Collector properties of new flotation reagent Z-96

Marković, Zoran; Stanojlovic, Rodoljub; Milenkovic, G.; Petkovic, Z.

doi:10.1016/s0167-4528(00)80070-8

Cited by 5 publications

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“…39 In water, the energy values of proton H(H + ) and of electron H(e À ) were À235.3 and À23.9 kcal mol À1 , respectively; calculation method was previously reported. 40 In order to evaluate the inuence of chemical nature of free radicals on the antioxidant potential of the studied compounds vs. representative radicals such as HOOc, the standard Gibbs free energies of the reaction (D r G 0 ) were calculated for HAT, PL, RAF and SET mechanisms according to the (R4)-(R7) reactions (( 4)-( 7)). The HOc radical scavenging reactions were similarly obtained.…”

Section: Proton Transfer (Pt)mentioning

confidence: 99%

Antioxidant and UV-radiation absorption activity of aaptamine derivatives – potential application for natural organic sunscreens

et al. 2021

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Section: Proton Transfer (Pt)mentioning

confidence: 99%

Antioxidant and UV-radiation absorption activity of aaptamine derivatives – potential application for natural organic sunscreens

et al. 2021

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“…The reaction enthalpy of the first step corresponds to the proton affinity (PA) of the phenoxide anion ArO − . The reaction enthalpy of the second step is denoted as electron transfer enthalpy, (ETE), [ 48,49 ] where PA and ETE are calculated using Equations –.

italicArOH \to {ArO}^{-} + H^{+}

italicPA = H_{{italicArO}^{-}} + H_{H^{+}} - H_{ArOH}

{ArO}^{-} \to {ArO}^{•} + e^{-}

italicETE = H_{{italicArO}^{•}} + H_{e^{-}} - H_{{italicArO}^{-}}

The fact that the main mechanism of the radical scavenging activity of CAP is still elusive is another motivation of this work.…”

Section: Methodsmentioning

confidence: 99%

DFT insights into the structure, reactivity and radical scavenging activity of cycloartocarpesin

Fouégué

Tedongmo

Ntieche

et al. 2021

J of Physical Organic Chem

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Daily increase in the number of patients suffering from illnesses due to reactive species has induced the permanent discovery and study of antioxidant compounds. The structure, reactivity, and antioxidant activity (AOA) of a phenolic compound named cycloartocarpesin (CAP), evaluated at DFT/B3LYP/6‐31 + G(d,p) level, is reported herein in the gas, pentyl ethanoate, and water phases. Bader topological analysis revealed that two of the three O‐H groups of CAP are involved in hydrogen bonds while the average local ionization energy (ALIE) and appropriate Fukui functions showed that electrons in the near vicinity of C7, C10, and C12 are the least tightly held and can easily be attacked by radicals. Analysis of the transition state of the reaction between CAP and HOO• radical shows that the proton coupled electron transfer process is not favored. Moreover, analyses of electronic spectra calculated at TD‐DFT/B3LYP/6‐31 + G(d,p) has interestingly demonstrate the ability of CAP to filtrate UVA, UVB, and UVC, thus exhibiting a photo‐protective activity.

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“…The enthalpies of the hydrogen atom, proton, and electron in vacuum and in water are taken from the literature [ 22 ] : the used proton enthalpy (Н (Н + ) ) in vacuum is 6.197 kJ/mol and in water is −1083.803 kJ/mol; the used enthalpy of an electron (H (e¯) ) in vacuum is 3.145 kJ/mol and in water is −232.676 kJ/mol; and the used enthalpy of a hydrogen atom (H (H˙) ) in vacuum is −1312.479 kJ/mol and in water is −1316.479 kJ/mol. The updated enthalpy values for an electron and a proton in aqueous solution suggested by Markovic et al [ 23 ] invoke no change in the trendlines established, so we will adhere to the values reported by Klein et al [ 22 ] in order to allow comparison with earlier results on analogous systems. [ 24 ] As the main objective of the paper is to reveal the structural origin of the radical‐scavenging proclivity of the isomers, no comparison between the calculated and experimentally evaluated enthalpies is attempted.…”

Section: Computational Protocolmentioning

confidence: 96%

Topology delimited radical‐scavenging propensity of monohydroxycinnamic acids

Borislavov

Velkov

Tadjer

2020

Int J of Quantum Chemistry

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Hydroxyl derivatives of cinnamic acid, both natural and synthetic, are well-known radical scavengers. However, not all of them feature the same radical-scavenging propensity. Establishing the relatinship between the structure of those species and their reactivity toward radicals plays a crucial role in the design of novel antioxidant pharmaceuticals founded on the same parent structure. This study aims to clarify, in a systematic and comprehensive way, the relationship between topology, geometry, and electron and spin density distribution on the one hand and the radical-scavenging activity on the other. Different mechanisms are discussed based on the enthalpies of the possible structures generated in the process of dissociation of the OH bonds. All structures are modeled utilizing the first principles methods and accounting for the polar medium (water) at neutral pH (B3LYP/6-311++G**/PCM). A hybrid mechanism is suggested, applicable not only to hydroxylated cinnamic acids but to phenolic acids in a polar environment in general.

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Collector properties of new flotation reagent Z-96

Cited by 5 publications

References 0 publications

Antioxidant and UV-radiation absorption activity of aaptamine derivatives – potential application for natural organic sunscreens

Antioxidant and UV-radiation absorption activity of aaptamine derivatives – potential application for natural organic sunscreens

DFT insights into the structure, reactivity and radical scavenging activity of cycloartocarpesin

Topology delimited radical‐scavenging propensity of monohydroxycinnamic acids

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