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A new nonionic surfactant (NIS), namely, 17-hydroxy-3,6,9,12,15-pentaoxaheptadecyl-5- ((4-(((17-hydroxy-3,6,9,12,15-penta oxa hepta decyl) oxy) sulfonyl) phenyl) diazenyl)-2-(2-oxo-2H- chromene-3-carboxamido) benzene sulfonate was synthesized based on condensation reaction between an azo dye and polyethylene glycol. The chemical structure was elucidated from IR and 1H NMR spectral data and surface activity was measured. The inhibitive effect of the resultant NIS toward corrosion of steel in 1.0 M HCl was evaluated by potentiodynamic polarization, impedance spectroscopy (EIS), non-electrochemical methods (weight loss), surface morphology (SEM and EDX) and DFT calculations. The anti-corrosion performance showed an optimal efficiency of 96.04% at the concentration of 7.50 × 10−4 M from polarization measurements. Both the anodic and cathodic inhibition were acquired from Tafel plots polarizations (TFP). The adsorption of NIS onto steel surface obeyed Langmuir isotherm. In addition, SEM images showed higher surface protection in presence of inhibitor in agreement with a molecular dynamic simulation which exhibited optimal surface alignment between inhibitor and steel. A good agreement between electrochemical methods and DFT calculations was achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel benzimidazole derivatives of three amino acids were prepared to prevent corrosion of steel. • Measurements of polarization and impedance were used to figure out how well metal was protected against corrosion. • The chemical structure was linked to the inhibitory efficiency using FMO and NBO calculations. • The average efficiencies of corrosion inhibition are outstanding, with values of 90.09%, 92.53%, and 93.43%. • The surface properties of steel were examined using the utilization of SEM-EDs measurements. Three benzimidazole derivatives, with tryptophan (BIT), tyrosine (BIY), and histidine (BIH) amino acid units, have remarkable protective properties as eco-friendly corrosion inhibitors for steel under severe acidic conditions. At a temperature of 303 K, the corrosion inhibition efficiency of BIT, BIY, and BIH at a concentration of 10 mM is 90.09 %, 92.53 %, and 93.43 %, respectively. Electrochemical tests indicate that the adsorption of these substances on the substrate leads to an increase in charge transfer resistance and interfacial electric double layer thickness. This effectively hinders the dissolution of metal and the evolution of hydrogen. The analysis of the surface structure and appearance using SEM-EDS indicates that the inhibitors have the ability to create a protective coating through both chemical and physical bonding, effectively protecting the metal from corrosive substances. Theoretical calculations, such as Density Functional Theory (DFT) and Natural Bond Orbital (NBO) analysis, along with FUKUI analysis, help identify active sites and adsorption configuration. This enhances our understanding of the corrosion mitigation mechanism. These findings align with the experimental conclusion that the formation of a stable protective film contributes to superior inhibition performance against acidic corrosion conditions. [ABSTRACT FROM AUTHOR]

A new non-ionic organic coumarin-based surfactant was synthesized and applied to the surface of the steel in 1.0 M HCl solution. The response of the steel surface to the corrosion suppression was probed by measuring polarization, impedance, and frequency modulation in different concentrations (0.5 × 10−4 M to 7.5 × 10−4 M). While fitting the experiments to different adsorption isotherms, the steel-inhibitor interface interacted according to the Langmuir model. The maximum efficiencies of 84.18 % and 97.93 % were obtained for the inhibitor's lowest and highest concentrations, respectively based on the impedance spectroscopy measurements. The inhibitor was able to combat the anodic and cathodic reactions simultaneously showing a mixed-type inhibition ability. The free energy ΔG ads was calculated to be from −36.75 to – 38.62 kJ/mol based on the Langmuire model, indicating chemical adsorption on steel surface. A narrow energy gap of 3.012 eV was predicted by DFT calculations in consistency with high inhibition efficiency. The molecular reactivity was attributed to the contiguous system of many π orbitals on naphthalene, chromone, thiazole, and diazene entities. In turn, the p-electrons of the oxaheptadecane chains exhibit a lower contribution to the adsorption of the surfactant on the metal surface. New experimental and theoretical insights were derived and related to corrosion inhibition. [Display omitted] • A novel nonionic surfactant was synthesized and utilized as a corrosion inhibitor. • The corrosion inhibition was analyzed using Wl, EFM, EIS, and PDP. • Surface convergence was confirmed by SEM and AFM analysis. • Fukui function, MD, MC, FMO, and NBO analyses showed effective electron compensation to the corroded metal. [ABSTRACT FROM AUTHOR]

