Interaction of superoxide with water hexamer clusters

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

doi:10.1016/j.chemphys.2006.06.003

Cited by 15 publications

(12 citation statements)

References 56 publications

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“…This may account for the apparent stabilization of the oxygen complex in 3 and provides a plausible explanation for the selectivity of this catalyst. Despite the fact that free superoxide disproportionates in water at high concentrations (20,21), at low concentrations, superoxide under basic conditions has been spectroscopically identified as superoxide di-, tetra-, and hexa-hydrate clusters (22)(23)(24)(25)(26). This observation is supported by ab initio calculations (22)(23)(24)(25)(26).…”

Section: Resultssupporting

confidence: 67%

“…Despite the fact that free superoxide disproportionates in water at high concentrations (20,21), at low concentrations, superoxide under basic conditions has been spectroscopically identified as superoxide di-, tetra-, and hexa-hydrate clusters (22)(23)(24)(25)(26). This observation is supported by ab initio calculations (22)(23)(24)(25)(26). This is a surprising analogy with the oxygen complex of 3: (i) 4 molecules of water are found in the pocket surrounding the superoxide, (ii) the concentration of superoxide-bound porphyrin is low, and (iii) the network of hydrogen bonds are known to increase the basicity of water, a condition that is known to increase the kinetic stability of superoxide (27,28).…”

Section: Resultsmentioning

confidence: 99%

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Role of a distal pocket in the catalytic O ₂ reduction by cytochrome c oxidase models immobilized on interdigitated array electrodes

Collman

Decréau

Lin

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Five iron porphyrins with different superstructures were immobilized on self-assembled-monolayer (SAM)-coated interdigitatedarray (IDAs) gold-platinum electrodes. The selectivity of the catalysts i.e., limited formation of partially reduced oxygen species (PROS) in the electrocatalytic reduction of dioxygen, is a function of 2 rates: (i) the rate of electron transfer from the electrode to the catalyst, which is controlled by the length, and conjugation of the linker from the catalyst to the electrode and (ii) the rate of bound oxygen (superoxide) hydrolysis, which correlates with the presence of a water cluster in the gas-binding pocket influencing the rate of oxygen binding; these factors are controlled by the nature of the porphyrin superstructure. The structurally biomimetic Trisimidazole model is the most selective.electron transfer rate ͉ oxygen binding rates ͉ water cluster ͉ oxygen complex stabilization ͉ partially reduced oxygen species A recent report showed that water may inhibit oxygen binding in hemoprotein models (1). This echoes the ''water displacement model'' proposed for oxygen binding in myoglobin (2-4). This finding is relevant to cytochrome c oxidase (CcO) for 2 reasons: (i) CcO binds and reduces oxygen to form water (5) and (ii) the hydrolysis of the oxygen complex in CcO and in other enzymes is an issue and occurs when water, protons, and electrons are present (6, 7). This reaction releases partially reduced oxygen species (PROS) that are toxic to organisms (Fig. 1). The study herein examines the formation of PROS during the electrocatalytic reduction of oxygen by several site-isolated CcO models ( Fig. 2) as a function of (i) the oxygen association rate [k on (O 2 )] and the rate of hydrolysis, both associated with the presence of water in the gas binding pocket, and (ii) the availability of electrons at the oxygen reduction site associated with the rate of electron arrival from the electrode to the catalyst [k(eT)] and/or the presence of redox active species in the vicinity of the heme. The latter aspects were specifically addressed in previous studies by immobilizing the active-site models onto self-assembled-monolayer (SAM)-coated rotating ring disk gold electrodes (RRDE) (8-10): k(eT) was controlled by the length and conjugated character of the linker between the catalyst and the gold electrode, and immobilization allowed site isolation. To get better collection efficiencies for the detection of PROS and to prevent damage to the SAM associated with high rotation rates, the present study used Au-Pt interdigitated array electrodes (IDAs). The collection efficiency of these IDA electrodes is in the 65-90% range as compared with Ͻ20% in RRDE (8).IDAs have 2 sets of alternating arrays of electrodes. The electrode widths and spacing are on similar dimensions, and this distance is within diffusion layers for typical electroactive species in solution. This results in diffusion gradients of adjacent microband electrodes that overlap with each other. Redox products created at the Au generator ...

