Coumarins as Potential Antioxidant Agents Complemented with Suggested Mechanisms and Approved by Molecular Modeling Studies

Syntheses of coumarins, which are a structurally interesting antioxidant activity, was done in this article. The modification of 7-hydroxycoumarin by different reaction steps was done to yield target compounds. Molecular structures were characterized by different spectroscopical techniques (Fourier transformation infrared and nuclear magnetic resonance). Antioxidant activities were performed by using various in vitro spectrophometric assays against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydrogen peroxide (H2O2). All compounds exhibited high efficiency as antioxidants compared to ascorbic acid. The highest efficiency scavenging activity was found for compound 3 (91.0 ± 5.0), followed by compounds 2 and 4 (88.0 ± 2.00; and 87.0 ± 3.00). Ascorbic acid C was used as a standard drug with a percentage inhibition of 91.00 ± 1.5. The mechanism of the synthesized compounds as antioxidants was also studied. Hartree–Fock–based quantum chemical studies have been carried out with the basis set to 3-21G, in order to obtain information about the three-dimensional (3D) geometries, electronic structure, molecular modeling, and electronic levels, namely HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), to understand the antioxidant activity for the synthesized compounds

Experimental studies on inhibition of mild steel corrosion by novel synthesized inhibitor complemented with quantum chemical calculations

One of best method, which was used to prevent the mild steel from corrosion, was through employed natural or synthetic organic chemical compounds. Here in, we displayed a Schiff base derivative which has nitrogen, oxygen and sulfur atoms as corrosion inhibitor for MS “mild steel” in 1 M HCl “hydrochloric acid” solution. Synthesized inhibitor was characterized by using of FT-IR “Fourier transform infrared” and NMR “Nuclear magnetic resonance” spectroscopies in addition to CHN analysis technique. The weight loss and SEM “Scanning electron microscope” studies showed that inhibitor have the ability to prevent the alloy surface from corrosive solution by adsorbing on MS surface to form stable adsorbed layer that results in the higher inhibition efficiency. The inhibition influence of the synthesized inhibitor was increased parallel with increasing concentration and decrease with rising temperature degrees. Furthermore, DFT “Density function theory” has been employed to calculate quantum chemical parameters “Energy, highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and electronegativity (χ)” which performed on synthesized corrosion inhibitor to determine the relationship between the structure of synthesized inhibitor molecule and inhibition performance. Keywords: Corrosion, Inhibitor, Mild steel, FT-I

Experimental and quantum chemical simulations on the corrosion inhibition of mild steel by 3-((5-(3,5-dinitrophenyl)-1,3,4-thiadiazol-2-yl)imino)indolin-2-one

Iraq has been one of the most extensive oil and natural gas industries in the world. The corrosion of mild steel is costly and insufficiency process. It is responsible for great loss in manufacture and environment. Natural and organic inhibitors have been utilized for a long time to inhibit the corrosion. Selected thiadiazol derivative, namely 3-((5-(3,5-dinitrophenyl)-1,3,4-thiadiazol-2-yl)imino)indolin-2-one (TDIO) was investigated for it inhibitive impacts in 1 M HCl medium on corrosion of mild steel using weight loss and scanning electron microscope techniques. The maximum inhibition efficiency up to 90.7% at the maximum inhibitor concentration 0.5 mM. Surface morphology of results demonstrated that TDIO formed adsorbed film on surface of mild steel in hydrochloric acid solution. Give molecular based clarifications to the inhibitive impacts of the studied. The interactions between mild steel surface and the inhibitor molecules have been undertaken to further corroborate the methodological results. Keywords: Dinitrophenyl, Indolin, Morphology, Corrosion inhibito