Computational study of some triazole derivatives (un- and protonated forms) and their copper complexes in corrosion inhibition process

Coordination Complexes Built from a Ditopic Triazole-Pyrazole Ligand with Antibacterial and Antifungal Performances

Four mononuclear complexes (H3O){[NiL3](ClO4)3} (1), [CoL3](ClO4)2·2H2O (2), [CdL2Cl2] (3) and [CuL3](NO3)2 (4) have been prepared employing a newly synthesized 1,2,4-triazole ligand: 3-(3,5-dimethyl-1H-pyrazol-1-yl)-1H-1,2,4-triazole (L). The structures of the complexes, which crystallized in P63/m (1), P-1 (2), P1 (3), and P21/c (4), are reviewed within the context of the cooperative effect of the hydrogen bonding network and counter anions on the supramolecular formations. Moreover, within the framework of biological activity examination, these compounds showed favorable antibacterial performances compared to those of various species of bacteria, including both Gram-positive and Gram-negative strains. Significant antifungal inhibitory activity towards Fusarium oxysporum f. sp. albedinis fungi was recorded for 3 and 4 over the ligand L.

Experimental and theoretical insights into copper corrosion inhibition by protonated amino-acids

The effects of cysteine (Cys) and l-methionine (l-Met) on copper corrosion inhibition were examined in 1 M HNO₃ solution for short and long exposure times. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were used. The EIS determined the potential for zero charges of copper (PZC) in the inhibitor solution. SEM and AFM have been used to study material surfaces. Energy-dispersive X-ray spectroscopy (EDS) was used to identify surface elemental composition. DFT and molecular dynamics simulations explored the interaction between protonated amino acids and aggressive media anions on a copper (111) surface.

The effects of cysteine (Cys) and l-methionine (l-Met) on copper corrosion inhibition were examined in 1 M HNO₃ solution for short and long exposure times.

Experimental Investigations of AlMg3 Components with Polyurethane and Graphene Oxide Nanosheets Composite Coatings, after Accelerated UV-Aging

The use of graphene (Gr) and its derivates graphene oxide (GO) showed that these materials are good candidates to enhance the properties of polyurethane (PU) coatings, especially the anticorrosion ones since graphene absorbs most of the light and provides hydrophobicity for repelling water. An important aspect of these multifunctional materials is that all these improvements can be realized even at very low filler loadings in the polymer matrix. In this work, an ultrasound cavitation technique was used for the proper dispersion of GO nanosheets (GON) in polyurethane (PU) resin to obtain a composite coating to protect the AlMg3 substrate. The addition of GON considerably improved the physical properties of coatings, as demonstrated by electrochemical impedance spectroscopy (EIS) analysis, promising improved anticorrosion performance after accelerated UV-ageing. Computational methods and Differential Scanning Calorimetry (DSC) measurements showed that GON facilitates the formation of additional bonds and stabilizes the PU structures during the ultraviolet (UV) exposure and aggressive attack of corrosive species. Limiting oxygen index (LOI) data reveal a slow burning behaviour of PU-GON coatings during UV exposure, which is better than PU alone.

Simulation and surface topology of activity of pyrazoloquinoline derivatives as corrosion inhibitor on the copper surfaces

In the present study, corrosion inhibition performances of some pyrazolo [3,4-b] quinoline-3,5-dione derivatives against the corrosion of copper metal were investigated using B3LYP/6-311++g(d,p) calculation level in aqueous media. Additionally, interaction energies were calculated for all the pyrazoloquinoline derivatives compounds. In the calculations it is observed that studied molecules adsorb on metal surface with the help of electron donor heteroatoms in their molecular structures. Chemical thermodynamic parameters regarding the interaction between inhibitor molecule and copper surface were estimated and discussed. Density of the electron profile analysis and chemical electrostatic potential of nuclear charges in the molecule were applied to consider the nature of a number of probable interactions between Cu metal surface and inhibitors in terms of bond critical point (BCP). Calculated quantum chemical parameters showed that the pyrazoloquinoline derivatives including the OH and NO₂ exhibit high inhibition performance.

Corrosion Inhibition of 3003 Aluminum Alloy in Molar Hydrochloric Acid Solution by Olive Oil Mill Liquid By-Product

According to the literature, the works on the inhibition of aluminum alloy corrosion using naturally occurring compounds are limited. For this, the inhibiting effect of oil mill liquid by-product (OMW) on the corrosion of 3003 aluminum alloy (AA3003) in molar hydrochloric acid solution was evaluated using electrochemical techniques. In parallel, a computational approach based on DFT/B3LYP and Monte Carlo methods was used to understand the inhibition process under electronic and atomic scales, respectively. The experimental results reveal that OMW has a good inhibiting effect on the corrosion of AA3003 alloy in the tested solution and acts as a cathodic inhibitor. The inhibitory efficiency increases by increasing OMW concentration to attain 89% at 6.0 ppm. The effect of temperature shows that the inhibition efficiency of OMW decreases with temperature rising. Nevertheless, a good prevention capacity of 83% is obtained at 338 K. Such interesting achieved protection property was attributed to the adsorption of OMW constituents onto the alloy surface via a mixed physichemisorption process. This process is found to obey the Langmuir adsorption isotherm. Furthermore, the activation thermodynamic parameters of the corrosion process of AA3003 alloy were also determined and discussed. The computational outcomes outlined the ability of the OMW components to interact favorably with the metal surface, hence the formation of a protective layer, which justified the observed inhibition behaviors. Conferring to the present study, OMW can be used as a good green corrosion inhibitor for AA3003 alloy in the acidic medium.

