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Singh B, Das RS. Studies on the oxidative degradation of paracetamol by a μ-oxo-diiron(III) complex. CAN J CHEM 2020. [DOI: 10.1139/cjc-2019-0193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In higher organisms, metalloenzymes like cytochrome P450, containing a Fe(III) metal center, play an active role in metabolism of paracetamol (APAP). Here, we have chosen a mimicking μ-oxo-diiron complex, [Fe(III)2(μ-O)(phen)4(H2O)2]4+(1, phen = 1,10-phenanthroline), to study spectrophotometrically the kinetics of the redox interactions with APAP. In acidic buffer media (pH = 3.4–5.1), APAP quantitatively reduces 1 following first-order reaction kinetics. Each molecule of 1 accepts two electrons from APAP and is reduced to ferroin [Fe(phen)3]2+. On oxidation, APAP produces N-acetyl-p-benzoquinone imine (NAPQI), which on hydrolysis results in a mixture of benzoquinone, quinone oxime, acetamide, and acetic acid. In reaction media due to successive deprotonations, 1 exists in equilibrium with the species [Fe(III)2(μ-O)(phen)4(H2O)(OH)]3+(1a) and [Fe(III)2(μ-O)(phen)4(OH)2]2+(1b) (pKa= 3.71 and 5.28, respectively). The kinetic analyses suggest for an unusual reactivity order as 1 < 1a ≫ 1b. The mechanistic possibilities suggest that although 1 is reduced by concerted electron transfer (ET) – proton transfer (PT) mechanism, 1a and 1b may be reduced by a concerted PT–ET mechanism where a slow proton-abstraction step is followed by a rapid ET process. It seems that the initial activation of the bridging μ-oxo group by a proton-abstraction results in the higher reactivity of 1a.
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Affiliation(s)
- Bula Singh
- Department of Chemistry, Visva-Bharati, Santiniketan 731235, India
| | - Ranendu Sekhar Das
- Department of Chemistry, Ranaghat College, Nadia, West Bengal 741201, India
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2
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Kerber WD, Perez KA, Ren C, Siegler MA. Speciation of Ferric Phenoxide Intermediates during the Reduction of Iron(III)−μ-Oxo Dimers by Hydroquinone. Inorg Chem 2014; 53:11507-16. [DOI: 10.1021/ic5014347] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- William D. Kerber
- Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania 17837, United States
| | - Kaitlyn A. Perez
- Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania 17837, United States
| | - Chuqiao Ren
- Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania 17837, United States
| | - Maxime A. Siegler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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Chakraborty M, Mandal PC, Mukhopadhyay S. Mechanistic studies on the oxidation of thiols by a {Mn4O6}4+ core in aqueous acidic media. Polyhedron 2012. [DOI: 10.1016/j.poly.2012.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Mandal PC, Das S, Mukhopadhyay S. Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn3O4}4+core in aqueous media. INT J CHEM KINET 2010. [DOI: 10.1002/kin.20488] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Mandal PC, Bhattacharyya J, Das S, Mukhopadhyay S, Kirschenbaum LJ. Mechanistic studies on the oxidation of pyruvic acid by an oxo-bridged diiron(III,III) complex in aqueous acidic media. Polyhedron 2009. [DOI: 10.1016/j.poly.2009.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Mishra R, Mukhopadhyay S, Banerjee R. Reaction of hydrogen peroxide with coordinated superoxide in [(NH3)5CoIII(micro-O2)CoIII(NH3)5]5+: a mechanistic study. Dalton Trans 2009:5469-73. [PMID: 19587989 DOI: 10.1039/b901280j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In aqueous acetate buffer media, hydrogen peroxide reduces the bridging superoxide in [(NH3)5CoIII(micro-O2)CoIII(NH3)5]5+ (1) to the corresponding peroxide in the complex, [(NH3)5CoIII(micro-O2H)CoIII(NH2)(NH3)4]4+ (2), itself being oxidized to HO2*. The complex 2 thus produced decomposes rapidly to the final products, CoII, NH3, etc. instead of reacting with a second molecule of hydrogen peroxide. In the presence of excess [H2O2] over (1), the reaction obeyed first-order kinetics and exhibited inverse proton dependence. [(NH3)5CoIII(micro-O2)CoIII((NH2)(NH3)4]4+ (3), a conjugate base of 1, seems to be the kinetically reactive species and the cause for the observed inverse proton dependence. Kinetics is little affected when one of the hydrogen atoms from hydrogen peroxide is replaced with an alkyl group, as in tert-butyl hydroperoxide. But replacement of both the H atoms with alkyl groups halts the reaction as seen with di-tert-butyl peroxides, and peroxodisulfate ion. The reaction rate with hydrogen peroxide significantly decreases with increasing proportion of D2O replacing water in the solvent and the rate-limiting step seems to be an H-atom transfer.