Permanent magnet stirring (PMS) is adjusted to increase the alloy corrosion resistance by modifying the crystallographic texture. According to the findings, the lamellar structure had been converted into equiaxed grains by the PMS processing. Following exposure to a 3.5 wt percent NaCl solution, the corrosion behavior of the Sn-2.0Ag-0.5Cu-2Zn alloy was examined using electrochemical methods (polarization and electrochemical impedance spectroscopy (EIS)) and surface analysis using SEM, EDX and XRD. According to the PDP curves, the PMS treatment procedure significantly reduces the values of corrosion current density (i corr) and shifts the corrosion potential (E corr) to more positive noble values. The E corr values of SAC (205)-2Zn and SAC (205)-2Zn with PMS are increased from −936.66 to −756.18 mV (vs. SCE). Also, the pitting resistance is higher in case of PMS treated alloy as indicated from cyclic polarization (CP). PMS treated alloy possess higher E rep values than E corr values, confirming the ability of passive film to restore itself. EIS data showed that the diameter of capacitive loop for PMS-treated SAC (205)-2Zn alloy is approximately four times as the untreated alloy indicating less corrosion rate and higher protection. [Display omitted] • PMS application for SAC (205)-2Zn produces homogenous distribution of IMCs and microstructure enhancement. • PMS treatment process improved the corrosion resistance of SAC (205)-2Zn alloy. • The hysteresis loop in the CP curves decreased after PMS confirming its enhanced pitting resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three novel cyano coumarin compound were synthesized and approved by FTIR, 1H NMR and Mass spectroscopy. • The synthesized inhibitors obeyed Langmuir adsorption mode with a chemical adsorption. • The metal was protected by the creation of a protective layer on the surface, according to SEM, EDX, and UV data. • The corrosion related to SRB can be controlled by the current organic coumarin inhibitors. New synthesized coumarin-buta-1, 3-diene conjugated dyes having donor–acceptor structure were prepared. The characterization of the synthesized dyes was approved by using IR, 1H NMR and Mass fragmentation analysis. The adsorption properties for the synthesized coumarin compounds were determined by experimental and theoretical methods. The corrosion inhibition effect of the synthesized coumarin dyes against steel in acid environment was investigated by plasma atomic emission spectrometer, weight loss and electrochemical methods. The highest corrosion efficiency was 97.62 % resulted from potentiodynamic polarization technique at the highest concentration for Dye 2 inhibitor. The adsorption mechanism of the inhibitors was investigated and thermodynamic parameters were calculated. The surface protection examination was carried out using scanning electron microscopy and the formation of the complex on the surface was approved using Energy dispersive X-ray spectroscopy and UV– visible spectroscopy. The quantum chemical calculations were used to confirm the donor–acceptor system of the synthesized coumarin compounds. The biological activity effect versus sulfate reducing bacteria was confirmed. The experimental and theoretical results assure that these current synthesized dyes have a good ability to protect the steel from corrosion by forming a protective layer on the surface. [ABSTRACT FROM AUTHOR]