Towards a theoretical understanding of alkaloid-extract Cytisine derivatives of Retama monosperma (L.) Boiss. Seeds, as eco-friendly inhibitor for carbon steel corrosion in acidic 1M HCl solution

Because of their availability, lower cost, biodegradability, respect for health, environmental standards and their extremely high efficiency [Benmessaoud Left D, Zertoubi M, Irhzo A, Azzi M, Revue: Huiles et extraits de plantes comme inhibiteurs de corrosion pour différents métaux et alliages dans le milieu acide chlorhydrique, J Mater Environ Sci 4:855–866, 2013], the green corrosion inhibitors are currently the most sought after candidates. The ultimate aim of this work is to study the selectivity and reactivity of a series of three molecules, namely Cytisine, Dehydro-Cytisine and N-methyl Cytisine which are the major constituents of Retama monosperma seeds alkaloid extract (AERS) as eco-friendly inhibitors of corrosion of carbon steel in acidic medium HCl (1M), using the density functional theory (DFT) at B3LYP/aug-cc-pvdz levels. Indeed, this alkaloid extract AERS has proven experimentally its corrosion inhibitory power for carbon steel in 1 M HCl even at lower concentration (94.42% at 400[Formula: see text]mg/L). Besides, its adsorption on the steel surface in 1 M HCl solution followed Langmuir’s isotherm [El Hamdani N, Fdil R, Tourabi M, Jama C, Bentiss F, Alkaloids extract of Retama monosperma (L.) Boiss. seeds used as novel eco-friendly inhibitor for carbon steel corrosion in 1 M HCl solution: Electrochemical and surface studies, Appl Surf Sci 357:1294–1305, 2015, doi: 10.1016/j.apsusc.2015.09.159; El Hamdani N, Contribution a la valorisation des parties aériennes de Retama Monosperma, phytochimie, activités antimicrobiennes et propriétés anticorrosives, Universite Chouaib Doukkali Faculte des sciences El jadida, 2015]. Herein, the major aim of this work is to investigate the likelihood of the carbon steel corrosion being inhibited by the protonated species in the aqueous acidic solution. For this purpose, after proving that the most favorable protonation site for protonation was N9, we have evaluated the structural, global and local reactivity descriptors, partial atomic charge in terms of Natural bond orbital (NBO) of the three protonated inhibitors at the level of N9, which are the most stable in the aqueous acidic solution. NBO analysis and the thermodynamic properties such as entropy, enthalpy, heat capacity and Gibbs free energy were also done. In conclusion, it was observed that three protonated molecules showed a high propensity to adsorb to the mild steel surface with a priority of the molecule d-CytN9H+.

Influence of 5-Chlorobenzotriazole on Inhibition of Copper Corrosion in Acid Rain Solution

This paper aims to examine the efficiency of 5-chlorobenzotriazole (5Cl-BTA) as a copper corrosion inhibitor in acidic rain solutions with a pH value of 2.42 by the electrochemical polarization method. 5-Chlorobenzotriazole acts similar to a mixed type inhibitor, according to the potentiodynamic polarization measurements. Results obtained in this research suggest that 5Cl-BTA is a good inhibitor; it decreases anodic and cathodic reaction rates, and the highest inhibition efficiency was 91.2%. The inhibitory effect of 5-chlorobenzotriazole is explained by the formation of the layer on the copper surface. Stability of the protective layer increased with inhibitor concentration. Scanning electron microscopy and energy-dispersive analysis of X-rays analysis confirmed that on the electrode surface, a protective layer was formed. Adsorption of 5Cl-BTA obeys the Langmuir adsorption isotherm. 5Cl-BTA showed good inhibitory characteristics even when the Cl^- ions were present in examined solutions.

Corrosion Behavior of Titanium in Simulated Body Solutions with the Addition of Biomolecules

Titanium is one of the most used biomaterials for different applications. The aim of this study is to investigate the influence of adenine, thymine, and l-histidine as important biomolecules in the human body on the corrosion behavior of titanium in simulated body solutions. Open circuit measurements, potentiodynamic measurements, electrochemical impedance spectroscopy measurements, and quantum chemical calculations were employed during the investigation. All electrochemical methods used revealed that the investigated biomolecules provide better corrosion resistance to titanium in artificial body solutions. The increase in corrosion resistance is a result of the formation of a stable protective film on the metal surface. Also, quantum chemical calculations are in compliance with electrochemical test results and indicate that adenine, thymine, and l-histidine may act as corrosion inhibitors in the investigated solutions.

