scholarly journals Theoretical Study about the Effect of Halogen Substitution on the Reactivity of Antitumor 3-Formylchromones and Their Free Radicals

2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
Maximiliano Martínez-Cifuentes ◽  
Boris Weiss-López ◽  
Ramiro Araya-Maturana
Keyword(s):  
Free Radicals ◽  
Hydrogen Atom ◽  
Gas Phase ◽  
Theoretical Study ◽  
Computational Study ◽  
Bond Dissociation Enthalpy ◽  
Radical Species ◽  
Anticancer Compounds ◽  
Dissociation Enthalpy ◽  
Polarizable Continuum

The mandatory presence of a chlorine atom on the aromatic ring of 6-hydroxy-3-formyl angular chromones, on the respiration inhibition of mammary carcinoma mouse, is explained through a computational study of these compounds. This study analyzes the reactivity of the neutral molecules and their free radicals, in gas phase and with water solvation, incorporated by the polarizable continuum medium (PCM) approach. Electrophilic reactivities were evaluated using Fukui (f+) and Parr (P+) functions. The stabilities of radical species formed by the abstraction of a hydrogen atom from the O-H bond were evaluated by bond dissociation enthalpy (BDE) and spin density (SD) calculations. This study has potential implications for the design of chromone analogues as anticancer compounds.

2-Deoxyribose Radicals in the Gas Phase and Aqueous Solution. Transient Intermediates of Hydrogen Atom Abstraction from 2-Deoxyribofuranose

2005 ◽  
Vol 70 (11) ◽  
pp. 1769-1786 ◽  
Author(s):  
Luc A. Vannier ◽  
Chunxiang Yao ◽  
František Tureček
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Atom ◽  
Gas Phase ◽  
Computational Study ◽  
Hydrogen Atom Abstraction ◽  
Oh Radical ◽  
Free Energies ◽  
Intramolecular Hydrogen ◽  
Solvation Free Energies ◽  
Transient Intermediates

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.

Adenine Radicals in the Gas Phase:  An Experimental and Computational Study of Hydrogen Atom Adducts to Adenine

2005 ◽  
Vol 109 (36) ◽  
pp. 8121-8132 ◽  
Author(s):  
Xiaohong Chen ◽  
Erik A. Syrstad ◽  
Minh Tho Nguyen ◽  
Pascal Gerbaux ◽  
František Tureček
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Computational Study

Comparison of the selectivity of [M(12-Crown-4)]+ (M=Li+, Na+, K+) complexes for halide anions and some neutral molecules; a computational study

2015 ◽  
Vol 14 (08) ◽  
pp. 1550057 ◽  
Author(s):  
Faranak Dastineh ◽  
Sadegh Salehzadeh ◽  
Mehdi Bayat ◽  
Yazdan Maghsoud
Keyword(s):  
Interaction Energy ◽  
Gas Phase ◽  
High Selectivity ◽  
Theoretical Study ◽  
Computational Study ◽  
Decomposition Analysis ◽  
Interaction Energies ◽  
Halide Anions ◽  
Bonding Interaction ◽  
M 12

A theoretical study on the selectivity of a series of [M(12C4)][Formula: see text] (M = Li[Formula: see text], Na[Formula: see text], K[Formula: see text], 12C4 = 12-crown-4) complexes for F[Formula: see text], Cl[Formula: see text] and Br[Formula: see text] anions and a number of neutral molecules (CH3CN, CH3OH, NH3, H2O, py, and 12C4) is reported. At first, it was shown that in the gas phase among all studied halide anions and neutral molecules, halides have much more bonding interaction with all [M(12C4)][Formula: see text] cations. Calculated interaction energies of above anions and [M(12C4)][Formula: see text] cations decrease from F[Formula: see text] to Br[Formula: see text]. Also the interaction energy of halide anions with [M(12C4)][Formula: see text] complexes, decreases from [Li(12C4)][Formula: see text] to [K(12C4)][Formula: see text]. The electron decomposition analysis showed that the bond between [M(12C4)][Formula: see text] complexes and both the neutral and anion guests is mainly electrostatic in nature. Then the selectivity of [M(12C4)][Formula: see text] complexes for studied anions and neutral molecules are compared in methanol, acetone, acetonitrile, and nitromethane solutions. It was shown that both the desolvation process of reactants and the strength of host–guest interactions have significant effect on the selectivities. Thus the selectivity of [Li(12C4)][Formula: see text] cation for NH3and H2O neutral molecules in solution, in contrast to the gas phase, is higher than that for bromide anion. The results of calculations showed that all [M(12C4)][Formula: see text] complexes, specially [Li(12C4)][Formula: see text], have high selectivity for F[Formula: see text] over other halide anions and neutral molecules.

scholarly journals Gallic acid: thermodynamics of the homolytic and heterolytic phenolic O—H bonds splitting-off

2016 ◽  
Vol 9 (2) ◽  
pp. 114-123
Author(s):  
Peter Škorňa ◽  
Martin Michalík ◽  
Erik Klein
Keyword(s):  
Gallic Acid ◽  
Gas Phase ◽  
Bond Dissociation Enthalpy ◽  
Carboxylic Group ◽  
Proton Affinities ◽  
Dissociation Enthalpy ◽  
Proton Dissociation ◽  
Pcm Model ◽  
Antioxidant Potency ◽  
Primary Antioxidant

Abstract The DFT study of primary antioxidant action of gallic acid and its carboxylic anion is presented in the gas-phase, benzene and water. Corresponding reaction enthalpies for three possible mechanisms was calculated using B3LYP/6-311++G** method. Bond dissociation enthalpy (BDE) and proton dissociation enthalpy (PDE) of 4-OH group was found to be the lowest in gas-phase as well as in both solvents approximated by IEF-PCM model. Ionization potentials (IPs) were higher than BDEs in all cases. Deprotonation of carboxylic group result in increased antioxidant potency as drop in BDE, proton affinities (PAs) and IPs was indicated in all environments.

