability of AMP can be returned to the hyper conjugative interactions that leading to its nonlinear optical activity. Also, the charge delocalization was analyzed using natural bond orbital technique. The molecular electrostatic potential surfaces (MEPS) plots have been generated. The rate coefficients of tautomerization processes (kuni, in s−1) were calculated from the transition state theory (TST) and unimolecular Rice-Ramsperger-Kassel-Marcus (RRKM) methods. The results indicate comparable chemical rates obtained from TST and RRKM. In addition, positive temperature dependencies were located for all channels and a high dominance of transferring H-atom from the external N-atom to the S-atom (R3 reaction) during the applied temperature range which can return to its lower activation energy. This study is the first stone in studying AMP under different conditions such as the atmosphere, combustion conditions and as a nano catalyst.