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Vibrational optical activity of 3-aminoquinuclidine
Jílek, Štěpán ; Profant, Václav (advisor) ; Kaminský, Jakub (referee)
1 The bachelor thesis deals with the study of the chiral molecule 3-aminoquinuclidine (AQN), which is an important pharmacophore. The derivates of this molecule form a basis for several biologically important molecules and drugs: serotonin receptors activity modulators, agents displaying neuronal activity and medicaments supressing side effects of chemotherapy administration (antiemetics). AQN is a chiral molecule and information on its absolute configuration and enantiomeric purity is crucial to the use of AQN in drug synthesis. AQN contains both primary and tertiary amine group and depending on pH value it can be found in three differently charged forms. This thesis presents characterization of AQN utilizing methods of vibrational spectroscopy - infrared absorption and Raman scattering, together with their variants - vibrational circular dichroism (VCD) and Raman optical activity (ROA), all these in combination with quantum chemical simulations. The attention was paid to a choice of the suitable solvents and settings of experimental conditions. Based on pH dependent Raman spectral series we determined pKA dissociation constants associated with transitions between AQN's protonated states, which were further characterized by ROA and VCD. The properties of AQN in various phases (aqueous solution, crystalline...
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Photochemical Derivatization of Helicenes.
Jakubec, Martin
Helicenes are a class of polyaromatic compounds that have been increasingly studied over the past years. Their chirality, extended π-system and other intriguing characteristics make them worth exploiting in various fields of chemistry and material science.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22019053108330 - PDF
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Development and applications of molecular dynamics for molecular spectroscopy
Kessler, Jiří
This Thesis deals with simulations of chiroptical spectra using a combination of molecular dynamics and quantum chemistry. Molecular dynamics was used to explore conformational behaviour of studied systems (proteins), quantum chemistry for calculation of spectral prop- erties. The Quantum chemical methods are limited to relatively small systems. We overcome this problem mostly by a fragmentation of studied systems, when smaller, computationally feasible, fragments are created and used for the quantum chemical calculations. Calculated properties were then transferred to the big molecule. Vibrational Optical Activity (VOA) spectra of poly-L-glutamic acid fibrils (PLGA), insulin prefibrillar form and native globular proteins were studied. The simulated spectra provided satisfactory agreement with the experiment and were used for its interpretation. Experimental Vibrational Circular Dichroism (VCD) spectra of poly-L-glutamic acid fibrils were only qualitatively reproduced by the simulation. We could reproduce the major amide I band and a smaller negative band associated with the side chain carboxyl group. Our simulation procedure was then extended to a set of globular proteins and their Raman Optical Activity (ROA) spectra. Here we achieved an exceptional precision. For example, we were able to reproduce...
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Development and applications of molecular dynamics for molecular spectroscopy
Kessler, Jiří ; Bouř, Petr (advisor) ; Bludský, Ota (referee) ; Setnička, Vladimír (referee)
This Thesis deals with simulations of chiroptical spectra using a combination of molecular dynamics and quantum chemistry. Molecular dynamics was used to explore conformational behaviour of studied systems (proteins), quantum chemistry for calculation of spectral prop- erties. The Quantum chemical methods are limited to relatively small systems. We overcome this problem mostly by a fragmentation of studied systems, when smaller, computationally feasible, fragments are created and used for the quantum chemical calculations. Calculated properties were then transferred to the big molecule. Vibrational Optical Activity (VOA) spectra of poly-L-glutamic acid fibrils (PLGA), insulin prefibrillar form and native globular proteins were studied. The simulated spectra provided satisfactory agreement with the experiment and were used for its interpretation. Experimental Vibrational Circular Dichroism (VCD) spectra of poly-L-glutamic acid fibrils were only qualitatively reproduced by the simulation. We could reproduce the major amide I band and a smaller negative band associated with the side chain carboxyl group. Our simulation procedure was then extended to a set of globular proteins and their Raman Optical Activity (ROA) spectra. Here we achieved an exceptional precision. For example, we were able to reproduce...
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Enantioselective separation of certain analytes using supercritical fluid chromatography and high performance liquid chromatography
Martínková, Monika ; Tesařová, Eva (advisor) ; Čabala, Radomír (referee)
(EN) Cellulose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase was used for separation of selected 24 analytes. Enantioseparations were realized using two systems, high performance liquid chromatography and supercritical fluid chromatography. Effect of mobile phase composition was studied. Five different aditives (isopropylamine, diethylamine, triethylamine, trifluoroacetic acid, isopropylamine combined with trifluoroacetic acid) and their influence on enantioseparation were tested. Influence of two different modifiers (methanol, propan-2-ol) combined with all aditives was also tested in supercritical fluid chromatography system. The aim of this work was to find optimized composition of mobile phase which was suitable for separation of the analytes studied and to compare separation potential among all mobile phases and also between used separations systems. The supercritical fluid chromatography was shown to yield better results, i.e. better resolution in shorter analysis time. However examples of analytes better resolved under optimized conditions in high performance liquid chromatography system have also been found. Keywords (EN) Chirality, enantiomers, enantioselective separation, chiral stationary phase, high performance liquid chromatography, supercritical fluid chromatography.