The role of pH in corrosion inhibition of tin using the proline amino acid: theoretical and experimental investigations

Herein, the effect of a mediums' pH on the interfacial interactions between proline (Pro) amino acid and tin metal was studied. In this work, acidic and near-neutral pH values were considered. DFT-based calculations and Monte Carlo simulations were carried out in the aqueous phase to understand the role of pH in Pro/tin interactions. To confirm this role in terms of inhibition efficiency, the CC and AC electrochemical techniques were used. Based on the calculated parameters, it was outlined that the partially protonated Pro form exhibits significant affinity to interact with tin metal in near-neutral media. However, in acidic media, its affinity is decreased, whereas the full protonated form was found to be solvated in the solution and its interaction with the tin surface was not favorable. These findings indicated that the inhibition capability of Pro for tin could be better in near-neutral media than in acidic media. This expected behavior was confirmed experimentally, wherein an inhibition effectiveness of around 65% was obtained for Pro at pH 5, and 16% was observed at pH 2. Additionally, the results highlight the capability of employing computational studies to predict the prevention efficiency of anti-corrosion compounds by varying the solution pH.

Herein, the effect of a mediums' pH on the interfacial interactions between proline (Pro) amino acid and tin metal was studied.

Electrochemical and DFT studies of brass corrosion inhibition in 3% NaCl in the presence of environmentally friendly compounds

The effects of adenine, salicylaldoxime and 4(5)-methylimidazole on brass corrosion in NaCl were investigated. The investigation comprised electrochemical techniques, scanning electron microscopy and quantum chemical calculation. The results obtained by polarization measurements show that the examined compounds successfully inhibited the corrosion of brass. Additionally, the quantum mechanical calculations indicate that there is a correlation between energy gap and inhibition efficiency. Moreover, the inhibition mechanism includes the adsorption of the inhibitor on active sites on the electrode surface, which was confirmed by SEM-EDS analysis of the brass.

Investigation of Polymer Coatings Formed by Polyvinyl Alcohol and Silver Nanoparticles on Copper Surface in Acid Medium by Means of Deep Convolutional Neural Networks

In order to assemble effective protective coatings against corrosion, electrochemical techniques such as linear potentiometry and cyclic voltammetry were performed on a copper surface in 0.1 mol·L−1 HCl solution containing 0.1% polyvinyl alcohol (PVA) in the absence and presence of silver nanoparticles (nAg/PVA). A recent paradigm was used to distinguish the features of the coatings, that is, a deep convolutional neural network (CNN) was implemented to automatically and hierarchically extract the discriminative characteristics from the information given by optical microscopy images. In our study, the material surface morphology, controlled by the CNN without the interference of the human factor, was successfully conducted to extract the similarities/differences between unprotected and protected surfaces in order to establish the PVA and nAg/PVA performance to retard copper corrosion. The CNN results were confirmed by the classical investigation of copper behavior in hydrochloric acid solution in the absence and presence of polyvinyl alcohol and silver nanoparticles. The electrochemical measurements showed that the corrosion current density (icorr) decreased and polarization resistance (Rp) increased, with both PVA and nAg/PVA being effective inhibitors for copper corrosion in an acid environment, forming polymer protective coatings by adsorption on the metal surface. Furthermore, scanning electron microscopy (SEM) certifies the formation of polymer coatings, revealing a specific morphology of the copper surface in the presence of PVA and nAg/PVA, very different from that of corroded copper in uninhibited solutions. Finally, the correlation of the CNN information with experimental data was reported.

Pinpointing the active species of the Cu(DAT) catalyzed oxygen reduction reaction

Dinuclear CuII complexes bearing two 3,5-diamino-1,2,4-triazole (DAT) ligands have gained considerable attention as a potential model system for laccase due to their low overpotential for the oxygen reduction reaction (ORR). In this study, the active species for the ORR was investigated. The water soluble dinuclear copper complex (Cu(DAT)) was obtained by mixing a 1 : 1 ratio of Cu(OTf)2 and DAT in water. The electron paramagnetic resonance (EPR) spectrum of Cu(DAT) showed a broad axial signal with a g factor of 2.16 as well as a low intensity Ms = ±2 absorption characteristic of the Cu2(μ-DAT)2 moiety. Monitoring the typical 380 nm peak with UV-Vis spectroscopy revealed that the Cu2(μ-DAT)2 core is extremely sensitive to changes in pH, copper to ligand ratios and the presence of anions. Electrochemical quartz crystal microbalance experiments displayed a large decrease in frequency below 0.5 V versus the reversible hydrogen electrode (RHE) in a Cu(DAT) solution implying the formation of deposition. Rotating ring disk electrode experiments showed that this deposition is an active ORR catalyst which reduces O2 all the way to water at pH 5. The activity increased significantly in the course of time. X-ray photoelectron spectroscopy was utilized to analyze the composition of the deposition. Significant shifts in the Cu 2p3/2 and N 1s spectra were observed with respect to Cu(DAT). After ORR catalysis at pH 5, mostly CuI and/or Cu0 species are present and the deposition corresponds to previously reported electrodepositions of copper. This leads us to conclude that the active species is of a heterogeneous nature and lacks any structural similarity with laccase.