Mohammed Bouachrine

Quantum Chemical Studies on the Inhibiting Effect of Bipyrazoles on Steel Corrosion in HCl

Correlation of the efficacy of some bipyrazoles, N,N-bis(3,5-dimethyl-pyrazol-1-ylmethyl)-cyclohexylamine (Bip 1), N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)-ethanolamine (Bip 2), N,N-bis(3,5-dimethylpyrazol-1-ylmethyl) allylamine (Bip 3) and N,N-bis(3-carboethoxy-5-methylpyrazol-1-ylmethyl)-cyclohexylamine (Bip 4), against the corrosion of mild steel in HCl is discussed using density functional approach B3LYP/6-31G(d) calculations. The bipyrazole inhibitors exhibited the highest inhibition efficiency. The quantum chemical parameters calculated are, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the gap energy (ΔE), the dipole moment (μ), the softness (σ) and the total energy (TE).

Theoretical approach to the corrosion inhibition efficiency of some quinoxaline derivatives of steel in acid media using the DFT method

Corrosion inhibition efficiencies of 1,4-dihydroquinoxaline-2,3-dione (Q1) and 2-phenylthieno[2,3-b]quinoxaline (Q2) as corrosion inhibitors against the corrosion of steel surface in hydrochloric acid is studied by means of density functional approach B3LYP/6-31G calculations. Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), dipole moment (μ), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ionization potential (I), the fraction of electrons transferred (∆N), the global electrophilicity ω, and the total energy were calculated. All calculations have been performed by considering density functional theory using the GAUSSIAN03W suite of programs.

QSAR analysis of the toxicity of phenols and thiophenols using MLR and ANN

Abstract This study gives a quantitative structure–activity relationship (QSAR) analysis of toxicity of phenols and thiophenols to Photobacterium phosphoreum, which is an important indicator for water quality. The chemical structures of 51 phenols and thiophenols have been characterized by electronic and physic-chemical descriptors. The present study was performed using principal components analysis (PCA), multiple regression analysis (MLR) and artificial neural network (ANN). The quantitative model was accordingly proposed and the toxicity of the compounds was interpreted based on the multivariate statistical analysis.

DFT and TD-DFT calculation of new thienopyrazine-based small molecules for organic solar cells

BackgroundNovel six organic donor-π-acceptor molecules (D-π-A) used for Bulk Heterojunction organic solar cells (BHJ), based on thienopyrazine were studied by density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches, to shed light on how the π-conjugation order influence the performance of the solar cells. The electron acceptor group was 2-cyanoacrylic for all compounds, whereas the electron donor unit was varied and the influence was investigated.MethodsThe TD-DFT method, combined with a hybrid exchange-correlation functional using the Coulomb-attenuating method (CAM-B3LYP) in conjunction with a polarizable continuum model of salvation (PCM) together with a 6-31G(d,p) basis set, was used to predict the excitation energies, the absorption and the emission spectra of all molecules.ResultsThe trend of the calculated HOMO–LUMO gaps nicely compares with the spectral data. In addition, the estimated values of the open-circuit photovoltage (Voc) for these compounds were presented in two cases/PC60BM and/PC71BM.ConclusionThe study of structural, electronics and optical properties for these compounds could help to design more efficient functional photovoltaic organic materials.

Theoretical study using DFT calculations on inhibitory action of four pyridazines on corrosion of copper in nitric acid

