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Benghodbane S.,Annaba University | Khatmi D.,Guelmas University
Journal of Inclusion Phenomena and Macrocyclic Chemistry | Year: 2013

A computational study of inclusion complexes of 2-methyl-βCD with Doxycycline tautomeric (enol and keto form) has been performed with several combinations of ONIOM hybrid calculations. The reliability of the ONIOM2 calculations at the integrated level, ONIOM2 (M05-2X/6-31G(d): M05-2X/3-21G*), ONIOM2 (M05-2X/6-31G(d):HF/3-21G*), ONIOM2 (B3LYP/6-31G(d):HF/3-21G*), ONIOM2 (B3LYP/6-31G(d):B3LYP/3-21G*) and ONIOM2 (B3PW91/6-31G(d):B3PW91/3-21G*) was examined. Their complexation, binding, deformation and stabilization energies, and geometrical data were compared with those of the target geometry structure optimized at the M05-2X/6-31G(d) level of theory. Mixed combinations ONIOM2 (M05-2X 6-31G(d):HF 3-21G*) and ONIOM2 (B3LYP 6-31G(d):HF 3-21G*) reproduces nearly the target geometry structure and provides realistic energetic results at a relatively low computational cost. © Springer Science+Business Media B.V. 2012.


Leila N.,Guelmas University | Sakina H.,Guelmas University | Abdelaziz B.,Guelmas University | Fatiha M.,Guelmas University | Fateh L.L.D.,Guelmas University
Journal of Biological Sciences | Year: 2011

We investigated the inclusion process of phenylurea herbicide metobromuron (MB) in beta cyclodextrin (β-CD) with 1:1 stoichiometry using: (1) MM+ force field of molecular mechanics in order to research the lowest energy structure of the inclusion complex. (2) Superior levels of calculations were made such PM3, B3LYP/6-31G*, HF/6-31G* and ONIOM2 methods in order to approach the ideal geometry and provide further insight into the different complexation properties of the guest molecule. The data suggest that: The B orientation is significantly more favourable than the A orientation by an energy difference of 1.02 kcal mol-1 according to PM3 calculations. The geometry of the most stable complex shows that the aromatic ring is deeply self-included inside the hydrophobic cavity of β-CD also an intermolecular hydrogen bond is established between host and guest molecules. The formation of the inclusion complex is predicted to be an enthalpy-driven process in gas phase which is in accord with the experimental results. The statistical thermodynamic calculations by PM3 demonstrate that 1:1 MB/β-CD complex is favored by a negative enthalpy change. © 2011 Asian Network for Scientific Information.


Leila N.,Guelmas University | Sakina H.,Guelmas University | Bouhadiba A.,Guelmas University | Fatiha M.,Guelmas University | Leila L.,Guelmas University
Journal of Molecular Liquids | Year: 2011

Geometry optimizations of para-nitrobenzoic acid (PNBA)/β-cyclodextrin complex were carried out using MM+, PM3 and density function theory B3LYP/6-31G*. Calculations were performed upon the inclusion complexation of β-cyclodextrin (CD) with neutral (PNBA1) and anionic (PNBA2) species of para-nitrobenzoic acid. The results obtained from both methods consistently indicate that the complex of PNBA2/β-CD (B) is significantly more favorable than the others energetically. The negative enthalpy changes calculated from the statistical thermodynamic calculation suggest that both the inclusion complexation is favored enthalpy-driven process. The geometry of the most stable complex shows that the aromatic ring is deeply self-included inside the hydrophobic cavity of β-CD and also intermolecular hydrogen bonds were established between host and guest molecules. This suggests that hydrophobic effect and hydrogen bond play an important role in the complexation process. © 2011 Elsevier B.V. All rights reserved.


Leila N.,Guelmas University | Sakina H.,Guelmas University | Bouhadiba A.,Guelmas University | Madi F.,Guelmas University
Journal of Molecular Liquids | Year: 2011

The inclusion process involving β-cyclodextrin (β-CD) and 3-amino-5-nitrobenzisothiazole (ANBT) has been investigated by using the MM+ force field, AM1, PM3, HF and B3LYP theories. In this study we took into account only the stochiometry1:1. The complexation and interaction energies for both orientations considered in this research are reported. All quantum computational methods gave the A orientation as the most favorable in which the guest molecule is totally embedded in the hydrophobic cavity of the cyclodextrin with the NO2 group located near the primary hydroxyls of the β-CD and the NH2 group near the secondary hydroxyls with no hydrogen bonding formation. The negative complexation and interaction energies calculated suggest that the inclusion complexes are stable. HOMO and LUMO orbital investigations confirm the better stability of the A orientation. © 2011 Elsevier B.V. All rights reserved.


