National Repository of Grey Literature 39 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Electrochemical Study of Selected Pyrene Derivatives as Precursors to Organic Semiconductors
Koláčná, Lucie ; Tobrman, T. ; Ludvík, Jiří
A series of 9 precursors for pyrene based biodegradable organic (semi)conductors having tetrasubstituted double bond as a central organic core and photo- or redox active centers attached at this core were electrochemically investigated in order to determine the influence of individual parts of the molecule on the redox properties, to describe the location of the reduction center and to understand the structure - redox activity relationship of the mentioned compounds.
Redox Properties of Fluorinated Derivatives of 1,3-Diphenylisobenzofuran Chromophores for Singlet Fission
Šimková, Ludmila ; Ludvík, Jiří
Derivatives of 1,3-diphenylisobenzofuran attract interest because they should be efficient as the molecules for singlet fission. The understanding of singlet fission in isolated molecules might be advantageous for use as solar cell sensitizers. This study is focused on fluorinated derivatives of 1,3-diphenylisobenzofuran and the effect of the position of fluorine atoms on their redox properties. For characterization of the redox properties standard electrochemical methods, and in situ UV-vis and EPR spectroscopy techniques were used.
Electrochemistry of Calixarenes
Liška, Alan ; Ludvík, Jiří (advisor) ; Zima, Jiří (referee) ; Cibulka, Radek (referee)
In the present thesis, both the published and the "ready-to-be-submitted" results concerning electrochemistry of calixarenes are summarized. The main focus is given to the detailed interpretation of experimental data, acquired during a systematic study of electroactive calixarene derivatives. The experiments were conducted under aprotic conditions (DMF) on mercury electrodes (mainly cyclic voltammetry and DC-polarography). It is demonstrated that electrochemistry should not serve only for redox characterization of studied compounds, but it offers a great number of other valuable information. The subject matter of the study are the calix[4]arenes (prevalently in the cone-conformation) which bear one to four reducible or oxidizable substituents ("redox probes") at various positions in order to be electrochemically investigable. Nitro- and nitroso compounds together with aldehydes, ketones, nitriles, aldoximes, carboxylic acids and corresponding esters, sulphones and esters of sulphonic acids are the most discussed compound series. Their relationship between structure and electrochemical response is presented in new connections ("stereoelectrochemistry"), in other words, how the redox probe position on the benzene ring (para-/meta-), bridging groups, or adjacent vs. opposite aromatic units...
Mercury Electrodes as Tools for Voltammetric Determination of Biologically Active Organic Compounds and for Detection of Their Interaction with DNA
Horáková, Eva ; Vyskočil, Vlastimil (advisor) ; Ludvík, Jiří (referee) ; Vytřas, Karel (referee)
The main aim of this work was to use traditional mercury electrodes for the development of voltammetric methods of determination of organic xenobiotics and for the electrochemical study of the interaction between double-stranded deoxyribonucleic acid (DNA) and these compounds. In relation to my previous research work (conducted in the framework of my diploma thesis), firstly, 4-nitrobiphenyl (4-NBP), the suspected carcinogen, was studied. Interaction of DNA with 4-NBP was studied using differential pulse voltammetry (DPV), cyclic voltammetry (CV), and chronocoulometry at a hanging mercury drop electrode (HMDE), and using CV and alternating current voltammetry at a DNA modified HMDE. Using CV, the reduction mechanism was investigated. The interaction of DNA with 4-aminobiphenyl (4-ABP), a metabolite of 4-NBP, and 4-NBP reduction intermediates was studied. It was found that the interaction of DNA with 4-NBP or 4-ABP results in a formation of a DNA aggregate with these analytes. The second studied analyte was methyl violet 2B (MV). For determination of MV in a buffered solution were used: direct current tast polarography and differential pulse polarography at a dropping mercury electrode, and direct current voltammetry, DPV, and differential pulse adsorptive stripping voltammetry (DPAdSV) at HMDE. The...
