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Noncovalent Interactions of Biologically Active Compounds
Osifová, Zuzana ; Dračínský, Martin (advisor) ; Lyčka, Antonín (referee) ; Sýkora, Jan (referee)
This thesis deals with the employment of nuclear magnetic resonance (NMR) spectroscopy in the studies of non-covalent interactions of biologically active compounds. The introduction serves as a brief overview of the literature, pointing out the milestones in determining and studying the most common non-covalent interactions - hydrogen bonding, π-π stacking and halogen bonding - by NMR spectroscopy. This part also includes the basics of this method to ensure that the results presented and the principles used will also be understandable for readers outside the field. Similarly, the employment and limitations of theoretical calculations are shortly discussed. The thesis aimed to determine the role of non-covalent interactions in biologically active compounds, including hydrogen bonding of modified nucleobases, interactions influencing ketoenol-diketo tautomerism of pharmacologically active curcuminoids, and the role of hydrogen bonding and amino acid sequence in the adoption of secondary structure in short peptides. Methylation and oxidation are nucleobases' most common natural modifications, causing changes in their hydrogen bonding pattern and preferences. We found that N-methylation of adenine residue stabilises its hydrogen-bonded base pairs with thymine and that these base pairs tend to adopt...
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Proton conductivity of powder samples
Taraba, Lukáš ; Havlíček, David (advisor) ; Matulková, Irena (referee)
Title: Proton Conductivity of Powder Samples Author: Lukáš Taraba Department: Department of Inorganic Chemistry, Faculty of Science Supervisor: Doc. RNDr. David Havlíček, CSc. Supervisor's e-mail address: david.havlicek@natur.cuni.cz Abstract This bachelor thesis is focused on the possibility of approximate determination of the specific conductivity of powder samples. It is based on X-ray diffraction analysis assuming the possibility of proton transfer by the system of properly arranged short hydrogen bonds in the structure of compounds. The selected substances were freshly prepared for the measurement. A newly prepared and investigated aminoguinidinium(1+) sulphamate was also measured. The specific conductivity of individual polycrystalline materials pressed into pellets or single crystal was calculated from the measured electrical resistance and dimensions of the samples. According to the results, this method of measurementis is fully sufficient for a gross estimate of whether the compound has a specific conductivity higher than that insulants usually have. Keywords proton conductivity - powder sample, hydrogen bond, aminoguanidinium(1+) sulphamate
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Study of proton conductivity on powder samples
Nižňanský, Matěj ; Havlíček, David (advisor) ; Kubíček, Vojtěch (referee)
The focus of this thesis is the synthesis and characterisation of one newly prepared and one previously prepared compound which based on the results of x-ray structure analysis both contain systems of conveniently long hydrogen bonds. These systems potentially allow proton transfer through their structure. The results acquired by measuring proton conductivity of the newly prepared substance are also discussed in this thesis. Furthermore, it contains the results of the characterisation of both prepared substances by IR spectroscopy, powder x-ray diffraction and diffraction on monocrystal. The measurement of proton conductivity was carried out using tablets consisting of pressed powder samples which had gold-palladium alloy electrodes applied to them. The specific conductivity of these samples was determined by the measured electric resistance and the size of these tablets. Based on the conducted measurements, it can be stated that the newly synthesised substance does not exercise proton conductivity within the detection limit of used hardware, whereas the previously prepared one does. These results are further discussed in corresponding chapter considering primarily the structure of both substances.
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Proton conductivity of powder samples
Taraba, Lukáš ; Havlíček, David (advisor) ; Matulková, Irena (referee)
Title: Proton Conductivity of Powder Samples Author: Lukáš Taraba Department: Department of Inorganic Chemistry, Faculty of Science Supervisor: Doc. RNDr. David Havlíček, CSc. Supervisor's e-mail address: david.havlicek@natur.cuni.cz Abstract This bachelor thesis is focused on the possibility of approximate determination of the specific conductivity of powder samples. It is based on X-ray diffraction analysis assuming the possibility of proton transfer by the system of properly arranged short hydrogen bonds in the structure of compounds. The selected substances were freshly prepared for the measurement. A newly prepared and investigated aminoguinidinium(1+) sulphamate was also measured. The specific conductivity of individual polycrystalline materials pressed into pellets or single crystal was calculated from the measured electrical resistance and dimensions of the samples. According to the results, this method of measurementis is fully sufficient for a gross estimate of whether the compound has a specific conductivity higher than that insulants usually have. Keywords proton conductivity - powder sample, hydrogen bond, aminoguanidinium(1+) sulphamate
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Building blocks of hydrogen-bonded supramolecular polymers
Roudná, Štěpánka ; Svoboda, Jan (advisor) ; Zedník, Jiří (referee)
The connection of molecular monomers through non-covalent interaction (e.g. hydrogen bonding, π-π interaction, coordination bonding) enables the formation of supramolecular polymers. The major advantage of these bonds is their reversibility and consequently their ability to self-assembly or to disconnect depending on given conditions. This thesis examines the self-assembly through quadruple hydrogen bonding, which is strong and the resulting structures stable. Ureidopyrimidinon A and aromatic amines were always used as the starting compound for the preparation of monofunctional and bifunctional ureidopyrimidinones.
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Pyrrolidine nucleotides conformationally constrained via hydrogen bonding
Pohl, Radek ; Poštová Slavětínská, Lenka ; Rejman, Dominik
Conformation of pyrroPME nucleotide analogues was studied by means of NMR at different pD values in D2O solutions. Surprisingly, two stable conformers were found at pD > 9 for both cis and trans configurations and their ratio depended on the acid-base properties of nucleobase attached to pyrrolidine ring. The results of conformational analysis suggest that the conformation of the pyrrolidine ring is locked via intramolecular hydrogen bond between negatively charged phosphonate oxygen atom and protonized pyrrolidine nitrogen.
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