antioxidants are compounds which can prevent biological and chemical substances from oxidative damage by reactive oxygen species. flavonoids are the most important class of polyphenolic compounds that because of their antioxidant characters possess biological activities and pharmacological effects. chrysin-6-c-fucopyranoside and chrysin-3-malonyl-6-c-fucopyranoside are mono c-glycosyl derivativ...

antioxidants are made for the struggle and reconstruction of the damaged cells, because of their ability in destroying the free radicals. on account of their importance, a theoretical procedure was applied for the study of the molecular structure and radical scavenging activity of six hydroxyphenols which have been introduced as antioxidant compounds. all geometry structures were optimized by m...

The bond dissociation energy (enthalpy) is also referred to as bond disruption energy, bond energy, bond strength, or binding energy (abbreviation: BDE, BE, or D) . It is defined as the standard enthalpy change of the following fission: R−X → R + X . The BDE, denoted by Do(R−X), is usually derived by the thermochemical equation, Do(R−X) = ∆fH o(R) + ∆fH o(X) – ∆fH o(RX) . The enthalpy of format...

Quantum chemical calculations at the B3LYP/6-31G* level of theory were employed for the structure-activity relationship and prediction of the antioxidant activity of edaravone and structurally related derivatives using energy (E), ionization potential (IP), bond dissociation energy (BDE), and stabilization energies (ΔE(iso)). Spin density calculations were also performed for the proposed antiox...

Collision-induced dissociation (CID) rates are measured for a suite of lanthanide (plus yttrium) monoxide ions stored in a quadrupole ion trap. Yttrium, neodymium, and gadolinium oxides, having the same nominal dissociation energy (D0 ≈ 735 kJ mol−1) but different masses, provide an empirical correction of −1.2 s−1 amu−1 for the measured CID rates. The CID rate correction enables the correlatio...

Nickel silicide has been studied with a range of computational methods to determine the nature of the Ni-Si bond. Additionally, the physical effects that need to be addressed within calculations to predict the equilibrium bond length and bond dissociation energy within experimental error have been determined. The ground state is predicted to be a (1)Σ(+) state with a bond order of 2.41 correspo...

The strength of the O-O bond is of fundamental importance in a variety of chemical processes. Traditionally, a value of 34 kcal/mol has been ascribed to a generic O-O bond dissociation energy. The present, high-level ab initio calculations indicate that the average O-O bond energy is significantly higher, ca. 45 kcal/mol, and that the bond energy is sensitive to the bonding environment. Calcula...

We apply a combination of state-of-the-art experimental and quantum-chemical methods to elucidate the electronic and chemical energetics of hydrogen adduction to a model open-shell graphene fragment. The lowest-energy adduct, 1H-phenalene, is determined to have a bond dissociation energy of 258.1 kJ mol-1, while other isomers exhibit reduced or in some cases negative bond dissociation energies,...

the present study is to study linear free energy relationships (lfers) for dechlorination ratesin cement/fe(ii) slurries of eight chlorinated hydrocarbons including carbon tetrachloride, chloroform produced from carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene produced from 1,1,2,2-tetrachloroethane, tetrachloroethylene, trichloroethylene, 1,1-dichloroethylene, and vinyl chloride,...

Isotopic effects on the formation and dissociation kinetics of hydrogen bonds are studied in real time with ultrafast chemical exchange spectroscopy. The dissociation time of hydrogen bond between phenol-OH and p-xylene (or mesitylene) is found to be identical to that between phenol-OD and p-xylene (or mesitylene) in the same solvents. The experimental results demonstrate that the isotope subst...