Electrochemical studies of the analytical utilization of self-assembled monolayers of calix[4]arene on the surface of polycrystalline gold electrode
Hrdlička, Vojtěch ; Navrátil, Tomáš (advisor) ; Ludvík, Jiří (referee)
This MSc. Thesis deals with electrochemical studies of the analytical utilization of self-assembled monolayers of thiolated calix[4]arene (C4A) and/or undecanthiole (C11SH) on the surface of a polycrystalline gold electrode. Hydroquinone, nitrobenzene, 2-nitrophenole and 4-nitrophenole have been used as tested model compounds. The real surface area of the electrode was determined using these two methods: From the charge of desorption peak of α-gold oxides (5.72±0.48 mm2 ) and using the Randles- Ševčík equation. (6.14±0.59 mm2 ). The preparation of the electrode consisted of polishing on alumina, immersing into piranha solution and cyclic voltammetry. The area of electrode surface was well reproducible. Stability of thiol monolayer in the area of negative potentials was tested. The C11SH layer is very stable; the desorption peak was recorded in basic solutions only (at −1.3 V vs. 3M Ag/AgCl). The position of the desorption peak of C4A is more pH dependent and it was recorded at −1.08 V at pH 13. The properties of the electrode modified by C11SH and or C4A were investigated using the model compound hydroquinone. It is assumed that the oxidation of the hydroquinone does not take place inside the C4A cavity; hence the hydroquinone molecule is too big to pass through the cavity. C11SH and C4 + C11SH act...
Possibilities of Electrochemical Analysis Using a System of Electrodes With Non-Specific Response
Ederer, Jakub ; Nesměrák, Karel (advisor) ; Ludvík, Jiří (referee)
The master thesis present the possibilities of processing of electrochemical data from a group of four electrodes with non-selective response (simple sensor array) for electrochemical analysis with potential application of the results achieved in the construction of the sensor field type "electronic tongue". This simple system was applied to the sample simulating the food product. Electrochemical data were processed through mathematical operations such as Gaussian approximation, deconvolution or using basic mathematical operations.
The use of carbon-based electrodes for the development of new electrochemical methods for the determination of aminonitrophenols
Dejmková, Hana ; Zima, Jiří (advisor) ; Ludvík, Jiří (referee) ; Vytřas, Karel (referee)
4 ABSTRACT Methods for the determination of five isomers of aminonitrophenol were developed, based on the technique of differential pulse voltammetry (DPV) and HPLC with amperometric detection. As the working electrodes, boron-doped diamond film electrode (BDDFE) and glassy carvon paste electrode (GCPE) were employed. Preliminary electrode testing was performed by cyclic voltammetry. The methods were aimed to the determination of all five aminonitrophenol isomers in hair dyes and to the determination of 2-amino-4- nitrophenol and 4-amino-2-nitrophenol in body fluids after solid phase extraction. From the voltammetric methods, the one using BDDFE for the cathodic determination in hair dyes exhibits sufficient selectivity. The performance of chromatographic methods was found suitable for the determination of aminonitrophenols in both observed matrices. The applicability of the developed methods was successfully confirmed by the determination of tested analyted in real samples of hair dyes and spiked samples of urine. Preceding measurements are described, dealing with the determination of other oxidizable compounds, containing phenolic or aniline moieties on BDDFE. The obtained results confirm that in some cases, BDDFE shows more resistance to fouling than other carbon-based electrodes, but in most cases, the...
Stereoelectrochemistry of Calixarenes
Liška, Alan ; Ludvík, Jiří ; Vojtíšek, P.
The relationship between the stereochemical properties (shape or molecular geometry in\ngeneral sense) and electrochemical ones (typically number of separate redox proceses, their\nnature and potentials) is very fundamental, however, not easily answerable. The nitro\nsubstituted calix[4]arenes appeared to be suitable series of compounds enabling correlation of\nelectrochemical data (redox potential, current, reversibility) with actual shape, conformation\nand dynamic behavior of the molecules dissolved in solution due to their well defined\ngeometry and clear polarographic and voltammetric response. Electrochemical methods can\nbe therefore used as a straightforward alternative to e.g. temperature dependent NMR\nspectroscopy. The present contribution is focused on thiacalix[4]arenes, their similarities and\ndistinctions from their methylene bridged analogues.\n

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See also: similar author names
1 Ludvík, Jakub
5 Ludvík, Jan
1 Ludvík, Jaroslav
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