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Structural, Redox and Spectrometric Characterization of Energetic Material FOX-7 (2,2-dinitroethene-1,1-diamine) in Solution
Šimková, Ludmila; Ludvík, Jiří
2016 - English
The investigation of energetic materials, especially organic nitro-amino-derivatives, always has attracted attention of physical chemists. However, published articles demonstrate lack of systematic study of molecules based on aliphatic backbones, rather than aromatic structures. This work represents the first systematic electrochemical and spectrometric characterization of 2,2-dinitroethene-1,1-diamine (FOX-7) in aqueous and aprotic solvent. Based on the results obtained from combination of electrochemistry with spectrometric methods, the actual structure of FOX-7 in various media was revealed, its reducibility described and radical intermediates as well as products were intercepted, isolated and characterized.
Keywords:
FOX-7; 2,2-dinitroethene-1,1-diamine; structure
Available at various institutes of the ASCR
Structural, Redox and Spectrometric Characterization of Energetic Material FOX-7 (2,2-dinitroethene-1,1-diamine) in Solution
The investigation of energetic materials, especially organic nitro-amino-derivatives, always has attracted attention of physical chemists. However, published articles demonstrate lack of systematic ...
Voltammetric determination of cancer biomarker 5-hydroxyindole-3-acetic acid at screen-printed carbon electrodes
Makrlíková, Anna; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2016 - English
Tumor biomarker 5-hydroxyindole-3-acetic acid (5-HIAA) is a breakdown product of serotonin; level of this neurotransmitter can predict carcinoid tumors. 5-HIAA has been determined at screen-printed carbpon electrodes in the iptimum medium found: Britton-Robinson buffer (0.04 mol l-1, pH=3.0). Dependence of the peak current on the concentration of 5-HIAA was linear in the concentration region from 0.1 to 100 micromol l-1, with the limit of qiantification of 0.2 micromol l-1.
Keywords:
differential pulse voltammetry; tumor biomarker; screen-printed carbon electrodes
Available at various institutes of the ASCR
Voltammetric determination of cancer biomarker 5-hydroxyindole-3-acetic acid at screen-printed carbon electrodes
Tumor biomarker 5-hydroxyindole-3-acetic acid (5-HIAA) is a breakdown product of serotonin; level of this neurotransmitter can predict carcinoid tumors. 5-HIAA has been determined at screen-printed ...
Noise Analysis of Ion Transfer Kinetics at the Micro Liquid/Liquid Interface
Josypčuk, Oksana; Holub, Karel; Mareček, Vladimír
2015 - English
Fluctuation analysis was utilized to determine the TEA ion transfer kinetics across the water/1,2-dichloroethane interface. The average value ks = 0.34 cm s-1 is comparable with the previously reported value ks = 0.2 cm s-1, derived from electrochemical impedance spectroscopy experiments. The experimental approach utilizing a thick wall glass microcapillary to fix the interface exhibits a very small stray capacitance value, proving this system to be suitable for determining the kinetics of the fast ion transfer across a liquid/ liquid interface. Application of a method employing a small perturbation signal prevents polarization of the inner capillary surface by current flowing through the cell. The induced polarization of the capillary can affect ion concentration at the interface due to electroosmosis and thus make the kinetics data evaluation difficult or erroneous.
Keywords:
noise analysis; liquid/liquid interface; ion transfer kinetics
Available at various institutes of the ASCR
Noise Analysis of Ion Transfer Kinetics at the Micro Liquid/Liquid Interface
Fluctuation analysis was utilized to determine the TEA ion transfer kinetics across the water/1,2-dichloroethane interface. The average value ks = 0.34 cm s-1 is comparable with the previously ...
Influence of Electrode Preparation on Electrocatalytic Activity of Tetrapyridinoporphyrazinato Cobalt(II) Complex to Propylene
Klusáčková, Monika; Janda, Pavel; Tarábková, Hana
2015 - English
The water-soluble complex N ,N' ,N' ',N' "-Tetramethyl-tetra-3,4-pyridinoporphyrazinocobalt (CoTmt-3,4-ppa) has been deposited by different techniques on two substrate. Electrochemical deposition, spontaneous adsorption, and spin coating have been used to the modification of two electrode material: annealed gold as hydrophilic substrate and highly oriented pyrolytic graphite as hydrophobic substrate. The modified electrodes have been characterized using cyclic voltammetry, backscattering VIS spectroscopy and atomic force microscopy. The influence of substrate material and modification techniques on electrocatalytic activity of CoTmt-3,4-ppa modified electrodes for propylene oxidation has been studied.
