Oxaziridine (C-CH3NO), C-CH2NO Radicals and Cl, NH2 and Methyl Derivatives of Oxaziridine; Structures and Quantum Chemical Parameters

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.

Download Full-text

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19791715 ◽

1979 ◽

Vol 44 (6) ◽

pp. 1715-1725 ◽

Cited By ~ 7

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.

Download Full-text

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

Pharmacy & Pharmacology ◽

10.19163/2307-9266-2020-8-2-112-123 ◽

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).

Download Full-text