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Search Results: 1 - 10 of 22546 matches for " Mamadou Guy-Richard Koné "
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ONIOM Method Characterization of Hydrogen Bonding Sites of Mycolactone A/B, a Buruli Ulcer Toxin  [PDF]
Kadjo Fran?ois Kassi, Mamadou Guy-Richard Koné, Sopi Thomas Affi, Nahossé Ziao
Computational Chemistry (CC) , 2017, DOI: 10.4236/cc.2017.53009
Abstract: Mycolactone molecules are responsible of Buruli ulcer disease. In this work, we are interested in the geometric, energetic and spectroscopic characterization of the hydrogen bonding interactions in mycolactone A/B, using quantum chemical method, especially ONIOM(HF/6-311+G(d,p):AM1) and ONIOM (B3LYP/6-311+G(d,p):AM1) levels. ONIOM two layers method has been used because mycolactones compounds are very large, taking into account diffuse and polarization functions are important whenever the matter is intermolecular interactions. Geometric, energetic and spectroscopic parameters of hydrogen bonding reaction on each of the nine oxygen heteroatoms of mycolactone A/B have revealed that the O5sp2 heteroatom is far away the hydrogen bonding site. The identification of such a site constitutes a tool for working out a methodology for the annihilation of the destruction effects of mycolactones.
Quantitative Structure Anti-Cancer Activity Relationship (QSAR) of a Series of Ruthenium Complex Azopyridine by the Density Functional Theory (DFT) Method  [PDF]
Kouakou Nobel N’guessan, Mamadou Guy-Richard Koné, Kafoumba Bamba, Ouattara Wawohinlin Patrice, Nahossé Ziao
Computational Molecular Bioscience (CMB) , 2017, DOI: 10.4236/cmb.2017.72002
Abstract: A series of ruthenium azopyridine complexes have recently been investigated due to their potential cytotoxic activities against renal cancer (A498), lung cancer (H226), ovarian cancer (IGROV), breast cancer (MCF-7) and colon cancer (WIDR). Thus, in order to predict the cytotoxic potentials of these compounds, quantitative structure-activity relationship studies were carried out using the methods of quantum chemistry. Five Quantitative Structure Activity Relationship (QSAR) models were obtained from the determined quantum descriptors and the different activities. The models present the following statistical indicators: regression correlation coefficient R2 = 0.986 - 0.905, standard deviation S = 0.516 - 0.153, Fischer test F = 106.718 - 14.220, correlation coefficient of cross-validation \"\"= 0.985- 0.895 and \"\"= 0.010 - 0.001. The statistical characteristics of the established QSAR models satisfy the acceptance and external validation criteria, thereby accrediting their good performance. The models developed show that the variation of the free enthalpy of reaction \"\", the dipole moment μ and the charge of the ligand in the complex Ql, are the explanatory and predictive quantum descriptors correlated with the values of the anti-cancer activity of the studied complexes. Moreover, the charge of the ligand is the priority descriptor for the prediction of the cytotoxicity of the compounds studied. Furthermore, QSAR models developed are statistically significant and predictive, and could be used for the design and synthesis of new anti-cancer molecules.
Theoretical Study of the Reaction of (2, 2)-Dichloro (Ethyl) Arylphosphine with Bis (2, 2)-Dichloro (Ethyl) Arylphosphine by Hydrophosphination Regioselective by the DFT Method  [PDF]
Kouadio Valery Bohoussou, Anoubilé Benié, Mamadou Guy-Richard Koné, Affi Baudelaire Kakou, Kafoumba Bamba, Nahossé Ziao
Computational Chemistry (CC) , 2017, DOI: 10.4236/cc.2017.53010
Abstract: For this work, we have selected two reactions for the formation of (2,2)-dichloro (ethyl) Arylphosphine and bis (2,2)-dichloro(ethyl)arylphosphine compounds by hydrophosphination. Global and local reactivity parameters, thermodynamic parameters of reactions, Transition states, the Fukui function, the local softness, the local electrophility index, and nucleophility index, Natural population analyses (NPA) and Mulliken (MK) were calculated with DFT method at B3LYP/6-311+G(d, p) level. The analysis of potential energy surfaces and the nature of the reaction mechanism have been determined. The various results obtained revealed that the addition of Arylphosphine is regiospecific. The phenylphosphine is more stable than the thiophenylphosphine. The theoretical results are consistent with experience.
