A new schiff base derivative as an effective corrosion inhibitor for mild steel in acidic media: Experimental and computer simulations studies

Synthesis of tetrazole hybridized with thiazole, thiophene or thiadiazole derivatives, molecular modelling and antimicrobial activity

Background

Tetrazole-based derivatives and their electronic structures have displayed interesting antimicrobial activity.

Methods

The tetrazole-based hybrids linked with thiazole, thiophene and thiadiazole ring systems have been synthesized through various chemical reactions. The computational method DFT/B3LYP has been utilized to calculate their electronic properties. The antimicrobial effectiveness was investigated against representative bacterial and fungal strains. Additionally, the synthesized derivatives binding interaction was stimulated by docking program against PDB ID: 4URO as a model of the ATP binding domain of S. aureus DNA Gyrase subunit B.

Results

The structures of the synthesized tetrazole-based derivatives were confirmed by IR, NMR, and Mass spectroscopic data. The DFT/B3LYP method showed that the thiadiazole derivatives 9a-c had lower ΔEH-L than the thiophenes 7a-c and thiazoles 5a-c. The hybrids 5b, 5c, and 7b exhibited proper antibacterial activity against Gram's +ve bacterial strains (S. aureus and S. pneumonia), while 9a displayed potent activity towards Gram's -ve bacterial strains (S. typhimurium and E. coli). Meanwhile, derivatives 5a-b, 7a, 7c, and 9c showed good effectiveness towards fungal strain (C. albicans).

Conclusion

The study provides valuable tetrazole core-linked heterocyclic rings and opens the door to further research on their electrical characteristics and applications. Tetrazoles and thiazoles have antibacterial properties in pharmacological frameworks, making these hybrids potential lead molecules for drug development. The conclusion summarizes the data and suggests that the synthesized chemicals' interaction with a particular protein domain suggests focused biological activity.

Electrochemical, surface morphological and computational evaluation on carbohydrazide Schiff bases as corrosion inhibitor for mild steel in acidic medium

Anticorrosion and adsorption behaviour of synthesized carbohydrazide Schiff bases, namely (Z)-N'-(4-hydroxy-3-methoxybenzylidene)-6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide(MBTC) and (Z)-N'-(3,4-dichlorobenzylidene)-6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide (CBTC) was examined for mild steel (MS) in 15% HCl medium. The corrosion inhibition study was performed by using gravimetric, thermodynamic, electrochemical and theoretical studies including density functional theory (DFT), molecular dynamic simulation (MDS) and Monte Carlo simulations (MCS). The outcomes in terms of corrosion inhibition efficiency using electrochemical impedance spectroscopy (EIS) method at 303 K and 150 ppm concentration were 96.75% for MBTC and 95.14% for CBTC. Both inhibitors adsorbed on the MS surface through physical as well as chemical adsorption and followed the Langmuir isotherm. The mixed-type nature of both inhibitors was identified by polarization results. Surface analysis was done using FESEM, EDX, AFM and XPS studies and results showed that a protective layer of inhibitor molecules was developed over the surface of MS. The results of DFT, MCS and MDS are in accordance with experimental results obtained by weight loss and electrochemical methods.

Data analysis for SEM-EDX, thermokinetics, surfactant, and corrosion inhibition activity of Co(II) and Zn(II) complexes of pyrrole-based surfactant ligand

This manuscript reports a dataset for the scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), surfactant properties, thermokinetics, and corrosion inhibition activity of [[Co(HL)₂.2H₂O] Cl₂.H₂O]] (1) and [[Zn(HL)₂.Cl] Cl.3H₂O]] (2) complexes with surfactant-based Schiff base ligand (HL). It contains analyzed data related to thermokinetics, such as the activation energy (E*), entropy change (∆S*), enthalpy change (∆H*), and free energy change (∆G*) of HL and metal complexes. It also contains the SEM micrographs and EDX images of the studied ligand and metal complexes. A detailed analysis of the critical micelle concentration (CMC) data and figures illustrating the surfactant behavior of the synthesized complexes are presented in this article. The data for the corrosion inhibition activity of all synthesized compounds are also included. The dataset is related to the research article entitled "Bioinorganic interest on Co(II) and Zn(II) complexes of pyrrole-based surfactant ligand: Synthesis, characterization, and in silico-ADME study".

