Publications
New N-Alkylated Heterocyclic Compounds as Prospective NDM1 Inhibitors: Investigation of In Vitro and In Silico Properties
A new family of pyrazole-based compounds (1–15) was synthesized and characterized using different physicochemical analyses, such as FTIR, UV-Visible, 1H, 13C NMR, and ESI/LC-MS. The compounds were evaluated for their in vitro antifungal and antibacterial activities against several fungal and bacterial strains. The results indicate that some compounds showed excellent antibacterial activity against E. coli, S. aureus, C. freundii, and L. monocytogenes strains. In contrast, none of the compounds had antifungal activity. Molecular electrostatic potential (MEP) map analyses and inductive and mesomeric effect studies were performed to study the relationship between the chemical structure of our compounds and the biological activity. In addition, molecular docking and virtual screening studies were carried out to rationalize the antibacterial findings to characterize the modes of binding of the most active compounds to the active pockets of NDM1 proteins.
Keywords: synthesis; pyrazole; antibacterial; antifungal; ADME-Tox; molecular dockingAn Insight into All Tested Small Molecules against Fusarium oxysporum f. sp. Albedinis: A Comparative Review
Bayoud disease affects date palms in North Africa and the Middle East, and many researchers have used various methods to fight it. One of those methods is the chemical use of synthetic compounds, which raises questions centred around the compounds and common features used to prepare targeted molecules. In this review, 100 compounds of tested small molecules, collected from 2002 to 2022 in Web of Sciences, were divided into ten different classes against the main cause of Bayoud disease pathogen Fusarium oxysporum f. sp. albedinis (F.o.a.) with structure–activity relationship (SAR) interpretations for pharmacophore site predictions as (δ−···δ−), where 12 compounds are the most efficient (one compound from each group). The compounds, i.e., (Z)-1-(1.5-Dimethyl-1H-pyrazole-3-yl)-3-hydroxy but-2-en-1-one 7, (Z)-3-(phenyl)-1-(1,5-dimethyl-1H-pyrazole-3-yl)-3-hydroxyprop-2-en-1-one 23, (Z)-1-(1,5-Dimethyl-1H-pyrazole-3-yl)-3-hydroxy-3-(pyridine-2-yl)prop-2-en-1-one 29, and 2,3-bis-[(2-hydroxy-2-phenyl)ethenyl]-6-nitro-quinoxaline 61, have antifungal pharmacophore sites (δ−···δ−) in common in N1---O4, whereas other compounds have only one δ− pharmacophore site pushed by the donor effect of the substituents on the phenyl rings. This specificity interferes in the biological activity against F.o.a. Further understanding of mechanistic drug–target interactions on this subject is currently underway.
Keywords: pyrazole; imidazole; B-keto-enol; amino acid; quinoxaline; Bayoud; Fusarium oxysporum f. sp. albedinisSynthesis, experimental and theoretical studies of sesquiterpenic thiosemicarbazone and semicarbazone as organic corrosion inhibitors for stainless steel 321 in H2SO4 1M
In this work, the compounds thiosemicarbazone and semi-carbazone sesquiterpene (TSC and SMC, respectively) were synthesized from sesquiterpene α,β-unsaturated ketone and investigated for their anti-corrosion behaviour and electrochemical activity. Various spectroscopic analyses were performed (FT-IR, 1H NMR, 13C NMR and HRMS) to characterize these molecules. The inhibitory performance of these inhibitors on corrosion of stainless steel 321 in 1 M H2SO4 medium was studied using the potentio-dynamic polarization (PDP) method that indicated that these compounds acted as mixed-type inhibitors with dominant cathodic inhibition. Cyclic voltammetry (CV) was performed to assess the electrochemical activity and calculate the experimental band of the tested molecules. The values of the band gap of SMC and TSC were comparable (∼0.52 eV). The electrochemical findings agree quite well with the functional density theory (DFT) and Monte Carlo (MC) theoretical studies. The strong adsorption of the tested molecules and stainless steel surface, through nitrogen groups, is demonstrated. No significant difference resulting from (C=S) and (C=O) groups on the electrochemical and theoretical behaviours is noted. The nitrogen sites present an important reactivity for the metal/inhibitor interaction as evidenced by Mullikan negative charges and HOMO/LUMO spatial distributions.
