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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.


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Arrhenius plots for the system (a) PAla-Cu(II), [PAla] = 2.0 × 10−3 M, [Cu2+] = 5.0 × 10−4 M, [H2O2] = 6.7 × 10−3 M, pH = 8.8 (b) PGlygly-Cu(II), [PGlygly] = 2.0 × 10−3 M, [Cu2+] = 5.0 × 10−4 M, [H2O2] = 6.7 × 10−3 M, pH = 8.8.
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fig4: Arrhenius plots for the system (a) PAla-Cu(II), [PAla] = 2.0 × 10−3 M, [Cu2+] = 5.0 × 10−4 M, [H2O2] = 6.7 × 10−3 M, pH = 8.8 (b) PGlygly-Cu(II), [PGlygly] = 2.0 × 10−3 M, [Cu2+] = 5.0 × 10−4 M, [H2O2] = 6.7 × 10−3 M, pH = 8.8.

Mentions: Using Arrhenius plots (Figure 4) and the Arrhenius equation the activation energies, Eα, were calculated at pH 8.8 (Table 1).


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)

Arrhenius plots for the system (a) PAla-Cu(II), [PAla] = 2.0 × 10−3 M, [Cu2+] = 5.0 × 10−4 M, [H2O2] = 6.7 × 10−3 M, pH = 8.8 (b) PGlygly-Cu(II), [PGlygly] = 2.0 × 10−3 M, [Cu2+] = 5.0 × 10−4 M, [H2O2] = 6.7 × 10−3 M, pH = 8.8.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig4: Arrhenius plots for the system (a) PAla-Cu(II), [PAla] = 2.0 × 10−3 M, [Cu2+] = 5.0 × 10−4 M, [H2O2] = 6.7 × 10−3 M, pH = 8.8 (b) PGlygly-Cu(II), [PGlygly] = 2.0 × 10−3 M, [Cu2+] = 5.0 × 10−4 M, [H2O2] = 6.7 × 10−3 M, pH = 8.8.
Mentions: Using Arrhenius plots (Figure 4) and the Arrhenius equation the activation energies, Eα, were calculated at pH 8.8 (Table 1).

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