The studied Schiff-base compounds in this work are multitasked investigated as corrosion inhibitors and also, to improve the physical and mechanical properties of reinforced concrete. The efficiency inhibition of the two novel Schiff-base compounds named (DHSiMF) and (DHSiB) for corrosion of carbon-steel in aqueous media of 1 M HCl was assessed via electrochemical methods and loss in weight. FT-IR, 1H-NMR spectra and elemental analysis were used to confirm the structure of such compounds. It was found to have successful inhibition even at low concentrations in tested media, as an increase in inhibitor concentration led to an improvement in the inhibition efficiency. The weight loss results clearly demonstrate that DHSiMF of C-steel in 1 M HCl has a higher inhibition efficiency than DHSiB, with a maximum inhibition efficiency (85%) attained at 1 × 10–2 M from DHSiMF. Electrochemical experiments likewise revealed the same order, but with a maximal inhibitory efficiency of 98.1%. The addition of inhibitors to the corrosive media dramatically changed the anodic Tafel constants (βa) and cathodic Tafel constants (βc), indicating a mixed type nature. Electrochemical polarization curves illustrated the functions of mixed-type inhibition and the action of adsorption matching with the Langmuir adsorption isotherm. The ∆Gads values for DHSiMF and DHSiB at temperatures (ranging from 303 to 333 K) are − 34.42 kilojoule/mole to − 37.51 kilojoule/mole. These values indicate that the compounds' adsorption types are chemo-physical adsorption. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) experiments were used to check the existence of the protection layer on the surface of carbon steel by analyzing the morphologies of the corrosion effects and the formed chemical compositions of the corrosion outcomes. For the concrete, the findings suggest that the chemical reaction that takes place between the DHSiMF and DHSiB and the concrete mix will result in an increase in the flexural strength, the compressive strength, and the indirect tensile strength of the concrete that is made of the gravel and dolomite aggregate. [ABSTRACT FROM AUTHOR]

The influence of branched N, N′-bis(p-hydroxybenzoyl) containing propylenediamine (PDA) and triethylenetetramine (TETA) composites for corrosion inhibition of carbon steel in acidic solution (1 M HCl) was investigated using several quantum chemical, electrochemical impedance spectroscopy and potentiodynamic polarization as electrochemical techniques. The investigated molecules were posteriorly characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR) while the surfaces of carbon steel test coupons were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The obtained results revealed that the two amino compounds, N, N′-bis(p-hydroxybenzoyl) propanediamine (N, N′-HBPDA) and N, N′-bis(p-hydroxybenzoyl) triethylenetetramine (N, N′-HBTETA), have significant efficiency toward steel corrosion attack and its inhibition performance was significantly boosted by increasing concentration of di- and tetramine containing inhibitors. The two inhibitors achieved a maximum corrosion inhibition efficiency of 99.1% as indicated from polarization measurements. The isotherm feature of Langmuir adsorption appeared to be proper factor for associating the experimental gains with an applicable mechanism of inhibition process. The free energy ∆Gads was calculated to be − 27.5, 29.1 kJ/mol based on the adsorption isotherm model, indicating physical adsorption on the carbon steel surface. Further, images of the morphological analysis exhibited various features of attack owing to the aggressive medium and the employed concentration of the inhibitor. These synthesized amines supplied many favorable scores in the fabrication of functional mixed-type inhibitors. The computational studies reveal that N, N′-HBPDA and N, N′-HBTETA molecules could absorb via several lone pairs and π clouds, confirming their ability to be good corrosion inhibitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two surfactants were synthesized and characterized by FTIR and 1HNMR. • These compounds revealed high inhibition efficiency approached 97.47% for steel corrosion. • Their activity against corrosion confirmed by EFM, EIS, Polarization and weight loss techniques. • The experimental techniques supported by detailed quantum and Monte Carlo simulation study. • The protection of steel surface observed by SEM, EDX and AFM techniques. Herein, two nonionic surfactants were prepared followed by structure confirmation using H1NMR, IR and so their surface activity were studied. The application of these compounds in the field of acid corrosion inhibitors was investigated by several empirical and computational methods. Additionally, these compounds were found to be promising inhibitors with high activity as a function of concentration attained at 96.71 % for NIS I at 7.50 × 10–4 M. The mixed behavior of inhibition predominates in the polarization results and their occurrence on carbon steel surface belongs to Langmuir model by chemisorption. The presence of organic protective layer on carbon steel surface was confirmed by SEM, AFM and EDX techniques. Further interpretation of the inhibiting action was carried out via DFT and MC computations. [ABSTRACT FROM AUTHOR]