Keywords: Thiosemicarbazone, Semicarbazone, Corrosion, Potentiodynamic polarization, Cyclic voltammetry, DFT, Monte CarloMetal corrosion inhibition by triazoles: A review
Metal corrosion and the prospects of inhibiting this process have received much interest from society and scientific research. The annual global cost of corrosion is $2.5 trillion, equivalent to roughly 3.4% of the world’s gross domestic product. Implementing corrosion prevention best practices could result in global savings of 15–35% of that cost. Numerous studies were documented and dedicated on the triazole nucleus based compounds as fascinating corrosion inhibitors of various metals in hostile media. Their unique electronic structure possessing conjugated π and unshared pairs of electrons on the nitrogen atoms facilitates their adsorption on metal surfaces. Thus, physical and chemical interactions between the active centers of triazoles and d-orbitals of metallic materials occur to form a film on the surface. The nature of inhibitor activity is disclosed through polarization studies (cathodic, anodic or mixed-type). The range of various substituents on the triazole ring offers a vast array of inhibitory effects. temperature and inhibitor concentration effects must also be regarded when evaluating the corrosion activation and adsorption parameters supported further by the quantum chemical parameters such as DFT and molecular dynamics simulations. In this review, we looked through several instances of the use of distinct substituted triazole nucleus based compounds as significant corrosion inhibitors for different metals in various aggressive media.
Keywords: corrosion, inhibition, metals, triazoles, DFT, simulationCorrelation between corrosion inhibition efficiency in sulfuric acid medium and the molecular structures of two newly eco-friendly pyrazole derivatives on iron oxide surface
The inhibition effect of newly synthesized eco-friendly pyrazole derivatives NPDM and NPD on the corrosion of the mild steel (MS) in 0.5 M H2SO4 solution was investigated by the open circuit potential (OCP) curves, potentio-dynamic polarization (PP) curves and electrochemical impedance spectroscopy (EIS) along with weight loss (WL) measurements. Both compounds were confirmed to be good anti-corrosion inhibitors and their efficiency was in the order NPD > NPDM for a concentration of 10−3 M. The adsorption of the two compounds on MS surface was studied by SEM and various isotherm models. The adsorption of NPD appeared to obey the Langmuir model while that of NPDM followed Freundlich model. Corrosion inhibition was explained based on experimental results as well as computational studies. The influence of the molecular-electronic-structure on the inhibition activity was inspected by the DFT method. The global and local reactivity, before their adsorption onto the MS surface, were calculated at the B3LYP/6-311G(d,p) theoretical level for the neutral and cationic forms. The solvation hydration energy (∆GSolv) was also considered to evaluate the protection efficiency of both products. Molecular Dynamics Simulations (MDs) were carried out to model the interaction mechanism and the adsorption behaviour of {10−3 M NPD or NPDM/α-Fe2O3(111)/0.5 M H2SO4} interfaces. Results derived from experimental (OCP, WL, PP and EIS) methods were supported by the theoretical investigations.