Keywords:
water-soluble phthalcyanine; electrocatalysis; propylene
Available at various institutes of the ASCR
Influence of Electrode Preparation on Electrocatalytic Activity of Tetrapyridinoporphyrazinato Cobalt(II) Complex to Propylene
The water-soluble complex N ,N' ,N' ',N' "-Tetramethyl-tetra-3,4-pyridinoporphyrazinocobalt (CoTmt-3,4-ppa) has been deposited by different techniques on two substrate. Electrochemical deposition, ...
Comparison of Techniques for Single-Molecule Conductance Measurements of Expanded Pyridinium Molecules
Lachmanová, Štěpánka; Hromadová, Magdaléna; Sokolová, Romana; Kocábová, Jana; Gasior, Jindřich; Mészáros, G.; Lainé, P. P.
2015 - English
This work is focused on the comparison of two techniques of single-molecule conductance measurements: Scanning Tunneling Microscopy Break Junction technique and Mechanically Controlled Break Junction technique. The structure of studied compound 9-(pyridin-4-yl)benzo[c]benzo[1,2]quinolizino[3,4,5,6-ija][1,6]naphthyridin-15-ium allows the formation of the molecular bridge between two gold electrodes, which are connected to a source of the constant voltage in both of the used methods. The differences, advantages and disadvantages of both of the techniques will be discussed. Both techniques provided two values of conductance of studied compound depending on the experimantal conditions.
Keywords:
Single-molecule conductance; Scanning Tunneling Microscopy Break Junction; Mechanically Controled Break Junction
Available at various institutes of the ASCR
Comparison of Techniques for Single-Molecule Conductance Measurements of Expanded Pyridinium Molecules
This work is focused on the comparison of two techniques of single-molecule conductance measurements: Scanning Tunneling Microscopy Break Junction technique and Mechanically Controlled Break Junction ...
Electrochemical Study of Oxazaborine Chromophores
Mikysek, T.; Josefík, F.; Vytřas, K.; Ludvík, Jiří
2015 - English
This contribution describes a basic electrochemical study of a series of newly synthesized chromophores based on the oxazaborine core. The attention was focused on determination of the first oxidation and the first reduction potentials, their difference and the relationship to the calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies. The oxidation is mostly a two-electron irreversible process, the first reduction is also irrevesible, but involving one-electron. For better understanding of the relationship between the structure and redox properties, the approach using sigma (para) constants of Hammett type was applied, the difference between E(ox) and E(red) was correlated with the HOMO-LUMO gap.
Keywords:
oxazaborines; chromophore; cyclic voltammetry
Available at various institutes of the ASCR
Electrochemical Study of Oxazaborine Chromophores
This contribution describes a basic electrochemical study of a series of newly synthesized chromophores based on the oxazaborine core. The attention was focused on determination of the first oxidation ...
Influence of Cadmium on its Metabolism and Changes of Content of Nutritionally Important Compounds in Spring Barley
Paznocht, L.; Vodičková, H.; Phuong, L. M.; Nováková, Kateřina; Zámečníková, B.; Kotíková, Z.; Miholová, D.; Navrátil, Tomáš
2015 - English
Very important agriculture products are cereals, which significantly contributes to securing of human nutrient needs. Cadmium is a toxic heavy metal, which is readily taken up and accumulated by plants in spite of its harmful effects. This metal cause a stress for the plants and results in many morphological, anatomical, physiological and biochemical changes. The effect of cadmium on the plant metabolism and changes in the content of nutritionally important compounds (protein and some metals – Fe, Zn, Cu, Mn content) was investigated. Results shown, that cadmium was effectively retained in the roots and content of studied compounds was influenced by present of cadmium in nutrient medium. In all the parts of cadmium-treated seedlings decrease in the iron content and increase in the zinc content (except of the first leaves) and decrease in the manganese content was found. The copper content in the root tissue increased by 112.1 %, on the other hand a significant decrease (by 44.4 % and 40.9 % respectively) in the first and the second leaves was observed. In the experimental varieties with cadmium in the concentration of 10-5 mol L-1, the content of soluble proteins was determined statistically higher in the root and basal parts than in the controlled varieties.
