Structural, Energetic, and Spectroscopic Features of Lower Energy Complexes of Superoxide Hydrates O2-(H2O)1-4

Antonchenko, V.Ya.; Kryachko, Eugene S.

doi:10.1021/jp046498z

Cited by 19 publications

(15 citation statements)

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“…− (H 2 O) m , 10,12,13 supported by theoretical studies, 14,15 showed that all species with n ≥ 2 form an O 4 − core anion. The relatively high binding energy of O 2 to O 2 − (0.455 ± 0.22 eV) (Ref.…”

Section: Introductionmentioning

confidence: 79%

Oxygen cluster anions revisited: Solvent-mediated dissociation of the core O4− anion

Khuseynov

Goebbert

Sanov

2012

The Journal of Chemical Physics

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The electronic structure and photochemistry of the O(2n)(-)(H(2)O)(m), n = 1-6, m = 0-1 cluster anions is investigated at 532 nm using photoelectron imaging and photofragment mass-spectroscopy. The results indicate that both pure oxygen clusters and their hydrated counterparts with n ≥ 2 form an O(4)(-) core. Fragmentation of these clusters yields predominantly O(2)(-) and O(2)(-)·H(2)O anionic products, with the addition of O(4)(-) fragments for larger parent clusters. The fragment autodetachment patterns observed for O(6)(-) and larger O(2n)(-) species, as well as some of their hydrated counterparts, indicate that the corresponding O(2)(-) fragments are formed in excited vibrational states (v ≥ 4). Yet, surprisingly, the unsolvated O(4)(-) anion itself does not show fragment autodetachment at 532 nm. It is hypothesized that the vibrationally excited O(2)(-) is formed in the intra-cluster photodissociation of the O(4)(-) core anion via a charge-hopping electronic relaxation mechanism mediated by asymmetric solvation of the nascent photofragments: O(4)(-) → O(2)(-)(X(2)Π(g)) + O(2)(a(1)Δ(g)) → O(2)(X(3)Σ(g)(-)) + O(2)(-)(X(2)Π(g)). This process depends on the presence of solvent molecules and leads to vibrationally excited O(2)(-)(X(2)Π(g)) products.

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Section: Introductionmentioning

confidence: 79%

Oxygen cluster anions revisited: Solvent-mediated dissociation of the core O4− anion

Khuseynov

Goebbert

Sanov

2012

The Journal of Chemical Physics

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“…A number of theoretical works have investigated the properties of solvated superoxide. A number of these studies focusing on the O 2 − ͑H 2 O͒ m clusters 25,26 have indicated that water forms a single hydrogen bond with the O 2 − core, leaving a free O-H group, which tends to form hydrogen bonds with adjacent water molecules in the larger hydrates. This structural motif has been confirmed by gas-phase infrared spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…20 For comparison, the O 2 − · · HOH bond lengths in O 2 − ͑H 2 O͒ is calculated to be 1.702 Å. 26 The shorter bond length in hydrated superoxide compared to O 4 − reflects the relative magnitudes of the binding energies for the two clusters.…”

Section: Introductionmentioning

confidence: 99%

Photodetachment, photofragmentation, and fragment autodetachment of [O2n(H2O)m]− clusters: Core-anion structures and fragment energy partitioning

Goebbert

Sanov

2009

The Journal of Chemical Physics

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Articles you may be interested inOxygen cluster anions revisited: Solvent-mediated dissociation of the core O4 − anion Photodetachment and photofragmentation pathways in the [ ( C O 2 ) 2 ( H 2 O ) m ] − cluster anionsBuilding on the past studies of the O 2n − and O 2 − ͑H 2 O͒ m cluster anion series, we assess the effect of the strong hydration interactions on the oxygen-core clusters using photoelectron imaging and photofragment mass spectroscopy of ͓O 2n ͑H 2 O͒ m ͔ − ͑n =1-4, m =0-3͒ at 355 nm. The results show that both pure-oxygen and hydrated clusters with n Ն 2 form an O 4 − core anion, indicated in the past work on the pure-oxygen clusters. All clusters studied can be therefore described in terms of O 4 − ͑H 2 O͒ m ͑O 2 ͒ n−2 structures, although the O 4 − core may be strongly perturbed by hydration in some of these clusters. Fragmentation of these clusters yields predominantly O 2 − and O 2 − ͑H 2 O͒ l ͑l Ͻ m͒ anionic products. The low-electron kinetic energy O 2 − autodetachment features, prominent in the photoelectron images, signal that the fragments are vibrationally excited. The relative intensity of photoelectrons arising from O 2 − fragment autodetachment is used to shed light on the varying degree of fragment excitation resulting from the cluster fragmentation process depending on the solvent conditions. − fragment autodetachment, are labeled a-d, in order of decreasing electron binding energy. 104308-3Photodetachment of superoxide clusters

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“…Free radicals form in biological reactions in living cells [1], but some external factors such as radiation, pollutants, physical stress, pesticides, several treatments etc. also cause its formation [2]. The highly reactive free radicals can initiate chain reactions interacting with proteins, lipids and DNA, and thereby damage the tissues [3].…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigations on the antioxidant potential of a non-phenolic compound thymoquinone: a DFT approach

2021

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Thymoquinone (TQ) is a natural compound occurred in black cumin (Nigella sativa L.), which possesses potent antioxidant activity without having any phenolic hydroxyl group believed to be responsible for antioxidant activity of a molecule. In the present study, computational calculation based on Density Functional Theory (DFT) have been executed to assess systematically the worth of antioxidant behavior of this compound. Geometrical characteristics, HOMO-LUMO and MEP surface have been studied. Thermochemical parameters correlated to the leading antioxidant mechanisms such as HAT, SETPT and SPLET have been studied in gas and water media. In addition, the changes of thermochemical parameters such as ∆G and ∆H have been computed for HA from TQ to hydroxyl radical in gas and water phases to investigate its free radical scavenging potency. The low and comparable values of BDE, PDE, IP, PA and ETE suggest the antioxidant activity. The ∆G and ∆H also convey apposite thermodynamic evidence in favor of antiradical capability of TQ. The attack of the free radical takes place preferentially at 3CH position of the molecule.

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Structural, Energetic, and Spectroscopic Features of Lower Energy Complexes of Superoxide Hydrates O₂^-(H₂O)_1-4

Cited by 19 publications

References 50 publications

Oxygen cluster anions revisited: Solvent-mediated dissociation of the core O4− anion

Oxygen cluster anions revisited: Solvent-mediated dissociation of the core O4− anion

Photodetachment, photofragmentation, and fragment autodetachment of [O2n(H2O)m]− clusters: Core-anion structures and fragment energy partitioning

Theoretical investigations on the antioxidant potential of a non-phenolic compound thymoquinone: a DFT approach

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