Minimum Polarizability Principle Research Articles

A Density Functional Theory (DFT) based Analysis on the Inhibition Performances of Some Triazole Derivatives for Iron Corrosion

Iron is one of the widely used metals in industry. For that reason, the prevention of the corrosion of such metals via new designed inhibitor systems is among the interest of corrosion scientists. In the present paper, we investigated the corrosion inhibition performance of 2-((1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl) methoxy) benzaldehyde (A), 4-((1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl) methoxy) benzaldehyde (B), 4-((4-nitrophenoxy) methyl)-1-(4-nitrophenyl)-1H-1,2,3-triazole (C), 4-methyl-7-((1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl) methoxy)-2H-chromen-2-one (D) against iron corrosion. For the mentioned inhibitor systems, important reactivity descriptors like frontier orbital energies, chemical potential, electronegativity, hardness, softness, polarizability, dipole moment, back-donation energy, electrophilicity, electroaccepting power and electrodonating power were calculated and discussed. Calculations were repeated using various methods and basis sets in different phases. The chemical reactivities of the inhibitors were predicted in the light of well-known electronic structure rules like Maximum Hardness and Minimum Polarizability Principles. The obtained data showed that the best corrosion inhibitor among them is molecule D while the most stable molecule is molecule C. The theoretical data support the experimental observations.

Molecular insights into the corrosion inhibition mechanism of omeprazole and tinidazole: a theoretical investigation

ABSTRACT In many studies published in recent years, corrosion scientists proved that various drug molecules can exhibit high inhibition performance against the corrosion of metal surfaces and alloys. This study presents the adsorption behaviour and inhibition mechanism of Omeprazole and Tinidazole on steel surface in gas phase and aqueous acidic conditions using quantum chemical calculations and molecular dynamics simulations. Well-known quantum chemical parameters such as EHOMO, ELUMO, energy gaps, dipole moment, global hardness, softness, electrophilicity, electrodonating power, electroaccepting power and the fraction of electron transfer, were calculated to understand the corrosion inhibition properties and interactions with the steel surface of the studied molecules. Fukui indices analysis was performed to identify the local reactivities of the molecules. Additionally, Monte Carlo simulations were used to determine the optimal adsorption configuration of the inhibitors onto a Fe (1 1 0) surface. The study's findings provide valuable insights into preventing corrosion of steel surfaces in aqueous acidic environments. The theoretical data obtained was evaluated in terms of Maximum Hardness, Minimum Polarizability and Minimum Electrophilicity Principles.

Atoms-In-Molecules' Faces of Chemical Hardness by Conceptual Density Functional Theory.

The chemical hardness concept and its realization within the conceptual density functional theory is approached with innovative perspectives, such as the electronegativity and hardness equalization of atoms in molecules connected with the softness kernel, in order to examine the structure-reactivity equalization ansatz between the electronic sharing index and the charge transfer either in the additive or geometrical mean picture of bonding. On the other hand, the maximum hardness principle presents a relation with the chemical stability of the hardness concept. In light of the inverse relation between hardness and polarizability, the minimum polarizability principle has been proposed. Additionally, this review includes important applications of the chemical hardness concept to solid-state chemistry. The mentioned applications support the validity of the electronic structure principles regarding chemical hardness and polarizability in solid-state chemistry.

New mixed‐ligand iron(III) complexes containing thiocarbohydrazones: Preparation, characterization, and chemical reactivity analysis through theoretical calculations

Five new mixed ligand Fe(III) complexes, namely, [FeL1(acac)] (L1Fe), [FeL2(acac)] (L2Fe), [FeL3(acac)] (L3Fe), [FeL4(acac)] (L4Fe), and [FeL5(acac)] (L5Fe), were synthesized from the reaction of iron(III) acetylacetonate with [ONS] donor dibasic tridentate symmetrical bisthiocarbohydrazone ligands. Synthesized mixed ligand Fe(III) complexes were characterized with infrared spectra, UV‐Vis spectra, mass spectra, elemental analysis, magnetic susceptibility measurements, and thermogravimetric analysis. The molar conductance measurement in DMF solution confirmed that the complexes are nonelectrolytic. TGA analysis results showed that the thermal stability of the ligands and complexes was high. Antioxidant capacity and free radical scavenging activity of the mixed ligand Fe(III) complexes were investigated using CUPRAC and the DPPH radical scavenging method. Mixed ligand Fe(III) complexes showed higher antioxidant activity than ligands and reference compound. Popular conceptual density functional parameters like hardness, electrophilicity, dipole moment, and chemical potential for new ligands and their Fe(III) complexes were calculated and discussed. Chemical reactivity and stabilities of the studied chemical systems were analyzed with the help of well‐known electronic structure principles like maximum hardness principle (MHP), hard and soft acid–base (HSAB) principle, minimum polarizability principle, and minimum electrophilicity principle. L1Fe, which has the highest chemical hardness value, is the most stable complex according to MHP.

