Yasameen K. Al-Majedy

New Coumarin Derivative as an Eco-Friendly Inhibitor of Corrosion of Mild Steel in Acid Medium

The anticorrosion ability of a synthesized coumarin, namely 2-(coumarin-4-yloxy)acetohydrazide (EFCI), for mild steel (MS) in 1 M hydrochloric acid solution has been studied using a weight loss method. The effect of temperature on the corrosion rate was investigated, and some thermodynamic parameters were calculated. The results indicated that inhibition efficiencies were enhanced with an increase in concentration of inhibitor and decreased with a rise in temperature. The IE value reaches 94.7% at the highest used concentration of the new eco-friendly inhibitor. The adsorption of inhibitor on MS surface was found to obey a Langmuir adsorption isotherm. Scanning electron microscopy (SEM) was performed on inhibited and uninhibited mild steel samples to characterize the surface. The Density Function theory (DFT) was employed for quantum-chemical calculations such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy) and μ (dipole moment), and the obtained results were found to be consistent with the experimental findings. The synthesized inhibitor was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic studies.

Novel macromolecules derived from coumarin: synthesis and antioxidant activity

The rational design of 4-hydroxycoumarins with tailor-made antioxidant activities is required nowadays due to the wide variety of pharmacologically significant, structurally interesting of coumarins and researcher orientation toward green chemistry and natural products. A simple and unique coumarins have been achieved by reaction of 4-hydroxycoumarin with aromatic aldehyde accompanied with the creation of a macromolecules have 2-aminothiazolidin-4-one. The molecular structures of the compounds were characterized by the Fourier transformation infrared and Nuclear magnetic resonance spectroscopies, in addition to CHN analysis. The scavenging abilities of new compounds against stable DPPH radical (DPPH•) and hydrogen peroxide were done and the results show that the compounds exhibited high antioxidant activates.

Hydrogen Peroxide Scavenging Activity of Novel Coumarins Synthesized Using Different Approaches.

New derivatives of 7-hydroxy-4-methylcoumarin were synthesized using a chemical method and a microwave-assisted method to compare the feasibility, reaction times, and yields of the product. The newly synthesized coumarins were characterized by different spectroscopic techniques (FT-IR and NMR) and micro-elemental analysis (CHNS). In vitro antioxidant activities of these compounds were evaluated against hydrogen peroxide and were compared with standard natural antioxidant, vitamin C. Our results reveal that these compounds exhibit excellent radical scavenging activities.

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.

Synthesis and Characterization of Some New 4-Hydroxy-coumarin Derivatives

Some novel coumarins were synthesized starting from 4-hydroxycoumarin and methyl bromoacetate. The structures of the newly obtained compounds were confirmed by elemental analysis, mass, IR and NMR spectra.

Synthesis of new coumarins complemented by quantum chemical studies

New coumarins, namely (E)-N′-(2-methylbenzylidene)-2-((2-oxo-2H-chromen-4-yl)oxy)acetohydrazide 4, N-(4-oxo-2-(o-tolyl)thiazolidin-3-yl)-2-((2-oxo-2H-chromen-4-yl)oxy)acetamide 5, and N-(4,7-dioxo-2-(o-tolyl)-1,3-oxazepin-3(2H,4H,7H)-yl)-2-((2-oxo-2H-chromen-4-yl)oxy)acetamide 6, were synthesized starting from 4-hydroxycoumarin and methyl bromoacetate. They were characterized by different spectroscopic techniques (FT-IR and NMR) and micro-elemental analysis (CHNS). Density Functional Theory calculations of the synthesized coumarins were performed using molecular structures with optimized geometries. Molecular orbital calculations have provided detail description of the orbitals, including spatial characteristics, nodal patterns, and the contributions of individual atoms.

Antioxidant Activities of 4-Methylumbelliferone Derivatives.

The synthesis of derivatives of 4-Methylumbelliferone (4-MUs), which are structurally interesting antioxidants, was performed in this study. The modification of 4-Methylumbelliferone (4-MU) by different reaction steps was performed to yield the target compounds, the 4-MUs. The 4-MUs were characterized by different spectroscopic techniques (Fourier transform infrared; FT-IR and Nuclear magnetic resonance; NMR) and micro-elemental analysis (CHNS). The in vitro antioxidant activity of the 4-MUs was evaluated in terms of their free radical scavenging activities against 2,2-diphenyl-1-picrylhydrazyl (DPPH), Nitric oxide radical scavenging activity assay, chelating activity and their (FRAP) ferric-reducing antioxidant power, which were compared with a standard antioxidant. Our results reveal that the 4-MUs exhibit excellent radical scavenging activities. The antioxidant mechanisms of the 4-MUs were also studied. Density Function Theory (DFT)-based quantum chemical studies were performed with the basis set at 3-21G. Molecular models of the synthesized compounds were studied to understand the antioxidant activity. The electron levels, namely HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), for these synthesized antioxidants were also studied.

Synthesis and Characterization of New 1,2-Dihydropyridine-3-Carbonitrile Compounds with Study of Expected Biological Activity

New 1,2-dihydropyridine-3-carbonitrile derivative compounds (3,4) were synthesized by cyclization of ketones (compound (1) and compound (2)) with appropriate aldehydes (4-N, Ndimethylaminobenzaldehyde and 4-chloro-2-oxo-2H-chromene-3-carbaldehyde) in presence of ethyl cyano acetate and ammonium acetate. The new synthesized compounds have been characterized using Melting point, FT-IR spectroscopy and 1 H-NMR and 13 C-NMR spectrum. The evaluation of biological activity of some synthesized compounds (1-4) with different concentration 10 mg mL −1 , 1 mg mL −1 and 0.1 mg mL −1 , against two types of bacteria on gram positive bacterial Staphylococcus aureus, Streptococcus pyogenus and gram nagetive bacterial Escherichia coli, Klebsiella pneumniae. [DOI: 10.22401/JNUS.21.2.07]

Efficient Catalyst One-Pot Synthesis of 7-(Aryl)-10,10-dimethyl-10,11-dihydrochromeno[4,3-b]chromene-6,8(7H,9H)-dione Derivatives Complemented by Antibacterial Activity

The problem of bacteria resistance to many known agents has inspired scientists and researchers to discover novel efficient antibacterial drugs. Three rapid, clean, and highly efficient methods were developed for one-pot synthesis of 7-(aryl)-10,10-dimethyl-10,11-dihydrochromeno[4,3-b]chromene-6,8(7H,9H)-dione derivatives. Three components are condensed in the synthesis, 4-hydroxycoumarin, 5,5-dimethyl-1,3-cyclohexanedione, and aromatic aldehydes, using tetrabutylammonium bromide (TBAB), diammonium hydrogen phosphate (DAHP), or ferric chloride (FeCl3), respectively. Each method has different reaction mechanisms according to the catalyst. The present methods have advantages, including one-pot synthesis, excellent yields, short reaction times, and easy isolation of product. All catalysts utilized in our study could be reused several times without losing their catalytic efficiency. All synthesized compounds were fully characterized and evaluated for their antibacterial activity.