Kinetics of the rapid reactions of the cobalt(II)-triethylenetetramine system with oxygen

Miller, F. W.; Wilkins, Ralph G.

doi:10.1021/ja00712a017

Cited by 34 publications

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“…[52] These species are interrelated as Co III À O 2 * can (possibly reversibly) bind to Co II molecules with one available coordination site, as shown for Co complexes in water. [54][55][56][57] Binuclear Co-peroxo complexes also form in DMF. [58] In the cited studies, the formation of peroxo-species was favored over the formation of superoxo-species.…”

Section: Discussionmentioning

confidence: 99%

Aerobic Epoxidation of Olefins Catalyzed by the Cobalt‐Based Metal–Organic Framework STA‐12(Co)

Beier

Kleist

Wharmby

et al. 2011

Chemistry A European J

115

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Section: Discussionmentioning

confidence: 99%

Aerobic Epoxidation of Olefins Catalyzed by the Cobalt‐Based Metal–Organic Framework STA‐12(Co)

Beier

Kleist

Wharmby

et al. 2011

Chemistry A European J

115

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“…Many of these complexes are soluble in aqueous solutions and are amenable for study by various spectroscopic probes (5)(6)(7). The most extensively studied have been cobalt(II) complexes of polyamines (8)(9)(10)(11)(12)(13), amino acids (8, [14][15][16], and dipeptide ligands (8,15,16) (6,17). Ligand X is a second bridging group, generally OH-or NH2 (11,15,18).…”

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Photodissociation of a (mu-peroxo)(mu-hydroxo)bis[bis(bipyridyl)-cobalt(III)] complex: a tool to study fast biological reactions involving O2.

MacArthur

Sucheta²,

Chong³

et al. 1995

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

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Upon photolysis at 355 nm, dioxygen is released from a (-peroxo)(,-hydroxo)bis[bis(bipyridyl)cobalt- (III)] complex in aqueous solutions and at physiological pH with a quantum yield of 0.04. The [Co(bpy)2(H20)z2+ (bpy = bipyridyl) photoproduct was generated on a nanosecond or faster time scale as determined by time-resolved optical absorption spectroscopy. A linear correspondence between the spectral changes and the oxygen production indicates that 02 is released on the same time scale. Oxyhemoglobin was formed from deoxyhemoglobin upon photodissociation of the (,iperoxo)(,u-hydroxo)bis[bis(bipyridyl)cobalt(III)I complex, verifying that dioxygen is a primary photoproduct. This complex and other related compounds provide a method to study fast biological reactions involving 02, such as the reduction of dioxygen to water by cytochrome oxidase.Many biological reactions involving dioxygen are so fast that studies by conventional stopped-flow techniques are impractical. Initiation of these and other fast reactions by photolysis offers a different approach. For example, the reaction of cytochrome c oxidase with dioxygen can be studied by a flow-flash method in which the reaction is initiated upon photodissociation of carbon monoxide (CO) bound to cytochrome a3 (1, 2). However, this method is potentially compromised by the fate of the photodissociated CO and, therefore, may not represent the physiological reaction of the enzyme under turnover conditions (3, 4). It is also not applicable to nonheme oxygen-activating systems. An alternative involves 02 production in situ by photodissociating synthetic caged dioxygen carriers. An ideal system would involve a direct source of dioxygen that does not react prematurely with the protein of interest but would release oxygen upon photodissociation on any relevant time scale. There should be no electrochemical or chemical reactions of the dioxygen carrier and its photoproduct with the protein, and interference from the photoproduct in the spectral region of the protein should be negligible. High solubility in aqueous solutions at physiological pH and high oxygen quantum yield are also desirable.Synthetic caged dioxygen carriers such as dicobalt ,u-peroxoor ,u-superoxo-bridged derivatives have the potential to fulfill the above requirements. Many of these complexes are soluble in aqueous solutions and are amenable for study by various spectroscopic probes (5-7). The most extensively studied have been cobalt(II) complexes of polyamines (8-13), amino acids (8, 14-16), and dipeptide ligands (8, 15, (11,15,18). The hydroxo bridge has been proposed to "lock in" the peroxo bridge, thereby shifting the equilibrium toward the oxygenated species (18). An advantage of the ,u-peroxo and ,-superoxo cobalt complexes is that such complexes have their major absorbances in the UV region. Therefore, electronic transitions of the protein in the visible region can be investigated without serious interference from transitions due to the cobalt complexes.Several studies of the photochemical...

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“…(8) und (9) verlaufen wahrscheinlich uber zwei weitere Addukte (7) CoIMEN(OH)+ + 0, [4] konnten jedoch keine derartigen Partikeln spektrophotometrisch direkt erfasst werden.…”

Section: Fig 1 Tztrationskurven Von 4 M Ht N'-his-(4-(5)-imidazounclassified

“…de 5 -10-6 mole$ de Hg2+, soit 1 ,ug/ml, en prCsence de 5 * lop4 moles/l d'organomercuriel, soit approxiniativement 2 mg/ml (prises initiales de 5-10 ml). [4] N. Lakhowa& W . Huerdi, Chimia25, 125 (1071).…”

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Reaktivität von Koordinationsverbindungen, XXIII [1]. Bildung und Zerfall des Sauerstoffadduktes mit N,N′‐Bis‐(4‐(5)‐imidazolylmethyl)‐äthylendiamin‐kobalt (II)‐Ionen

Zuberbühler¹,

Kaden²,

Koechlin³

1971

Helvetica Chimica Acta

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In aqueous solution N, N′‐bis‐(4‐(5)‐imidazolylmethyl)‐ethylenediamine‐cobalt (II) (CoIMEN2+) takes up molecular oxygen giving μ‐dioxygen‐μ‐hydroxo‐bis‐[N, N′‐bis‐(4‐(5)‐imidazolylmethyl)‐ethylenediamine]‐dicobalt (II). (Co IMEN)2 O2 (OH)3+ is exceptionally stable against irreversible autoxydation to CoIII species. Its absorption spectrum is very similar to that of the known analogous complex (CoTRIEN)2 O2 (OH)3+. The kinetics of formation and dissociation of (CoIMEN)2O2(OH)3+ are studied by spectrophotometry and with an oxygen specific electrode. The rate of the forward reaction is described by vf = [CoIMEN2+]2 · [O2] · (k1 + k2 · [OH−]) with k1 = 9 · 104 M−2 s−1 and k2 = 1 · 1012M−3 S−1, at 25° and I = 0,2. A mechanism including hydroxylated as well as nonhydroxylated intermediates is proposed. Dissociation is preceeded by protonation of the oxygen adduct. At pH 1–2 the rate of dissociation is independent of [H+] and follows first order kinetics: vD = k3 · [(CoIMEN)2O2(OH)3+] with k3 = 2.15 · 10−2 S−1.

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Kinetics of the rapid reactions of the cobalt(II)-triethylenetetramine system with oxygen

Cited by 34 publications

References 0 publications

Aerobic Epoxidation of Olefins Catalyzed by the Cobalt‐Based Metal–Organic Framework STA‐12(Co)

Aerobic Epoxidation of Olefins Catalyzed by the Cobalt‐Based Metal–Organic Framework STA‐12(Co)

Photodissociation of a (mu-peroxo)(mu-hydroxo)bis[bis(bipyridyl)-cobalt(III)] complex: a tool to study fast biological reactions involving O2.

Reaktivität von Koordinationsverbindungen, XXIII [1]. Bildung und Zerfall des Sauerstoffadduktes mit N,N′‐Bis‐(4‐(5)‐imidazolylmethyl)‐äthylendiamin‐kobalt (II)‐Ionen

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