|
|
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...
|
|
|
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...
|
|
|
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...
|
|
|
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...
|
|
| |
|
|
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...
|
|
|
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.
|
|
|
Automatic data analysis in capillary zone electrophoresis
Ördögová, Magda ; Dubský, Pavel (advisor) ; Heyda, Jan (referee)
Evaluating data in capillary zone electrophoresis usually involves many steps that require using several different programmes. Apart from evaluating the electrophoreogram itself, it is usual to process the obtained data in some other way. For example, a suitable model is fit to the data in order to obtain physical and chemical parameters of the separation (e.g. stability constant in case of complexation). It is also important to know the accuracy of the evaluation (the calculation error). In this work, new parts of the Eval programme, originally developed for electrophoreogram evaluation, were implemented. The programme now automatically estimates the Haarhoff-van der Linde function (solution of continuity equation in capillary) parameters for analyte peak. Complexing agents are often used to improve the separation in the capillary zone electrophoresis. Complexation in the capillary can be described by its physical and chemical parameters. A new part was added to the Eval programme that allows the user to fit a rectangular hyperbole function to the obtained data. Thus, the regression parameters of this dependence can be gained. The programme can also draw profile diagrams for these parameters, from which the confidence intervals can be read. An option that allows two dependencies to be fitted at...
|
|
|
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...
|
|
|
Determination of stability constants of charged cyclodextrine complexes by capillary electrophoresis
Beneš, Martin ; Dubský, Pavel (referee) ; Zusková, Iva (advisor)
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...
|
guest ::