Variation in electrophilicity on electronic excitation

AbstractThe rationality of the minimum electrophilicity principle (MElP) as a companion of minimum polarizability principle and maximum hardness principle is studied for simple diatomic, triatomic, and tetratomic molecules. The applicability is further justified considering organic molecules (e.g., pyrene and acridine yellow) are known for their photophysical properties and accordingly their excited state properties. Single excitation CI (CIS) and time‐dependent density functional theory (TDDFT) are employed to study the excited state reactivity. Two types of excitations, namely vertical and adiabatic, are considered. Processes involving conservation and change in spin multiplicity are included during excitation. The general trend is that the molecules are less electrophilic in the ground state than those in the corresponding excited states. It is found that adiabatic excitation validates the principle even for the triplet ground state molecules undergoing an excitation where spin multiplicity gets altered. The TDDFT method explains the validity of the MElP augmenting the CIS method. This study echoed the MElP during molecular electronic excitation.

Can van der Waals constants be used in the chemical reactivity analysis? A new approach as a support to minimum magnetizability principle

AbstractOne of the most important purposes of theoretical chemists is to derive new, useful, and reliable equations to compute the well‐known parameters like hardness, polarizability, magnetizability, and electrophilicity providing enough hints for the reactivity analysis of the chemical systems. In the derivation of such equations, our research team widely considers the popular electronic structure rules like electronegativity equalization, maximum hardness, minimum polarizability, minimum magnetizability, and minimum electrophilicity principles. Recently, in the light of maximum entropy and minimum magnetizability principles, Kaya and Chattaraj (2021) presented a simple way to calculate their standard absolute entropies (S0298) based on molar diamagnetic susceptibilities (χm) of inorganic ionic systems. In the present paper, a new and useful molar diamagnetic susceptibility calculation method including the use of van der Waals constants (a and b) is introduced. Here, we named this method as Kaya–Şimşek approach. Through the relations between molar diamagnetic susceptibility and van der Waals constants, we can easily predict the magnetic susceptibility of molecules that their magnetic susceptibilities are unknown. The results of the equations derived are quite close to experimentally reported data. The analyses made proved that van der Waals constants can be considered as chemical reactivity descriptors. We propose that in stable states, van der Waals constants are minimized. The validity of minimum magnetizability principle is supported with solid evidences.

Kaya's composite descriptor and Maximum Composite Hardness Rule for chemical reactions

Within the framework of Maximum Hardness and Minimum Polarizability Principles and as compatible with Jenkins Volume Based Thermodynamics approach, Kaya and coworkers calculated the lattice energies of inorganic ionic crystals using their ηM/Vm1/3 ratio (here ηM and Vm represent the chemical hardness and molar volume of any molecule, respectively). This ratio is called as Kaya's composite descriptor. It is apparent that Kaya's composite descriptor can be considered in the analysis of the chemical stability of compounds and the directions of chemical reactions. In a recent paper, Szentpaly, Kaya and Karakuş proposed Maximum Composite Hardness Rule for solid state double exchange reactions. To see the validity in other reaction types also of Kaya's composite descriptor and Maximum Composite Hardness Rule, twenty-eight chemical reactions including especially organic molecules were investigated. Reactivity descriptors such as chemical hardness, molar volume, polarizability regarding reactants and products putting in an appearance were calculated at B3LYP/6-31++g (d, p) calculation level with the help of computational chemistry tools. The result showed that instead of using separately the chemical hardness, polarizability and molar volume concepts, the use of Kaya chemical reactivity approach will be more useful to predict whether the reactions are exothermic or endothermic. It can be concluded from here that new composite descriptors should be derived and used for the accurate prediction of the reactivities of the chemical systems.