• Three azo acetyl coumarin dyes are prepared and confirmed with FTIR, 1HNMR and mass spectroscopy. • The adsorption isotherm of prepared dyes obeyed Longmuir adsorption isotherm according to results obtained from ICPE. • The prepared dyes showed high ability to inhibit steel corrosion reaction as a mixed type inhibitors. • The prepared dyes showed high efficiency to inhibit the growth of SRB bacteria. The new azo acetyl coumarin derivatives were synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and mass spectral studies. The ability for these three dyes to act as corrosion inhibitors for mild steel in 1.0 M HCl was confirmed by potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). The state of mixed adsorption with the PP effect is shown. The azo acetyl coumarin derivatives showed the strongest corrosion inhibition of 85.29–93.01% at a corrosion of 7.5 × 10−4 M. Adsorption of the inhibitory molecules on the mild steel surface followed Langmuir adsorption isotherm. The adsorption phenomenon was verified using UV–Vis, scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) technique, whereas FTIR confirmed the presence of several functional groups containing heteroatoms. Also, quantum chemical parameters, inductively coupled plasma atomic emission spectroscopy, and the anti-bacterial effect of these new derivatives against sulfate reducing bacteria (SRB) were studied. All obtained results ensure that these derivatives can form an effective blocking layer and control the corrosion process. [ABSTRACT FROM AUTHOR]

• Raman, Infrared and NMR spectra were interpreted based on keto-thione tautomer of 6-Methyl-2-thiouracil molecule. • Polarization and impedance measurements were analyzed for corrosion inhibition efficiency of mild steel in HCl. • FMO and NBO calculations were to correlate the active sites with the inhibition efficiency. • Adsorption annealing simulations locate the best adhering geometry of the inhibitor to the metal surface. Raman (3500-100 cm−1) and FT-ATR (4000-360 cm−1) spectra of solid 6-Methyl-2-thiouracil (6M2TU) have been recorded in addition to 1H and 13C NMR along with Mass fragmentation patterns. Moreover, the hydroxy-thiole, keto-thiole, hydroxy-thione and keto-thione tautomer's stability were theoretically probed using (DFT) B3LYP/6-31G(d,p) calculations in favor of keto-thione in the gaseous phase by ~12-24.5 kcal/mol. Moreover, the monomer and dimer structures were verified by MS/MS spectral measurements owing to the recorded m/z peaks at 141.2 and 281.1, respectively. The inhibition efficiency of 6M2TU towards mild steel iron (MSFe) against 1.0 M HCl has been investigated with molar concentrations of 0.75-7.5 × 10−3 at 30±2°C using potentiodynamic polarization, impedance measurements and electrochemical frequency modulation. The entitled compound shows a superior inhibition capability against corrosion ranged from 72-94% was obtained. The polarization curves suggest a mixed-type inhibitor for 6M2TU obeying the Langmuir adsorption model while the impedance data ensures an increase in the charge transfer resistance upon its adsorption on the surface of FeMS. Natural bond orbital (NBOs) showed an effective charge transfer from the inhibitor to d -orbitals of the metal in the following order; LP (S) > LP (O) > LP (N 1) > π (C=S) > LP (N 3) > π (C 5 =C 6) > π (C=O). The calculated low Δ E g a p (4.21 eV) predicts that 6M2TU have an efficient inhibition efficiency. Finally, The kinetic parameter F number (5.369673 cm−1) and the potential function (V 3) was estimated at 454±19 cm−1 (1.30±1.05 kcal/mol) implementing B3LYP/6-31G(d,p) optimized SPs and the calculated torsion frequency at 133 cm−1. [Display omitted] Raman, infrared and NMR spectra were used to study the molecular conformational/tautomeric structures of 6-Methyl-2-thiouracil. Vibrational interpretations were suggested for keto-thione tautomer based on normal coordinate analysis. The corrosion its inhibition effect on iron mild steel in HCl was investigated using potentiodynamic polarization and electrochemical impedance measurements favors a dominant/minor chemical/physical adsorption mechanism. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Synthesis and applications of novel Schiff base derivatives as corrosion inhibitors and additives for improvement of reinforced concrete" published in Scientific Reports. The correction addresses errors in the affiliations of the authors. Ehab S. Gad's affiliation was incorrectly listed as 'Department of Chemistry, Faculty of Science (Men's Campus), Al-Azhar University, Nasr City 11884, Cairo, Egypt', but the correct affiliation is Chemistry Department, College of Science and Arts, Jouf University, Alqurayat, Saudi Arabia. The incorrect affiliation was also removed. The original article has been corrected. [Extracted from the article]

• Raman, ATR-IR and Mass spectra of 4,5-Dicyanoimidazole (DCI) have been recorded. • Electrochemical impedance spectroscopy was used to evaluate DCI inhibition efficiency. • Polarization measurements were used to account for anodic and cathodic reactions of DCI. • FMO and NBO calculations were carried to correlate DCI molecular structure to experimental findings. Raman (3500-50 cm−1) and FT-ATR/FT-infrared (3500-500/4000-200 cm−1) spectrum of 4,5-Dicyanoimidazole (DCI) were recorded and analyzed by normal coordinate analysis calculations. In addition, we have studied the molecular structure of DCI by means of B3LYP Density Functional Theory (DFT) using 6-31g(d) basis set. Aided by computational outcomes, all vibrational bands were assigned quantitatively to their corresponding fundamentals. The corrosion inhibition efficiency of DCI towards mild steel in 1.0 M HCl has been investigated experimentally and theoretically. Electrochemical impedance spectroscopy, electrochemical frequency modulation and polarization measurements along with thermodynamic predictions were assigned to both the anodic and cathodic inhibition. DCI-metal interactions and charge reallocation were analyzed in terms of Frontier molecular orbital (FMO) and Natural bond orbital (NBO) analysis. Global reactivity descriptors; ionization potential (IP), electron affinity (A), electronegativity (χ), chemical potential (µ), chemical hardness (η), and electrophilicity index have been calculated and assigned to the inhibition efficiency. Good correlation between the theoretical calculations and experimental measurments has been achieved. The results are compared with similar molecular systems whenever appropriate. Raman and infrared spectral and computational study of 4,5-Dicyanoimidazole were adapted with electrochemical measurements to account for structural and corrosion inhibition relationship. The findings verify that the investigated molecule has high inhibition efficiency toward corrosion of mild steel in 1 M HCl. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Tetraethyl orthosilicate (TEOS) was used as a chemical precursor to deposit ultra-thin SiOxCy plasma polymer films onto mild steel surfaces for preventing the corrosion process. The structure--property relationships of the coatings were evaluated by X-ray Photo Spectroscopy (XPS), X-Ray Diffraction (XRD), Fourier Transform InfraRed spectroscopy (ATR-FTIR) and Energy Dispersive X-ray spectroscopy (EDX) completed with Scanning Electron Microscopy (SEM). The SEM micrographs confirmed a pinhole-free surface morphology of the low-pressure deposited plasma polymer films. The TEOS molecules become fragmented in the plasma by numerous collisions with energy-rich electrons and heavier particles. Recombination of fragments and condensation onto the steel substrate is responsible for the formation of organic SiO containing plasma polymer layers. Such thin layers consist of predominantly SiOx structures. Their properties are determined largely by the gap distance between the two samples used as electrodes in the plasma. The efficiency of the corrosion-protecting coating was compared with uncoated samples. The corrosion protection was determined by exposure of samples to 3.5% NaCl aqueous solutions. For this purpose, polarization and Electrochemical Impedance Spectroscopy (EIS) were used to monitor the corrosion. The optimal gap distance between the electrodes was determined for corrosion protection. The best protective efficiency reached more than 97% of the total protection as measured at room temperature. [ABSTRACT FROM AUTHOR]