Synthesis, DFT investigations, antioxidant, antibacterial activity and SAR-study of novel thiophene-2-carboxamide derivatives

Synthetic strategy for the synthesis of thiophene 2-carboxamide derivatives substituted with hydroxyl, methyl and amino groups at position-3 was proposed. The strategy includes the cyclization of the precursor ethyl 2-arylazo-3-mercapto-3-(phenylamino)acrylate derivatives, 2-acetyl-2-arylazo-thioacetanilide derivatives and N-aryl-2-cyano-3-mercapto-3-(phenylamino)acrylamide derivatives with N-(4-acetylphenyl)-2-chloroacetamide in alcoholic sodium ethoxide. IR, ¹H NMR, and mass spectroscopic analyses were used to characterize the synthesized derivatives. In addition, molecular, electronic properties of the synthesized products were studied by the density functional theory (DFT) where they exhibited close HOMO-LUMO energy gap (ΔE_H-L) in which the amino derivatives 7a-c have the highest while the methyl derivatives 5a-c were the lowest. Using the ABTS method, the antioxidant properties of the produced compounds were evaluated, where amino thiophene-2-carboxamide 7a exhibit significant inhibition activity 62.0% compared to ascorbic acid The antibacterial activity against two pathogenic Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two of pathogenic Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) revealed that 7b records the highest activity index compared to ampicillin 83.3, 82.6, 64.0, 86.9%, respectively. Furthermore, the thiophene-2-carboxamide derivatives were docked with five different proteins with the use molecular docking tools and the results explained interactions between amino acid residue of enzyme and compounds. Compounds 3b and 3c showed the highest binding score with 2AS1 protein.

Molecular Dynamics Study on the Diffusion Behavior of Water Molecules and the Dielectric Constant of Vegetable/Mineral Oil Blends

Insulating oil plays a crucial role in internal insulation of oil-impregnated transformers. It has been demonstrated in a variety of experimental studies that mineral oil (MO) and vegetable oil (VO) can be blended in different ratios to improve insulation properties; however, the mechanisms underlying this phenomenon remain unclear. In this study, a molecular dynamics (MD) simulation approach was used to investigate diffusion of water molecules in VO/MO blends and dielectric constants of a mixture. The results show that the diffusion coefficient of water molecules is negatively correlated with the proportion of VO; thus, addition of VO helps to improve the insulation properties of a mixture. Due to introduction of strong polar functional groups, a decrease in the diffusion behavior of water molecules can be attributed to an increase in the interaction energy and formation of hydrogen bonds between water molecules and the mixed oil system. There is a direct correlation between the dielectric constant of a mixture and VO content; however, it is very sensitive to water content. The presence of strong polar water molecules or functional groups in a mixture leads to an increase in the dielectric constant, which results in a reduction in insulating properties. Accordingly, presence of polar groups plays an important role in determining the insulating properties of a mixture. To increase the insulation performance of a mixture, it is important to consider the diffusion-inhibiting and dielectric effects of the stronger polar groups in vegetable oil compared to those in mineral oil.

Inhibition Effect and Mechanism Explanation of Perilla Seed Extract as a Green Corrosion Inhibitor on Q235 Carbon Steel

The development of environmentally friendly corrosion inhibitors has become a research hotspot. Aiming at the potential corrosion inhibition effect of perilla seed extract on Q235 carbon steel, the corrosion inhibition effect was quantitatively evaluated by various research methods, and the effective corrosion inhibition composition and mechanism were discussed. The research methods include potentiodynamic polarization curve method, HPLC-MS, FT-IR, XPS and chemical calculation. The experimental results show that the inhibitor prepared from perilla seed extract is a mixed inhibitor, and its adsorption behavior accords with Langmuir adsorption theory and its adsorption free energy is -22.70 kJ/mol. Combined with the experimental results and theoretical calculation, the effective corrosion inhibiting components are luteolin and apigenin. Theoretical calculation shows that both of them are adsorbed parallel to the surface of carbon steel to form thin films. The adsorption mechanism is that carbonyl O atoms in luteolin and apigenin hybridize with the 3 d empty orbit of Fe. From the point of view of quantum chemistry, the smaller the HOMO value and the energy gap value, the better the adsorption of corrosion inhibitor on the surface of carbon steel. From the point of view of molecular dynamics simulation, the greater the absolute value of adsorption energy, the better the adsorption of corrosion inhibitor on carbon steel surface.

