scholarly journals USING QUANTUM-CHEMICAL PARAMETERS FOR PREDICTING ANTI-RADICAL (НО∙) ACTIVITY OF RELATED STRUCTURES CONTAINING A CINNAMIC MOLD FRAGMENT. I. DERIVATIVES OF CINNAMIC ACID, CHALCON AND FLAVANON

2019 ◽  
Vol 7 (1) ◽  
pp. 53-66 ◽  
Author(s):  
E. T. Oganesyan ◽  
S. S. Shatokhin ◽  
A. A. Glushko
Keyword(s):  
Hydroxyl Radical ◽  
Electron Density ◽  
Cinnamic Acid ◽  
Quantum Chemical ◽  
The Body ◽  
Mulliken Charge ◽  
Structural Fragment ◽  
Chemical Parameters ◽  
Quantum Chemical Parameters ◽  
Derivatives Of

45 compounds uniting 3 groups of derivatives of cinnamic acid, chalcone and flavanone, have been studied. Each of them includes 15 substances. The analyzed compounds contain a common structural fragment, which is a cinnamic acid residue (cinnamoyl fragment).The aimis to study the quantum-chemical parameters of the listed groups of the compounds in order to predict possible ways of their interaction with the most aggressive and dangerous of the active oxygen species (ROS) – a hydroxyl radical.Materials and methods.For the analyzed structures, the Mulliken charges (a.u.), bond numbers (Nμ), unsaturation index (IUA), and electron density values on all 9-carbon atoms of the cinnamoyl fragment have been determined. The calculations have been carried out on a workstation with an Intel Xeon E5-1620 3.5 GHz processor, 20 GB of RAM. The semi-empirical method PM7 was used (WinMopac 2016 program). The ORCA 4.1 program was used to calculate the energies of homolytic cleavage of the O – H bond.Results.The analysis of Mulliken charges (a.u.), bonded numbers (Nμ), unsaturation indices (IUA), and electron density revealed a number of regularities on the basis of which it can be concluded, that taking into account the nature of the substituent, the most probable for addition in the aryl residueare positions C-1, C-2, C-3, C-4 and C-5. In the propenone fragment, the radical НО∙ first attacks position 8, then 7. For the hydroxy-substituted, the energy of the homolytic breaking of the H – O bond has been determined and it has been established that the spatial difficulty of phenols (compounds 13k, 13x, 13f, 14k, 14x, 14f) H-O bonds are the smallest and on average are -160.63 kJ/mol. It has also been established that the higher the positive Mulliken charge on the carbon atom with which the phenolic hydroxyl is bound, the lower the energy of the homolytic breaking of the H – O bond and the more stable the resulting phenoxy radicalis.Conclusion.The carried out quantum chemical calculations allow us to conclude that the studied classes of compounds can be used to bind the hydroxyl radical formed in the body, causing various kinds of mutations, leading, among other things, to the development of oncological diseases.

scholarly journals USING QUANTUM-CHEMICAL PARAMETERS FOR PREDICTING ANTI-RADICAL (НО∙) ACTIVITY OF RELATED STRUCTURES CONTAINING A CINNAMOYL FRAGMENT II. DERIVATIVES OF 2’,4’-DIHYDROXYCHALCONE, FLAVANONE AND FLAVONE, CONTAINING A HYDROXY GROUP IN POSITION 7

2020 ◽  
Vol 8 (2) ◽  
pp. 112-123
Author(s):  
Eduard T. Oganesyan ◽  
Stanislav S. Shatokhin
Keyword(s):  
Electron Density ◽  
Hydroxy Group ◽  
Quantum Chemical ◽  
Empirical Method ◽  
Mulliken Charge ◽  
Reactive Oxygen Intermediate ◽  
Electronic Effects ◽  
Chemical Parameters ◽  
Quantum Chemical Parameters ◽  
Derivatives Of

