National Repository of Grey Literature 17 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Electroplating of 3D Printed Electrodes for Selective Electrochemical Reduction of C02
Vaněčková, Eva ; Bouša, Milan ; Shestivska, Violetta ; Kubišta, Jiří ; Rathouský, Jiří ; Sebechlebská, Táňa ; Kolivoška, Viliam
In this work, computer assisted design and fused deposition modelling 3D printing are\nemployed to devise and manufacture electrodes from polylactic acid-carbon nanotube\nconductive composite. Electrodes are further modified by copper electroplating to prepare\ncatalysts for the electrochemical reduction of carbon dioxide. Scanning electron microscopy\nand energy dispersive X-ray analysis are used to inspect the surface morphology and chemical\ncomposition of obtained catalysts. Cyclovoltammetric investigations reveal that the copper\nelectroplating leads to the increase of electrode activity by three orders of magnitude.
Oxidation Processes of N-methylguanines
Trnková, L. ; Třísková, I. ; Liška, Alan ; Ludvík, Jiří
The oxidation processes of N-methylguanines were investigated in both experimental and\ntheoretical way. Voltammetric oxidation potentials of guanine and its methyl analogues,\nacquired on polymer pencil graphite electrode (pPeGE), were compared with the HOMO\n(SOMO) energies calculated by density functional (DFT) methods. Our study contributes to\nunderstanding not only the oxidation processes of methylated guanines but also their role in\nepigenetics.
Differences in Electrochemical Reduction of Mono- and Polynuclear Acylgermanes
Šimková, Ludmila ; Dunlop, David ; Liška, Alan ; Ludvík, Jiří
Recently, titanocene derivatives have been investigated in term of their potential use as\ncytostatics in the treatment of oncological diseases. The potentials for reduction or oxidation of\nindividual substances are one of the key properties which fundamentally affect the cytostatic\nefficiency. Our previous results led us to investigate the redox properties of series of titanocene\ndifluoride and dichloride derivatives. This study is mainly focused on the effect of the\nsubstitution of cyclopentadienyl ring and the halide anion on the redox properties of the\nderivative.
UV-Vis and IR Spectroelectrocbemistry of Copper Complexes and Bioactive Compounds
Sokolová, Romana ; Obluková, Michaela ; Sýs, M. ; Mikysek, T. ; Wantulok, J. ; Nycz, J. E. ; Degano, I.
The interpretation of the change of absorption spectrum of an oxidized and reduced molecule\nrecorded during the electron transfer is an efficient tool for the determination of oxidation or\nreduction mechanism. This technique provides the information about the electroactive\nchromophore and is performed in two regimes of electrochemical measurement, cyclic\nvoltammetry and chronoamperometry, respectively. This approach was successfully applied to\nstudy the fundamental electrochemical behavior of recently synthesized copper complexes\nproviding biomimetic activity, ofpolyphenolic bioactive compounds, and also for the reduction\nof halogenated phenanthrolines. The identification of redox products was done by\nchromatographic techniques as HPLC-DAD and HPLC-ESI-MS/MS.
Looking into the Photo-stability of Eosin by Electrochemical Methods
Sabatini, F. ; Sokolová, Romana ; Degano, I.
Eosin Y is a synthetic organic dye belonging to the xanthene family. Its bright and fluorescent\npink hue attracted and intrigued the painters of the 19th century, who experimented eosin as\npigment lake (often called Geranium lake) in their paintings. Nevertheless, eosin coloration is\nas beautiful as unstable, and examples of work of arts with faded hues have been documented.\nEosin is not only photo-sensitive but also pH sensitive, making its study very complex. In this\nwork, the combination of electrochemical and spectroscopic techniques revealed to be effective\nfor correlating the physical evidence of eosin fading with its chemical degradation.
