The study aimed to investigate the corrosion inhibition performance of two new pyridazine derivatives namely ((E)-2-(3-(4-(carboxymethoxy)-3-methoxystyryl)-5-(2-chlorobenzyl)-6-oxopyridazin-1(6H)-yl)acetic acid (CO6) and (E)-6-(4-hydroxy-3-methoxystyryl)pyridazin-3(2H)-one (CO39) for carbon steel (C.S) in 1M HCl by combining electrochemical techniques, surface analysis and theoretical studies. The electrochemical impedance spectroscopy (EIS) data indicated that the inhibitory efficiencies of CO6 and CO39 increased with increasing inhibitor concentration but decreased with increasing temperature, achieving 97.0% and 95.3%, respectively. The results of the potentiodynamic polarization (PDP) measurements show that the two pyridazine derivatives acted as mixed inhibitors. In addition, experimental studies have shown that CO6 and CO39 reduce corrosion rates by adsorbing on the steel surface following Langmuir adsorption isotherms. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) indicated that a protective layer had been developed on the surface of the carbon steel, which prevented corrosion from progressing. Quantum chemical computations and the molecular structures of the inhibitors were employed to investigate the mechanism of inhibition. The adsorption of the compounds investigated on C.S was validated by theoretical calculations including density functional theory (DFT) and molecular dynamics simulation (MDS).

The anti-corrosive properties of the newly synthesized compound pyridazinone, especially 2-(3-(4-fluorophenyl)2-oxopropyl)-4-(3-nitrobenzyl)-6-phenylpyridazin-3(2 H)-one (FOPP), on carbon steel in a 1 M hydrochloric acid solution were thoroughly investigated. We used multiple techniques, including potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), surface morphology analysis, contact angle measurements, UV-visible spectrometry, and quantum chemical calculations. The maximum corrosion inhibition efficiency of FOPP was found to be 96.3 % at 10-3-3 M concentration and 303 K temperature. PDP studies showed that FOPP acts as a mixed-type inhibitor with anodic predominance. The hydrophobicity of the surface of the metal studied showed considerable improvement by the FOPP coating using the contact angle technique. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) were used to confirm the results obtained using the contact angle technique. The two methods of theoretical chemistry, namely density functional analysis (DFT) and molecular dynamics simulation, were used to gain a better understanding of the interactions between the inhibitor and the surface of the metal studied and the ability of this inhibitor to adhere to the surface of the iron and form a protective film.

The anti-corrosion characteristics of a synthesized pyridazinone analog, namely, 4-benzyl-2-(3-(4-fluorophenyl)-2-oxopropyl)-6-phenylpyridazin-3(2H)-one (BOPP), on carbon steel (CR/S) in a 1-M HCl medium were assessed by potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), contact angle, UV–Visible, and modeling methods. Outcomes demonstrate that BOPP hindered (CR/S) corrosion in a 1-M HCl medium and disclose that the performance of inhibition improved with BOPP amount (95.7

The assessment of the corrosion inhibitory efficacy of two novel pyridine derivatives, specifically (E)-2-(5-(2-chlorobenzyl)-6-oxo-3-styrylpyridazin-1(6H)-yl)acetic acid (CO4) and (E)-6-(4-hydroxystyryl)pyridazin-3(2H)-one (CO38), was conducted through Numerous methods, such as Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis, UV–visible spectroscopy, and theoretical calculations, were used to evaluate the effectiveness in preventing corrosion for carbon steel (C.S). In response to the increasing demand for environmentally friendly and biodegradable products, CO38 and CO4 inhibitors were used. Tests revealed that CO38 and CO4 inhibitory efficacy increased with concentration, reaching 96.2% and 93.7%, respectively. In a 1 M HCl solution, PDP investigations demonstrated that these inhibitors act as mixed-type inhibitors. Scanning electron microscopy (SEM) revealed the creation of protective layers that prevent C.S dissolution in the acid solution. These findings were supported by theoretical investigations that employed density functional theory (DFT) and molecular dynamics (MD) simulations.

