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Kinetic Studies and Mechanism of Hydrogen Peroxide Catalytic Decomposition by Cu(II) Complexes with Polyelectrolytes Derived from L-Alanine and Glycylglycine.

Skounas S, Methenitis C, Pneumatikakis G, Morcellet M - Bioinorg Chem Appl (2010)

Bottom Line: The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media.The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293-308 K.The trend in catalytic efficiency is in the order PGlygly>PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands.

View Article: PubMed Central - PubMed

Affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, University of Athens, Panepistimiopolis, 15771 Athens, Greece.

ABSTRACT
The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media. The reactions were of pseudo-first order with respect to [H(2)O(2)] and [L-Cu(II)] (L stands for PAla or PGlygly) and the reaction rate was increased with pH increase. The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293-308 K. A suitable mechanism is proposed to account for the kinetic data, which involves the Cu(II)/Cu(I) redox pair, as has been demonstrated by ESR spectroscopy. The trend in catalytic efficiency is in the order PGlygly>PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands.

No MeSH data available.


Related in: MedlinePlus

The variation of [H2O2] in the reaction mixture (% of the initial concentration) versus time for different Cu(II) concentrations, and (insert) logarithm of the initial rate (vo) versus logarithm of the [Cu(II)] for the system (a) PAla-Cu(II), R = [PAla]/[Cu(II)] = 4, initial concentration [H2O2] = 6.8 × 10−3 M, pH = 8.5,  T = 298 K. (b) PGlygly-Cu(II), R = [PGlygly]/[Cu(II)] = 4, initial concentration [H2O2] = 6.2 × 10−3 M, pH = 8.9,  T = 298 K.
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fig2: The variation of [H2O2] in the reaction mixture (% of the initial concentration) versus time for different Cu(II) concentrations, and (insert) logarithm of the initial rate (vo) versus logarithm of the [Cu(II)] for the system (a) PAla-Cu(II), R = [PAla]/[Cu(II)] = 4, initial concentration [H2O2] = 6.8 × 10−3 M, pH = 8.5, T = 298 K. (b) PGlygly-Cu(II), R = [PGlygly]/[Cu(II)] = 4, initial concentration [H2O2] = 6.2 × 10−3 M, pH = 8.9, T = 298 K.

Mentions: The reactions are found to be of pseudo-first order with respect to H2O2 (Figure 1) for all the studied pH and [H2O2]/catalyst ratios. The order of the reactions was not found to decrease with the increase of the initial H2O2 concentration. The reactions were, also, found to be of pseudo-first order with respect to the total concentration of Cu(II) (Figure 2) for all the studied pH and [H2O2]/catalyst ratios.


Kinetic Studies and Mechanism of Hydrogen Peroxide Catalytic Decomposition by Cu(II) Complexes with Polyelectrolytes Derived from L-Alanine and Glycylglycine.

Skounas S, Methenitis C, Pneumatikakis G, Morcellet M - Bioinorg Chem Appl (2010)

The variation of [H2O2] in the reaction mixture (% of the initial concentration) versus time for different Cu(II) concentrations, and (insert) logarithm of the initial rate (vo) versus logarithm of the [Cu(II)] for the system (a) PAla-Cu(II), R = [PAla]/[Cu(II)] = 4, initial concentration [H2O2] = 6.8 × 10−3 M, pH = 8.5,  T = 298 K. (b) PGlygly-Cu(II), R = [PGlygly]/[Cu(II)] = 4, initial concentration [H2O2] = 6.2 × 10−3 M, pH = 8.9,  T = 298 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2913805&req=5

fig2: The variation of [H2O2] in the reaction mixture (% of the initial concentration) versus time for different Cu(II) concentrations, and (insert) logarithm of the initial rate (vo) versus logarithm of the [Cu(II)] for the system (a) PAla-Cu(II), R = [PAla]/[Cu(II)] = 4, initial concentration [H2O2] = 6.8 × 10−3 M, pH = 8.5, T = 298 K. (b) PGlygly-Cu(II), R = [PGlygly]/[Cu(II)] = 4, initial concentration [H2O2] = 6.2 × 10−3 M, pH = 8.9, T = 298 K.
Mentions: The reactions are found to be of pseudo-first order with respect to H2O2 (Figure 1) for all the studied pH and [H2O2]/catalyst ratios. The order of the reactions was not found to decrease with the increase of the initial H2O2 concentration. The reactions were, also, found to be of pseudo-first order with respect to the total concentration of Cu(II) (Figure 2) for all the studied pH and [H2O2]/catalyst ratios.

Bottom Line: The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media.The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293-308 K.The trend in catalytic efficiency is in the order PGlygly>PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands.

View Article: PubMed Central - PubMed

Affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, University of Athens, Panepistimiopolis, 15771 Athens, Greece.

ABSTRACT
The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media. The reactions were of pseudo-first order with respect to [H(2)O(2)] and [L-Cu(II)] (L stands for PAla or PGlygly) and the reaction rate was increased with pH increase. The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293-308 K. A suitable mechanism is proposed to account for the kinetic data, which involves the Cu(II)/Cu(I) redox pair, as has been demonstrated by ESR spectroscopy. The trend in catalytic efficiency is in the order PGlygly>PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands.

No MeSH data available.


Related in: MedlinePlus