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Application of Quantitative Electron Paramagnetic Resonance (EPR) and Commercially Available EPR Standards for Electrochemical Study of the Subsituted Tetrathiafulvalene Oxidation.
Habániková, Shannelle Diana ; Tarábek, Ján (advisor) ; Mazúr, Milan (referee)
Tetrathiafulvalene derivatives are remarkable molecules, with various application, reported relatively recently. The radical cation of these compounds has very inter- esting optical, electronic, electrocatalytic superconducting and magnetic properties that have been intensively studied recently. Quantitative in-situ EPR voltammetric spectroelectrochemistry studies of 2-(2-hydroxyethylsulfanyl)-3-(benzylsulfanyl)-6,7- bis(octadecylsulphanyl)tetrathiafulvalene (TTF-Der3) have been carried out with the aim to confirm the oxidation sites, follow-up reactions (after the first electron transfer), and electrochemical behaviour. The diffusion process was confirmed by the depen- dence of current on the square root of the scan rate. It was claimed that the ratio of the number of generated radicals to transferred charge (electrons) for two representative TTF derivatives was determined to 5.5:500 for and 7:500 for TTF, indicating the follow- up reactions. Experiments were performed using the commercially available EPR standards, calibrated for this method (experimental setup). The latter was validated by quantitative EPR with standard 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical concentration (1·10−4 mol dm−3). For the ratios the confidence interval was reported for the first time for TTF-Der3 it was...
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Polymeric framework materials as noble metal free heterogeneous catalysts
Piatková, Mária ; Bojdys, Michael Janus (advisor) ; Tarábek, Ján (referee)
4 Abstract A functional triazine-based polymer framework with embedded copper (Cu) nanoparticles (Cu@TzP) is obtained from a one-pot, "wet" chemistry process that is easily scaled up to industrial demand. The polymer framework has permanent, guest-accessible microporosity and can be obtained as a membrane with 124 m2 g-1 , or as a bulk powder with 660 m2 g-1 (by Ar sorption). The Cu nanoparticles are generated in situ during the formation process of the polymer framework, and they serve as ideal, heterogenised active sites for C-N bond formation and enzyme-mimetic peroxidase catalysis. Further, we tune the porosity of the polymeric support matrix by thermal tempering (carbonisation). It turns out, that Cu@TzP performs best as a peroxidase-mimic in the form of a thin, accessible flake with 2 nm-sized Cu nanoparticles (NPs). Although no records were broken in terms of catalytic activity, we establish an attractive design principle of a scalable membrane support for noble-metal free catalysis.
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