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Your search keyword '"María J. Aguirre"' showing total 3 results
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3 results on '"María J. Aguirre"'

1. Electrical and Electrochemical Behavior of Carbon Paste Electrodes Modified with Ionic Liquids Based in N-Octylpyridinium Bis(Trifluoromethylsulfonyl)Imide. A Theoretical and Experimental Study

Author

Carla Báez, Freddy Navarro, Francesca Fuenzalida, María J. Aguirre, M. Carmen Arévalo, María Afonso, Camilo García, Galo Ramírez, and J. Antonio Palenzuela

Subjects
ionic-liquid carbon paste electrodes, N-octyl pyridinium bis(trifluoromethylsulfonyl)imide, intramolecular forces of ionic liquid, Organic chemistry, QD241-441
Abstract

In this work, we studied carbon paste electrodes (CPEs) with two kinds of binders: mineral oil or ionic liquids (IL) derived from N-substituted octyl pyridinium bis(trifluoromethylsulfonyl)imide with the substituents H-, CH3-, CN- and CF3-. The work aims to study this series of IL and determine a possible effect of the substituent of the cation in the behavior of the IL as a binder of graphite for obtaining IL-CPEs. The electrochemical response and the electrical behavior were measured by cyclic voltammetry and electrochemical impedance spectroscopy, respectively. Surprisingly, the substituent does not affect the cyclic voltammetry response because in all the cases, high resistance and high capacitive currents were obtained. The best response in terms of conductivity is obtained by CPE. In the case of impedance measurements, the substituent does not cause differences, and in all the cases, the IL-CPEs show nearly the same responses. CPE shows lower capacitance and higher resistance for diffusion compared to the IL-CPEs due to his lower porosity. The high resistance showed by the IL-CPEs by cyclic voltammetry can be attributed to poorly intermolecular forces among graphite, water, electrolyte, and ILs as demonstrated by theoretical calculations.

Published
2019
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2. Electrical and Electrochemical Behavior of Carbon Paste Electrodes Modified with Ionic Liquids Based in N-Octylpyridinium Bis(Trifluoromethylsulfonyl)Imide. A Theoretical and Experimental Study

Author

Freddy Navarro, J. Antonio Palenzuela, Carla Báez, Francesca Fuenzalida, Galo Ramírez, Camilo García, María M. Afonso, María J. Aguirre, and M. Carmen Arévalo

Subjects
Materials science, Inorganic chemistry, Substituent, Ionic Liquids, Pharmaceutical Science, Electrolyte, Conductivity, Electrochemistry, Article, Analytical Chemistry, lcsh:QD241-441, chemistry.chemical_compound, lcsh:Organic chemistry, intramolecular forces of ionic liquid, Drug Discovery, Graphite, Physical and Theoretical Chemistry, Electrodes, Molecular Structure, N-octyl pyridinium bis(trifluoromethylsulfonyl)imide, Organic Chemistry, Electric Conductivity, Models, Theoretical, Carbon, Dielectric spectroscopy, ionic-liquid carbon paste electrodes, chemistry, Chemistry (miscellaneous), Ionic liquid, Molecular Medicine, Cyclic voltammetry, Algorithms
Abstract

In this work, we studied carbon paste electrodes (CPEs) with two kinds of binders: mineral oil or ionic liquids (IL) derived from N-substituted octyl pyridinium bis(trifluoromethylsulfonyl)imide with the substituents H-, CH3-, CN- and CF3-. The work aims to study this series of IL and determine a possible effect of the substituent of the cation in the behavior of the IL as a binder of graphite for obtaining IL-CPEs. The electrochemical response and the electrical behavior were measured by cyclic voltammetry and electrochemical impedance spectroscopy, respectively. Surprisingly, the substituent does not affect the cyclic voltammetry response because in all the cases, high resistance and high capacitive currents were obtained. The best response in terms of conductivity is obtained by CPE. In the case of impedance measurements, the substituent does not cause differences, and in all the cases, the IL-CPEs show nearly the same responses. CPE shows lower capacitance and higher resistance for diffusion compared to the IL-CPEs due to his lower porosity. The high resistance showed by the IL-CPEs by cyclic voltammetry can be attributed to poorly intermolecular forces among graphite, water, electrolyte, and ILs as demonstrated by theoretical calculations.

Published
2019
Full Text
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3. Fungitoxicity against Botrytis cinerea of a Flavonoid Isolated from Pseudognaphalium robustum

Author

Leonora Mendoza, Paulo Castro, Alexis Muñoz, María J. Aguirre, Karen Yañez, and Milena Cotoras

Subjects
antifungal activity, Botrytis cinerea, 5,7-dihydroxy-3,8-dimethoxyflavone, Pseudognaphalium robustum, pro-oxidants, Flavonoid, Pharmaceutical Science, Biology, Pseudognaphalium, High-performance liquid chromatography, Article, Analytical Chemistry, Conidium, lcsh:QD241-441, lcsh:Organic chemistry, Drug Discovery, Botany, Physical and Theoretical Chemistry, Mycelium, chemistry.chemical_classification, Chromatography, Organic Chemistry, fungi, food and beverages, biology.organism_classification, Thin-layer chromatography, chemistry, Chemistry (miscellaneous), Germination, Molecular Medicine
Abstract

The fungotoxicity against Botrytis cinerea of a flavonoid isolated from Pseudognaphalium robustum was analyzed. Two absorption column chromatographies and one semipreparative thin layer chromatography were used to purify the active flavonoid. It was determined, by 1H-NMR spectroscopy and co-elution with standards in HPLC, that this compound was 5,7-dihydroxy-3,8-dimethoxyflavone (gnaphaliin A). To determine the fungitoxicity of the purified compound, the effect on in vitro mycelial growth and conidial germination was studied. The compound concentration that reduced mycelial growth by 50% was 45.5 mg/mL. This compound also partially affected conidial germination of B. cinerea, reduced oxygen consumption by germinating conidia and affected the integrity of plasma membrane. Finally, using cyclic voltammetry, it was shown that the purified flavone had a pro-oxidant effect.

Published
2011

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