It is well known that metal corrosion causes serious economy losses worldwide. One of the most effective ways to prevent corrosion is the continuous development of high-efficient and environment-friendly corrosion inhibitors. Among the widely used organic and inorganic corrosion inhibitors, plant extracts are top candidates due to their nontoxic nature. The present study reports a novel application of the methanolic extract of Terminalia bellerica fruits as an environment friendly corrosion inhibitor for steel in sulphuric acid medium. The phytochemicals of the extract, namely Ellagic, Gallic, and Malic acids, play a key role of the anti-corrosive behavior of the extract. The corrosion prevention activity was studied on the steel in 1 M H2SO4 using a variety of approaches including weight loss analysis (WL), scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), density functional theory (DFT), natural bond orbital analysis (NBO), Fukui function and Monte Carlo simulations (MC). In 1 M H2SO4 solution, the maximum electrochemical inhibition efficiency of 91.79% was observed at 4000 mg/L concentration of the extract. The NBO analysis showed that the charge density of the double bonds and the oxygen atoms of carbonyl and hydroxyl groups of the phytochemicals lies on the top of the natural bond orbitals which promotes the anticorrosive properties of the investigated inhibitors. The surface coverage of steel was validated by SEM measurements. According to DFT studies, numerous nucleophilic regions were present in the active phytochemical constituents of the inhibitor, demonstrating their favorable nucleophilicity. The computed electronic structure of the phytochemicals revealed band gaps of 4.813, 5.444, and 7.562 eV for Ellagic, Gallic, and Malic acids respectively suggesting effective metal-inhibitor interactions. A good correlation between experimental and theoretical findings was addressed. [ABSTRACT FROM AUTHOR]

[Display omitted] • La+3, Sm+3, and Ce+3 were adsorbed via activated carbon derived from date seeds. • The ACDS was characterized through XRD, TG-DTA, and FTIR. • Q max for La3+, Ce3+, and Sm3+ onto ACDS were 18.18 mg/g, 24.58 mg/g, and 27.82 mg/g. In the present investigation, Lanthanum (III), Samarium (III), and Cerium (III) were subjected to adsorption onto activated carbon derived from date seeds (ACDS), which underwent activation using 40 % sulfuric acid. The activated carbon (ACDS) was characterized through X-ray Diffraction (XRD), Thermogravimetric Analysis-Differential Thermal Analysis (TG-DTA), and Fourier Transform Infrared Spectroscopy (FTIR). Thermodynamic parameters were calculated to assess the sorption process, revealing an endothermic and spontaneous nature, accompanied by an increase in system randomness. The findings showed that when the pH rose to an ideal level of 5.7 and the contact duration was extended to 180 min, the number of cerium (III) and samarium (III) ions absorbed increased. the distribution coefficient (K d) of La(III) from 22.22 to 1000 mL/g, Ce(III) from 28.07 to 1865.38 mL/g, and Sm(III) from 35.71 to 3971.43 mL/g, with the pH varying from 1.2 to 5.7. The Langmuir model exhibited superior fitting to the experimental data compared to the Freundlich model, suggesting homogeneous adsorption on the ACDS surface. The maximum adsorption capacities (Q max) for La3+, Ce3+, and Sm3+ onto ACDS were determined as 18.18 mg/g, 24.58 mg/g, and 27.82 mg/g, respectively. [ABSTRACT FROM AUTHOR]

