scholarly journals QSAR Studies and Structure Property/Activity Relationships Applied in Pyrazine Derivatives as Antiproliferative Agents Against the BGC823

2021 ◽  
Vol 68 (4) ◽  
pp. 882-895
Author(s):  
Fatima Soualmia ◽  
Salah Belaidi ◽  
Noureddine Tchouar ◽  
Touhami Lanez ◽  
Samia Boudergua
Keyword(s):  
Density Functional ◽  
Dipole Moments ◽  
Structure Property ◽  
Functional Theory ◽  
Qsar Studies ◽  
Qsar Models ◽  
Artificial Neural Network Ann ◽  
Ab Initio Hf ◽  
Similarity Method

Electronic structures, the effect of the substitution, structure physicochemical property/activity relationships and drug-likeness applied in pyrazine derivatives, have been studied at ab initio (HF, MP2) and B3LYP/DFT (density functional theory) levels. In the paper, the calculated values, i.e., NBO (natural bond orbitals) charges, bond lengths, dipole moments, electron affinities, heats of formation and quantitative structure-activity relationships (QSAR) properties are presented. For the QSAR studies, we used multiple linear regression (MLR) and artificial neural network (ANN) tatistical modeling. The results show a high correlation between experimental and predicted activity values, indicating the validation and the good quality of the derived QSAR models. In addition, statistical analysis reveals that the ANN technique with (9-4-1) architecture is more significant than the MLR model. The virtual screening based on the molecular similarity method and applicability domain of QSAR allowed the discovery of novel anti-proliferative activity candidates with improved activity.

scholarly journals DFT-based QSAR studies and Molecular Docking of 1-Phenylcyclohexylamine Analogues as anticonvulsant of NMDA Receptor

2019 ◽  
Vol 9 (5) ◽  
pp. 390-402
Author(s):  
Hanine Hadni ◽  
Charif EL M'Barki ◽  
Mohamed Mazigh ◽  
Menana Elhallaoui
Keyword(s):  
Molecular Docking ◽  
Density Functional ◽  
Phenyl Group ◽  
Qsar Model ◽  
Equatorial Position ◽  
Ann Model ◽  
Functional Theory ◽  
Qsar Studies ◽  
Aspartate Receptor ◽  
Artificial Neural Network Ann

The phencyclidine (PCP) and their analogues have been reported to exhibit inhibitory activities toward the N-methyl-D-aspartate receptor (NMDAR). To discover the QSAR between structure of PCP derivatives and Ki activities we have used density functional theory (DFT) to generate quantum descriptors, multiple regression linear (MLR) method was applied to establish QSAR model, and an artificial neural network (ANN), considering the relevant descriptors obtained with the MLR method is explored, a correlation coefficient of RANN = 0.912 was obtained with 6-4-1 ANN model. This model is tested by using a cross-validation method with the LOO procedure (RCV = 0.841). To study the configuration impact on activity, we proceed to the Molecular Docking of four configurations, two configurations of compound have (Ki = 502 nM) and two configurations of compound have (Ki = 1200nM). The phenyl group, when placed in an equatorial position in cis9e, a configuration of the less active compound, does not form π-sigma interaction. The superimposition of this configuration with trans7e reveals that the phenyl group of cis9e configuration is shifted from the binding site compared to trans7e which forms an interaction π-sigma throughout its phenyl group with ARG B: 894. So, we could claim that the cis9e is the configuration adopted by compound having (Ki = 502 nM).

Assessing the Calculation of Exchange Coupling Constants and Spin Crossover Gaps Using the Approximate Projection Model to Improve Density Function Calculations

2019 ◽  
Author(s):  
Xianghai Sheng ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Density Functional Theory ◽  
Exchange Coupling ◽  
Density Functional ◽  
Spin Crossover ◽  
Coupling Constants ◽  
Spin Projection ◽  
Coupling Constant ◽  
Projection Model ◽  
Functional Theory

This work evaluates the quality of exchange coupling constant and spin crossover gap calculations using density functional theory corrected by the Approximate Projection model. Results show that improvements using the Approximate Projection model range from modest to significant. This study demonstrates that, at least for the class of systems examined here, spin-projection generally improves the quality of density functional theory calculations of J-coupling constants and spin crossover gaps. Furthermore, it is shown that spin-projection can be important for both geometry optimization and energy evaluations. The Approximate Project model provides an affordable and practical approach for effectively correcting spin-contamination errors in molecular exchange coupling constant and spin crossover gap calculations.

scholarly journals Voltammetric and theoretical studies of electrochemical behavior of cephalosporins at the mercury electrode

2015 ◽  
Vol 80 (8) ◽  
pp. 1035-1049 ◽  
Author(s):  
Katarina Nikolic ◽  
Mara Aleksic ◽  
Vera Kapetanovic ◽  
Danica Agbaba
Keyword(s):  
Density Functional ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Structure Property ◽  
Qspr Model ◽  
Functional Theory ◽  
Partial Charges ◽  
The Density Functional Theory ◽  
Structure Property Relationship ◽  
Qspr Study

