Fodil Hamzaoui

Theoretical and Experimental Electrostatic Potential around the m-Nitrophenol Molecule

This work concerns a comparison of experimental and theoretical results of the electron charge density distribution and the electrostatic potential around the m-nitrophenol molecule (m-NPH) known for its interesting physical characteristics. The molecular experimental results have been obtained from a high-resolution X-ray diffraction study. Theoretical investigations were performed using the Density Functional Theory at B3LYP level of theory at 6-31G* in the Gaussian program. The multipolar model of Hansen and Coppens was used for the experimental electron charge density distribution around the molecule, while we used the DFT methods for the theoretical calculations. The electron charge density obtained in both methods allowed us to find out different molecular properties such us the electrostatic potential and the dipole moment, which were finally subject to a comparison leading to a good match obtained between both methods. The intramolecular charge transfer has also been confirmed by an HOMO-LUMO analysis.

Crystal structure of (2Z,5Z)-3-(4-meth­oxy­phen­yl)-2-[(4-meth­oxy­phenyl)­imino]-5-[(E)-3-(2-nitro­phen­yl)allyl­idene]-1,3-thia­zolidin-4-one

The thiazole ring of the title compound is twisted with respect to the three benzene rings, making dihedral angles of 25.52 (12), 85.77 (12) and 81.85 (13)°.

Electron Charge Density Distribution from X-Ray Diffraction Study of the 4-Methoxybenzenecarbothioamide Compound

The molecular electron charge density distribution of the title compound is described accurately using the multipolar model of Hansen and Coppens. The net atomic charge and the in-crystal molecular dipole moment have been determined in order to understand the nature of inter- and intramolecular charge transfer. The study reveals the nature of intermolecular interactions including charge transfer and hydrogen bonds in the title compound. In this crystal, the molecules form dimers via N–HS intermolecular hydrogen bonds. The dimers are further linked by C–HO hydrogen bonds into chains along the c crystallographic axis. This study has also allowed us to determine the electrostatic potential and therefore locate the electropositive part and the electronegative part in molecular scale of the title compound.

Crystal structure and Hirshfeld surface analysis of ethyl 2-{[4-ethyl-5-(quinolin-8-yloxymeth­yl)-4H-1,2,4-triazol-3-yl]sulfan­yl}acetate

In the title compound, the 1,2,4-triazole ring is twisted with respect to the mean plane of quinoline moiety at 65.24 (4)°. In the crystal, molecules are linked by weak C—H⋯O and C—H⋯N hydrogen bonds.

Determination of electrostatic parameters of a coumarin derivative compound C_（17）H_（13）NO_3 by x-ray and density functional theory

This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7-(salicylidene amino) coumarin(C17H13NC3) using high resolution x-ray diffraction data. The experimental results are compared with those obtained theoretically from calculation type ab initio. The experimental investigation is carried out using the molecular electron charge density distribution based on the multipolar model of Hansen and Coppens. However the theoretical calculations are conducted by using the molecular orbital B3 LYP method and the Hartree–Fock(HF) approximation with the basis set 6-31G(d,p) implemented in the Gaussian program. In addition to the structural analysis,the thermal agitation is also analyzed in terms of rigid blocks to ensure a better precision of the results. Subsequently, the electrostatic atomic and molecular properties such as the net charges, the molecular dipolar moment to highlight the nature of charge transfer existing within the molecule studied are derived. Moreover, the obtained electrostatic potential enables the localization of the electropositive and the electronegative parts of the investigated molecule. The present work reports in detail the obtained electrostatic properties of this biologically important molecule.