• The utilized ERE acts as an efficient eco-friendly and cost-effective corrosion inhibitor in 1.0 M HCl solution. • The polarization results stated that ERE exhibits as a mixed-type inhibitor. • The EIS data proved the mechanism of ERE as a corrosion inhibitor. • The excellent inhibiting ability of ERE was confirmed by QC calculations, MC simulations, and SEM studies. Considerable attention has been paid to utilizing eco-friendly and cost-effective corrosion inhibitors in oilfields. Regarding these criteria, the main objective of this work is the evaluation of the corrosion inhibition performance of an expired herbal drug on carbon steel in a 1.0 M HCl solution using electrochemical techniques. It was found that the herbal drug is an effective mixed-type inhibitor and the inhibition efficiency increased with an increase in concentration to achieve 97.5% at 1.2 g/L of the inhibitor. The adsorption model obeys the Langmuir adsorption isotherm out of both polarization and impedance results. Depending on the effect of temperature on the corrosion rate, the activation parameters E a , Δ H a o and Δ S a o were estimated and discussed. The structural–corrosion inhibition relationships have been assessed using quantum chemical calculations and Monte Carlo simulations on the chief chemical constituents of the extract. The computational studies confirmed the formation of an adsorbed film on the metal surface through several active centers of polysaccharides and glycosides constituents besides nitrogen atoms of alkylamides ones. Also, they supported the interaction of the unshared electron pairs of O and N atoms with the d-orbitals of Fe which, played a vital role in the adsorption of herbal drug molecules on the carbon steel surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • The anticorrosion effect of two inhibitors on C-steel in 1 M HCl was studied. • The polarization results show that (HBEDA) and (HBDETA) are mixed-type inhibitors. • The impedance data suggest the adsorption of the inhibitors on C-steel surface. • The Langmuir adsorption isotherm governs the adsorption mechanism. • QC and MC show that hetero atoms serve as active sites to facilitate adsorption. As part of the efforts made by many researchers to evaluate a lot of chemical compounds as inhibitors for carbon steel corrosion, this research focuses on novel two compounds of benzamide derivatives. The investigated compounds namely N, N -bis (p-hydroxybenzoyl) ethylenediamine (HBEDA) and N, N -bis (p-hydroxybenzoyl) Diethylenetriamine (HBDETA), were formulated then characterized using FTIR, 1HNMR, and elemental analysis to elucidate the structures chemically. Theoretical and experimental (electrochemical and morphology) studies made clear that (HBEDA) and (HBDETA) improve carbon steel (C-steel) inhibition efficiency in 1 M hydrochloric acid as concentrations increase (25, 50, 100, 150, 200, 250 ppm). The benzamide derivatives acted as interface corrosion inhibitors in an electrochemical impedance spectroscope (EIS) experiment, and they acted as mixed type corrosion inhibitors in a polarization test. They yielded best efficiency gains of 95.8 percent for HBEDA and 99.6 percent for HBDETA. Information collected from the EIS technique was studied in order to represent the corrosion inhibition procedure using an equivalent circuit (EC). The elevated K ads values and negative ΔG ads (-28.71, −28.79 kJ/mol) values of the two compounds (understudy) revealed that they were strongly and spontaneously adsorbed at C-steel/electrolyte connections respectively, and the adsorption isotherm of Langmuir fitted widely with the empirical data. The Surface examination (morphology) of metal employing energy dispersive X-ray (EDX) and scanning electron microscope (SEM) evaluations confirmed the adsorption of (HBEDA) and (HBDETA) on the substrate (C-steel). [ABSTRACT FROM AUTHOR]

• Polarization measurements and impedance spectra were reported for some triazole derivatives as corrosion inhibitors for Al in HCl. • FMO and NBO calculations were used to relate the molecular structure to the inhibition efficiency. • Adsorption annealing simulations were performed to locate the best adhering geometry of inhibitors to the metal surface. The corrosion inhibition of three triazole derivatives; p-tolyl-1H-1,2,3-triazol-5-ol (Z1), 4-Chlorophenyl-1H-1, 2, 3-triazol-5-ol (Z2) and Methyl-4-(5‑hydroxy-1H-1, 2, 3-triazol-1-yl) benzoate (Z3) towards aluminum metal in 1.0 M HCl have been investigated using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), B3LYP Density Functional Theory (DFT) and adsorption annealing simulations. The electrochemical findings exhibit an inhibition efficiency increase in the order: Z3 > Z2 > Z1 with a maximum inhibition efficiency (74.7%) obtained at 500 ppm from Z3. Both anodic (βa) and cathodic (βc) Tafel constants was significantly affected by adding inhibitors to the corrosion medium proposing a mixed type nature. The adsorption of