Theoretical Study by Density Functional Theory Method (DFT) of Stability, Tautomerism, Reactivity and Prediction of Acidity of Quinolein-4-One Derivatives  [PDF]
Affoué Lucie Bédé, Amon Benjamine Assoma, Kicho Denis Yapo, Mamadou Guy-Richard Koné, Soleymane Koné, Mawa Koné, Boka Robert N’Guessan, El-Hadji Sawaliho Bamba
Computational Chemistry (CC) , 2018, DOI: 10.4236/cc.2018.63005
Abstract:
A theoretical study of the reactivity of quinoline-4-one derivatives is undertaken in order to understand the involved mechanisms. The calculations were carried out in gas phase and in N, N-Dimethylformamide (DMF) solution. The Density Functional Theory (DFT) with B3LYP functional associated to 6-311G (d) and 6-311+G (d) bases is used to perform these calculations. The results of the thermodynamic parameters showed that there is an equilibrium relation between the different tautomers. This equilibrium can be used to explain the failure to obtain tetrahydroquinoline from 5,8-dimethoxy-quinolin-4-one. Reactivity analysis from Frontier Molecular Orbitals theory and Fukui function calculations revealed that ketone forms are less reactive than enol ones. The methoxyl substituent decreases the acidity of the nitrogen and oxygen atoms of quinolin-4-one while the bromine increases the acidity of the same sites. These results foresee that nitrogen deprotonation in the case of the brominated compound is easier than in the case of methoxylated ones.
Development of Predictive QSPR Model of the First Reduction Potential from a Series of Tetracyanoquinodimethane (TCNQ) Molecules by the DFT (Density Functional Theory) Method  [PDF]
Fatogoma Diarrassouba, Mawa Koné, Kafoumba Bamba, Yafigui Traoré, Mamadou Guy-Richard Koné, Edja Florentin Assanvo
Computational Chemistry (CC) , 2019, DOI: 10.4236/cc.2019.74009
Abstract: In this work, which consisted to develop a predictive QSPR (Quantitative Structure-Property Relationship) model of the first reduction potential, we were particularly interested in a series of forty molecules. These molecules have constituted our database. Here, thirty molecules were used for the training set and ten molecules were used for the test set. For the calculation of the descriptors, all molecules have been firstly optimized with a frequency calculation at B3LYP/6-31G(d,p) theory level. Using statistical analysis methods, a predictive QSPR (Quantitative Structure-Property Relationship) model of the first reduction potential dependent on electronic affinity (EA) only have been developed. The statistical and validation parameters derived from this model have been determined and found interesting. These different parameters and the realized statistical tests have revealed that this model is suitable for predicting the first reduction potential of future TCNQ (tetracyanoquinodimethane) of this same family belonging to its applicability domain with a 95% confidence level.
Studies of the Chemical Reactivity of a Series of Rhodanine Derivatives by Approaches to Quantum Chemistry  [PDF]
Wacothon Karime Coulibaly, Jean Stéphane N’dri, Mamadou Guy-Richard Koné, Camille Déliko Dago, Christelle N’ta Ambeu, Jean-Pierre Bazureau, Nahossé Ziao
Computational Molecular Bioscience (CMB) , 2019, DOI: 10.4236/cmb.2019.93005
Abstract: This theoretical chemical reactivity study was conducted using the Density Functional Theory (DFT) method, at computational level B3LYP/6-31G (d). It involved a series of six (06) 5-arylidene rhodanines and allowed to predict the chemical reactivity of these compounds. DFT global chemical reactivity descriptors (HOMO and LUMO energies, chemical hardness, softness, electronegativity) were examined to predict the relative stability and reactivity of rhodanin derivatives. Thus, the compound 6 which has an energy gap between the orbitals of ΔEgap = 3.004 eV is the most polarizable, the most reactive, the least stable, the best electron donor and the softest molecule. Calculation of the local indices of reactivity as well as dual descriptors revealed that the sulfur heteroatom of the Rhodanine ring is the privileged site of electrophilic attack in a state of sp3 hybridization and privileged site of nucleophilic attack in a state of sp2 hybridization.
Protonation Sites in Benzimidazolyl-Chalcones Molecules: An ab Initio and DFT Investigation  [PDF]
Mamadou Guy-Richard Kone, Sopi Thomas Affi, Nahossé Ziao, Kafoumba Bamba, Edja Florentin Assanvo
Computational Chemistry (CC) , 2016, DOI: 10.4236/cc.2016.43006
Abstract: In this work, we have focused our investigations on the protonation sites predilection in the benzimidazolyl- chalcones (BZC) derivatives. Particularly, we are interested in the study of geometrical and energetical parameters. BZC are well known for their particularly nematicidal activity. Ten (10) BZC derivatives coded BZC-1 to BZC-10, with various larvicidal concentrations, have been selected for this work. They all are different one from another by the phenyl ring which is substituted by electron modulators such as alkyl, hydroxyl, alkoxy, aminoalkyl, halogen and nitro or replaced by the furan. Quantum chemical methods, namely HF/6-311 + G(d,p) and MPW1PW91/6- 311 + G(d,p) theory levels have been used to determine the geometrical and energetical parameters by the protonation on each heteroatom of the BZC derivative. An accuracy results with relatively less time consuming has been obtained using Hartree-Fock (HF) and Density Functional Theory methods (DFT/MPW1PW91). The calculations results allow identifying the sp2 nitrogen as the preferential site of protonation in BZC derivative compounds.
