Schiff's base derived from 2-acetyl thiophene as corrosion inhibitor of steel in acidic medium

Electrochemical and computational insights into the utilization of 2, 2- dithio bisbenzothiazole as a sustainable corrosion inhibitor for mild steel in low pH medium

Industries today place a high premium on environmentally friendly supplies that may effectively inhibit metal dissolution at a reasonable cost. Hence, in this paper, we assessed the corrosion inhibition effectiveness of the Thiazole derivative namely, 2, 2-Dithio Bisbenzothiazole (DBBT) against mild steel (MS) corrosion in 1 M HCl. Several experimental approaches, including gravimetric analysis, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and surface exploration using scanning electron/atomic force microscopy (SEM/AFM) and contact angle (CA), were utilized to conduct the measurements. In 1 M HCl corrosive medium at 298 K in the subsistence of 800 ppm of DBBT, this experiment indicated DBBT as an environment-friendly and sustainable corrosion inhibitor (CI) for MS, demonstrating an inhibition efficiency (IE %) of 97.71%. To deliver a deeper knowledge of the mechanism behind inhibitive behavior, the calculated thermodynamic and activation characteristics were applied. The calculated Gibbs free energy values indicated that the CI interacted physically and chemically with the MS surface, validating physio-chemical adsorption. The findings of the EIS research revealed that an upsurge in the doses of the CI is escorted by an upsurge in polarization resistance (Rp) from (88.05 → 504.04) Ωcm2, and a diminution in double layer capacitance (Cdl) from (97.46 → 46.33) μFcm-2 at (50 → 800) ppm respectively, affirming the inhibitive potential of DBBT. Additionally, the greatest displacement in Ecorr value being 76.13 mV < 85 mV, indicating that DBBT act as a mixed-form CI. To study the further impacts of DBBT on the inhibition capabilities of the compound under investigation, density functional theory (DFT) and molecular dynamics (MD) simulation were employed. Chemical and electrochemical approaches are in agreement with the computational analysis indicating DBBT is the most efficient CI.

A Review of Electrochemical Techniques for Corrosion Monitoring - Fundamentals and Research Updates

Interculturally, corrosion has been counted as one of the most expensive factors toward the retrogression of concrete and metallic structures resulting in huge monetary losses and unanticipated loss of life. To a large extent, corrosion-related catastrophes can be avoided by having the ability to monitor corrosion before structural integrity is jeopardized. This paper critically reviews the various accustomed electrochemical techniques utilized for corrosion monitoring in terms of their definition, timeline, experimental set-up, advantages, and shortcomings. Additionally, literature exploiting these techniques as their corrosion detection technique has been focused on here. Furthermore, a comparison between recently reported methods has been made to provide better insights into the research progress in this arena.

Synthesis, experimental and computational studies on the anti-corrosion performance of substituted Schiff bases of 2-methoxybenzaldehyde for mild steel in HCl medium

Corrosion inhibition performance of two synthesized Schiff base ligands; (E)-2-((2-methoxybenzylidene)amino)phenol L1 and (E)-2-((4-methoxybenzylidene)amino)phenol L2 were carried out by weight loss measurement in 0.1 M hydrochloric acid (HCl) solution. Density Functional Theory (DFT) and Molecular dynamics (MD) simulation were applied to theoretically explain the inhibitors' intrinsic properties and adsorption mechanism in the corrosion study. The result of the inhibition performances carried out at varying concentrations and temperatures were compared. The corrosion inhibition efficiencies of L1 and L2 at an optimal concentration of 10 × 10^-4 M were 75% and 76%. Langmuir isotherm model fits the data obtained from the experiment with a correlation coefficient (R²) value closer to unity. The adsorption mechanism of inhibitor on the surface of the Fe metal occurred via chemisorption inferred from the Gibbs free energy (ΔG_ads). Scanning electron microscopy showed a mild degradation on the surface of the mild steel immersed in the L1, and L2 inhibited acid solution, which could be due to surface coverage. The energy dispersive X-ray spectroscopy showed the metal surface's elemental composition and the existence of the chlorine peak, which emanates from the HCl medium. DFT calculations revealed that the hybrid B3LYP functional performed better than the M06-2X meta-functional in estimating the energies of the synthesized Schiff bases for corrosion inhibition as seen in the lower ΔE values of 3.86 eV and 3.81 eV for L1 and L2. The MD simulation revealed that the orientation of inhibitors on the surface of the metal resulted in the coordination bond formation and that the interaction energy of L2 was -746.84 kJ/mol compared to -743.74 kJ/mol of L1. The DFT and MD results agreed with the observed trend of the experimental findings.

N-((1H-Pyrrol-2-yl)methylene)-6-methoxypyridin-3-amine and Its Co(II) and Cu(II) Complexes as Antimicrobial Agents: Chemical Preparation, In Vitro Antimicrobial Evaluation, In Silico Analysis and Computational and Theoretical Chemistry Investigations

Researchers are interested in Schiff bases and their metal complexes because they offer a wide range of applications. The chemistry of Schiff bases of heterocompounds has got a lot of attention because of the metal's ability to coordinate with Schiff base ligands. In the current study, a new bidentate Schiff base ligand, N-((1H-pyrrol-2-yl)methylene)-6-methoxypyridin-3-amine (MPM) has been synthesized by condensing 6-methoxypyridine-3-amine with pyrrole-2-carbaldehyde. Further, MPM is used to prepare Cu(II) and Co(II) metal complexes. Analytical and spectroscopic techniques are used for the structural elucidation of the synthesized compounds. Both MPM and its metal complexes were screened against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Klebsiella pneumoniae species for antimicrobial studies. Furthermore, these compounds were subjected to in silico studies against bacterial proteins to comprehend their best non-bonded interactions. The results confirmed that the Schiff base ligand show considerably higher binding affinity with good hydrogen bonding and hydrophobic interactions against various tested microbial species. These results were complemented with a report of the Conceptual DFT global reactivity descriptors of the studied compounds together with their biological scores and their ADMET computed parameters.

Synthesis of thiophene derivatives and their anti-microbial, antioxidant, anticorrosion and anticancer activity

Background

A new series of thiophene analogues was synthesized and checked for their in vitro antibacterial, antifungal, antioxidant, anticorrosion and anticancer activities.

Results

A series of ethyl-2-(substituted benzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate derivatives were synthesized by using Gewald synthesis and their structures were confirmed by FTIR, MS and ¹H-NMR. The synthesized compounds were further evaluated for their in vitro biological potentials i.e. antimicrobial activity against selected microbial species using tube dilution method, antiproliferative activity against human lung cancer cell line (A-549) by sulforhodamine B assay, antioxidant activity by using DPPH method and anticorrosion activity by gravimetric method.

Conclusion

Antimicrobial screening results showed that compound S ₁ was the most potent antibacterial agent against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhi having MIC value 0.81 µM/ml and compound S ₄ also displayed excellent antifungal activity against both Candida albicans and Aspergillus niger (MIC = 0.91 µM/ml) when compared with cefadroxil (antibacterial) and fluconazole (antifungal) as standard drug. The antioxidant screening results indicated that compound S ₄ and S ₆ exhibited excellent antioxidant activity with IC₅₀ values 48.45 and 45.33 respectively when compared with the ascorbic acid as standard drug. Anticorrosion screening results indicated that compound S ₇ showed more anticorrosion efficiency (97.90%) with low corrosion rate. Results of anticancer screening indicated that compound S ₈ showed effective cytotoxic activity against human lung cancer cell line (A-549) at dose of 10^-4 M when compared with adriamycin as standard.