Keywords: Corrosion resistance, Mild steel, Eco-friendly inhibitor, Fe-inhibitor complexes, Theoretical calculations & surface, Thermodynamic parametersSynthesis, characterization, reaction mechanism prediction and biological study of mono, bis and tetrakis pyrazole derivatives against Fusarium oxysporum f. sp. Albedinis with conceptual DFT and ligand-protein docking studies
Twelve heterocyclic compounds were prepared using the condensation of hydroxy-methanol pyrazole derivatives with different primary amines as example 2-aminothiazole and 1-aminobenzotriazole to have a diverse production good yield up to 97%. Those ligands were tested against Fusarium oxysporum f. sp. Albedinis fungi (BAYOUD Disease) with IC50 = 25.6–33.2 µg/ml. After experiments, theoretical investigations were done as DFT study to know the ligands molecular reactivity and the-ligand-protein docking study to know the possible binding between the prepared ligands with two biological targets: FGB1 (Fusarium oxysporum Guanine nucleotide-binding protein beta subunit primary amino acid sequence) and Fophy (Fusarium oxysporum phytase domain enzyme). Of all the obtained results, the experimental ones were well correlated with the theoretical with the most common thing between those compounds is (Nδ−-Nδ+) which is the antifungal pharmacophore as proposed pincers for Foa inhibition. From docking studies over FGB1 and Fophy, the ligand 9 has the best binding energy of −6.4872 kcal/mol in FGB1 active site and −5.5282 kcal/mol in Fophy active site, but better correlation with Fophy than FGB1 which is followed by PLIF graph to get that Arg116, Arg120 and Lys336 are the vital amino acids of Fophy protein based the study over the chosen active site.
Keywords: Pyrazole, Bayoud, Fusarium oxysporum, Antifungal, DFT, DockingSynthesis, Molecular Docking, MEP and SAR Analysis, ADME-Tox Predictions, and Antimicrobial Evaluation of Novel Mono- and Tetra-Alkylated Pyrazole and Triazole Ligands
Newly synthesized compounds of N-alkylated heterocyclic compounds were prepared by condensation of amine with alcohol which undergoes a reaction of SN2. These newly synthesized derivatives were characterized by spectral analysis. The objective is to prepare new potent nontoxic antimicrobial agents which are easy to synthesize and could be scaled up in pharmaceutical industries. Thirteen new heterocyclic compounds containing a pyrazole moiety were synthesized with good yields (29.79 to 99.6%) and were characterized by FTIR, 1H NMR, 13C NMR, and CG-MS techniques. The compounds were divided into two series—monoalkylated compounds (1–11) and tetra-alkylated compounds (12 and 13)—and then evaluated for their in vitro antifungal and antibacterial activities against several fungal and bacterial strains. None of the monoalkylated compounds had antibacterial or antifungal activity. However, the two tetra-alkylated pyrazole ligands displayed strong antibacterial potential. Moreover, compound 12 was more potent against all tested bacterial strains than compound 13. Interestingly, compounds 12 and 13 acted as weak antifungal agents against Saccharomyces cerevisiae. ADME-Tox studies suggested that compounds 12 and 13 exhibit better toxicity profiles than the commercial antibiotic streptomycin. MEP studies suggested that compounds 12 and 13 have the same charge locations but differ in their values which are due to the condensed geometry of compound 13 that make it more polarizable than compound 12. Of particular interest, these different MEPs were evident in ligand protein docking, suggesting that compound 12 has better affinity with MGL enzyme than compound 13. All these findings suggested that these novel compounds represent promising antibacterial lead compounds.
New Heterocyclic Compounds: Synthesis, Antioxidant Activity and Computational Insights of Nano-Antioxidant as Ascorbate Peroxidase Inhibitor by Various Cyclodextrins as Drug Delivery Systems
The synthesis of seven new antioxidant agents based on the combination of thiazole, pyridine, triazole and pyrazole moieties. The studies of their antioxidant activity using DPPH reduction method. The DFT analysis of the 7 ligands. The docking study was also investigated. The better binding affinity with α-cyclodextrin as best drug delivery system. The screening of new antioxidant compounds and find the good mechanism for binding sites, with correlating between experience and computer theory. The DFT analysis of the 7 synthesized ligands. The docking study was also investigated by using the amino acids Ala167 and Arg172. The better binding affinity with α-cyclodextrin as best drug delivery system. The studies of their antioxidant activity using DPPH reduction method. Synthesis of 7 ligands by condensation reaction with 89% yield. Antioxidant activities using DPPH reduction with a good value IC50=13.05 ± 3.73 μg/ml. Using DFT (EHOMO and ELUMO) and Docking APX with the amino acids Ala167 and Arg172 compared to the ascorbic acid. Correlation between all these properties. α-cyclodextrin as best drug delivery system (better binding affinity than caffeic acid). For the drug delivery study, The ACD is best system for all the compounds due to the smallest cavity size which makes the binding affinities favourable and possible to prepare prospective nano-antioxidants.