Benghodbane S.,Annaba University | Khatmi D.,Guelmas University
Comptes Rendus Chimie | Year: 2012

The geometry of the inclusion complexes of 2-O-methyl-beta-cyclodextrin (called MeβCD or Crysmeb) with the two tautomers (enol and keto) isomer of doxycycline (DOX) in the gas phase, is determined using PM6 and ONIOM2 calculations with [B3LYP/6-31G(d):HF/3-21G*] level. Inclusion process pathways are described and the most probable structure of the 1:1 complex is sought through a potential energy scan using the PM6 method. Within the ONIOM2 procedure two levels of calculation are defined: B3LYP/6-31G(d) for DOX and the HF/3-21G* level for Meβ CD. The geometry of the most stable complex in the keto or enol forms obtained with the two methods, in which the aromatic ring is included inside the hydrophobic cavity of Crysmeb. The energetic differences between the two forms are 0.17 and 6.27 kcal/mol, respectively with PM6 and [B3LYP/6-31G(d):HF/3-21G*] calculations. These energies also include ZPE corrections. The energetically more favorable structure obtained with the ONIOM2 method leads to the formation of six intermolecular H-bonds between DOX and Crysmeb, i.e. three conventional H-bonds, one between the oxygen atom (O197) of the OH bond of DOX and the hydrogen atom (H140) of Crysmeb and the second between oxygen atom (O53) and a hydrogen atom (H218) of the hydroxyl group of DOX. The last one is between the oxygen atom (O73) and a hydrogen atom (H214) of the hydroxyl group of DOX. These H-bond are assisted by three weak H-bonds of type (C-H⋯O). All these interactions were investigated using the Natural Bond Orbital (NBO) approach. © 2012 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.


Mallem N.,Annaba University | Khatmi D.,Guelmas University | Azzouz S.,Annaba University | Benghodbane S.,Annaba University | Yahia O.A.,Annaba University
Journal of Inclusion Phenomena and Macrocyclic Chemistry | Year: 2012

[M05-2X/6-31G :PM3MM] and [B3LYP/6-31G :PM3] ONIOM2 methods have been used to investigate the vitamin A propionate/β cyclodextrin complex with 1:2 stoichiometry. Both methods give almost the same lowest energy minimum. The minimum energy structure of the complex is found in good agreement with experimental data. In this configuration, the major structure of propionate of vitamin A (PVA) is embedded inside the two cavities of βCD while the propionate group is kept outside. However, the three methyl groups of PVA are positioned in the free space between both βCD molecules. The driving forces for complexation are dominated by Van der Waals interactions between PVA and the βCD molecules assisted with multiple hydrogen bond interactions between the two cyclodextrin molecules. These interactions were investigated using the natural bond orbital approach. © 2011 Springer Science+Business Media B.V.


Djemil R.,Guelmas University | Khatmi D.,Guelmas University
Journal of Computational and Theoretical Nanoscience | Year: 2012

The structural aspects for complexation of dopamine (DA) and epinephrine (EP) to β-CD were explored by using PM6, HF and ONIOM methods. The most stable structure was obtained at the optimum position and angle. The complex orientation in which the catechol ring of the guest penetrates into β-CD cavity near primary hydroxyls is preferred in energy. The inclusion complex of DA with β-CD is more stable than that of EP. The structures show the presence of several intermolecular hydrogen bond interactions that were studied on the basis of NBO analysis employed to quantify the donor-acceptor interactions between the guest molecules and β-CD. Copyright © 2012 American Scientific Publishers All rights reserved.


Fatiha M.,Guelmas University | Khatmi D.E.,Guelmas University | Largate L.,Guelmas University
Journal of Molecular Liquids | Year: 2010

The formation of the inclusion complex of sulconazole with β-CD has been studied theoretically using MM+ force field, AM1,PM3, HF/3-21G and B3LYP/3-21G theories. In this study we took into account only the stoichiometry 1:1. The penetration of sulconazol in the cavity of the β-cyclodextrin can be done according two orientations, A and B. In A orientation, the imidazole was introduced firstly however when it was introduced in the last the orientation is named, B. The results indicate that the complexation of sulconazole/β-CD with A orientation is significantly more favorable than that of B orientation. The negative complexation energy calculated suggests that the inclusion complexes are stable. © 2010 Elsevier B.V. All rights reserved.


Djemil R.,Guelmas University | Khatmi D.,Guelmas University
Canadian Journal of Chemistry | Year: 2011

The inclusion process involving β-cyclodextrin (β-CD) with dopamine (DA) was investigated by using PM6, HF, and ONIOM methods. The most stable structure was obtained at the optimum position and angle. The complex orientation in which the catechol ring of dopamine penetrates into the β-CD cavity near primary hydroxyls is preferred in energy. The structures show the presence of several intermolecular hydrogen bond interactions that were studied on the basis of natural bonding orbital analysis, employed to quantify the donor-acceptor interactions between dopamine and β-CD. A study of these complexes in solution was carried out using the CPCM model to examine the influence of solvation on the stability of the dopamine β-CD complex. © 2011 Published by NRC Research Press.

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