Quantum Chemical Characterization of Hydrogen Bonding Sites in Three 4-(4-Halo-Phenyl)-6-(Furan-2-yl) Pyrimidin-2-Amine Derivatives  [PDF]
Yafigui Traore, Kafoumba Bamba, Nahossé Ziao, Sopi Thomas Affi, Mamadou Guy-Richard Kone
Computational Chemistry (CC) , 2017, DOI: 10.4236/cc.2017.53008
Abstract: Hydrogen bonding (HB) sites in three pyrimidine compounds derivatives (DP), namely 4-(4-fluorophenyl)-6-(furan-2-yl) pyrimidin-2-amine (DP-1), 4-(4-chlorophenyl)-6-(furan-2-yl) pyrimidin-2-amine (DP-2) and 4-(4-bromophenyl)-6-(furan-2-yl) pyrimidin-2-amine (DP-3), have been investigated by quantum chemistry methods, especially at HF/6-311+G(d,p) and B3PW91/6-311+G(d,p) levels. Hydrogenfluori deserved as probe for hydrogen bonding complexes. Molecular electrostatic potential maps, geometricparameters of HB complexes, as well as energetic parameters of the complexation reactions have been computed. Finally, one out of two nitrogen atoms of pyrimidine nucleus has been identified as the major hydrogen bonding site in the three pyrimidine derivatives, with respective percentages of around 83.0% and 93.2% at HF/6-311+G(d,p) and B3PW91/6-311+G(d,p) levels.
DFT Study, Linear and Nonlinear Multiple Regression in the Prediction of HDAC7 Inhibitory Activities on a Series of Hydroxamic Acids  [PDF]
Doh Soro, Lynda Ekou, Bafétigué Ouattara, Mamadou Guy-Richard Kone, Tchirioua Ekou, Nahossé Ziao
Computational Molecular Bioscience (CMB) , 2019, DOI: 10.4236/cmb.2019.93006
Abstract: In this work, we conducted a QSAR study on 18 molecules using descriptors from the Density Functional Theory (DFT) in order to predict the inhibitory activity of hydroxamic acids on histone deacetylase 7. This study is performed using the principal component analysis (PCA) method, the Ascendant Hierarchical Classification (AHC), the linear multiple regression method (LMR) and the nonlinear multiple regression (NLMR). DFT calculations were performed to obtain information on the structure and information on the properties on a series of hydroxamic acids compounds studied. Multivariate statistical analysis yielded two quantitative models (model MLR and model MNLR) with the quantum descriptors: electronic affinity (AE), vibration frequency of the OH bond (ν(OH)) and that of the NH bond (ν(NH)). The LMR model gives statistically significant results and shows a good predictability R2 = 0.9659, S = 0.488, F = 85 and p-value < 0.0001. Electronic affinity is the priority descriptor in predicting the activity of HDAC7 inhibitors in this study. The results obtained suggest that the descriptors derived from the DFT could be useful to predict the activity of histone deacetylase 7 inhibitors. These models were evaluated according to the criteria of Tropsha et al.
Concrete Formulation Study for Informal and Semi-Informal Construction Sectors  [PDF]
Narcisse Malanda, Paul Louzolo-Kimbembe, Louis Ahouet, Jarlon Brunel Makela, Guy-Richard Mouengue
Open Journal of Civil Engineering (OJCE) , 2019, DOI: 10.4236/ojce.2019.91005
Abstract: The present work consisted in carrying out a study on the effective formulation of concrete for an optimal resistance to compression (fc28) between 20 and 30 MPa for the sites animated by the actors of the informal and semi-informal sectors of the construction. Studies have been carried out on projects under construction, by taking samples of fresh concrete in order to evaluate their real compressive strengths. These surveys show that there is a problem in the concrete formulation, as nearly 2/3 of the results show the lack of technical knowledge on concrete formulation practices. Indeed, on eight sites surveyed and whose fresh concrete samples were taken, only two sites (7 and 8) report fairly consistent results. Their 28-day compressive strength values are respectively 35.36 and 22.18 MPa. In addition, various formulations proposed with aggregates from different quarries or extracts from the bed of the Congo River, were determined in the laboratory. This study allowed us to obtain fairly objective results overall, which is characteristic of concretes of required quality. Of the six (06) formulation proposals, average resistances of 19.6 MPa at 07 days and 25.28 MPa at 28 days were obtained. These results at 28 days are in the range of 20 to 30 MPa, set as objective in this study. These formulations can be a reliable source for concrete manufacturers in these construction sectors. Similarly, the statistical study based on principal component factor analysis tests has shown that the most appropriate formulation, in terms of mechanical resistance, is that proposed with sand extracted from the Congo River (formulation 3). This is justified by the fact that this sand is consistent and has a good granular distribution.
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