Keywords: DFT, DPPH, Pyrazole, cyclodextrin, docking, drug delivery system, triazoleMono-Alkylated Ligands Based on Pyrazole and Triazole Derivatives Tested Against Fusarium oxysporum f. sp. albedinis: Synthesis, Characterization, DFT, and Phytase Binding Site Identification Using Blind Docking/Virtual Screening for Potent Fophy Inhibitors
Twelve recent compounds, incorporating several heterocyclic moieties such as pyrazole, thiazole, triazole, and benzotriazole, made in excellent yield up to 37–99.6%. They were tested against Fusarium oxysporum f. sp. albedinis fungi (Bayoud disease), where the best results are for compounds 2, 4, and 5 with IC50 = 18.8–54.4 μg/mL. Density functional theory (DFT) study presented their molecular reactivity, while the docking simulations to describe the synergies between the trained compounds of dataset containing all the tested compounds (57 molecules) and F. oxysporum phytase domain (Fophy) enzyme as biological target. By comparing the results of the docking studies for the Fophy protein, it is found that compound 5 has the best affinity followed by compounds 2 and 4, so there is good agreement with the experimental results where their IC50 values are in the following order: 74.28 (5) < 150 (2) < 214.10 (4), using Blind docking/virtual screening of the homology modeled protein and two different tools as Autodock Vina and Dockthor web tool that gave us predicted sites for further antifungal drug design.
Keywords: pyrazole, triazole, Fusarium oxysporum, antifungal, DFT, dockingThe inhibition behavior of two pyrimidine-pyrazole derivatives against corrosion in hydrochloric solution: Experimental, surface analysis and in silico approach studies
Two pyrimidine-pyrazole derivatives have been investigated as corrosion inhibitors for mild steel in acidic medium using weight loss measurement, polarization curve and electrochemical impedance spectroscopy (EIS). The results obtained reveal that these compounds perform as corrosion inhibitors for mild steel in 1 M HCl. The values of inhibition efficiency calculated from three experimental techniques are reasonably in good agreement. The adsorption process of these compounds on surface of mild steel obeys to El Awady isotherm. Also, the adsorption process of inhibitors studied explaining by surface analysis (EDX). This work followed by in silico approach studies. Firstly, we used Marvinsketch.18 program in order to detect predominant form of inhibitors in electrolytic solution and then computed by Gaussian 09 based on the DFT method at B3LYP/6-31G (d,p).The results obtained theoretically are in good correlation with those obtained experimentally.
Keywords: Pyrimidine-pyrazole, DFT, EIS, Mild steel, In silico approach studies, El Awady isothermCatecholase catalytic properties of copper (II) complexes prepared in-situ with heterocyclic ligands: Experimental and DFT study
The objective of our work is the preparation of the new catalysts for catecholase, whose principle is based on the catechol oxidation reaction which presents a major challenge in both biology and medicine. First, we synthesized nine pyrazole and triazole ligands, then we evaluated the catalytic properties of certain of those ligands in situ complexes to catalyze the oxidation reaction of catechol to o-quinone. The aim of this study is to find the right models to reproduce the catalytic activity of the enzyme (catecholase), so we used complexes formed in situ by pyrazole and triazole derivatives with copper (II) salts. The reason behind the interest of these complexes is their resemblance to biological systems, capability of activating the catalyst for many chemical reactions. Among these complexes, some of them showed good catalytic activity for this reaction. We have demonstrated that the nature of ligand, the concentration of ligand, the nature of the solvent and the nature of the copper (II) salt, influences the efficiency of the catecholase activity. Pyrocatechol is benzene-1,2-diol (nomenclature IUPAC), also known as catechol with formula C6H6O2 crude used in many organic syntheses. Some catecholamines have important physiological functions. The Government of Canada has determined that catechol is "toxic" as defined by the Canadian Environmental Protection Act, 1999. So, to reduce the toxic effect of catechol we try to oxidize o-quinone which is less dangerous than catechol. The DFT study has big interest in many researches to know the reactivity of the ligands by calculating different quantum descriptors as: EHOMO, ELUMO, The gap energy, Ionisation potential, The electron affinity and The hardness.
