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Experimental Investigation of selected supramolecular systems by NMR spectroscopy
Šoltésová, Mária ; Lang, Jan (advisor) ; Kříž, Jaroslav (referee)
The thesis describes investigation of two selected supramolecular systems by means of NMR spectroscopy and hydrodynamic calculations. The first system studied was inclusion complex of cryptophane-C with chloroform. Initially, the kinetics of complexation was determined. The measurements of longitudinal relaxation and heteronuclear Overhauser enhancement on carbon-13 nuclei revealed very large motional coupling between the host and the molecular guest bound inside the cavity. Hydrogen bonded clusters of ethanol in a non-polar solvent were the second system addressed. The diffusion coeffcients of ethanol were measured in a broad temperature range (180 - 330 K) by means of NMR spectroscopy. The average cluster sizes dependent upon experimental conditions were determined. At low temperature (around 180 K), the cluster sizes vary from hexamer (0.16 M sample) to octamer or larger structures (1.4 M sample). On the other hand, the average cluster size at ambient temperature corresponds to trimer (1.4 M), pure monomer occurs in the less concentrated sample above 308 K. Experimental results for monomer are in excellent agreement with the calculated values.
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Raman optical activity and conformation of structurally important groups in peptides and proteins
Kubáňová, Markéta ; Baumruk, Vladimír (advisor) ; Kapitán, Josef (referee)
Raman optical activity (ROA) represents a modern spectroscopic technique that can be applied to a wide range of chiral molecules starting from small organic molecules up to complex biomolecular systems. Among other things ROA provides information about solution structure of peptides and proteins. The aim of the thesis was to determine the relationship between three-dimensional structure and Raman optical activity of disulphide and amide groups in peptides. Characteristic band patterns of the polyproline II conformation (left-handed 31-helix) were found in the ROA spectra of poly(Pro-Gly-Pro), oxytocin and hinge peptide linked to the antigen sequence. ROA signal in the S-S and C-S stretching region was observed in ROA spectra of model cyclodextrin compounds connected with disulphide bonds. Positive ROA band in the S-S stretching region was found in the ROA spectrum of oxytocin (the peptide with one S-S bridge). According to the theoretical studies of model disulphides, positive ROA signal in this region indicates positive dihedral angle C- S-S-C. This result is in agreement with the crystal structure. We have also worked on extension of ROA measurements to the hydrogen stretching region (2500-3200 cm-1).
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Study of chiral aspects of drug metabolism using instrumental analytic methods
Holmanová, Veronika ; Nobilis, Milan (advisor) ; Kovaříková, Petra (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Chemistry and Drug Control Candidate: Bc. Veronika Holmanová Supervisor: Doc. PharmDr. Milan Nobilis, CSc. Title of diploma thesis: Study of chiral aspects of drug metabolism using instrumental analytic methods For the evaluation of stereospecificity of rat and human cytosolic carbonyl reductases and activity of microsomal oxidases involved in nabumetone biotransformation, a new chiral high-performance liquid chromatographic method was developed. The prepared LLE-HPLC-PDA method enabled extraction, separation and ultraviolet detection of prochiral nabumetone and its five phase I metabolites including enantiomers of two chiral biotransformation products of carbonyl reduction. Methyl ester of naproxen served as an internal standard. Diethyl ether was used for liquid-liquid extraction (LLE) of biomatrices. Chiralcel OD-R 250 mm×4.6 mm column with a mobile phase methanol-1M NaClO4/HClO4 aqueous solution pH=3 (75:25, v/v) were employed in isocratic sufficient separation of nine analytes. The whole analysis lasted 60 minutes at the flow rate of 0.5 ml/min. The column effluent was monitored using a photodiode-array detector (scan or single wavelength at λ=265 nm). The results of in vitro nabumetone...
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Use of chiral stationary phases based on teicoplanin and teicoplanin aglycone for enantioseparation of FMOC-derivatized amino acids.
Repko, Pavel ; Bosáková, Zuzana (advisor) ; Tesařová, Eva (referee)
In this work, an enantioselective HPLC method with UV and fluorimetric detection was developed and subsequently optimized for chiral separation of four aminoacids (D/L-alanine, D/L-valine, D/L-leucine, D/L-isoleucine) in native and particularly in derivatized form with an emphasis on enantioseparation of D-analogues. Retention and enantioseparation behavior of studied analytes was investigated on three chiral stationary phases based on teicoplanin (Chirobiotic T, Chirobiotic T2) and teicoplanin aglycone (Chirobiotic TAG). At the Chirobiotic T column, enantioseparations of underivatized aminoacids were performed with UV detection at 205 nm in the mobile phases methanol/water with different volume ratios. Baseline separation of L- and D-forms was achieved, however, the sensitivity of detection was very low. In order to increase detection sensitivity, derivatization of aminoacids was performed using 9-fluorenylmethyl chloroformate (FMOC-Cl) and the derivatization procedure was monitored on Chirobiotic T column with fluorimetric detection (λEx = 254 nm, λEm = 314 nm) in a buffered mobile phase methanol/0.5% TEAA buffer, pH 6.0 40/60 (v/v). In terms of derivatization, volume ratio D/L-aminoacid/derivatization agent 1/1 with ten times higher concentration of derivatization agent was found to be the most suitable....