42 derivatives of 2’,4’-dihydroxychalcone, flavanone and flavone, containing the hydroxy group in position 7 (ring "A"), as well as substituents in the ring "B", have been studied.The aim is to study the quantum-chemical parameters of 2',4'-dihydroxychalcone, flavanone and flavone derivatives containing a hydroxy group in position 7, in order to identify the effect of substituents on Mulliken charges (a.e) in the aromatic core "A", bond numbers (Nµ), the unsaturation index (IUA) and the electron density of the carbon atoms of the cinnamoyl fragment.Materials and methods. The listed above parameters have been calculated by the semi-empirical method PM7 (WinMopac 2016 program) on the workstation with an Intel Xeon E5-1620 3.5 GHz processor, 20 GB of RAM.Results. The analysis of the values of quantum-chemical parameters, as well as their comparison with the corresponding indicators presented in Report I, revealed a number of important features associated with the influence of the hydroxy group in position 7 (ring "A") on the studied quantum-chemical parameters of molecules. It has been established that the hydroxy group in the ring “A” does not significantly affect the Mulliken charge and the electron density of the carbon atoms of the propenone unit C-7→C-8→C-9. On atom C-9 (carbonyl carbon), the Mulliken charge always has a positive value, and the electron density is about 3.4670-3.4840 for all three groups of compounds. The transition from 2’,4’-dihydroxychalcone to flavanone and flavone by the formation of the pyrone heterocycle, is accompanied by an increase in the negative charge on C-8, which can be explained by the involvement of the oxygen heteroatom in the transmission of electronic effects. The hydroxy group in the ring “A”, has practically no effect on the charge and electron density of atoms. An analysis of the values of bond numbers and unsaturation indices suggests that atoms C-1 of 2’,4’-dihydroxychalcone and 7-hydroxyflavanone derivatives, are characterized by the lowest Nµ value; the lowest bond numbers are characteristic for atom C-8 derivatives of 7-hydroxyflavone. Consequently, the primary attack of the HO·radical will be directed at C-1 (in chalcones and flavanones) and at C-8 in flavones.Conclusion. The performed quantum-chemical calculations make it possible to analyze the effect on the main quantum-chemical parameters of the molecule, which can be useful in predicting the biological activity of flavanoid compounds due to their antiradical effect on reactive oxygen intermediate species (ROIs).

scholarly journals USING QUANTUM-CHEMICAL PARAMETERS FOR PREDICTING ANTIRADICAL (HO•) ACTIVITY OF RELATED STRUCTURES CONTAINING A CINNAMOIL FRAGMENT. IV. STRUCTURE-ACTIVITY RELATIONSHIP BETWEEN UNSATURATION INDICES AND FLAVONE DERIVATIVES WITH FLOROGLUCIN RING “A”

2021 ◽  
Vol 9 (2) ◽  
pp. 161-169
Author(s):  
E. T. Oganesyan ◽  
S. S. Shatokhin
Keyword(s):  
Electron Density ◽  
Quantum Chemical ◽  
Multiple Bond ◽  
Mulliken Charge ◽  
Simultaneous Increase ◽  
Free Valence ◽  
Chemical Parameters ◽  
Quantum Chemical Parameters ◽  
Conjugation Chain ◽  
Vinyl Group

The quantum-chemical parameters of 52 derivatives related to flavanones, flavanonoles, flavones and flavonoles with a phloroglucinic type of the A ring and containing electron-donating substituents in the B ring were studied.The aim is the analysis of the dynamics of changes in the electron density, bond numbers, free valence indices and unsaturation indices on carbon atoms C-7 → C-8 of the vinyl group of the main conjugation chain in relation to the position and number of substituents in the “B” ring and the type of the pharmacological activity.Materials and methods. The quantum-chemical parameters of the 4 analyzed groups of the compounds, have been calculated by the semi-empirical method PM7 (WinMopac 2016 program) on the workstation with an Intel Xeon E5-1620 3.5 GHz processor, 20 GB of RAM.Results and discussion. When comparing the quantum chemical parameters of the analyzed compounds, it was established that when the C-7 → C-8 multiple bond is formed, the free valency and unsaturation indices increase on both carbon atoms of the vinylene group in flavones and flavonols compared to the corresponding flavanones and flavanonols. This is explained by the fact that the value of the bond numbers Nµ on these atoms, on the contrary, decreases (Fµ = 4.732-Nµ). The transition from flavanone to flavone is accompanied by the formation of a vinyl group C-7 → C-8, and therefore both atoms from the sp3-hybridized state go into the sp2-state. The consequence of this transformation is a change in the electronegativity value and an increase in the unsaturation index of C-7 and C-8 atoms: C sp3 = 2.5;  Csp2 = 2.8. At the same time, the transition from flavanone to flavone leads to the formation of a conjugated system with the participation of π-electrons of the aromatic system “B”, C-7, C-8 atoms and the carbonyl group, which is commonly called the “main conjugation chain”. These structural changes, namely, the transition from a less oxidized flavanone to a more oxidized flavone, contribute to a decrease in the electron density on C-7 and C-8 atoms, and an increase in the total unsaturation of the molecules in general. Mulliken charges on C-7 of all groups of compounds are characterized by a positive value. As for the carbon atoms of the B fragment, the following features are revealed here: in the presence of one substituent -OH or -OCH3 on the carbon atom to which the substituent is bounded, the Mulliken charge is positive; if there are two substituents in the B ring -OH or -OCH3, as well as two -OCH3 groups, then the carbon atoms bonded to the indicated substituents also have a positive Mulliken charge; in the case of trihydroxy substituted in the C-2, C-3 and C-4 B ring, all three carbon atoms are characterized by a positive Mulliken charge; if there are methoxy groups in positions C-2, C-3 and C-4, then the positive Mulliken charge is concentrated only on C-2 and C-4 atoms, and on C-3 atom this charge has a negative value.Conclusion. The above data on the quantum-chemical parameters of the main conjugation chain indicate that the transition of C-7 and C-8 atoms to the sp2-hybrid state, leads to a decrease in the electron density and a decrease in the bond numbers, with a simultaneous increase in the indices of unsaturation and free valence on these atoms. Thus, the trigger mechanism of the anti-radical activity, primarily with respect to the HO • radical, is determined by the fact that this particle, electrophilic in its properties, will attach in the C-8  atom during an initial attack. 

