Publications Internationales
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Item Theoretical investigation of the self-association of antitumor drug imexon(Springer, 2020) Guemmour, Hind; Kheffache, DjaffarThe dimers resulting from self-association of oxo-imino, oxo-amino, and hydroxyl-imino tautomers of imexon, that present two hydrogen bonds, were fully optimized with the density functional methods B3LYP, M06-2X in conjunction with 6-311++G(d,p) basis set. Additionally, second-order Møller-Plesset (MP2) level in combination with 6-311++G(d,p) basis set was employed for comparison purpose. The thermodynamic stability of the self assembled structures in gaseous phase has been obtained according to the analyses of total electronic energies and hydrogen bonding interactions. The bulk water environment has been simulated using the universal solvation model based on solute electron density (SMD). Stability and structure of homochiral and heterochiral imexon dimers resulting from the three imexon tautomers have been carried out to investigate the chiral discrimination. The imexon dimer with heterochiral configuration resulting from self-assembling oxo-amino tautomer is found to be thermodynamically most stable in both gas and aqueous phases. The interaction energies for these self assembled structures were further evaluated with the basis set superposition error corrections. The so-called seven-point interaction energy which includes corrections for BSSE and deformation was calculated. The intermolecular interactions of the selected dimers have been analyzed by calculation of electron density (ρ) and Laplacian (∇2ρ) at the bond critical points (BCPs) using atoms-in-molecule (AIM) theory.Item A computational study of the main degradation product of antitumor drug imexon(World Scientific Publishing Co. Pte Ltd, 2017) Kheffache, Djaffar; Ouamerali, OuridaWe theoretically study, from the thermodynamic point of view, the possibility of the two degradation pathways of antitumor drug of imexon. According to the theoretical results obtained at DFT level in both gas and aqueous phases, the two degradation pathways of imexon are characterized by negative reaction Gibbs free energies. It has been found that 4-imino-5-methylene-imidazolidin-2-one is the favored degradation product of imexon. Herein, the focus of this work has been on calculating the geometries, relative energies and electronic properties of all possible prototropic tautomers of 4-imino-5-methylene-imidazolidin-2-one using the DFT and MP2 levels. The bulk water environment has been simulated by continuum model using Solvation Model based on Density (SMD). The UV spectra of two dominant tautomers of 4-imino-5-methylene-imidazolidin-2-one are also predicted using time-dependent density functional theory and the results are compared with the available experimental data. The comparison of the simulated and the experimental absorption spectra has allowed us to accurately characterize the predominant tautomer of the degradation product in aqueous mediumItem What is the real existing form of imexon? - Quantum chemical studies(Elsevier, 2010) Kheffache, Djaffar; Ouamerali, O.