Keywords: Oxidation, Catechol, Pyrazole, Triazole, Quinone, DFT.Synthesis of two new pyrazole based ligands for the liquid–solid extraction of heavy metals Pb, Cd and Cu in the aqueous medium
Most of heavy metals (Pb(II), Cu(II), Cd(II)) which are toxic even at a low concentration. These toxic metals are released into the environment by various natural or industrial sources. Faced with this situation, many methods have been developed to extract these toxic metals from the environment and namely when they are present in water. This work consists of the development of a synthesis based on two new heterocyclic ligands L1 (N1, N1, N5, N5-tetrakis ((3,5-dimethyl-1H-pyrazol-1-yl) methyl) naphthalene-1,5-diamine) and L2 (2-(bis ((1H-pyrazol-1-yl) methyl) amino) pyrimidine-4,6-diol) based on pyrasole. The outcome is to extract certain heavy metals when present in an aqueous medium. The synthesis of these two ligands L1 and L2 is achieved via condensation reactions between hydroxymethyl pyrazoles units and an aromatic primary amines and diamines. The characterization of these two synthetic ligands is carried out by IR and NMR analysis techniques. Subsequently a study of their capacities and their selectivity in the liquid–solid extraction of the metal cations Pb(II), Cd(II) and Cu(II) was made from an aqueous solution in batch mode. The effect of the operating conditions (C0, ph, T) on this extraction is also studied. The modelling of the adsorption of heavy metals studied by our two ligands is established by the isotherms of the Langmuir and Freundlich models. The results obtained show a high adsorption capacity and an excellent selectivity of the two ligands towards Pb(II) (80% for L1 and 60% for L2).
Keywords: Heavy metals, Pyrazole, Synthesis, Adsorption, Kinetic parameters, Adsorption isothermsNew thiazole, pyridine and pyrazole derivatives as antioxidant candidates: synthesis, DFT calculations and molecular docking study
Novel heterocyclic compounds containing pyrazole, thiazole and pyridine moieties were designed and prepared based on the condensation reaction between 1,3-thiazole or aminopyridine derivatives and 1H-pyrazole,3,5-dimethyl-1H-pyrazole or 1,2,4-triazole. Their structures were confirmed with FTIR, 1H and 13C NMR analyses. DPPH scavenging assay was used to evaluate their antioxidant potential. The ligand 4 showed the best antioxidant activity with an IC50 = 4.67 μg/mL, while IC50 values of the other compounds were found to be ranging from 20.56 to 45.32 μg/mL. DFT and molecular docking studies were performed in order to gain better insights and to understand the relationship between the structures of the studied compounds and their antioxidant activities. The results obtained revealed a good agreement between the experimental and the theoretical findings.