the inhibitors on the metal surface was found to be a spontaneous process and obeyed Langmuir isotherm. The conformational scan along with annealing adsorption simulations showed a dihedral angle between the triazole ring and the phenyl ring of only 30° which promotes optimal surface coverage. Global reactivity descriptors, Fukui indices, atomic charges and NBO analysis showed that the priority of charge reallocation form inhibitor MOs to the metal surface is easier in the order: Z3 > Z2 >Z1 which reveal good agreement to the electrochemical measurements. Based on DFT results, an inhibition mechanism was proposed. Molecular structure of some triazole derivatives were investigated in the context of their inhibition efficiency to the corrosion of Al in HCl. The FMO and NBO were used to account for the direction of electron flow within the investigated molecules and hence reallocation onto the metal surface. Electrochemical measurements were compared and assigned to the molecular structure outcomes. [Display omitted] [ABSTRACT FROM AUTHOR]

Despite the extensive use of carbon steel in all industrial sectors, particularly in the petroleum industry, its low corrosion resistance is an ongoing problem for these industries. In the current work, two malonyl dihydrazide derivatives, namely 2,2'-malonylbis (N-phenylhydrazine-1-carbothiamide (MBC) and N'1, N'3-bis(-2-hydroxybenzylidene) malonohydrazide (HBM), were examined as inhibitors for the carbon steel corrosion in 1.0 M HCl. Both MBC and HBM were characterised using thin-layer chromatography, elemental analysis, infrared spectroscopy, and nuclear magnetic resonance techniques. The corrosion tests were performed using mass loss measurements, polarisation curves, and electrochemical impedance spectroscopy. It is obtained from the mass loss studies that the optimal concentration for both inhibitors is 2.0 × 10−5 mol/L, and the inhibition efficiencies reached up to 90.7% and 84.5% for MBC and HBM, respectively. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) indicate an increased impedance in the presence of both MBC and HBM and mixed-type inhibitors, respectively. Both inhibitors can mitigate corrosion in the range of 298–328 K. Values of free energy changes obtained from the Langmuir model suggest that the inhibitors suppress the corrosion process principally by chemisorption. The computational investigations were conducted to identify the factors connected with the anti-corrosive properties of the examined inhibitors. [ABSTRACT FROM AUTHOR]

• Synthesis of a newly coumarin ligand and its complexes with Sm(III) and Eu(III) metal ions. • Photophysical and Luminescence results of Sm(III) and Eu(III) complexes exhibit strong red emissions. • Molecular Docking study observes the inhibition activity of coumarin compound toward xanthine oxidase enzyme. • DFT calculations show the optimized structure and separation energies of the coumarin compound. Herein, [M(HL) 2 (H 2 O) 2 NO 3 ·2H 2 O (M = Sm (III) /or Eu (III); HL = 4-(2-hydroxy benzylidene acetohyrazide)-7-hydroxy coumarin) were synthesized and characterized using several spectroscopic methods. The complexes stoichiometry with molar ratio 2L:1M were confirmed by Job's method. Tridentate ligand (HL) was coordinated to the lanthanide ions Sm(III) or Eu(III) through azomethine nitrogen atom, phenolic oxygen of hydrazide, and ketonic oxygen of the amide group. The photophysical properties of the ligand and its complexes were studied in different organic solvents and their fluorescence quantum yields were determined as well. Strong fluorescence emissions to red shifts of europium complex were observed at 580, 593, 617, 653, 693, 704 nm which were attributed to Eu(III) emission of 5D 0 →7F 0 , 5D 0 →7F 1 , 5D 0 →7F 2 , 5D 0 →7F 3, 5D 0 →7F 4, and 5D 0 →7F 5 , respectively. First-principles DFT calculations were performed to evaluate the optimized structure and separation energies of the HL compound, using the B3LYP/6-311++g(d,p) basis set. Molecular docking studies were carried out to predict the binding modes between the HL compound and active site of the xanthine oxidase enzyme [EC# (1.17.3.2) PDB ID: 1FIQ] which produced from liver patients of hepatitis C. The observed activity of the HL gave rise to the conclusion that it might exert its action through inhibition of the xanthine oxidase enzyme. [ABSTRACT FROM AUTHOR]