Two new structurally related pyridazine derivatives, Ortho (PO) and Para (PP), were synthesized by greener chemical pathway, and were spectroscopically specified by 1H NMR and 13C NMR. Their application in corrosion inhibition of mild steel (MS) in 1.0 M HCl was explored by experimental electrochemical tests of Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy (EIS), with a surface and corrosive solution analyses by means of Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) analysis, and UV-vis spectroscopy, as well as by Density functional theory (DFT) calculations for corroboration and development of an interpretation of the experimentally obtained anticorrosive activity by referring to the particular effects of molecular structure. Electrochemical experiments tests provided that the two compounds act by physisorption and chemisorption adsorption modes, with a maximum efficiency of 94.4% and 95.4% for PO and PP, respectively at 10-3 mol L-1, and obey of Langmuir's theory of monolayer adsorption. SEM/EDX and UV-vis analysis confirmed this state of adsorption by an inhibitor film. DFT quantum chemical descriptors and molecular dynamics simulations showed a reasonable correlation with experimentally corrosion inhibition performance.

The anticorrosive activity of two novel synthesized nontoxic, effective and affordable pyridazine-based compounds, namely PZ-H and PZ-O-CH3, for MS in 1 M HCl acidic medium, was implemented using DFT quantum chemistry and Monte Carlo simulation. The results achieved were subsequently confirmed by electrochemical methods and UV-visible spectroscopic analysis, SEM/EDX surface analysis was also used as support tool. The impedance results revealed that the charge transfer resistance increased progressively with concentration, and the polarization plots showed that the molecules exhibited mixed-type behavior with a fit to the Langmuir adsorption model. The alteration of the surface morphology of both structures compared to the blank solution confirmed the protective ability of the studied compounds. The maximum inhibition was found to be 92 % for the compound PZ-H and 95 % for the compound PZ-O-CH3 at a concentration of 1 x 10(-3) M at 298 K temperature. Both compounds show the particularity to keep a good stability of the inhibitory efficiency even with increasing temperature and immersion time. The theoretical findings are in good accordance with the experimental data.

A novel series of imidazopyridine Schiff bases have been synthesized by the acid-catalyzed reaction of 7-methyl-2-phenylimidazo[1,2- a ]pyridin-3-amine with different aromatic aldehydes. The newly synthesized compounds were characterized by 1 H and 13 C NMR spectra and LC/MS data and screened for their antibacterial and antifungal activities against two bacterial strains ( Pseudomonas aeruginosa and Escherichia coli ) and one pathogenic fungal strain ( Fusarium oxysporum f. sp. Albedinis ) using disk diffusion method. Also, their antioxidant activity was evaluated using DPPH free radical scavenging method. Preliminary bioassay results showed that one of the synthesized compounds showed significant activity against the tested bacterial and fungal strains, while all the compounds displayed moderate antioxidant activities. The structure–activity relationship study revealed that the activity strongly depends on the substitution pattern. On the other hand, in silico ADME-Tox predictions and molecular docking studies were carried out to determine the bioavailability of the synthesized compounds and confirm the antifungal and antibacterial experimental findings.

Two imidazopyridine derivatives 6-chloro-2-(4-chlorophenyl) imidazo [1,2-a]pyridine (IPCl1) and 6-chloro-2-(4-chlorophenyl)imidazo[1,2-a]pyridine-3-carbal-dehyde (IPCl2) were investigated as corrosion inhibitors of mild steel in 1.0M HCl medium using potentiodynamic polarization curves and electrochemical impedance spectroscopy. The concentrations used in this work ranged between 1.0 × 10–6 and 1.0 × 10–3 M. Those compounds were found to be good inhibitors. In addition, their adsorption on the mild steel surface obeyed the Langmuir adsorption isotherm. A quantum chemical calculation was computed using Gaussian 09 based on the density-functional theory method at B3LYP/6-31G (d, p) in order to relate some electronic properties of the studied compounds to the inhibition efficiencies achieved experimentally. The Fukui functions were calculated to estimate the most reactive sites of nucleophilic and electrophilic attacks. Finally, the molecular dynamics simulation was implemented to search for the equilibrium configurations of IPCl1 and IPCl2/Fe(110) adsorption systems in a hydrochloric acid solution at various temperatures. The theoretical and experimental results obtained were in good correlation.

A series of imidazothiazole derivatives were synthesized via Claisen–Schmidt condensation of aldehyde 3, and different methyl ketones and their chemical structures were confirmed using 13C NMR, 1H NMR and LC–MS. In addition, the molecular structure of compound 3 was defined by single-crystal X-ray diffraction. The antibacterial and antifungal activities of synthesized compounds were investigated by diffusion method against three pathogenic bacteria (Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus) and one pathogenic fungus (Fusarium oxysporum). Compound 3 displayed significant antibacterial activity against E. coli and P. aeruginosa (MIC ≤ 0.2 mg/ml). Concerning the antifungal activity, all the molecules show very interesting results versus F. oxysporum (IC50 ≤ 0.07 mg/ml). These results were confirmed by the molecular docking studies such as some compounds showing optimum binding energy and affinity to the active site of the receptor.

