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Electrochemistry of Potential Eu MRI Complexes
Gál, Miroslav ; Sokolová, Romana ; Kielar, P.
Properties of the several potential contrast agents for magnetic resonance imaging (MRI) with Eu(III)/Eu(II) redox couple were investigated by means of the electrochemical methods. Cyclic voltammetry, phase sensitive AC voltammetry, and DC polarography were utilized to elucidate the mechanism of the reduction/oxidation of Eu ion in the presence of these compounds. Moreover, the stability constants of the Eu(II)-MRI agent complexes were also determined. Some suggestions on the chemical structure of the potential contrast agents for MRI are also made.
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Electrochemistry of halogenated benzenonitrils
Sokolová, Romana ; Pospíšil, Lubomír ; Hromadová, Magdaléna ; Ludvík, Jiří
Autoprotonation in reduction mechanism of 3,5-dihalogeno-4-hydroxy-benzonitriles was studied in dimethylsulfoxide by electrochemical methods. The overall one electron reduction process was found. Aryl radical formed by the cleavage of halogenide undergroes further electron transfer in EC type reaction. The anion is protonated by parent molecule resulting in total consumption of two electrons per two starting molecules. Addition of stronger proton donor increases the height of reduction wave up to two electrons per molecule. The addition of potassium hydroxide causes the decrease of the reduction wave. The reduction products were identified by GC/MS analysis in the absence and presence of strong proton donor.
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Fullerene C60 in Aqueous Medium
Kocábová, Jana ; Gál, Miroslav ; Hromadová, Magdaléna ; Kavan, Ladislav ; Pospíšil, Lubomír ; Sokolová, Romana
The aqueous solution of C60 was investigated by electrochemical and spectroscopis methods such as UV-Vis, Raman, FTIR and AFM techniques. The association constants of fullerene-gamma-cyclodextrin complex and ,ethanofullerene conjugates with beta-cyclodextrins in aqueous solution were evaluated from the shifts of the formal redox potential of complexed and uncomplexed fullerene. The most suitable techniques for electrochemical characterization of fullerene derivatives proved to be the low-frequency phase-sensitive AC polarography and the steady-state voltammetry.
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The Electrochemistry of Natural Pigments
Sokolová, Romana ; Degano, I. ; Hromadová, Magdaléna ; Pospíšil, Lubomír
The electrochemical properties of flavonoid compounds (hemotoxylin, quercetin) were studied in buffered aqueous and non-aqueous solutions. The role of the preceding protonation/deprotonation on the electron transfer was estimated. The absorption spectra of these compounds, which contain a chromophore, were recorded during their oxidation. The electrochemical techniques were combined with GC-MS analysis in order to identify the degradation products. The mechanism of the formation of degradation products will be discussed.
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Electrochemistry of selected halogenated pesticides and their complexes with cyclodextrins
Sokolová, Romana ; Hromadová, Magdaléna ; Pospíšil, Lubomír
A detailed investigation of electrochemical properties of triazine pesticides, carboxyimid-type pesticides and benzonitrile pesticides was studied. Their degradation pathways include the protonization reactions coupled with electron transfer and several side chemical reactions. The study of inclusion complexes of halogenated pesticides with cyclodextrins was performed. The inclusion into the molecular cavities markedly influenced the decomposition mechanism of these compounds by protection of reactive groups by cyclodextrin environment. The degradation products were identified by GC-MS analysis and in-situ IR spectroelectrochemistry.
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