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In this study, the adsorption of Cytisine derivatives as an eco-friendly inhibitor for mild steel corrosion [ 1 , 2 ] on the iron surface was modeled using density functional theory (DFT) calculations and the Monte Carlo (MC) as well as Molecular dynamics (MD) simulations to elucidate the interactions involved. Firstly, the interaction of these inhibitors with iron clusters Fen (n=1-5) was studied by DFT as a representative example of a corrosion inhibition process. Moreover, structures, binding energies, partial atomic charge NBO and natural bond orbital analysis of the resulting complexes support the existence of considerable binding between these inhibitors and Fen (n=1-5) clusters. Then, the dynamic Monte Carlo (MC) simulation was also adopted to simulate the adsorption of Cytisine derivatives on the iron Fe (111) surface in vacuum as well as in acidic solution containing 491 H2O, 4 hydronium ion H3O+ and 5 chlorine ion Cl−. Besides, to advance the understanding of interactions between these molecules and iron surface, the radial distribution function (RDF), mean square displacement (MSD) and fractional free volume (FFV) were also studied in this paper. Our results of both the Fen (n=1-4) clusters and the Fe (111) surface made it possible to show noticeable competitiveness between the three protonated inhibitors with a slight superiority for the n-CytN9H+ molecule. Furthermore, based on the diffusion coefficient we found that the three protonated inhibitors have a good capacity to slow down the movement of corrosive particles and consequently to inhibit the metallic substrate against corrosive electrolyte.

A new selective synthesis of novel quinoline carboxamides was developed by the N-alkylation reaction of methyl (2-oxo-1,2- dihydroquinolin-4-yl)-L-alaninate via phase transfer catalysis in a basic medium at room temperature. The compounds were obtained in excellent yields (70-90%) and characterized by H-1, (CNMR)-C-13 spectroscopy and mass spectra. In addition, theoretical studies at B3LYP/6-311G(d,p) level were carried out to explain the observed selectivity of the N-alkylation reaction of compound 2 . The biological activities of the synthesized compounds were studied using some bacterial and fungal strains. The results show that compounds 3h and 3i exhibit stronger antibacterial activity against Bacillus subtilis and Staphyloccocus aureus. Compound 3e showed high antifungal activity against Candida Albicans compared to other substituted quinoline carboxamides. Molecular docking and molecular dynamics studies were also carried out to investigate the binding affinities of some compounds with the target proteins, and the results were in good correlation with the experimental findings. (C) 2021 Elsevier B.V. All rights reserved.

In this study, different QSAR approaches based on the multiple linear regression (MLR), the kernel-based Partial Least-Square (kPLS) and Pharma-RQSAR models have been applied to investigate the relationship between chemical structure descriptors of thiadiazole derivatives and their anticorrosion activity. The screened classical descriptors were firstly used to establish the linear regression model. In addition, six binary fingerprints were successfully applied using the kernel-based Partial Least-Square (kPLS), with priority given to the atom-pair fingerprint model. The Pharma-RQSAR model was also used to analyze the role of the various substitutions in the common substructure. The atom-pair descriptors and Pharma-RQSAR models have the advantage of visualizing the contribution maps, suggesting the general substitution requirements of the thiadiazole derivatives as potential corrosion inhibitors.