Keywords:
Barley; cadmium; cereals
Available at various institutes of the ASCR
Influence of Cadmium on its Metabolism and Changes of Content of Nutritionally Important Compounds in Spring Barley
Very important agriculture products are cereals, which significantly contributes to securing of human nutrient needs. Cadmium is a toxic heavy metal, which is readily taken up and accumulated by ...
Electrochemical Characterization of Poly(methylene Blue) Modified Graphite Electrodes
Zlámalová, Magda; Janda, Pavel; Nesměrák, K.
2015 - English
This work deals with electrochemical study of methylene blue (MB) polymerization as well as characterization of deposited conductive film on basal plane highly oriented pyrolytic graphite (HOPG) and pencil-graphite electrode (PGE). Poly(methylene blue) modified electrodes (HOPG/pMB and PGE/pMB) have been prepared by potential cycling in aqueous electrolyte solution containing methylene blue monomer. It has been found that electrochemical properties and electrocatalytic activity of deposited film are greatly influenced by the type of electrode substrate. Developed electrodes have been further investigated as potential sensors for sulfhydryl-containing compounds.
Keywords:
Poly(methylene blue); Electropolymerization; cyclic voltammetry
Available at various institutes of the ASCR
Electrochemical Characterization of Poly(methylene Blue) Modified Graphite Electrodes
This work deals with electrochemical study of methylene blue (MB) polymerization as well as characterization of deposited conductive film on basal plane highly oriented pyrolytic graphite (HOPG) and ...
Influence of electrode preparation on electrocatalytic activity of water soluble porphyrazine complex to hydrogen
Klusáčková, Monika; Janda, Pavel; Tarábková, Hana
2015 - English
The influence of electrode preparation and used electrode substrate on electrocatalytic activity of N, N`,N``,N```tetramethyl-tetra-3,4-pyridinopor-phyrazinocobalt (CoTmt-3,4-ppa) complex deposited on electrode surface for hydrogen reaction has been studied. Electrochemical deposition, spontaneous adsorption, and spin coating have been used to the modification of two different electrode substrates: annealed gold and highly oriented pyrolytic graphite. Prepared electrodes have been characterized using cyclic voltammetry, backscattering VIS spectroscopy and atomic force microscopy. The detailed comparison of surface morphology, surface coverage, surface roughness parameters, and thickness of deposited layers of CoTmt-3,4-ppa mediatoronhydrogen reaction has been investigated.
Keywords:
reduction; oxidation; atomic force microscopy; backscattering microscopy; cyclic voltammetry; electrocatalysis; water soluble phthalocyanine
Available at various institutes of the ASCR
Influence of electrode preparation on electrocatalytic activity of water soluble porphyrazine complex to hydrogen
The influence of electrode preparation and used electrode substrate on electrocatalytic activity of N, N`,N``,N```tetramethyl-tetra-3,4-pyridinopor-phyrazinocobalt (CoTmt-3,4-ppa) complex deposited on ...
Lab-made Sensors Based on Boron-doped Diamond for Determination of Herbicide Linuron
Štěpánková, M.; Šelešovská, R.; Janíková, L.; Vojs, M.; Marton, M.; Behúl, M.; Nováková, Kateřina; Chýlková, J.
2015 - English
Voltammetric behaviour of substituted urea herbicide linuron (LIN) was investigated using two types of boron-doped diamond electrodes (BDDE): commercial BDDE and lab-made sensors based on boron-doped diamond (LM-BDDE). Various methods like cyclic voltammetry (CV), direct current voltammetry (DCV) and differential pulse voltammetry (DPV) were examined. It was found that LIN provides one oxidation peak using all of the tested working electrodes and the highest current response was recorded in the acidic media. Thus, Britton-Robinson (B-R) buffer of pH 2 was used as a supporting electrolyte. Parameters of DPV were optimized and the low limits of detection (LOD) were reached 1.41×10−7 M for commercial boron-doped diamond electrode and 8.81×10−9 M, respectively, which represents the lowest LOD obtained for lab-made boron-doped diamond electrodes.
Keywords:
Boron doped diamond electrode; sensors; voltammetry
Available at various institutes of the ASCR
Lab-made Sensors Based on Boron-doped Diamond for Determination of Herbicide Linuron
Voltammetric behaviour of substituted urea herbicide linuron (LIN) was investigated using two types of boron-doped diamond electrodes (BDDE): commercial BDDE and lab-made sensors based on boron-doped ...
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