Structural and electron charge density studies of a nonlinear optical compound 4,4 di-methyl amino cyano biphenyl

The 4,4 dimethyl amino cyano biphenyl crystal (DMACB) is characterized by its nonlinear activity. The intra molecular charge transfer of this molecule results mainly from the electronic transmission of the electro-acceptor (cyano) and electro-donor (di-methyl-amino) groups. An accurate electron density distribution around the molecule has been calculated based on a high-resolution X-ray diffraction study. The data were collected at 123 K using graphite-monochromated Mo K α radiation to sin(β)/λ = 1.24 A−1. The integrated intensities of 13796 reflections were measured and reduced to 6501 independent reflections with I ≥ 3σ(I). The crystal structure was refined using the experimental model of Hansen and Coppens (1978). The crystal structure has been validated and deposited at the Cambridge Crystallographic Data Centre with the deposition number CCDC 876507. In this article, we present the thermal motion and the structural analysis obtained from the least-square refinement based on F2 and the electron density distribution obtained from the multipolar model.

Crystal and mol­ecular structure of (2Z,5Z)-3-(2-meth­oxy­phen­yl)-2-[(2-meth­oxy­phen­yl)imino]-5-(4-nitro­benzyl­idene)thia­zolidin-4-one

In the title molecule, both methoxyphenyl groups are nearly perpendicular to the thiazole ring and are nearly perpendicular to each other. In the crystal, a series of C—H⋯N, C—H⋯O and C—H⋯S hydrogen bonds, augmented by several C—H⋯π(ring) interactions, produce a three-dimensional architecture of molecules stacked along the b-axis direction.

Molecular structure investigation by ab initio, DFT and X-ray diffraction of thiazole-derived compound

We report here the synthesis of Z-3-(2-Ethoxyphenyl)-2-(2-Ethoxyphenyl)-1,3-Thiazolidin-4-one compound. The crystal structure has been determined by X-ray diffraction. The compound crystallizes in the monoclinic system with space group P21/n and cell parameters: a = 9.4094(10), b = 9.3066(10), c = 20.960(2) Å, β=99.0375(10)°, V = 1812.7(3)Å3 and Z = 4. The structure has been refined to a final R = 0.05 for 2083 observed reflections. The refined structure was found to be significantly non planar. The molecule exhibits intermolecular hydrogen bond of type C–H...O, C–H...N and C–H...S. Ab initio calculations were also performed at Hartree– Fock and density functional theory levels. The full HF and DFT geometry optimization was carried out using 6-31G(d,p) basis set. The observed molecular structure is compared with that calculated by both HF and density functional theory methods. The optimized geometry of the title compound was found to be consistent structure determined by X-ray diffraction.

Theoretical and X-ray diffraction studies of organic photovoltaic compounds

The electronic and structural properties of thiazolic ring derivatives were studied using density functional theory (DFT) and X-ray diffraction in terms of their application as organic semiconductor materials in photovoltaic devices. The B3LYP hybrid functional in combination with Pople type 6-31G(d) basis set with a polarization function was used in order to determine the optimized geometries and the electronic properties of the ground state, while transition energies and excited state properties w re obtained from DFT with B3LYP/6-31G(d) calculation. The i vestigation of thiazolic derivatives formed by th arrang ment of several monomeric units revealed that three-dimensional (3D) conjugated architectures present the best geometric and electronic characteristics for use as an organic semiconductor material. The highest occupied molecular orbital (HOMO) . lowest unoccupied molecular orbital (LUMO) energy gap was reased in 3D structur s that ex e d the abso ption sp ctrum toward longer wav lengths, revealing a feasible intramolecular charge transfer process in these systems. All calculations in this work were performed using the Gaussian 03 W software package. Compound I Compound II Compound III Key words : Structure, Thiazole, HOMO, LUMO, dipole moment References 1. N. Benhalima, K. Toubal, A. Chouaih, G. Chita, S. Maggi, A. Djafri, F. Hamzaoui, Journal of Chemical Crystallography, November 2011, Volume 41, Issue 11, pp 1729-1736 2. Shokol TV, Gorbulenko NV, Turov AV, Khilya VP (2013) Chemistry of Heterocyclic Compounds, Vol. 49, No. 2:325 Keywords: Structure, Thiazole, Dipole moment