Study of the adsorption and electroreduction behavior of cefpodoxime proxetil, cefotaxime, desacetylcefotaxime, cefetamet, ceftriaxone, ceftazidime, and cefuroxime axetile at the mercury electrode surface has been performed using Cyclic (CV), Differential Pulse (DPV), and Adsorptive Stripping Differential Pulse Voltammetry (AdSDPV). The Quantitative Structure Property Relationship (QSPR) study of the seven cephalosporins adsorption at the mercury electrode has been based on the density functional theory DFT-B3LYP/6-31G (d,p) calculations of molecular orbitals, partial charges and electron densities of analytes. The DFT-parameters and QSPR model explain well the process of adsorption of the examined cephalosporins. QSPR study defined that cefalosporins with lower charge of sulphur in the thiazine moiety, lower electron density on the nitrogen atom of the N-O bond, higher number of hydrogen bond accepting groups, and higher principal moment of inertia should express high adsorption on the mercury electrode.

scholarly journals Structure–Property Relationships in Transition Metal Dichalcogenide Bilayers under Biaxial Strains

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2639
Author(s):  
Pingping Jiang ◽  
Pascal Boulet ◽  
Marie-Christine Record
Keyword(s):  
Density Functional ◽  
Compressive Strain ◽  
Bond Critical Point ◽  
Transition Metal Dichalcogenide ◽  
Structure Property ◽  
Photovoltaic Properties ◽  
Functional Theory ◽  
Leading Role ◽  
Structure Property Relationships

This paper reports a Density Functional Theory (DFT) investigation of the electron density and optoelectronic properties of two-dimensional (2D) MX2 (M = Mo, W and X = S, Se, Te) subjected to biaxial strains. Upon strains ranging from −4% (compressive strain) to +4% (tensile strain), MX2 bilayers keep the same bandgap type but undergo a non-symmetrical evolution of bandgap energies and corresponding effective masses of charge carriers (m*). Despite a consistency regarding the electronic properties of Mo- and WX2 for a given X, the strain-induced bandgap shrinkage and m* lowering are strong enough to alter the strain-free sequence MTe2, MSe2, MS2, thus tailoring the photovoltaic properties, which are found to be direction dependent. Based on the quantum theory of atoms in molecules, the bond degree (BD) at the bond critical points was determined. Under strain, the X-X BD decreases linearly as X atomic number increases. However, the kinetic energy per electron G/ρ at the bond critical point is independent of strains with the lowest values for X = Te, which can be related to the highest polarizability evidenced from the dielectric properties. A cubic relationship between the absolute BD summation of M-X and X-X bonds and the static relative permittivity was observed. The dominant position of X-X bond participating in this cubic relationship in the absence of strain was substantially reinforced in the presence of strain, yielding the leading role of the X-X bond instead of the M-X one in the photovoltaic response of 2D MX2 material.

Density functional theory study on the structural, reactivity, and electronic properties of all mono-, di-, tri-, tetra-, and penta-fluoroanilines as monomers for conducting polymers

2012 ◽  
Vol 90 (10) ◽  
pp. 902-914 ◽  
Author(s):  
Hossein Shirani Il Beigi
Keyword(s):  
Density Functional Theory ◽  
Conducting Polymers ◽  
Structural Properties ◽  
Density Functional ◽  
Dipole Moments ◽  
Radical Cations ◽  
The Other ◽  
Functional Theory ◽  
Density Distributions ◽  
Electric Polarizabilities

Electrical and structural properties of mono-, di-, tri-, tetra-, and penta-fluoroanilines as candidate monomers for new conducting polymers have been investigated using hybrid density functional theory (B3LYP/6–311+G**) based methods. The effects of the number and position of the fluorine atoms on the electrical and structural properties of fluoroanilines and their radical cations have also been investigated. The values of the vibrational frequencies, charge and spin-density distributions, ionization potentials, dipole moments, electric polarizabilities, HOMO-LUMO gaps, and the NICS values of these compounds have been calculated and analyzed as well. The results showed that the double bonds in 2-fluoroaniline and 2,5-difluoroaniline are more delocalized compared with other fluoroanilines; therefore, these molecules have the most aptitude for the electropolymerization reactions. The frequency analysis showed that the electrochemical stability of 2-fluoroaniline is greater than the other fluoroanilines. Also, this molecule possesses the largest NICS value compared to the other fluoroanilines. Consequently, 2-fluoroaniline has the largest ring current and the highest conductivity among all other monomers. Based on the results obtained, 2-fluoroaniline and 2,5-difluoroaniline are the best candidate monomers among all fluoroanilines for the synthesis of corresponding conducting polymers.

The Interaction between Graphene and the SiC Substrate: Ab Initio Calculations for Polar and Nonpolar Surfaces

2016 ◽  
Vol 858 ◽  
pp. 1125-1128
Author(s):  
Ioannis Deretzis ◽  
Filippo Giannazzo ◽  
Antonino La Magna
Keyword(s):  
Density Functional Theory ◽  
Energy Spectrum ◽  
Density Functional ◽  
Low Energy ◽  
Electrical Characteristics ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structural And Electronic Properties ◽  
Exclusive Property

Notwithstanding the graphitization of SiC under high thermal treatment can take place for all SiC surfaces, the quality of the resulting graphene as well as its structural and electrical characteristics strongly depend on the SiC face where growth has taken place. In this paper we use the density functional theory to analyze the structural and electronic properties of epitaxial graphene grown on three different SiC planes. Calculations are presented for the (6√3×6√3)R30°-reconstructed SiC(0001) surface (Si face) as well as the nonpolar SiC(11-20) and SiC(1-100) planes. We argue that the formation of a strongly-bound interface buffer layer is an exclusive property of the SiC(0001) surface. Moreover, our results indicate that nonpolar planes give rise to graphene with a nearly ideal low-energy spectrum.

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