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Affiliation(s)
- Ritu Mishra
- Department of Chemistry, Jadavpur University, Kolkata, 700 032, India
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Das S, Bhattacharyya J, Mukhopadhyay S. Mechanistic studies on oxidation of hydrogen peroxide by an oxo-bridged diiron complex in aqueous acidic media. Dalton Trans 2008:6634-40. [DOI: 10.1039/b810011j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Das S, Mukhopadhyay S. Oxidation of N
III
and N
–I
by an {Mn
4
O
6
}
4+
Core in Aqueous Media: Proton‐Coupled Electron Transfer. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700363] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Suranjana Das
- Department of Chemistry, Jadavpur University, Calcutta 700 032, India
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Das S, Mukhopadhyay S. Mechanistic studies on oxidation of nitrite by a {Mn3O4}4+ core in aqueous acidic media. Dalton Trans 2007:2321-7. [PMID: 17534493 DOI: 10.1039/b702740k] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
[MnIV3(micro-O)4(phen)4(H2O)2]4+ (, phen=1,10-phenanthroline) equilibrates with its conjugate base [Mn3(micro-O)4(phen)4(H2O)(OH)]3+ in aqueous solution. Among the several synthetic multinuclear oxo- and/or carboxylato bridged manganese complexes known to date containing metal-bound water, to the best of our knowledge, only deprotonates (right harpoon over left harpoon+H+, pKa=4.00 (+/-0.15) at 25.0 degrees C, I=1.0 M, maintained with NaNO3) at physiological pH. An aqueous solution of quantitatively oxidises NIII (HNO2 and NO2-) to NO3- within pH 2.3-4.1, the end manganese state being MnII. Both and are reactive oxidants in the title redox. In contrast to a common observation that anions react quicker than their conjugate acids in reducing metal centred oxidants, HNO2 reacts faster than NO2- in reducing or . The observed rates of nitrite oxidation do not depend on the variation of 1,10-phenanthroline content of the solution indicating that the MnIV-bound phen ligands do not dissociate in solution under experimental conditions. Also, there was no kinetic evidence for any kind of pre-equilibrium replacement of MnIV-bound water by nitrite prior to electron transfer which indicates the substitution-inert nature of the MnIV-bound waters and the 1,10-phenanthroline ligands. The MnIV3 to MnII transition in the present observation proceeds through the intermediate generation of the spectrally characterised mixed-valent MnIIIMnIV dimer that quickly produces MnII. The reaction rates are substantially lowered when solvent H2O is replaced by D2O and a rate determining 1e, 1H+ electroprotic mechanism is proposed.
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Affiliation(s)
- Suranjana Das
- Department of Chemistry, Jadavpur University, Calcutta 700 032, India
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Bhattacharyya J, Das S, Mukhopadhyay S. Mechanistic studies on oxidation of l-ascorbic acid by an oxo-bridged diiron complex in aqueous acidic media. Dalton Trans 2007:1214-20. [PMID: 17353953 DOI: 10.1039/b615593f] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
[Fe2(micro-O)(phen)4(H2O)2]4+ (1) (Fig. 1, phen = 1,10-phenanthroline) equilibrates with [Fe2(micro-O)(phen)4(H2O)(OH)]3+ (2) and [Fe2(micro-O)(phen)4(OH)2]2+ (3) in aqueous solution in the presence of excess phen, where no phen-releasing equilibria from 1, 2 and 3 exist. 1 quantitatively oxidizes ascorbic acid (H2A) to dehydroascorbic acid (A) in the pH range 3.00-5.50 in the presence of excess phen, which buffers the reaction within 0.05 pH units and ensures complete formation of end iron product ferroin, [Fe(phen)3]2+. The reactive species are 1, 2 and HA- and the reaction proceeds through an initial 1 : 1 inner-sphere adduct formation between 1 and 2 with HA-, followed by a rate limiting outer-sphere one electron one proton (electroprotic) transfer from a second HA- to the ascorbate-unbound iron(III).
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Das S, Bhattacharyya J, Mukhopadhyay S. Mechanistic Studies on the Oxidation of Glyoxylic and Pyruvic Acid by a [Mn4O6]4+ Core in Aqueous Media: Kinetics of Oxo-Bridge Protonation. Helv Chim Acta 2006. [DOI: 10.1002/hlca.200690186] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Mukherjee R, Bijayi Dhar B, Banerjee R, Mukhopadhyay S. Kinetics of oxidation of phenylhydrazine by aμ-oxo diiron(III,III) complex in acidic aqueous media. J COORD CHEM 2006. [DOI: 10.1080/00958970500410614] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Ritam Mukherjee
- a Department of Chemistry , Jadavpur University , Calcutta 700 032, India
| | - Basab Bijayi Dhar
- a Department of Chemistry , Jadavpur University , Calcutta 700 032, India
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Mechanistic Studies on the Oxidation of Hydroquinone by an Oxo-bridged Diiron(III,III) Complex in Weakly Acidic Aqueous Media. TRANSIT METAL CHEM 2006. [DOI: 10.1007/s11243-005-6387-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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