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Optical characterization of supramolecular complexes of selected organic fluorophores with cyclodextrins
Haiklová, Simona ; Dian, Juraj (advisor) ; Červený, Václav (referee)
The content of this thesis is the optical characterization and determination of the strength of supramolecular interaction of selected organic fluorophores and cyclodextrins (CD) using the stability constant with optical methods: UV-Vis absorption and fluorescence. Two series of fluorophores differed in the presence of groups with two positive charges, and two types of cyclodextrins (-CD a -CD) with different cavity sizes were chosen for the study. Fluorophores with charged end groups can be efficiently bound by electrostatic interaction on solid surfaces of suitable chemical composition or thin films with an excess of negative charge and thus immobilized by a very strong interaction on a given support. These prepared surfaces or layers can then be used for the optical detection of chemical substances. The aim of this work was to determine the influence of cyclodextrin cavity size, the presence of a charged anchor, and solution pH on the supramolecular interaction of the studied systems and evaluate the application possibilities of the studied systems for optical chemosensors. In the presented thesis, the change in optical absorption and fluorescence intensity of four pairs of fluorophores: PRODAN, RhB, RhB-Si, DANSA, and their derivatives with a charged anchor was studied during supramolecular...
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Use of capillary electrophoresis with UV photometric and electrospray ionization mass spectrometric detection for the study of interaction of compounds
Konášová, Renáta ; Jaklová Dytrtová, Jana (advisor) ; Mikšík, Ivan (referee) ; Tůma, Petr (referee)
Capillary electrophoresis (CE) is highly efficient separation method based on the different migration velocity of ions in liquid media in electric field. It is commonly used in analytical laboratories and due to the different separation principle it is applied as a complementary method to the chromatographic methods (HPLC and UHPLC). Beside the applicability of CE for quantitative/qualitative analysis, the method can be used also for physico-chemical characterization of compounds (e.g. determination of acid dissociation constants of weak electrolytes or stability constants of complexes). This work is focused on the applicability of CE methods for determination of physico- chemical characteristic of compounds (acid dissociation constants of triazole fungicides and stability constants of dibenzo-18-crown-6, benzo-18-crown-6 and 18-crown-6 ether complexes with metal ions in hydro-organic solvent mixtures) and on the possibility to use affinity CE (ACE) with electrospray ionization-mass spectrometric detection (ACE- ESI/MS) for the study of non-covalent interactions of compounds. For the online hyphenation of CE and ESI/MS, two highly sensitive CE-ESI/MS interfaces were tested: i) porous tip and ii) nano-sheath liquid flow. The ability of the CE-ESI/MS interfaces to effectively decouple spray and...
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Determination of stability constants of charged cyclodextrine complexes by capillary electrophoresis
Beneš, Martin ; Zusková, Iva (advisor) ; Dubský, Pavel (referee)
Martin Beneš Determination of stability constants of charged cyclodextrin comlexes by capillary electrophoresis Abstract Stability constant characterizes binding interaction between an analyte and complexation agent. These interactions play very important role in separation processes of, in other way undistinguishable, compounds, e.g. enantiomers. The most widely used complexation agents are cyclodextrins. Affinity capillary electrophoresis (ACE) belongs to methods suitable for the determination of stability constants. The stability constant is determined from the dependence of the effective mobility of analyte on the increasing concentration of complexation agent in background electrolyte (BGE). If charged CDs are used, the attention must be paid not only to viscosity of the BGE and to the influence of Joule heating on the temperature in the capillary but also to the increasing ionic strength. The thermodynamic stability constants of R,R- and S,S-hydrobenzoin and R- and S-(3-brom- 2-methyl-1-propanol) with cationic modified β-cyclodextrin: 6-monodeoxy-6-mono(3- hydroxy)propylamino-β-cyclodextrin hydrochlorid (PABCD) were determined by affinity capillary electrophoresis. The average temperature (25řC) of the BGE in the capillary was kept constant. This was achieved by decreasing of the cassette temperature...