Predicting the substituent and solvent effects on the radical scavenger activity of ethoxyquin derivatives: a DFT/B3LYP study

2013 ◽  
Vol 91 (6) ◽  
pp. 457-464
Author(s):  
Mohammad Najafi ◽  
Meysam Najafi ◽  
Malihe Najafi
Keyword(s):  
Ionization Potential ◽  
Gas Phase ◽  
Proton Affinity ◽  
Hydrogen Atom Transfer ◽  
Radical Scavenger ◽  
Bond Dissociation Enthalpy ◽  
Bond Dissociation ◽  
Dissociation Enthalpy ◽  
Radical Scavenger Activity ◽  
Scavenger Activity

The radical scavenger activity of X1- and X2-substituted ethoxyquin derivatives has been investigated in the gas phase and water. The reaction enthalpies of radical scavenger activity of the studied derivatives have been calculated and compared with corresponding values of ethoxyquin. Results show that electron-withdrawing group substituents increase the bond dissociation enthalpy and ionization potential, while electron-donating group substituents cause a rise in the proton affinity. The ethoxyquin derivatives with the lowest bond dissociation enthalpy, ionization potential, and proton affinity values were identified as the compounds with high radical scavenger activity. Results show that the substituents in the X1 position have high potential for synthesis of novel ethoxyquin derivatives. Results show that ethoxyquin derivatives can process their protective role via hydrogen atom transfer and sequential proton loss electron transfer mechanisms in the gas phase and solvent, respectively. The calculated reaction enthalpies of the substituted ethoxyquins have linear dependences with Hammett constants and energy of the highest occupied molecular orbital that can be utilized in the selection of suitable substituents for the synthesis of novel radical scavengers based on ethoxyquin.

scholarly journals Theoretical Study of O-CH3 Bond Dissociation Enthalpy in Anisole Systems

ACS Omega ◽  
2021 ◽  
Author(s):  
Rui Li ◽  
Tianshu Du ◽  
Jingxing Liu ◽  
Adelia J. A. Aquino ◽  
Jianyu Zhang
Keyword(s):  
Theoretical Study ◽  
Bond Dissociation Enthalpy ◽  
Bond Dissociation ◽  
Dissociation Enthalpy

scholarly journals THERMOCHEMICAL PARAMETERS OF ERGOTHIONEINE: A DFT STUDY USING M06, WB97XD AND TPSSTPSS METHODS

2018 ◽  
Vol 54 (2C) ◽  
pp. 299
Author(s):  
Chinh Thi Ngo
Keyword(s):  
Gas Phase ◽  
Antioxidant Properties ◽  
Basis Set ◽  
Bond Dissociation Enthalpy ◽  
Single Electron Transfer ◽  
Dft Methods ◽  
Dissociation Enthalpy ◽  
Proton Dissociation ◽  
B3lyp Method ◽  
Thermochemical Parameters

Antioxidant properties of ergothioneine (ESH) have been investigated via hydrogen atomtransfer (HAT), single electron transfer-proton transfer (SET-PT) and sequential proton losselectron transfer (SPLET) mechanisms. Three new DFT methods including M06, WB97XD andTPSSTPSS at the 6-311++G(2df,2p) basis set were used to compute the thermochemicalparameters of ESH in the gas phase. Based on these methods, bond dissociation enthalpy (BDE),ionization energy (IE), proton dissociation enthalpy (PDE), proton affinity (PA) and electrontransfer enthalpy (ETE) were calculated. The results were also compared with the valuesobtained by B3LYP method. The calculated results show that ergothioneine plays a role as apotential antioxidant via HAT mechanism.

scholarly journals Calculated antioxidant activity of selected phenolic compounds

2018 ◽  
Vol 96 (3) ◽  
pp. 345-350
Author(s):  
Sandra Cotes ◽  
José Cotuá ◽  
Amner Muñoz
Keyword(s):  
Antioxidant Activity ◽  
Dipole Moment ◽  
Phenolic Compounds ◽  
Data Visualization ◽  
Basis Set ◽  
Bond Dissociation Enthalpy ◽  
Radical Species ◽  
Dissociation Enthalpy ◽  
Highest Occupied Molecular Orbital

Determination of the corresponding bond dissociation enthalpy, ionization potential and proton affinity, dipole moment values, highest occupied molecular orbital eigenvalues, and spin density along with the bioactivity score is central to the antioxidant activity evaluation in this paper. Molecular geometries were optimized with DFT using B3LYP and UB3LYP for parent, ionic, and radical species and 6-311+G(d,p) basis set. Bioactivity, drug likeness, and drug scores were calculated using freely available cheminformatics programs for data visualization and analysis. Overall, the values revealed two structures as promising molecules because of good reaction enthalpies (ΔHr). Lipinski rules were fully satisfied for all molecules.

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