PurposeThe purpose of this paper is to study the inhibition effect of (6-phenyl-3-oxopyridazin-2-yl) acetohydrazide (GP4) on the corrosion of mild steel in acidic medium by gravimetric measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS).Design/methodology/approachWeight loss measurements, potentiodynamic tests and EIS were performed during this study.Findings(6-phenyl-3-oxopyridazin-2-yl) acetohydrazide (GP4) was found to be a very efficient inhibitor for mild steel in 1.0 M HCl solution, reaching about 85 per cent with inhibitor concentration 1.0 × 10-3 M at 303 K.Practical implications(6-phenyl-3-oxopyridazin-2-yl) acetohydrazide (GP4) was found to play an important role in the corrosion inhibition of mild steel in acidic solution.Originality/valueThis paper is intended to be added to the family of pyridazine derivatives which are highly efficient inhibitors and can be used in the area of corrosion prevention and control.

The corrosion inhibition of carbon steel C38 in 1 M HCl solution by a new synthesized compound of imidazopyridine namely (2E)-3-[2-(4-chlorophenyl)imidazo[1,2a]pyridin-3-yl]-1-(4 methoxy phenyl)prop-2-en-1-onewas studied using Tafel polarization, electrochemical impedance spectroscopy (EIS) and gravimetric measurements. The experimental results showed that the inhibition efficiency around 93% for 5.10 -5 M at 303K. The thermodynamic and activation parameters for adsorption process were calculated. This compound was adsorbed according to the Langmuir isotherm and it’s selected into a mixed-type. In other case a Quantum chemical parameters most calculated in corrosion inhibitor have been calculated and discussed. The quantum chemical calculations based on DFT methods at B3LYP / 6-31G (d,p) level of theory, were performed using Gaussian 09 program. Received 25 Feb 2017 Revised 1 June 2017 Accepted 3 June 2017

The inhibition effect of the synthesized organic compound 2-phenylimidazo [1,2-a] pyrimidine-3-carbaldehyde (IPM) on the corrosion of carbon steel (C-steel) in hydrochloric acid solution. The experiments were carried out using gravimetric (weight loss) measurements, potentio dynamic polarization and, impedance spectroscopy techniques. The results revealed that the corrosion rate increases with the increase of the concentration of IPM inhibitor. Polarization studies indicate that this compound acts as a mixed type inhibitor. The adsorption of the inhibitor was well described by the Langmuir isotherm model. Furthermore, quantum chemical calculations were carried out using density functional theory (DFT) at the B3LYP/6-31 + G(d,p) level for all atoms by Gaussian 09 W program, to provide molecular based explanations for the inhibitive effects of the compound. The molecular dynamics simulation results show that the single molecule (IPM) can adsorb on the alpha-Fe2O3(111) surface in hydrochloric acid as solution through the oxygen and nitrogen atoms as well as pi-electrons in the imidazo-pyrimidine structure. Theoretical results are in accordance with experimental data to good extend.

A series of new pyrazolic heterocyclic compounds were prepared in good and excellent yields and characterized by proton and carbon nuclear magnetic resonance , infrared, and mass spectroscopy studies. These products were screened in vitro against three bacterial pathogens, namely Bacillus subtilis, Micrococcus luteus, and Escherichia coli and antifungal potential, against Fusarium oxysporum f.sp.albedinis. A considerable and excellent activity was recorded with respect to the two studied microorganisms. A good correlation was obtained between the experimental results and the theoretical predictions of bioavailability using Petra/Osiris/Molinspiration suite (Petra/Osiris/Molinspiration containing Lipinski's rule-of-five). The quantitative structure activity relationship approach has been analyzed to support the Petra/Osiris/ Molinspiration results and composite indexes of some quantum chemical parameters were constructed in order to characterize the inhibition performance of the tested molecules.