Spectral, thermal and DFT studies of novel nickel(II) complexes of 2-benzoylpyridine-N4-methyl-3- thiosemicarbazone: Crystal structure of a square planar azido-nickel(II) complex

Novel six Ni(II) complexes of an NNS donor 2-benzoylpyridine-N4-methyl-3- thiosemicarbazone(HL) are synthesized and characterized. Various physicochemical techniques are applied for the study of the coordination behavior of the thiosemicarbazone to the nickel center. In all the complexes, thiosemicarbazone is coordinated in the thiolate form. A four coordinated Ni(II) complex [NiLN3] is crystallized and its molecular and crystal structures are determined by single-crystal X-ray crystallography. Single-crystal XRD reveals that the complex got crystallized in the monoclinic space group P21/n and nickel(II) has a square planar environment. Intramolecular hydrogen bonding interactions make the complex more rigid and in the crystal lattice, the intermolecular hydrogen bonding interactions generate a supramolecular 1 D chain. The chemical reactivity behavior of the HL and six Ni(II) complexes was evaluated with the CAM-B3LYP quantum chemical calculations. The validity of electronic structure principles like Maximum Hardness, Minimum Polarizability, and Minimum Electrophilicity Principle in the study is discussed.

Synthesis, single crystal structures, DFT and in vitro anti oxidant superoxide dismutase studies of copper(II) complexes derived from the di-(2-picolyl)amine and co-ligands: Promising antioxidants

Three new copper(II) complexes, [Cu(DPA)(ClO4)2(H2O)]MAP 1, [Cu(DPA)(ImH)(ClO4)2] 2 and [Cu2(DPA)2(2COO−)(ClO4)2]H2O 3 (where, DPA = di-(2-picolyl)amine, MPA = 2-methoxyacetophenone, ImH = Imidazole and 2COO− = oxalate anion), have been synthesized and characterized using various physico-chemical techniques. DPA is a tridentate ligand with NNN donors atoms and imidazole is a monodentate ligand whereas, oxalate anion is a bridging ligand. Single crystal X-ray analysis reveals that 1–3 are neutral complexes. The X-band Epr spectral study in polycrystalline at RT and in DMSO solution at LNT have been analyzed. To examine the stability of complexes, density functional theory (DFT) calculations were performed. The obtained quantum chemical parameters like electron affinity, ionization potential, electronegativity, electrophilicity and global hardness and softness were discussed within the frame work of electronic structures and principles known as maximum hardness, minimum polarizability and minimum electrophilicity principles. Hirshfeld surface analysis showed that the supramolecular structures of the complexes 1–3 is stabilized mainly by CH⋯π, lp⋯π and various hydrogen bonding intermolecular interactions. Complex 3 shows ferromagnetic interaction, with J = +1.5 cm−1, due to perchlorate bridging anion complex. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) support the electrochemical features of these complexes. The Hirshfeld surface analysis exhibited short-range forces of the hydrogen bonds in all studied complexes. In addition, antioxidant superoxide dismutase activity measurements of these complexes were also performed and discussed. The increased SOD activity of 1 can be assigned due to presence of labile coordinated water molecule. The results of SOD activity reveal that the coordination geometries have significant effect on the SOD catalytic activity.

Synthesis, spectroscopic characterization, DFT calculations, and molecular docking studies of new unsymmetric bishydrazone derivatives

Three new unsymmetric isatin bishydrazone compounds; Comp. I, II, III, were synthesized by the condensation of 3,5-dichloro-salicylaldehyde, 3-bromo-5-chloro-salicylaldehyde, and 3,5-dibromo-salicylaldehyde with isatin monohydrazone, respectively. The synthesized compounds were characterized by elemental analysis, 1H-NMR, FT-IR, UV-Vis spectroscopy, and mass spectrometry technique. For studied molecules, chemical parameters like frontier orbital energies, energy gap, electronegativity, chemical potential, chemical hardness, softness, electrophilicity, nucleophilicity, electrodonating power, electroaccepting power, polarizability, and dipole moment were calculated and discussed. Investigating the validity of well-known electronic structure principles like Maximum Hardness, Minimum Polarizability, and Minimum Electrophilicity Principles in the study, it was determined which compound is more stable compared to others. In recent days, a new software having PRIMorDIA name was developed to explore reactivity and electronic structure in large biomolecules by some of the authors of this paper. Molecular docking studies for these newly synthesized molecules were performed using PRIMorDIA software. Considering the intramolecular interactions, NBO analyzes of three bishydrazone derivatives were conducted to evaluate the chemical behavior.