Electrochemical Characterization of Molecular Conductors Containing Redox Switching Element
Nováková Lachmanová, Štěpánka ; Vavrek, František ; Sebechlebská, Táňa ; Šebera, Jakub ; Kolivoška, Viliam ; Lukášek, J. ; Balzer, N. ; Valášek, M. ; Mayor, M. ; Hromadová, Magdaléna
Electrochemical properties of new molecules containing tripodal anchor and redox switching\nelement have been studied by cyclic voltammetry and DFT quantum mechanical calculations.\nComparison of their redox properties with individual organometallic [Ru(terpy)2]2+t3+ and\n[Os(terpy)2]2+t3+ redox centers shows that covalently bonded tripodal anchor does not\ncompromise the reversibility of a redox process and has no effect on the stability of new\nmolecules. New molecular conductors have smaller HOMO-LUMO gap and both are oxidized\nat only slightly more positive potentials after tripodal substitution making them suitable for the\ndevelopment of molecular conductors with switching abilities.
EPR/UV-VIS-NIR Spectroelectrochemical Examination of the Association Properties of Thienoacene-Bridged Tetrathiafulvalenes Supported by DFT Calculations
Lušpai, Karol ; Rapta, P. ; Zalibera, M. ; Darvasiová, D. ; Lukeš, V.
This work was focused on the EPR/UV-VIS-NIR spectroelectrochemical examination of\nassociation properties of radical cations electrochemically produced from tetrathiafulvalene\n(TTF) derivatives, in relation to the molecular structure, mainly the number and orientation of\nthiophene rings in the spacer between fulvalene redox centers. Results from EPR/UV-VIS-NIR\nspectroelectrochemistry were supported by DFT calculations.
Differences in Electrochemical Reduction of Mono- and Polynuclear Acylgermanes
Liška, Alan ; Frühwirt, P. ; Haas, M. ; Ludvík, Jiří ; Gescheidt-Demmer, G.
Ail the studied compounds accept first electron under formation a stable anion radical. The\ncorresponding reduction potentials in aprotic media depend on electronic (inductive,\nmesomeric) properties of the substituents, their number, and position. Here, aromatic acyl group\n(benzoyl group with various substitution on aromatic ring) is the principal substituent. The\nredox properties of presented organoelement compounds with central heteroatom Ge (Si, Sn)\nare controlled by peripheral carbonyl groups (in role of redox centers), their number, and\naromatic ring substitution. The measured first reduction potentials E1 values are found in wide\nrange (> 900 mV) due to the fact that the redox centers are carbony 1 groups connected through\nheteroatom in case of acylgermanes, while for di- and trinuclear derivatives (which are\nmolecules with multiple redox centers) the easiest reducible center is the bridging aromatic unit\ninfluenced by the closest carbonyl groups. Thus, it is possible to distinguish both groups ofnonequivalent\ncarbonyl substituents.
EPR-Electrochemical Study of Reduction Mechanism of Pyrene-Cyclobutene Conjugates
Koláčná, Lucie ; Polák, P. ; Klíma, Jiří ; Tobrman, T. ; Ludvík, Jiří
Reduction mechanism of pyrene-cyclobutene conjugates were studied electrochemically and\nspectro-electrochemically. Analysis and interpretation of spectro-electrochemical data of\nconjugates revealed intramolecular communication of electrons and enabled determination of\nredox mechanism of conjugates. This knowledge is fundamental for tuning the required redox\nproperties of molecules just by chemical modification. Studied molecules represent promising\nmaterial for organic semiconductor materials.
Electrochemistry of Phospholes
Koláčná, Lucie ; Liška, Alan ; Ludvík, Jiří
Seventeen pentasubstituted phospholes with expected application in organic electronics were\nsynthesized and characterized electrochemically and by UV-vis spectra. Quantum chemical\ncalculations ofredox potentials and HOMO-LUMO energies were performed and experimental\nand theoretical data were successfully correlated. Tuning of redox properties can be achieved\nby combination of induction and resonance effects of substituents, extension / diminution of\nthe pi- delocalized system and by steric changes which affect intramolecular electron\ncommunication.

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