In this work, we are interested in studying the effect of the addition of a heterocyclic organic compound derived from pyridazine named ethyl (6-methyl-3-oxopyridazin-2-yl) acetate (GK2) on inhibition of the corrosion of mild steel (C38) in a molar hydrochloric acid solution. This study was performed using the method of weight loss, potentiodynamic polarization and the electrochemical impedance spectroscopy (EIS). Gravimetric measurements indicate that the inhibitor has GK2 efficiency increases with the concentration to reach a maximum value of 83.1% at 10(-3) M. In addition, studies revealed that the potentiodynamic polarization act as a mixed inhibitor with predominance at cathodic domain. EIS shows that increasing the concentration of the inhibitor leads to an increase of the charge transfer resistance and reducing the double layer capacitance. Effect of temperature was studied between 308 and 343 K and determination of adsorption and activation parameters is also discussed. (C) 2016 Elsevier B.V. All rights reserved.

The corrosion behavior of C38 steel in HCl solutions and its inhibition by 6-phenylpyridazin-3(2H) one (PPO) has been studied in different temperature using polarization and electrochemical impedance spectroscopy (EIS) techniques as well as weight loss measurements. The 6-phenylpyridazin-3(2H) one has shown good inhibitive properties and acts as mixed inhibitor as observed in polarization method. The EIS results confirmed the efficiency of tested inhibitor and showed that the charge transfer resistance increase with the rise in the concentration following the same trend of the inhibition efficiency. The effect of the temperature, Langmuir adsorption isotherm and their parameters are discussed to examine the mechanism of the interactions between metal surface and tested compound. A chemisorption mechanism is proposed.

The corrosion inhibition performances of three pyridazine derivatives, 6-methyl-4,5-dihydro-2H-pyridazine-3-one (MPYO), 6-phenyl-2H-pyridazine-3-one (PPYO) and 6-phenyl-2H-pyridazine-3-thione (PPYS) for mild steel in 1 M HCl solution were studied by gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Some thermodynamic parameters were calculated and discussed. The effect of molecular structure on the inhibition efficiency was theoretically studied by density functional theory (DFF). Experimental and theoretical studies agreed well and confirmed that PPYS is the best corrosion inhibitor among the studied organic compounds which was related to the presence of a more favorable adsorption center of S atom in its molecular structure. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

B3LYP/6-311G(d,p) quantum calculations are performed to optimize geometries and obtain properties depending on the electronic, optical and photovoltaic parameters for some pyridazine derivatives. These novels four organic donor-π-acceptor dyes (D-π-A) used for dye-sensitized solar cells (DSSC). The results have shown that the polarizable continuum model (PCM) were reasonably capable of predicting the excitation energies, the absorption and the emission spectra of the molecules. The HOMO and LUMO energy levels of these dyes can ensure a positive effect on the process of electron injection and dye regeneration. Gaps energy ΔEg, short-circuit current density (Jsc), light-harvesting efficiency (LHE), injection driving force (ΔGinject), total reorganization energy (λtotal) and opencircuit photovoltage (Voc) permit qualitative predictions about the reactivity of these derivatives.

The new series of Schiff base were synthesized from 7-methyl-2-phenylimidazo[1,2-a]pyridin-3-amine condensed with different substituted aldehydes (4-Hydroxybenzaldehyde, Vanillin, 3-Nitrobenzaldyde, 4Nitrobenzaldehyde)in presence of catalytic quantities of acetic acid. So the structure offers for this synthesis well coincide with the results obtained bydifferent spectroscopic techniques (IR, 1 H NMR, 13 C NMR and Mass spectroscopy). These new compounds were evaluated for their antibacterial, againstGram positive and Gram negative bacteria, and antifungal activityagainst yeasts and moulds, using micro-dilution tests. The biological activityof the synthesized compoundswere compared with standard drugs. The best results are observed in the amine starting (new 7-methyl-2-phenylimidazo [1,2-a]pyridin-3-amine), it showed interesting antibacterial activity of all tested strains, particularly against Proteus strain is a Gram -.

B3LYP/6-311G(d,p) quantum calculations are performe d to optimize geometries and obtain properties depe nding on the electronic, optical and photovoltaic paramet ers for some pyridazine derivatives. These novels f our organic donor-π-acceptor dyes (Dπ-A) used for dye-sensitized solar cells (DSSC). The results have shown that the polarizable continuum model (PCM) were reasonably c apable of predicting the excitation energies, the a bsorption and the emission spectra of the molecules. The HOMO and LUMO energy levels of these dyes can ensure a positive effect on the process of electron injection and dye reg neration. Gaps energy ∆Eg, short-circuit current density (J sc), light-harvesting efficiency (LHE), injection drivin g force (∆G), total reorganization energy ( λtotal) and opencircuit photovoltage (Voc) permit qualitative predictions about the reactivi ty of these derivatives.