Iron oxide and pyrocatechol: a spectroscopy study of the reaction products

Barreto, Wagner José; Barreto, Sônia Regina Giancoli; Moreira, Ivan; Kawano, Yoshio

doi:10.1590/s0100-40422006000600021

Cited by 14 publications

(7 citation statements)

References 14 publications

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“…Each of these two major intense peaks has originated from the in-plane deformation mode involving the C-C and C-O stretching and the C-H bending of the biphenyl pyrocatecholate, which is in the good agreement with the experimental results 22 . The O-Fe stretching (νFe-O) was observed in the range of 401-651 cm -1 .The stretching frequencies at 570 cm -1 and 634 cm -1 are originated from the interaction between Fe(III) ion and C 3 and C 4 oxygens (here the two carbon atoms that attached with oxygens are denoted as C 3 and C 4 ) of the pyrocatecholate respectively.…”

Section: Structural Parameterssupporting

confidence: 86%

“…The O-Fe stretching (νFe-O) was observed in the range of 401-651 cm -1 .The stretching frequencies at 570 cm -1 and 634 cm -1 are originated from the interaction between Fe(III) ion and C 3 and C 4 oxygens (here the two carbon atoms that attached with oxygens are denoted as C 3 and C 4 ) of the pyrocatecholate respectively. The intense νFe(III)-O band experimentally observed 22 at 636 cm -1 . The C-O stretching (νC-O) vibrational frequencies of the complex were obtained in the range of 1283-1517 cm -1 .…”

Section: Structural Parametersmentioning

confidence: 80%

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A DFT Investigation of Tris-(4´-(Amino)(1,1´-biphenyl)-3,4-diol) Fe(III) Complex

Matin

Aziz

Islam

2018

Dhaka Univ. J. Sci.

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Phenolic compounds, known as the pyrocatechol act as a metal chelating agent. Molecular details of cross-linking of pyrocatechol by transition metal ions are largely unknown. In the present study, the molecular properties of the tris-(4´-(amino)(1,1´-biphenyl)-3,4-diol)- Fe(III) complex have been investigated using density functional theory (DFT) at 6-311G(d,p). Calculated molecular properties of the optimized structure, the binding energies and spectroscopic properties are compared with the available experimental results. For the tris-complex investigated, the binding of Fe (III) with the catechol derivative is not as strong as the binding of other metal ions with catechol. The IR stretching bands show that the strong IR intensities is due to large charge polarization. Calculated electronic band gap is 2.45 eV which is in the range of transition metal ion-tris-(4´-(amino)(1,1´-biphenyl)-3,4-diol) complexes. The metal-ligand binding energy is 513.54 kcal mol-1, which could be used in understanding the speciation of Fe(III)-catechol complex. Structural parameters obtained from the DFT calculations are in good agreement with the crystallographic data. Dhaka Univ. J. Sci. 66(1): 67-71, 2018 (January)

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Section: Structural Parameterssupporting

confidence: 86%

Section: Structural Parametersmentioning

confidence: 80%

A DFT Investigation of Tris-(4´-(Amino)(1,1´-biphenyl)-3,4-diol) Fe(III) Complex

Matin

Aziz

Islam

2018

Dhaka Univ. J. Sci.

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“…A characteristic band for pyrocatechol at 280 nm is observed at zero time. [11] During autoxidation, the increase in the optical density at 280 nm is accompanied by the appearance, in the electronic spectra, of two bands at 320 nm and 480 nm. The rate of the spectrum transformation increases in the presence of calcium ions; however, no other spectrum components were found in the long-wavelength region of the spectrum.…”

Section: Pyrocatechol Autoxidationmentioning

confidence: 99%

Effect of Group II Metal Cations on Catecholate Oxidation

Lebedev¹,

Иванова²,

Тимошин³

et al. 2007

ChemPhysChem

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The unexpected effects of Ca(2+) on the free-radical chain reactions of dopamine, norepinephrine, isoproterenol, and pyrocatechol oxidation are studied using oxygen consumption measurements, EPR-spectroscopy, UV/VIS spectrophotometry, and by potentiometric titration. It is found that the formation of Ca(2+)-catecholate complexes is accompanied by an increase in the dissociation constants (K(ai) ) of their phenolic hydroxyls. At pH>pK(ai) and in the presence of alkaline-earth metal cations, the rate of catecholate oxidation increases (Ca(2+), Mg(2+)> Sr(2+), Ba(2+)), whereas on addition of Zn ions the rate decreases. The effects of Group II metal cations on catecholate autoxidation are concomitant with a transient increase of the EPR signal for metal-semiquinonate complexes. Therefore, the effects of Ca(2+) and other alkaline-earth metal cations on catecholate autoxidation can be defined as 1) additional deprotonation of catechol OH-groups involved in the formation of M(2+)-catecholate complexes, the latter exceeding catechols in the susceptibility to dioxygen-induced oxidation and 2) formation of relatively stable free-radical intermediates responsible for chain propagation.

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“…Quaternary ammonium surfactants widely provide crystalline molecular complexes with various aromatic compounds as catechol. Barreto et al [39] claimed that highly stable Mn(II) and Fe(II) complexes with catecholate and semiquinonate ligands could be precipitated with CTAB.…”

Section: Introductionmentioning

confidence: 99%