Adsorption and Quantum Chemical Studies on the Inhibition Potentials of Some Thiosemicarbazides for the Corrosion of Mild Steel in Acidic Medium

Zaid

et al. 2014

J. Electrochem. Soc.

The electrochemical response of two biologically important phenazine derivatives was examined by using cyclic, differential pulse and square wave voltammetry in a wide pH range of 2.0 -12.0. Cyclic voltammetry was employed for the determination of heterogeneous electron transfer rate constant and diffusion coefficient of the analytes. The value of electron transfer rate constant was used for evaluation of Gibbs free energy, enthalpy and entropy changes of redox reactions of the compounds. Differential pulse voltammetry was used for the determination of number of protons and electrons involved in the redox processes. Limits of detection and quantification were assessed by square wave voltammetry. The detailed pH dependent redox mechanisms of the compounds were proposed on the basis of experimental results which were further supported by theoretical calculations. These redox mechanistic pathways are expected to play a key role in understanding the necessary aspects of structure-activity relationships and exploring the hidden routes by which this class of compounds exert its biochemical actions. Phenazines have broad range applications in biology and chemistry.1 This class constitutes a large group of nitrogen containing heterocyclic compounds, the members of which differ in their chemical and physical properties on the basis of type and position of functional groups present. Naturally, phenazines are produced by limited genera of bacteria including Pseudomonas, Burkholderia and Brevibacterium.2 Starting from different parent materials, phenazines can be synthesized by various reactions including oxidative condensation, electrochemical reduction, reductive cyclization and photochemical reactions.From the last 50 years, phenazines are the subject of extensive research investigations because of their broad range applications in pharmaceutical and clinical research.3 Such compounds have been reported for their wide variety of biological activities such as antitumor, anti-parasitic and antibiotic activities. Benzo [a] phenazine acts as efficient DNA intercalating ligand with antitumor activity in leukaemia and solid tumors. 4 1-Hydroxyphenazine has been reported to have promising antifungal activity against various microbes such as aspergillus fumigatus and candida albicans.5 Macrolactone synthesized from benzo [a] phenazine shows good activity against mycobacterium tuberculosis. 6 In general, natural and synthetic phenazines find useful applications against malaria 7 and hepatitis C viral replication. 8The biological activity of phenazines is due to their redox reactions leading to the formation of toxic radicals. 9 Different functional groups attached to phenazine determine their redox potential and solubility. The redox behavior and concomitant modulation of biological activities of phenazines by changing the nature and position of substituents attached to their aromatic rings have been reported by several research groups.10-12 Phenazines can alter cellular redox states and act as transporters of electrons to altern...

Section: Differential Pulse Voltammetry (Dpv)-mentioning

confidence: 99%

pH Dependent Electrochemical Characterization, Computational Studies and Evaluation of Thermodynamic, Kinetic and Analytical Parameters of Two Phenazines

Zaid

et al. 2014

J. Electrochem. Soc.

“…The 1, 3-dipolar cycloaddition is a chemical reaction between two organic compounds, a dipolarophile and a 1, 3-dipole which combine to form five-membered heterocycles containing multiple stereogenic centers. In our research on 5-Chloroisatin and its derivatives [9][10][11][12], we have found it useful to use these compounds as precursors for the synthesis of various heterocyclic systems capable of exhibiting pharmacological properties. For our part, we used 1-propargyl-5-chloro-indole-2, 3-dione, which can be employed with dipoles (three azides) in the synthesis of many natural and pharmaceutical products [13].…”

Section: Introductionmentioning

confidence: 99%

DFT Study and Synthesis of New 1, 2, 3-triazoles Obtained by 1, 3-Dipolar Cycloaddition Derived from 5-chloro-1-(prop-2-yn-1-yl)indoline-2, 3-dione

2017

IJSR

Abstract:We report in this paper the reaction of 1, 3-Dipolar Cycloaddition between azides and 5-chloro-1-(prop-2-yn-1-yl)indoline-2, 3-dione in order to synthesize new cycloadducts. The configuration of the products obtained was determined by the magnetic resonance of the proton and carbon. A theoretical study was also carried out, based on the DFT-B3LYP calculation method. The results are in agreement with experimental regiochemistry.

“…The distances of separation as shown in Table 2 are 3.394 Å for HDM and 3.336 for HDE. This suggests ineffective overlap of orbitals thus weak interaction between the orbitals giving rise to bonds with relatively low energy which is possible when the molecules are physically adsorbed unto the metal surface (Oliver et al 1979, Ebenso et al 2010, Bouayed et al 1998, Gece 2008, Obot and Obi-Egbedi 2010. Geometry optimized structures, equilibrium geometry structures and energies of HDM and HDE Fig 2 shows the optimized geometry and equilibrium structures of HDM and HDE.…”

Section: Interaction/binding Energymentioning

confidence: 99%

Molecular dynamics simulations and quantum chemical calculations for the adsorption of some imidazoline derivatives on iron surface

Uwakwe¹,

Okafor²,

Obike³

et al. 2017

Glo Jnl Pure Appl Sci

The molecular dynamic (MD) simulation and quantum chemical calculations for the adsorption of [2-(2-Henicos-10-enyl-4,5-dihydro-imidazol-1-yl)-ethyl]-methylamine (HDM) and 2-(2-Henicos-10-enyl-4,5-dihydro-imidazol-1-yl)-ethanol (HDE) on iron surface was studied using Materials Studio software. Molecular dynamic simulation results indicate that the imidazoline derivative molecules uses the imidazoline ring to effectively adsorb on the surface of iron, with the alkyl hydrophobic tail forming an n shape (canopy like covering) at geometry optimization and at 353 K. The n shape canopy like covering to a large extent may prevent water from coming in close contact with the Fe surface. The quantum chemical calculation based on the natural atomic charge, the frontier molecular orbital and the Fukui indices values and plots shows the active sites of the molecules to be mainly the N=C-N region in the imidazoline ring, others include the nitrogen and oxygen heteroatoms in the pendant part and the double bonded carbon atoms in the hydrophobic tail of the imidazoline derivative molecules. The quantum chemical calculations also reveal that the amine group in HDM and the hydroxyl group in HDE which is attached to the imidazoline ring do not result in a significant increase in the HOMO nor the LUMO density which can aid adsorption.HDM has a lower energy gap of 4.434 eV and 3.824 eV, a higher E HOMO of -4.273 eV and -4.152 eV and a higher global softness of 0.45 and 0.52 compared to HDE which have an energy gap of 4.476 eV and 4.084 eV, a E HOMO of -4.349 eV and -4.607 eV and a global softness of 0.45 and 0.49 at geometry optimization and at 353 K. The adsorption ability of the molecule is given as at geometry optimization HDM > HDE and at 353 K HDM > HDE. Theoretically HDM is a better inhibitor than HDE. The adsorption ability of the molecule is in line with the binding energy at the temperature studied.