Keywords: Organic chemistry, Theoretical chemistry, Pharmaceutical chemistry, 1,3-Thiazole, Pyridine, Phenol, DPPH, Antioxidant activity, DFT, DockingStudy of the catecholase catalytic properties of copper (II) complexes prepared in-situ with monodentate ligands
Two families of pyrazole, triazole and imidazole copper (II) complexes has NH nitrogen, (L1-L5), and hydroxymethyl nitrogen, (L6-L9), have been prepared to oxidize catechol to o-quinone. The effect of counter anion of copper (II) salts, Cu(NO3)2, Cu(CH3COO)2, CuSO4 and CuCl2, beside the concentration of ligand and the polarity of solvents (MeOH, THF, CH3CN, DMF, acetone, CH2Cl2) also investigated. It was found that for the group has NH nitrogen the best catalyst for the catechol oxidation is L5 : Cu(NO3)2 : MeOH with a Vmax is equal to 27.40 µmol.L-1.min-1. While hydroxymethyl nitrogen the best catalyst are L7/Cu(CH3COO)2 : DMF with a 33.54 µmol.L-1.min-1.
Keywords: Pyrazole, catalysis, Catechol, Quinone, Imidazole, TriazolePyrazole Compounds : Synthesis, molecular structure, chemical reactivity, experimental and theoretical DFT FTIR spectra
Eight Pyrazole ligands which are prepared by condensation of different amines with Pyrazole and 3,5-diméthylpyrazole, then characterized using FTIR. This analysis was recorded using KBr pellets on FTIR-8400S spectrometer, and then the spectra are compared with the ones calculated by the Density Functional Theory (DFT) calculations with GAUSSIAN 09W suite. Experimental and calculated vibrational spectra demonstrate a good correlation with some difference in %T and frequency (cm-1) shown in the theoretical spectra due to the presence of all predicted vibrational modes. The optimized structure, HOMO, LUMO orbitals and some other quantum descriptors were also determined to reveal their chemical reactivity properties. The similarities and the differences between the theoretical and the experimental vibrational analysis of all the prepared ligands have been highlighted. The calculated FTIR spectra by DFT shows perfect agreement with the experimental ones and generated positive value of vibrations indicate calculations are at the global minima.
Keywords: Pyrazole, DFT, FTIR analysis, HOMO, LUMOCrystal structure of fac-bis[bis(pyridin-2-yl)methanamine]iron(II) 1,1,3,3-tetracyano-2-(dicyanomethylidene)propane-1,3-diide, [Fe(dipa)2](tcpd)
In the title compound, [Fe(C11H11N3)2](C10N6), the FeII cation is coordinated by two bis(pyridin-2-yl)methanamine (dipa) ligands and has crystallographic twofold symmetry. There are deviations from ideal octahedral geometry due to the steric requirements of the ligands. The polynitrile 1,1,3,3-tetracyano-2-(dicyanomethylidene)propane-1,3-diide (tcpd2) dianion is disordered about an inversion center and is not coordinated to the Fe atom. The anion is not planar but has a propeller shape. In the crystal, weak N—HN interactions between the amine H atoms of the dipa ligands and two nitrile groups of the anion form an alternating chain of cations and anions related by the C-centring of the unit cell.
Keywords: crystal structure, iron(II) complex, polynitrile anion, terdentate ligands.Synthesis of four new tridentate pyrazolic ligands
Two tripodal pyrazolic ligands: N, N-bis ((3, 5-diméthyl-1H-pyrazol-1-yl) methy)-2, 4-difluoroaniline (2Fpyr 1) and N, N-bis ((1H-pyrazol-1-yl) methyl)-2, 4-difluoroaniline (2Fpyr 2) were synthetized in good yiels. Then we applied them against corrosion of mild steel in HCl 1M solution. Weight loss measurement give us the inhibition efficiencies values reached 80.2% for 2Fpyr1 and 77.3% for 2Fpyr 2 at the concentration 10-3, then by changing the temperature from 313K to 343 K, which give us the activation and adsorption parameters, and we reveal from it that the ligands 2Fpyr 1 were adsorbed according to Langmuir Isotherm, but 2Fpyr 2 were was adsorbed according to El-Awady adsorption Isotherm, we obtain these results using certain isotherms as Langmuir, Freundlich, Temkin, Frumkin, Florry-Huggins, Adejo-Ekwenchi and El-Awady. We conclude from polarization curves that all the ligands are mixed type inhibitors (anodic and cathodic type inhibitors), and from the impedance diagrams in the Nyquist presentation which are in the form of one half loop because that the corrosion is controlled by charge transfer process. We used GAUSSIAN 09W program to do theoretical investigations by considering the Density Functional Theory (DFT) method to calculate quantum parameters as E HOMO, E LUMO,∆ E HOMO-E LUMO and μ dipolar moment that allows us to confirm experimental results obtained from gravimetric and electrochemical studies.