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Studies of Lanthanide Complexes by a Combination of Spectroscopic Methods
Krupová, Monika ; Bouř, Petr (advisor) ; Kapitán, Josef (referee)
Studies of Lanthanide Complexes by a Combination of Spectroscopic Methods Monika Krupová (Department of Physical and Macromoecular Chemistry, Faculty of Science, Charles University in Prague) Since conventional structural analysis offers rather limited means for the chirality detection, a series of lanthanide tris-(β-diketonates) are investigated as effective receptors for a better chirality sensing in biomolecular substrates. These lanthanide complexes containing β-diketonate ligands are electrically neutral; they can further coordinate with various small organic molecules such as chiral alcohols, amino alcohols or amino acids in organic solvents and produce a strong chiral signal. Previously, a resonance in Raman scattering was observed in the studied systems due to the correspondence of europium electronic transition energy to the laser excitation wavelength, about a 100-fold signal enhancement if compared to non-resonant vibrational ROA was observed. This enabled shorter detection times as well as lower sample concentrations. In the current work, interaction of the Eu(FOD) complex with (R)- and (S)- enantiomer of 1-phenylethanol in n-hexane was studied using IR spectroscopy, Raman spectroscopy and Raman optical activity (ROA), UV-Vis spectroscopy and ultraviolet circular dichroism (UVCD). Only...
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Spektroskopické a teoretické studium supramolekulárních komplexů symetrických porfyrinů s chirálními guesty
Březina, Václav ; Hanyková, Lenka (advisor) ; Šoltésová, Mária (referee)
Certain types of porphyrins can be used as achiral agent for determination of enantiomeric excess (ee) of chiral molecules. Particular organic chiral molecule (guest) and porphyrin (host) form host-guest complex while inducing nonequiv- alency of particular proton resonances in symmetrical host. It causes splitting of NMR signals linearly dependent on ee of guest. In this work we investigated com- plexation of di-brombenzylated oxoporphyrin with chiral camphorsulfonic acid. NMR titration revealed that they form complex with 1:1 stoichiometry with as- sociation constant K ≈ 5 × 104 l/mol. We confirmed linear dependence of split- ting of host β-protons on ee of guest. Low temperature measurements revealed two conformations of host-guest complex with population around 0.7:0.3 (at −60 ◦ C). DFT quantum mechanical computations at BLYP/3-21G* level revealed also two conformations with population 0.79:0.21. NMR shifts were computed on this geometries with method GIAO/PBE1PBE/6-31G(2df,2pd) and compared to experimental values. 1
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Chiral recognition by mass spectrometry
Kosíková, Lenka ; Roithová, Jana (advisor) ; Bednář, Petr (referee)
Title: Chiral recognition by mass spectrometry Author: Bc. Lenka Kosíková Department: Department of Organic Chemistry Supervisor: doc. Mgr. Jana Roithová, Ph.D. This work is focused on the use of mass spectrometry as the analytical method for chiral recognition in the gas phase. We have examined formation of complexes (S and R) isomers [dimethyl-2,2'-dihydroxy-1,1'binaphthalene-3,3'-dicarboxylate] with sodium. Chiral effect for the fomation of sodium dimers is 1,34±0,06 and that for formation of trimers 2,38±0,22 in favor of the formation of homochiral complexes. Part of the work is devoted to the preparation of isotopically labeled ester [(R)-(−)- di(D3-methyl)-2,2'-dihydroxy-1,1'binaphthalene-3,3'-dicarboxylate]. Mixing of equimolar amounts of D3-(R) and unlabeled (S) isomers leads to the artificial racemate, while we can still distinguish the enantiomers using mass spectrometry. Another part represents the study of the complex formation between (S and R) isomers of [dimethyl-2,2'-dihydroxy-1,1'binaphthalene-3,3'-dicarboxylate] with the metal complex [(S,S)-1,5-diaza-cis-decalin]Cu(OH)I depending on the molar ratios in the solution. I have showed that the molar concetration of the catalyst in the solution plays an important role in the complex formation and that the ESI source spectra of...
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Determination of enantiomers of amino acids by HPLC
Michalčíková, Regina ; Janečková, Lucie (referee) ; Tesařová, Eva (advisor)
This Bachelor's thesis deals with determination of amino acids enantiomers, namely alanine in the experimental part, by high performance liquid chromatography using chiral stationary phases based on teicoplanin. The theoretical part is focused on summarizing the fundamental issue of chirality and chiral amino acids in foods, the characteristics of high-performance liquid chromatography, as one of the most appropriate methods to enantioseparation amino acids, and description of the methods of derivatization, which are used in determination of enantiomers of amino acids. The experimental part deals with the separation of alanine enantiomers, with the choice of the best separation system for the separation and determination of D-and L-alanine in fruit juice.
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