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System peaks in elektromigration systems with complexing agents
Dvořák, Martin ; Gaš, Bohuslav (advisor) ; Coufal, Pavel (referee)
Capillary zone electrophoresis (CZE) is a widely used analytical method. CZE is described theoretically very well and there are many simulation programs, which enable one to predict results of electrophoretic separations, and alternatively to study phenomena taking place during the electrophoretic separation in detail. The CZE method is not only an analytical method, but is often used for determination of many physical parameters of compounds, such as stability constants or complex mobilities. Among methods most often used for determination of complexation parameters belongs the affinity capillary electrophoresis (ACE). Its alternative is the vacancy affinity capillary electrophoresis (VACE). Whereas by the ACE method the stability constant is determined from the dependence of the analyte effiective electrophoretic mobility on the background electrolyte (BGE) composition, in the case of the VACE system peaks are used for this purpose. In this work the legitimacy of using system peaks in the VACE method for determination of stability constants was investigated. Several approaches dealing with the concentrating of complexing agent in the peak area were compared, both for the ACE and the VACE method. Two different kinds of electrophoretic systems were studied. In the first one, neutral cyclodextrin was used as...
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Chiral separation of diquats and determination of stability constants of their complexes with cyclodextrins by capillary electrophoresis
Bílek, Jan ; Kašička, Václav (advisor) ; Jelínek, Ivan (referee)
Capillary zone electrophoresis was used for chiral separation of eleven diquat derivatives. These N-heteroaromatic dications containing structural motif of 2,2'-bipyridine have recently been studied for their interesting electrochemical properties as well as for the axial chirality of their molecules. The combination of these properties could potencially lead to interesting applications in the future. For enantioseparation of diquats (DQ) commercially available randomly sulfated α-, β-, and γ-cyclodextrins with high degree of substitution were used. A succesfull chiral separation was achieved using all of the three sulfated cyclodextrins as chiral selectors (CS). Baseline enantioseparation was achieved for 82 %, 91 % respectively 100 % of the analyzed DQ in the presence of HS-α-CD, HS-β-CD, HS-γ-CD respectively. The highest separation efficiency and resolution were obtained in the backround electrolyte containing 22 mmol/L NaOH, 35 mmol/L H3PO4 (pH2,5) and 6 mmol/L HS-β-CD. Using three available nonracemic DQ an identification of the particular M- and P-enantiomers was done for the three corresponding DQ structures. Apparent stabillity constants of complexes of the DQ derivatives with above mentioned cyclodextrins as CS were determined by means of capillary affinity electrophoresis. The stability...
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Spectrophotometric determination of stability constants of cyclodextrin derivatives by phenolphthalein method
Haiklová, Simona ; Dian, Juraj (advisor) ; Červený, Václav (referee)
This bachelor thesis deals with the determination of stability constants of cyclodextrins and their derivatives in the formation of supramolecular complexes with phenolphthalein. Cyclodextrins - macrocyclic oligosaccharides - are characterized by the shape of a truncated cone, whose internal hydrophobic cavity can form, with suitable substances, host-guest inclusion complexes. The formation of these inclusion complexes is accompanied by a change of a number of physicochemical parameters of the included compounds. In this bachelor thesis, the change of optical absorption of phenolphthalein, which has characteristic violet color in the alkaline area, was studied during its interaction with selected CD macrocycles. The formation of a supramolecular complex resulted in a decrease in optical absorption, which was quantified and used to determine stability constant. In the bachelor thesis, the supramolecular interaction of phenolphthalein with six derivatives of cyclodextrins were studied - basic cyclodextrins β-CD a γ-CD and their two derivatives. In the selected derivatives of these CDs the -OH groups in positions 2, 3, and 6 were replaced either by hydroxypropyl groups (hydroxypropyl-β-CD and hydroxypropyl-γ- CD) or (randomly) by methyl groups (RaMe-β-CD and RaMe-γ-CD). For these CD derivatives, the...