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Study of Enantioseparation of Selected Substituted Binaphthyls
Loukotková, Lucie
Over the last two decades, high-performance liquid chromatography (HPLC) has become one of the most common techniques in chiral separations and has been successfully employed for determination of the optical purity of newly synthesized organic compounds. Binaphthyl derivatives have been extensively used to control many asymmetric processes and have demonstrated outstanding chiral discrimination properties, due to their unique properties derived from their rigidity and spatial arrangement. Most of 1,1'-binaphthyl molecules are C2 symmetric with two identical naphthyl units often substituted in the 2,2'-positions. Chirality of these compounds is caused by restricted rotation of atoms or groups of atoms around the single bond on the binaphthyl skeleton. Cyclodextrins (CDs) and polysaccharides are natural oligomers and polymers, respectively, their basic constituents are glucose units. CDs and polysaccharides and their derivatives have been successfully used as chiral stationary phases (CSPs) in HPLC for enantioselective separation of a wide range of structurally different compounds. Among CSPs based on polysaccharide derivatives, celulose tris(3,5-dimethylphenylcarbamate) ones exhibit a very good resolution capability. Besides natural polymeric chiral selectors, purely synthetic polymers can provide...
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Study of interactions participating in the separation mechanism of chromatographic separation systems
Kalíková, Květa
The Thesis combines a theoretical part focused on better understanding of separation processes and interaction mechanisms with experimental applications for specific analytical purposes. HPLC is one of the preferently used separation techniques. As various interaction types can participate in the retention mechanism of analytes, the choice of the optimal separation system is often ambiguous. The selection of suitable separation conditions is very often made empirically. Such approach is rather time consuming. Therefore, it could be advantageous to utilize some physicochemical characteristics of the separation system. Linear free energy relationship (LFER) is one of the comprehensive semiempirical methods that allows characterization and comparison of stationary phases/separation systems and yield to better understanding of the intermolecular interactions, which play role in the separation processes. The optimization of separation processes can be disturbed or complicated by phenomena called system peaks. In the case of detectable system zone the resultant chromatogram includes more peaks than is the number of analytes in the sample. A serious problem that can arise if an analyte interacts with the system zones is resonance. This phenomenon can disturb completely the separation results and make...
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Resumovaná chirální poruchová teorie a studium Kl4 rozpadů
Motloch, Pavel ; Novotný, Jiří (advisor) ; Kampf, Karol (referee)
The F and G formfactors of Kl4 decays are calculated to O(p4 ) in isospin limit in Resummed Chiral Perturbation Theory. Formulae for reparametrization of low-energy constants L1 - L3 in terms of physical observables are derived. They are used to obtain values of these low-energy constants from recent experimental data, theoretical error of the result is estimated and dependence on parameters X, Z of spontaneous symmetry breaking of SU(3) × SU(3) chiral symmetry and quark mass ratio r is investigated. Convergence of the formfactors in Resummed Chiral Perturbation Theory is discussed and it is suggested that inclusion of σ as an explicit degree of freedom into Chiral Perturbation Theory could significantly improve overall covergence of chiral series. 1
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Molecular recognition in the gas phase: Chiral recognition
Vinklová, Nicole ; Roithová, Jana (advisor) ; Bednář, Petr (referee)
This thesis deals with molecular recognition of chiral compounds in the gas phase. Tandem mass spectrometry was used as a detection method in this case. Compounds, which have been studied, were MacMillan organocatalysts and proline with different chirality. Three experiments were carried out. Determination of activation energy for fragmentation of proline complexes with amines, where we have studied complexes with 2-aminobutane and 2-aminohexane of different chirality. Fragmentation studies of diastereoisomeric complexes of Cu2+ and three chiral ligands were carried out at two different collision energies. There the largest chiral effect was observed. The last topic was a measurement of the rate constants. It was aimed at dissociation and exchange reactions of complexes. Keywords: mass spectrometry, kinetic method, chiral compounds, chiral recognition, proline, organocatalysis
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