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Reaction intermediates in homogeneous gold catalysis
Shcherbachenko, Elena ; Roithová, Jana (advisor) ; Matoušová, Eliška (referee)
The presented master thesis is devoted to the investigation of reaction intermediates in homogeneous gold catalysis. Electrospray ionization mass spectrometry (ESI-MS) was used as the primary research technique in this study. Delayed reactant labeling was used as the main method. I have focused mainly on the hydration of 1-phenyl-1-propyne catalyzed by the gold complex [Au(IPr)(MeCN)]BF4 (IPr = 1,3-bis(2,6-di-iso-propylphenyl)imidazol-2- ylidene). I have detected two main intermediates containing one or two gold atoms, respectively (monoaurated and diaurated intermediate). I have obtained rate constants for the degradation of the reaction intermediates and their half-lives. I have derived kinetic isotope effects for the formation and the decomposition of the detected intermediates. I have shown that the kinetics of the degradation of both intermediates is identical, therefore I conclude that hydration of alkynes catalyzed by gold complex [Au(IPr)(MeCN)]BF4 proceeds most probably via neutral monoaurated intermediates. These neutral intermediates are detected by ESI-MS as protonated (monoaurated intermediate) or tagged by a second gold cation (diaurated intermediate). Key words: gold catalysis, reaction intermediates, electrospray ionization, mass spectrometry.
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Study of Boron-Carbohydrate Interaction
Vejvodová, Tereza ; Jelínek, Ivan (advisor) ; Coufal, Pavel (referee)
The interaction between boron and sugars is significant for understanding the role of boron as a carrier for nucleotides and carbohydrates. Arylboronic acids also have wide application as sugars sensors because they are small and flexible molecules. Boron complexes play a key role in boron neutron capture therapy. This radiotherapy is important in the treatment of melanoma, glioblastoma multiforme and other types of cancer. Boron complexes with ascorbic acid and glucose were prepared in this thesis and then characterized by high-resolution mass spectrometry (HRMS). Synthesised complexes were studied using collision-induced dissociation (CID), which led to the clarification of their fragmentation mechanism. Key Words Boron complexes, ascorbic acid, glucose, carbohydrates, mass spectrometry, electrospray ionization, ESI-MS, collision-induced dissociation
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Reaction intermediates in homogeneous gold catalysis
Shcherbachenko, Elena ; Roithová, Jana (advisor) ; Matoušová, Eliška (referee)
The presented master thesis is devoted to the investigation of reaction intermediates in homogeneous gold catalysis. Electrospray ionization mass spectrometry (ESI-MS) was used as the primary research technique in this study. Delayed reactant labeling was used as the main method. I have focused mainly on the hydration of 1-phenyl-1-propyne catalyzed by the gold complex [Au(IPr)(MeCN)]BF4 (IPr = 1,3-bis(2,6-di-iso-propylphenyl)imidazol-2- ylidene). I have detected two main intermediates containing one or two gold atoms, respectively (monoaurated and diaurated intermediate). I have obtained rate constants for the degradation of the reaction intermediates and their half-lives. I have derived kinetic isotope effects for the formation and the decomposition of the detected intermediates. I have shown that the kinetics of the degradation of both intermediates is identical, therefore I conclude that hydration of alkynes catalyzed by gold complex [Au(IPr)(MeCN)]BF4 proceeds most probably via neutral monoaurated intermediates. These neutral intermediates are detected by ESI-MS as protonated (monoaurated intermediate) or tagged by a second gold cation (diaurated intermediate). Key words: gold catalysis, reaction intermediates, electrospray ionization, mass spectrometry.
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Complexes of zinc salts and flavonoids
Křížová, Tereza ; Roithová, Jana (advisor) ; Volný, Michael (referee)
Modern mass spectrometry (MS) is very well suited for analysis of flavonoids and their complexes. Progress during the last two decades has made MS the most sensitive method for molecular analysis of flavonoids. MS has a potential to provide information on the exact molecular mass, as well as on the structure. Flavonoids are acting as chelating agents on various metal ions. The goal of this study was to discover, which types of ions are formed in solutions of zinc salts and flavonoids by using mass spectrometry attached with electrospray ionization. First, we have studies substructures of flavonoid - resorcin, pyrokatechin a pyron - in order to find out, how individual parts of flavonoid interact with zinc ions.
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Complexes of iron(II) salts and flavonoids
Schröpferová, Tereza ; Volný, Michael (referee) ; Roithová, Jana (advisor)
This work is devoted to a study of the interaction between iron(II) ions and flavonoids (epicatechin, catechin, quercetin) by means of mass spectrometry and electrospray ionization. First, a measurement with model molecules (pyrocatechol, resorcinol, 3-hydroxy-2-methyl-4- pyrone) has been performed in order to find how iron(II) intereacts with the OH groups on the hydrocarbon rings. It has been found that Fe2+ coordinates to epicatechin and probably also catechin (the measurement with catechin was unsuccesfull because of contamination by sodium) between the OH groups at the ring B and the fragmentation of the complex can proceed via a retro-Diels-Alder's reaction and thus lead to cleavage of the pyrone ring. Quercetin has at the pyrone ring the keto function next to the OH group, therefore the iron ion binds to these functions rather than to the OH groups at the ring B. Accordingly, the retro- Diels-Alder's reaction is not possible and the complex loses only small molecules of water and carbon oxide from the side rings as it was found for the complexes of model molecules.
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