scholarly journals USE OF QUANTUM-CHEMICAL PARAMETERS FOR FORECASTING ANTIRADICAL (HO·) ACTIVITY OF RELATED STRUCTURES CONTAINING A CINNAMIC MOLD FRAGMENT. III. CHALCONES, FLAVANONES AND FLAVONES WITH PHLOROGLUCINIC TYPE OF RING “A”

2021 ◽  
Vol 8 (6) ◽  
pp. 446-455
Author(s):  
E. T. Oganesyan ◽  
S. S. Shatokhin
Keyword(s):  
Electron Density ◽  
Quantum Chemical ◽  
Empirical Method ◽  
Mulliken Charge ◽  
Radical Mechanism ◽  
Free Valence ◽  
Coupling Reactions ◽  
Free Radical Mechanism ◽  
Initial Stage ◽  
Derivatives Of

42 derivatives of chalcone, flavanone and flavone having a phloroglucinic type of ring “A” and containing the same electron-donating substituents on ring “B”, have been studied. Flavonoids with the phloroglucinic type of ring “A” are the most common in nature, which is due to the peculiarities of biogenetic formation with the participation of malonyl and acetyl fragments.The aim of the article is to determine the effect of the hydroxy group in position 6' of chalcones and in position 5 of flavanones and flavones on bond numbers (Nµ), free valence indices (Fµ), Mulliken charges (a.e), electron density, unsaturation indices (IUA) of the carbon atoms C-1 → C-6 → C-7 → C-8.Materials and methods. The calculations of the listed above parameters with the use of the semi-empirical method PM7 (WinMopac 2016 program) have been carried out on a workstation with an Intel Xeon E5-1620 3.5 GHz processor, 20 GB of RAM.Results. The quantum-chemical characteristics of the considered derivatives having a phloroglucinic type of the “A” ring, indicate that the OH group in position 6' of chalcones (in the corresponding flavanones and flavones in position 5) has different effects: a slight increase occurs in chalcones negative charge (a.e.) and electron density, the bond numbers take different values, which depends on the position and number of substituents on the ring "B". In flavanones, Nµ practically remains at the same level of 3.822-3.829. For flavones, the binding numbers Nµ for C-8 are in the range of 3.700-3.706, and the Mulliken charges are in the range from -0.4120 to -0.4356. For position-substituted C-3 (6anone and 7anone), the charges are -0.4436 and -0.4479, respectively. The charge on C-7 of chalcones is negative for compounds 4x, 5x, 10x and 13x from -0.0204 to -0.0470. The remaining derivatives of the chalcone, as well as the corresponding flavanones and flavones, are characterized by a positive value of a.e. on C-7. Based on the bond numbers (Nµ), free valency indices (Fµ) have been found for the carbon atoms of the cinnamoyl fragment C-1 → C-6 → C-7 → C-8. When comparing the obtained data, it was found out that for chalcones on C-1 → C-8 atoms, the values of the free valence indices are in the range of 0.900-0.980 for compounds 12x, 13x, where Fµ> 1. For flavanones on C-1, C-3, and C-5 atoms (compounds 12anone and 13anone), the free valence indices are in the range of 0.984-1.024, and for the remaining atoms the value of Fµ is approximately the same as that of chalcones. On the C-8 atoms of all the derivatives, as well as on C-1, C-3 and C-5 (compounds 12one, 13one), Fµ ≥ 1.0. It can be assumed that at values of Fµ = 0.850-0.955 for all the analyzed compounds, coupling reactions on the double bond are possible, and if Fµ ≥1, the coupling will take place according to the free radical mechanism. The data obtained indicate that the OH group in position 6’ for the chalcone and 5 for the flavanones, does not significantly effect the Mulliken charge (a.e) and the electron density on C-8 atoms.Conclusion. It has been established that the OH group in position 6' of the "A" ring of chalcones (in position 5 of the "A" ring in flavones and flavanones) has a conflicting effect on the bond numbers: when passing from chalcone to flavanone, Nµ increases, and then, in flavone, sharply decreases. For C-8 of all flavone derivatives, Fµ ≥1. The following conclusion has been confirmed: at the initial stage of the reaction the electrophilic hydroxyl radical is attached at the C-8 position of the cinnamoyl fragment

scholarly journals Investigation of Inhibition Effect and Determination of Some Quantum Chemical Parameters of an Organic Compound on the Carbon Steel in Sulfuric Acid Medium