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Section: Resultssupporting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Role of a distal pocket in the catalytic O ₂ reduction by cytochrome c oxidase models immobilized on interdigitated array electrodes

Collman

Decréau

Lin

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…The resulting species, O 2 À (superoxide ion), rapidly hydrates and may take up several water molecules depending on relative humidity and temperature. [9][10][11] Using mass spectrometry, the reactivity of O 2 À (H 2 O) n with several atmospheric trace gases, including SO 2 , has been studied by several groups, all finding that the reaction rate of…”

Section: Introductionmentioning

confidence: 99%

On the gas-phase reaction between SO₂ and O₂⁻(H₂O)_0–3 clusters – an ab initio study

Tsona

Bork

Vehkamäki

2014

Phys. Chem. Chem. Phys.

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We present an ab initio investigation of the gas-phase reaction between SO2 and a O2(-)(H2O)n molecular cluster, n = 0-3. The associative product cluster, O2SO2(-)(H2O)n, is formed with high energy gain although the binding energies decrease with increasing hydration. About 54 kcal mol(-1) may be gained by isomerization of O2SO2(-)(H2O)n to the sulfate radical, SO4(-)(H2O)n, but a high energy barrier separates the two states. Although the isomerization is catalysed by the presence of a second SO2 molecule, the formation of SO4(-)(H2O)nvia O2(-)(H2O)n and SO2 is found to be negligible under atmospheric conditions. At thermal equilibration at 298.15 K and 50% relative humidity the end products are mainly O2SO2(-) and O2SO2(-)(H2O)1.

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“…Seta et al reported a density functional theory (DFT) study of the structures of O 2 – (H 2 O) n , with n = 1–4 clusters . Antonchenko et al studied the structural, energetic, and spectroscopic features for O 2 – (H 2 O) 1–4 and O 2 – (H 2 O) 6 . Li et al.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Molecular Dynamics Investigation of the Electronic and Structural Stability of Anionic O₂^–(H₂O)_n, n = 1–16 Clusters

et al. 2019

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We report an ab initio molecular dynamics investigation of the electronic and structural stability of water molecules binding to a nucleation O2 – particle, O2 –(H2O) n with n = 1–16, to ascertain the factors that create particularly stable species. Our results compare well with previous experimental and theoretical reports for clusters with less water content, find three new geometries for species with 7, 9, and 10 water molecules, and determine that 8, 11, 13, and 15 water molecules form remarkably stable structures around O2 –. These special clusters correspond to well-defined compact structures formed by cubes and four-member rings made of water’s hydrogen bonds interacting with a negative kernel formed by O2 – with five water molecules, O2 –(H2O)5, in which the negative charge is localized in the first four water molecules, while the fifth molecule provides geometrical stability. We assess the clusters’ energetic stability based on dissociation energies, analyze electron detachment energies to understand its geometrical evolution, and investigate its charge distribution based upon isosurfaces of the highest occupied molecular orbital (HOMO). This research can help provide theoretical insight into the starting steps of nucleation of water clusters around ionic particles.

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Interaction of superoxide with water hexamer clusters

Cited by 15 publications

References 56 publications

Role of a distal pocket in the catalytic O ₂ reduction by cytochrome c oxidase models immobilized on interdigitated array electrodes

Role of a distal pocket in the catalytic O ₂ reduction by cytochrome c oxidase models immobilized on interdigitated array electrodes

On the gas-phase reaction between SO₂ and O₂⁻(H₂O)_0–3 clusters – an ab initio study

Ab Initio Molecular Dynamics Investigation of the Electronic and Structural Stability of Anionic O₂^–(H₂O)_n, n = 1–16 Clusters

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Interaction of superoxide with water hexamer clusters

Cited by 15 publications

References 56 publications

Role of a distal pocket in the catalytic O 2 reduction by cytochrome c oxidase models immobilized on interdigitated array electrodes

Role of a distal pocket in the catalytic O 2 reduction by cytochrome c oxidase models immobilized on interdigitated array electrodes

On the gas-phase reaction between SO2 and O2−(H2O)0–3 clusters – an ab initio study

Ab Initio Molecular Dynamics Investigation of the Electronic and Structural Stability of Anionic O2–(H2O)n, n = 1–16 Clusters

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Role of a distal pocket in the catalytic O ₂ reduction by cytochrome c oxidase models immobilized on interdigitated array electrodes

Role of a distal pocket in the catalytic O ₂ reduction by cytochrome c oxidase models immobilized on interdigitated array electrodes

On the gas-phase reaction between SO₂ and O₂⁻(H₂O)_0–3 clusters – an ab initio study

Ab Initio Molecular Dynamics Investigation of the Electronic and Structural Stability of Anionic O₂^–(H₂O)_n, n = 1–16 Clusters