Keywords: Ligand, pyrazole, corrosion, HCl, mild steel, Tafel, EIS, weight loss, adsorption, Langmuir, Freundlich, Temkin, Frumkin, Florry-Huggins, Adejo-Ekwenchi, El Awady, quantum calculations, GAUSSIAN 09W, DFTTwo tripodal pyrazolic ligands: application against corrosion of mild steel in HCl 1M
Two tripodal pyrazolic ligands: N, N-bis ((3, 5-diméthyl-1H-pyrazol-1-yl) methy)-2, 4-difluoroaniline (2Fpyr 1) and N, N-bis ((1H-pyrazol-1-yl) methyl)-2, 4-difluoroaniline (2Fpyr 2) were synthetized in good yiels. Then we applied them against corrosion of mild steel in HCl 1M solution. Weight loss measurement give us the inhibition efficiencies values reached 80.2% for 2Fpyr1 and 77.3% for 2Fpyr 2 at the concentration 10-3, then by changing the temperature from 313K to 343 K, which give us the activation and adsorption parameters, and we reveal from it that the ligands 2Fpyr 1 were adsorbed according to Langmuir Isotherm, but 2Fpyr 2 were was adsorbed according to El-Awady adsorption Isotherm, we obtain these results using certain isotherms as Langmuir, Freundlich, Temkin, Frumkin, Florry-Huggins, Adejo-Ekwenchi and El-Awady. We conclude from polarization curves that all the ligands are mixed type inhibitors (anodic and cathodic type inhibitors), and from the impedance diagrams in the Nyquist presentation which are in the form of one half loop because that the corrosion is controlled by charge transfer process. We used GAUSSIAN 09W program to do theoretical investigations by considering the Density Functional Theory (DFT) method to calculate quantum parameters as E HOMO, E LUMO,∆ E HOMO-E LUMO and μ dipolar moment that allows us to confirm experimental results obtained from gravimetric and electrochemical studies.
Keywords: Ligand, pyrazole, corrosion, HCl, mild steel, Tafel, EIS, weight loss, adsorption, Langmuir, Freundlich, Temkin, Frumkin, Florry-Huggins, Adejo-Ekwenchi, El Awady, quantum calculations, GAUSSIAN 09W, DFTTridentate Pyrazole Ligands: Synthesis, Characterization and Corrosion Inhibition properties with Theoretical investigations
4-(bis((3,5-dimethyl-1H-pyrazol-1-yl) methyl) amino) benzonitrile (L1) and 4-(bis((1H-pyrazol-1-yl) methyl) amino) benzonitrile (L2) were prepared with good yields (up to 90 %), they were characterized using different physicochemical methods as FTIR, 1H NMR, 13C NMR and MS. We have studied their inhibition efficiencies against corrosion of mild steel in molar hydrochloric acid solution by weight loss and electrochemical measurements. The inhibition efficiency using weight loss measurement reached 92.4 % for L1 and 92.3 % for L2 at the highest concentration 10-3.
By studying the temperature effect, we conclude that the ligands were adsorbed according to Langmuir adsorption isotherm. And from polarization curves that all the ligands are mixed type inhibitors. The impedance diagrams in the Nyquist presentation shows that the corrosion is controlled by charge transfer process. We used GAUSSIAN 09W program to do theoretical investigations by considering the Density Functional Theory (DFT) method to calculate quantum parameters as EHOMO, ELUMO, ∆EHOMO-ELUMO and μ dipolar moment that allows us to confirm the experimental results.
