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| Author(s): |
Vânia Mori
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2003-05-19 |
| Examining board members: |
Mauro Bertotti;
Eder Tadeu Gomes Cavalheiro;
Ivano Gebhardt Rolf Gutz;
Jorge Cesar Masini;
Maria Valnice Boldrin Zanoni
|
| Advisor: | Mauro Bertotti |
| Abstract | |
The trans-[Ru(NH3)4NOL]3+ (L = 4-NH2py, Him, L-hist, 4-pic, py, 4-Clpy, nia, isn, 4-CNpy and pz) complexes were eletrochemically investigated by using double potencial step chronoamperometry and rotating ring-disc electrode voltammetry. Values for the rate of NO substitution by water molecule ranged from 0.02 s-1 (4-pic) to 0.34 s-1 (pz) at 25ºC. Gold surfaces were modified with an electrochemically deposited layer of non-stoichiometric molybdenum oxides. At these surfaces, trans-[Ru(III)(NH3)4(4pic)SO4]+ complex was incorporated in a controlled way by cycling consecutively the potential in the range +0.50 to -0.25 V at pH ˜ 3. Very reproducible voltammetric curves corresponding to the electrochemical process of the ruthenium complex were obtained, confirming the immobilisation of the material into the molybdenum oxide film. The anodic oxidation of nitric oxide at physiological pH ˜7.4 in phosphate buffer was investigated at the modified electrode containing the molybdenum oxide + trans-[Ru(III)(NH3)4(4pic)SO4]+ complex and an enhancement in the current response was observed compared to the signal at a bare electrode. The rate for NO electrochemical oxidation was dependent on the amount of catalytic ruthenium sites dispersed into the molybdenum oxide film, suggesting the participation of the metallic ion in an out-sphere mechanism. A linear relationship between current signals measured by square wave voltammetry and NO concentration was obtained in the 0 to 10 µM range. The applicability of the modified electrode as a sensor for real-time NO monitoring was also demonstrated. (AU) | |