In this part 3, The inhibitive effect of four substituted pyridazines, 5-[hydroxy(phenyl)methyl]-6-methylpyridazin-3(2H)-one (P1), 4-(2-chlorobenzyl)-6-hydrazino-3-methyl-1,6-dihydro pyridazine (P2), 5-(2,6-dichlorobenzyl)-6-methylpyridazin-3(2H)-one (P3) and 5-[(2-chlorophenyl) (hydroxy)methyl]-6-methyl pyridazin-3(2H)-one (P4) against the copper corrosion in nitric acid solution is investigated using density functional approach B3LYP/6-31G* calculations. Results obtained by weight loss and polarization measurements in part 1 show that P1, P3, and P4 are the best inhibitors. The kinetic and adsorption parameters obtained in part 2 indicated that pyridazine acted preferentially by physical adsorption. The calculated quantum chemical parameters are the highest occupied molecular orbital, the lowest unoccupied molecular orbital, the separation energy, dipole moment, electronegativity, electron affinity, global hardness, softness, ionization potential, the fraction of electrons transferred, and the total energy. The obtained data are discussed according to the inhibition efficiencies obtained.

The optoelectronic properties of organic materials based on triphenylamine that are relevant to organic solar photovoltaic cells

In this paper, six symmetrical compounds with a donor–acceptor–donor (D–A–D) structure based on triphenylamine as a core and bridged with various spacer fragments with electron-acceptor character, such as quinoxaline, phenazine, benzo[g]quinoxaline, benzo[b]phenazine, thieno[3,4-b]pyrazine and thieno[3,4-b]quinoxaline, have been studied theoretically using two quantum methods, DFT and TD-DFT, together by considering their use in organic BHJ solar cells as potential donors of electron. Intramolecular charge transfer (ICT) interactions have been found for all of the compounds due to the electron withdrawing properties caused by the two imine nitrogen atoms in the pyrazine and the electron-donating properties of the other two amine nitrogen atoms in the two triphenylamines that compose the bridge. The ICT interactions are strengthened when the benzene or thiophene ring are fused on the pyrazine acceptor unit, which leads to a bathochromic shift of the ICT band. Moreover, our quantum calculations show that thiophene is a more appropriate ring than the benzene ring for enlarging the ICT interactions and expanding the absorption spectrum. We remark also that when a thiophene ring is fused on the quinoxaline unit in the D6 compound, a significant shift towards the near-infrared is realized, and it exhibits a maximum absorption wavelength at 690 nm compared to the other studied compounds with a threshold that is over 800 nm. This is attributed to the enhanced charge density on the acceptor spacer and narrow band gap of this compound, as revealed by our theoretical calculations. Finally, these results show that extending the conjugation of a compound based on pyrazine as an acceptor in a D–A–D structured compound can be realized by incorporating the thiophene unit in the bridge and then strengthening the ICT interactions.

3D QSAR studies, molecular docking and ADMET evaluation, using thiazolidine derivatives as template to obtain new inhibitors of PIM1 kinase

Proviral Integration site for Moloney murine leukemia virus-1 (PIM1) belongs to the serine/threonine kinase family of Ca2+-calmodulin-dependent protein kinase (CAMK) group, which is involved in cell survival and proliferation as well as a number of other signal transduction pathways. Thus, PIM1 is regarded as a promising target for treatment of cancers. In the present paper, a three-dimensional quantitative structure activity relationship (3D-QSAR) and molecular docking were performed to investigate the binding between PIM1 and thiazolidine inhibitors in order to design potent inhibitors. The comparative molecular similarity indices analysis (CoMSIA) was developed using twenty-six molecules having pIC50 ranging from 8.854 to 6.011 (IC50 in nM). The best CoMSIA model gave significant statistical quality. The determination coefficient (R2) and Leave-One-Out cross-validation coefficient (Q2) are 0.85 and 0.58, respectively. Furthermore, the predictive ability of this model was evaluated by external validation((n = 11, R2test = 0.72, and MAE = 0.170 log units). The graphical contour maps could provide structural features to improve inhibitory activity. Furthermore, a good consistency between contour maps and molecular docking strongly demonstrates that the molecular modeling is reliable. Based on these satisfactory results, we designed several new potent PIM1 inhibitors and their inhibitory activities were predicted by the molecular models. Additionally, those newly designed inhibitors, showed promising results in the preliminary in silico ADMET evaluations, compared to the best inhibitor from the studied dataset. The results expand our understanding of thiazolidines as inhibitors of PIM1 and could be of great help in lead optimization for early drug discovery of highly potent inhibitors.