Environmental Remediation through Catalytic Inhibition of Steel Corrosion by Schiff’s Bases: Electrochemical and Biological Aspects

The environmental impact of corrosion is very dangerous and consumes much of world’s efforts and funds. This work discusses the safeguarding of the environment, metals, and metal-infra structures by efficient Schiff’s base inhibitors. The corrosion inhibitors [(1E,3E)-N1,N3-dibutyl-1-(thiophen-2-yl)butane-1,3-diimine] (GSB-I) and [(1Z,3Z)-N1,N3-bis(4-methylhexan-2-yl)-1-(thiophen-2-yl)butane-1,3-diimine] (GSB-II) were successfully synthesized and evaluated for the protection of API 5L X65 steel (CS) in 1 M HCl media using electrochemical techniques, SEM/EDS, and quantum chemical calculations. GSB-I and GSB-inhibitory I’s efficiency is proportional to the concentration of the test. In the presence of 1 mM GSB-I and GSB-II, the maximum inhibitory efficiency was determined to be 90.6 and 93.8 percent, respectively. According to potentiodynamic polarization tests, the two compounds are effective inhibitors of mixed-type corrosion. The physisorption and chemisorption of both inhibitors followed the Langmuir adsorption isotherm on CS surfaces. The biological reactivity of both GSB has been examined, and encouraging results have been obtained as antifungal, antibacterial, and biocidal agents against sulfate-reducing bacteria (SRB). In addition, using DFT calculations and molecular dynamic (MD) simulation, the effect of GSB-I and GSB-II molecular configuration on corrosion inhibition behavior in acidic environments was investigated.

Molecular dynamics study of three amino acids as corrosion inhibitor for copper in hydrochloric acid solution

Molecular dynamics (MD) simulation is used to study the corrosion inhibition mechanism of cysteine (Cys), glutamic (Glu) and glycine (Gly) for copper in hydrochloric acid solution. The adsorption energy and radial distribution function results show that all three amino acids can spontaneously adsorb on Cu (111) surface by chemical adsorption. The absolute value of adsorption energy and intensity is Cys > Glu > Gly. The diffusion coefficient and relative concentration curve show that all the three amino acids can inhibit the diffusion and aggregation ability of corrosion particles, so the three amino acids not only can slow down the aggregation of corrosive particles, but also effectively repel corrosive particles to protect the substrate. The inhibition ability obtained by the MD simulation shows the trend of Cys > Glu > Gly, which is consistent with the experimental results. The inhibition efficiency is determined by both the adsorption strength on the substrate surface and inhibition ability for the diffusion and aggregation ability of corrosion particles.

Theoretical evaluation of the corrosion inhibition performance of aliphatic dipeptides

The peptide molecular group participates in donor-accepting processes by interacting with the metal surface. It boosts adsorption interaction with the metal surface which enhances the inhibitory effect.

Understanding the anticorrosive mechanism of a cross-linked supramolecular polymer for mild steel in the condensate water: comprehensive experimental, molecular docking, and molecular dynamics investigations

A supramolecular polymer (CDP-DA) was prepared through the crosslinking reaction among the assembled complexes (CDDA) based on β-cyclodextrin (β-CyD) and octadecylamine (ODA). The structural properties of CDP-DA were clarified by experimental techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, and thermal analysis. Based on the results of molecular docking, the crosslinking unit, CDDA, in the CDP-DA structure favors to exhibit the configuration that narrow rims of two host compounds (β-CyD) are opposite to each other leaving the amino group of ODA outside the host cavity. The corrosion inhibition performance of CDP-DA for mild steel in industrial condensate water was evaluated by electrochemical measurements and surface analyses, the mechanism of which was disclosed by molecular dynamics simulations in the aspects of adsorption equilibrium and ions diffusion models. The results of electrochemical tests indicate that CDP-DA effectively retards the anodic and cathodic reactions and improves the interfacial charge transfer resistance of mild steel in condensate water, which can be categorized as the mixed-type inhibitor. Surface analyses reveal that CDP-DA adsorbs on the steel surface in the integral form showing a monolayer nature, which is consolidated by molecular dynamics simulations. The diffusion behavior of in situ ions in the adsorbed layer is prominently suppressed as compared with those in bulk solution. The robust barrier layer and the mitigated diffusion of ions may contribute to the effective inhibition for CDP-DA against steel deterioration in the condensate water. Anticorrosive mechanism of a cross-linked supramolecular polymer for mild steel in the condensate water.