کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10275756 | 463392 | 2005 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Catechin antioxidant action at various pH studied by cyclic voltammetry and PM3 semi-empirical calculations
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Catechin antioxidant action at various pH studied by cyclic voltammetry and PM3 semi-empirical calculations Catechin antioxidant action at various pH studied by cyclic voltammetry and PM3 semi-empirical calculations](/preview/png/10275756.png)
چکیده انگلیسی
The mechanism of catechin electro-oxidation at various pH was studied using cyclic voltammetry (CV) on the glassy carbon (GC) electrode and PM3 semi-empirical calculations. The influence of activation of the surface of the GC electrode on CV results has been discussed. Mixed adsorption-diffusion control has been observed by applying mechanistic criteria of CV to the results obtained at the activated electrode. The calculated catechin diffusion coefficient D = 2.78 Ã 10â6 cm2 sâ1. A linear increase of the current peak has been observed with the increase of substrate concentration up to 40 μmol dmâ3 (surface coverage Πâ¼Â 10â11 mol cmâ2). In the whole investigated pH range, the dE/dpH value is very close to the anticipated Nernstian dependence of â59 mV/pH indicating that the slope is not affected by the different sequences of eâ and H+ transfer. Molecular modeling results show a decrease of â5 kcal molâ1 in ÎHoF (between radical and parent molecule) and a decrease of â6 eV in IP (of the parent molecule) when the parent molecule is changed from neutral to monoanionic form of catechin showing that both processes - hydrogen and electron abstraction are facilitated by deprotonation. Electrochemical oxidation of catechin is known to proceed as a two step one-electron oxidation of the B-ring of o-phenolic groups. Upon an increase in the pH, the mechanistic pathway of catechin electro-oxidation in both oxidation steps changes from an eH to the He process. In the reaction with a free radical, this may induce the change from hydrogen to electron donation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Electroanalytical Chemistry - Volume 584, Issue 2, 15 October 2005, Pages 92-99
Journal: Journal of Electroanalytical Chemistry - Volume 584, Issue 2, 15 October 2005, Pages 92-99
نویسندگان
S. Martinez, L. Valek, Ž. PetroviÄ, M. MetikoÅ¡-HukoviÄ, J. Piljac,