Opto-electronic properties and molecular design of new materials based on pyrrole studied by DFT

In this work, we investigate oligopyrroles and derivatives, which serve as models for corresponding polymers. In order to discuss these materials, we carried out DFT calculations and used DFT methods to calculate ground state electronic structures. We are particularly interested in exploring the potential of several substituent groups as electron donors with numerous ties to electronic materials by exploring and comparing the energies of HOMO, LUMO, Gap energies, and structural properties. Results are discussed in comparison with the properties of the doped oligomers. The theoretical ground-state geometry and electronic structure of the studied molecules were obtained by the DFT method at B3LYP level with 6-31G(d) basis set. The opto-electronic properties of these materials were determined by ZINDO/s and TD//B3LYP/6-31G(d) calculations performed on the B3LYP/6-31(d) optimized geometries. The results of this study demonstrate how electronic properties can be tuned by the backbone ring or side group and suggest these compounds as good candidates for opto-electronic applications.

Furanone derivatives as new inhibitors of CDC7 kinase: development of structure activity relationship model using 3D QSAR, molecular docking, and in silico ADMET

Cell division cycle 7 (CDC7) is a serine/threonine kinase, which plays a vital role in the replication initiation of DNA synthesis. Overexpression of the CDC7 in various tumor growths and in cell proliferation makes it a promising target for treatment of cancers. To investigate the binding between the CDC7 and furanone inhibitors, and in order to design highly potent inhibitors, a three-dimensional quantitative structure activity relationship (3D-QSAR) with molecular docking was performed. The optimum CoMSIA model showed significant statistical quality on all validation methods with a determination coefficient (R2 = 0.945), bootstrapping R2 mean (BS-R2 = 0.960), and leave-one-out cross-validation (Q2) coefficient of 0.545. The predictability of this model was evaluated by external validation using a test set of nine compounds with a predicted determination coefficient R2test of 0.96, besides the mean absolute error (MAE) of the test set was 0.258 log units. The extracted contour maps were used to identify the important regions, where the modification was necessary to design a new molecule with improved activity. Furthermore, a good consistency between the molecular docking and contour maps strongly demonstrates that the molecular modeling is reliable. Based on those obtained results, we designed several new potent CDC7 inhibitors, and their inhibitory activities were validated by the molecular models. Additionally, those newly designed inhibitors showed promising results in the preliminary in silico ADMET evaluations.

The bridged effect on the geometric, optoelectronic and charge transfer properties of the triphenylamine–bithiophene-based dyes: a DFT study

The dye-sensitized solar cells containing a triphenylamine unit as the electron donor connected with a terminal cyanoacrylic acid electron acceptor by 2,2′-bithiophene as π-bridged (D-π-A) has been investigated by density functional theory (DFT) at the B3LYP/6-31G(d) level to shed light on the bridged effect on geometric and electronic properties of the designed dyes. Also, time-dependent DFT (TD-DFT) at a TD-BH and H/6-31+G(d)//BH and H/6-31G(d) level of theory was selected to modulate the electronic absorption spectra and charge-transfer properties of studied dyes. The calculated results show that the strong electron-withdrawing groups bridged the 2,2′-bithiophene efficiently, reduce the energy gaps and provide a red shift of the absorption spectra. The calculated absorption spectra in tetrahydrofuran (THF) are in good agreement with available experimental value for dye D1. Generally, the fundamental parameters, such as vertical and adiabatic ionization potentials (IPa/IPv), vertical and adiabatic electron affinities (EAa/EAv), electron extraction potentials and hole extraction potentials, including hole/electron reorganization energies (λ+/λ−), of studied dyes have been discussed. The improved electronic coupling constant (