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Use of capillary electrophoresis with UV photometric and electrospray ionization mass spectrometric detection for the study of interaction of compounds
Konášová, Renáta ; Jaklová Dytrtová, Jana (advisor) ; Mikšík, Ivan (referee) ; Tůma, Petr (referee)
Capillary electrophoresis (CE) is highly efficient separation method based on the different migration velocity of ions in liquid media in electric field. It is commonly used in analytical laboratories and due to the different separation principle it is applied as a complementary method to the chromatographic methods (HPLC and UHPLC). Beside the applicability of CE for quantitative/qualitative analysis, the method can be used also for physico-chemical characterization of compounds (e.g. determination of acid dissociation constants of weak electrolytes or stability constants of complexes). This work is focused on the applicability of CE methods for determination of physico- chemical characteristic of compounds (acid dissociation constants of triazole fungicides and stability constants of dibenzo-18-crown-6, benzo-18-crown-6 and 18-crown-6 ether complexes with metal ions in hydro-organic solvent mixtures) and on the possibility to use affinity CE (ACE) with electrospray ionization-mass spectrometric detection (ACE- ESI/MS) for the study of non-covalent interactions of compounds. For the online hyphenation of CE and ESI/MS, two highly sensitive CE-ESI/MS interfaces were tested: i) porous tip and ii) nano-sheath liquid flow. The ability of the CE-ESI/MS interfaces to effectively decouple spray and...
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Chiral separation of diquats and determination of stability constants of their complexes with cyclodextrins by capillary electrophoresis
Bílek, Jan ; Kašička, Václav (advisor) ; Jelínek, Ivan (referee)
Capillary zone electrophoresis was used for chiral separation of eleven diquat derivatives. These N-heteroaromatic dications containing structural motif of 2,2'-bipyridine have recently been studied for their interesting electrochemical properties as well as for the axial chirality of their molecules. The combination of these properties could potencially lead to interesting applications in the future. For enantioseparation of diquats (DQ) commercially available randomly sulfated α-, β-, and γ-cyclodextrins with high degree of substitution were used. A succesfull chiral separation was achieved using all of the three sulfated cyclodextrins as chiral selectors (CS). Baseline enantioseparation was achieved for 82 %, 91 % respectively 100 % of the analyzed DQ in the presence of HS-α-CD, HS-β-CD, HS-γ-CD respectively. The highest separation efficiency and resolution were obtained in the backround electrolyte containing 22 mmol/L NaOH, 35 mmol/L H3PO4 (pH2,5) and 6 mmol/L HS-β-CD. Using three available nonracemic DQ an identification of the particular M- and P-enantiomers was done for the three corresponding DQ structures. Apparent stabillity constants of complexes of the DQ derivatives with above mentioned cyclodextrins as CS were determined by means of capillary affinity electrophoresis. The stability...
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Determination of complexation constants by partial Filling method and Flow Induced Dispersion Analysis and their comparison with values determined by Affinity Capillary Electrophoresis
Ansorge, Martin ; Ušelová, Kateřina (advisor) ; Křížek, Tomáš (referee)
Partial Filling method (PF) and Flow Induced Dispersion Analysis (FIDA) were used for the determination of stability constants of model system of four profens (R-Flurbiprofen, S-Ibuprofen, S-Ketoprofen and S-Naproxen) complexing with β-cyclodextrin. When using PF method, only a part of capillary is filled with the selector and thus the analyte must migrate through the zone of selector first and then through the neat BGE (it has different mobilities in both zones). Dependency of the differences in migation time on the length of the selector zone is then studied. When FIDA is used, the analyte in pushed through the capillary by external pressure and dependency of the rate of peak dispersion of the analyte on the concentration of selector in capillary is observed. Moreover, PF experiments were theoretically studied by Simul 5 Complex computing programme. Values of stability constants obtained by both methods were compared with values obtained by frequently used Affinity Capillary electrophoresis (ACE) method. The comparison of stability constants values determined by PF method and FIDA shows that both investigated methods grants results comparable with those obtained by the ACE.
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Determination binding constant of beta-blockers by capillary zone electrophoresis
Kanizsová, Lívia ; Zusková, Iva (advisor) ; Šteflová, Jana (referee)
Capillary zone electrophoresis identifies and determines various analytes based on their mobilities in a solution of the background electrolyte, which is exposed to an effect of the electric field. Besides that, it is a suitable method for determination of dissociation and complexation (stability) constants. In this paper the adrenergic β-blockers were chosen as analytes. β-blockers have at least one chiral center in the structure and separation of their enantiomers in presence of the chiral selectors by capillary electrophoresis is possible. For the enantioseparation, variously modified β-cyclodextrins are most often added to the background electrolyte. If the enantiomers of β-blockers have a different affinity to the chiral selector, they exhibit different effective mobilities. Based on a dependence of the effective mobility of analytes on the concentration of chiral selector, we are able to determine their stability constants. Key words: β-blockers, cyclodextrins, stability constant, capillary zone electrophoresis
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