Model compounds for microbial iron-transport compounds. Part IV. Further solution chemistry and Mössbauer studies on iron(II) and iron(III) catechol complexes

Hider, Robert C.; Howlin, Brendan J.; Miller, John R.; Mohd-Nor, A.Rahim; Silver, Jack

doi:10.1016/s0020-1693(00)91261-1

Cited by 44 publications

(23 citation statements)

References 19 publications

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“…gallates, pirogallates and plant extracts) [11,23,24]. Mössbauer parameters at 80 K are very close to the blue complex of catechol-iron (II) determined from freeze-dried solutions of pH 5.4, and the predominant green complex at pH of 2.9 [25]. These Mössbauer parameters refer to a kind of Fe 2+ in a distorted octahedral environment, in which ferrous ion is bound by dative bonds to phenolic oxygen atoms forming a complex of iron tannate.…”

Section: Resultssupporting

confidence: 55%

Application of Mössbauer spectroscopy to the study of tannins inhibition of iron and steel corrosion

2011

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The inhibitory effect of tannins was investigated using, among others, potentiodynamic polarizations and Mössbauer spectroscopy. These techniques confirmed that the nature, pH and concentration of tannic solution are of upmost importance in the inhibitory properties of the solutions. It is observed that at low tannin concentration or pH, both, hydrolizable and condensed tannins, effectively inhibit iron corrosion, due to the redox properties of tannins. At pH ≈ 0, Mössbauer spectra of the frozen aqueous solutions of iron(III) with the tannin solutions showed that iron is in the form of a monomeric species [Fe(H 2 O) 6 ] 3+ , without coordination with the functional hydroxyl groups of the tannins. The suspended material consisted of amorphous ferric oxide and oxyhydroxides, though with quebracho tannin partly resulted in complex formation and in an iron (II) species from a redox process. Other tannins, such as chestnut hydrolysable tannins, do not complex iron at this low pH. Tannins react at high concentrations or pH (3 and 5) to form insoluble blue-black amorphous complexes of mono-and bis-type tannate complexes, with a relative amount of the bis-ferric tannate generally increasing with pH. Some Fe 2+ in the form of hydrated polymeric ferrous tannate could be obtained. At pH 7, a partially hydrolyzed ferric tannate complex was also formed. The latter two phases do not provide corrosion protection. Tannin solutions at natural pH react with electrodeposited iron films (approx. 6 μm) to obtain products consisting only on the catecholate mono-complex of ferric tannate. Some aspects of the mechanism of tannins protection against corrosion are discussed.

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Section: Resultssupporting

confidence: 55%

Application of Mössbauer spectroscopy to the study of tannins inhibition of iron and steel corrosion

2011

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“…gallates, pirogallates and plant extracts) [13,14]. The mean Mössbauer parameters at 80 K are IS = 1.38 ± 0.08 mm/s and QS = 3.05 ± 0.17 mm/s, close to those of the water soluble blue iron(II)-catechol complexes determined from the freeze dried solutions at pH 5.4 [15].…”

Section: Resultsmentioning

confidence: 59%

Mössbauer and infrared spectroscopy as a diagnostic tool for the characterization of ferric tannates

Jaén

Navarro

2009

Hyperfine Interact

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Fourier transform infrared spectroscopy and Mössbauer spectroscopy are use for the characterization and qualitative analysis of hydrolysable and condensed tannates. The two classes of tannates may be differentiated from the characteristic IR pattern. Mössbauer proof that a mixture of mono-and bis-type ferric tannate complexes, and an iron(II)-tannin complex are obtained from the interaction of hydrolysable tannins (tannic acid and chestnut tannin) and condensed tannins (mimosa and quebracho) with a ferric nitrate solution. At pH 7, a partially hydrolyzed ferric tannate complex was also obtained.

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“…The semiquinone can reduce another Fe 3+ to Fe 2+ forming the corresponding quinone ( Figure 7) (102) . Evidence of the formation of semiquinone-Fe 2+ complex, has been found through Mössbauer spectroscopy (66) and by magnetic moment measure (103) . (II) Semiquinone is also an oxidant specie, therefore in addition to oxidize substrates may also react with H 2 O 2 (104,105) (12).…”

Section: Dhb Driven Fenton Reactionmentioning

confidence: 99%

Fenton Reaction Driven by Iron Ligands

Salgado

Melín

Contreras

et al. 2013

J. Chil. Chem. Soc.

107

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One of the most important sources of reactive oxygen species (ROS) in biological systems is the Fenton reaction. In this, the Fe 2+ or Fe 3+ reacts with H 2 O 2 to produce ROS as the hydroxyl radical (•OH), superoxide radical (O 2 •-) and singlet oxygen ( 1 O 2 ). The main ROS, responsible for the high oxidizing power of the Fenton reaction, is not clear. Some authors claim that the principal reactive species is •OH, while others propose a ferryl specie (Fe 4+ or [FeO] 2+ ) (1,2) . Recently, have been proposed that the kind of reaction species produced depends mainly of pH and the iron composition of the coordination sphere. This is highlighted for Fe 3+ , because in mono and (some) bis-complexes Fe 3+ is reduced to Fe 2+ and there are some positions occupied by water or hydroxide ligands, readily to be exchanged by H 2 O 2 . On the other hand, in tris-complexes there are not any positions occupied by water or hydroxide, avoiding the formation of peroxo-complexes, necessary for Fenton or Fenton like reaction.The 1,2-dihydroxybenzenes (DHBs) have been described as modulators of Fenton reaction. The DHBs driven Fenton reaction have been used for environmental applications as an advanced oxidation process. Furthermore, these systems participate in different biological process, as the wood biodegradation by fungi and oxidative stress in neurodegenerative diseases.In this review, the effect of 1,2-dihydroxybenzenes on the activated species production by the Fenton and Fenton like reaction will be discussed and its participation in different systems.

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Model compounds for microbial iron-transport compounds. Part IV. Further solution chemistry and Mössbauer studies on iron(II) and iron(III) catechol complexes

Cited by 44 publications

References 19 publications

Application of Mössbauer spectroscopy to the study of tannins inhibition of iron and steel corrosion

Application of Mössbauer spectroscopy to the study of tannins inhibition of iron and steel corrosion

Mössbauer and infrared spectroscopy as a diagnostic tool for the characterization of ferric tannates

Fenton Reaction Driven by Iron Ligands

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