2015 ◽  
Vol 11 (8) ◽  
pp. 3804-3818
Author(s):  
Mohamad Javad Bahrami ◽  
M. Yazdizadeh ◽  
M. Shahidi ◽  
S.M.A. Hosseini
Keyword(s):  
Sulfuric Acid ◽  
Carbon Steel ◽  
Potentiodynamic Polarization ◽  
Quantum Chemical ◽  
Acid Ethyl Ester ◽  
Mulliken Charge ◽  
Chemical Parameters ◽  
Charge Densities ◽  
Sulfuric Acid Medium ◽  
Quantum Chemical Parameters

The inhibition ability of [3-(4-methyl-pyridin-2-y1)-4-oxo-2-phenylimino-thiazolidin-5-ylidene]-acetic acid ethyl ester (MOTAE) on the corrosion behavior of carbon steel in 0.5 M sulfuric acid solution was investigated using weight loss and potentiodynamic polarization techniques. The inhibition efficiencies increased as the concentration of the compound was increased. The calculated inhibition efficiencies from the investigated methods were in good agreement. Potentiodynamic polarization measurements indicate that MOTAE acts as a mixed type inhibitor. The adsorption of inhibitor on the steel surface obeys Langmuir adsorption isotherm. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM)‎ were used to characterize the surface of the alloy. The structure of inhibitor was optimized using three quantum chemical levels. Some quantum chemical parameters as well as Mulliken charge densities for this molecule were computed and discussed.

scholarly journals Molecular Geometry, Vibrational Spectroscopic, Molecular Orbital and Mulliken Charge Analysis of 4-(Carboxyamino)-Benzoic Acid: Molecular Docking and Dft Calculations

2021 ◽  
Author(s):  
S.N. Saravanamoorthy ◽  
B. Vasanthi ◽  
R. Poornima
Keyword(s):  
Molecular Docking ◽  
Benzoic Acid ◽  
Quantum Chemical ◽  
Chemical Reactivity ◽  
Normal Mode Analysis ◽  
Mode Analysis ◽  
Potential Energy Distribution ◽  
Mulliken Charge ◽  
Chemical Parameters ◽  
Quantum Chemical Parameters

Structure based biological and chemical properties of 4-(carboxyamino)-benzoic acid has been studied by quantum chemical methods. The revamped geometric structure and its quantum chemical parameters were obtained by DFT-B3LYP/6-311G method. Normal mode analysis is performed to assign the fundamental vibrational frequencies as per the potential energy distribution (PED) by using the VEDA program. Simulation of IR and Raman spectral patterns are observed by refinement of scale factors. TD-DFT approach is used to explore the excited states of molecule and prediction of electronic absorption spectra. NMR chemical shifts of the molecule are determined by the gauge independent atomic orbital method. The molecular docking is performed to recognize the binding energy of the ligand with the dynamic site of protein. In our docking analysis, the protein 5DT6 shows the best results than other three proteins which could be used for further analysis. Further inter and intra molecular interactions, electrophilic, nucleophilic and chemical reactivity sites are found by molecular electrostatic potential, HOMO-LUMO and Global chemical reactivity descriptors. Thermodynamic property of the title compound is also reported. The determined quantum chemical parameters show high reactivity and the dipole moment was sufficiently high enough to induce nonlinear characteristics which are required for applications in optoelectronic devices.

Correlation of electrochemical and quantum chemical data for reduction of halogen derivatives of benzene and biphenyl

1979 ◽  
Vol 44 (6) ◽  
pp. 1715-1725 ◽  
Author(s):  
Jaro Komenda ◽  
Pavel Janderka
Keyword(s):  
Quantum Chemical ◽  
Halogen Bond ◽  
Electrode Reaction ◽  
Electron System ◽  
Chemical Parameters ◽  
Reduction Potentials ◽  
Quantum Chemical Parameters ◽  
Derivatives Of ◽  
Hybrid Carbon ◽  
Quantum Chemical Data

Electrochemical splitting of the sp2 hybrid carbon-halogen bond was chosen as a typical example of an irreversible electrode reaction. It was shown in the series of chloro derivatives of benzene and biphenyl and bromo derivatives of benzene that the correlation of the electrochemical reduction potentials with the energies of the lowest unoccupied π-orbital are in these cases not physically grounded, whereas correlations with quantum-chemical parameters characterizing the carbon-halogen bond turned out to be real. Most suitable is the correlation with Wheland's localization energies calculated with the assumption of separating the carbon-halogen group from the total delocalized π-electron system in forming the transition state.

Sign in / Sign up

Export Citation Format

Share Document