Diversities in the chelation of aroylhydrazones towards cobalt(II) salts: Synthesis, spectral characterization, crystal structure and some theoretical studies

Five cobalt complexes synthesized from two aroylhydrazones were characterized by elemental analyses, thermogravimetric analysis, molar conductivity, magnetic susceptibility measurements, IR and electronic spectra. Single crystal X-ray structure of one of the complex is also reported and it got crystallized in triclinic space group P1¯ and the crystal structure shows a distorted octahedral geometry around the metal center. Spectral data reveal that both the aroylhydrazones are tridentate and coordinate through the azomethine nitrogen, hydrazonic oxygen, and pyridyl nitrogen. Magnetic susceptibility measurements confirm the paramagnetic nature of the Co(II) complexes and one of the complex was found to be diamagnetic in nature. Additionally, HF/6-311G(d,p)/LANL2DZ calculations were performed to predict the possible intramolecular interactions contributing to the lowering of the stabilization energy. Accordingly, π→ π* transitions were found to be responsible for the stabilization energy for the ligands and their cobalt complexes. To describe and discuss the chemical reactivity and stability of synthesized complexes, quantum chemical parameters like frontier orbital energies, hardness, softness, energy gap, electronegativity, chemical potential, electrophilicity, polarizability and dipole moment were calculated. Also, the main electronic structure principles such as maximum hardness, minimum polarizability, and minimum electrophilicity principles were considered to evaluate the stability of the complexes.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

A Density Functional Theory Study of the Isomerization of Substituted 2'-hydroxychalcones to the Corresponding Flavanones

The transformation of 2'-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

Structural, electronic, vibrational and optical properties of all 23 isolated-pentagon rule isomers of C58N2 azafullerene; a DFT study

The disagreements between the results of the previous studies on C58N2 encouraged us to investigate all 23 possible isolated-pentagon rule isomers (21 separated nitrogen (SN) and 2 adjacent nitrogen (AN) structures) with more details and higher precision. The calculations by B3LYP hybrid and B97D long-range dispersion-corrected DFT methods with different basis sets have been performed to investigate stability, vibrational and different electronic and optical properties of the target azafullerene as compared with C60. Though the AN-isomers are the least stable isomers, they have reasonable thermodynamic stabilities. A bridge between the skeletal and exohedral chemistries of fullerene has been traced. Minimum polarizability principle (MPP) is not observed over this set of the isomeric molecules. A quadratic correlation has been found between anisotropies of polarizability and N∙∙∙N distances. The studied isomers show variable electronic and photonic properties with potential applications in molecular electronics.

Theoretical Study for Isomerization of Some 2´-Hydroxychalcone Derivative by Using DFT Calculation

In this work we present a study about the molecular structure and electrochemical behavior of a series of substituted 2´-hydroxychalcones and their conversion to the corresponding flavanones. The study was performed using density function theory (DFT) based on B3YLP with 6-311G basis set was used in order to investigate the effect of the electronic and structure properties for the isomerization process. Reactants, intermediates and products have an equilibrium state and one transition state that possess one imaginary frequency. The optimized structure, total energies ,hardness ,polarizability ,chemical potential and electrophilicity index were calculated. The relative energy calculated using DFT corresponds with those calculated in a practical way by the use of HPLC technique, the hardness profile along the reaction path in agreement with maximum hardness principle, and the minimum polarizability principle is obeyed in all cases.

Mixed ligand copper(II) chelates derived from an O, N, S- donor tridentate thiosemicarbazone: Synthesis, spectral aspects, FMO, and NBO analysis

Five new copper(II) chelates [(Cu(bmct))2] (1), [Cu(bmct)(phen)] (2), [Cu(bmct)(bipy)] (3), [Cu(bmct)(4,4′-dmbipy)] (4) and [Cu(bmct)(5,5′-dmbipy)] (5) with 5-bromo-3-methoxysalicylaldehyde-N(4)-cyclohexylthiosemicarbazone (H2bmct) as the chelating ligand and 1,10-phenanthroline, 2,2′-bipyridine, 4,4′-dimethylbipyridine, 5,5′-dimethylbipyridine as coligands have been synthesized and characterized by different physicochemical techniques like CHNS analysis, molar conductivity and magnetic studies, IR, UV/Vis and EPR spectral studies. In all the complexes, the thiosemicarbazone exists in thioiminolate form and coordinates to the metal through azomethine nitrogen, thioiminolate sulfur, and phenolate oxygen. EPR spectra in polycrystalline state at 298 K showed that compounds 1, 4, and 5 are isotropic, 2 is axial and 3 is rhombic in nature. In DMF at 77 K, compound 1 showed hyperfine lines in the parallel and perpendicular regions as well as superhyperfine lines due to the interaction of copper center with azomethine nitrogen of the ligand. Complex 2, in which g||>g⊥> 2.0023 suggests a distorted square pyramidal structure. To analyze the stability of the complexes, quantum chemical parameters like hardness, softness, polarizability, electrophilicity, electronegativity, and dipole moment were calculated and discussed within the framework of electronic structure principles known as Maximum Hardness, Minimum Polarizability and Minimum Electrophilicity Principles. Besides, the intramolecular donor–acceptor interactions for all complexes were evaluated by using NBO analysis. All calculations proved that Compound 3 is the most stable chelate among them.

Theoretical study of the electronic structure and electrical properties of Al-doped niobium clusters

A methodology previously suggested for niobium clusters is here applied to the prediction of the ground spin-state of the niobium clusters doped with aluminum atoms. By using all-electron density functional theory with Douglas-Kroll-Hess correction, the spin-state, geometry, hardness, binding energy, ionization potential, electron affinity, and mean static dipole polarizability of the NbxAly clusters are examined. The ground spin-states obtained from the energy minimization were confronted with the results provided by the maximum hardness principle (MHP) and by the minimum polarizability principle (MPP). In general, the MHP and MPP have yielded the expected results, i.e., in agreement with the ones obtained from the minimum energy. Additionally, were compared the theoretical results for polarizability, ionization potential, and reactivity with the available experimental values.

Role of π-electron conjugation in determining the electrical responsive properties of polychlorinated biphenyls: a DFT based computational study

Global reactivity descriptors e.g. average polarizabilty (αav), chemical hardness (η), electrophilicity index (ω) of some donor–acceptor substituted polychlorinated biphenyl (PCBs) i.e. 2,2′,5,5′-tetrachloro-1,1′-biphenyl (PCB-1a), 2,5,2′,5′-Tetrachloro-4′-dimethylamino-biphenyl-4-carbonitrile (PCB-1b), Dimethyl-(2,5,2′,5′-tetrachloro-4′-nitro-biphenyl-4-yl)-amine (PCB-1c), 3,3′,5,5′-tetrachloro-1,1′-biphenyl (PCB-2a), 3,5,3′,5′-Tetrachloro-4′-dimethylamino-biphenyl-4-carbonitrile (PCB-2b) and Dimethyl-(3,5,3′,5′-tetrachloro-4′-nitro-biphenyl-4-yl)-amine (PCB-2c) were computed along the torsional potential of biphenyl ring. Density functional based hybrid functional CAM-B3LYP with 6-31G(d) basis were used to all the computational study. Out of the six compounds, variation of the global reactivity descriptors e.g. αav, η, ω as a function of torsional angle of biphenyl ring, three compounds are not in conformity with the respective optimum principle i.e. minimum polarizability, maximum hardness and minimum electrophilicity principle. In this present research article, we have raised this issue that apart from electronically stable conformation, localization of π-electron plays a major role in determining the optimum values of global reactivity descriptors, αav, η & ω. On the other hand computation of first average hyper polarizability (βav) as a function of torsional angle shows that the variation of βav are in good agreement with the optical gap as well as electronic spatial extent ( ) of the conformers of all the six compounds.