Molecular recognition in chiral discrimination (original) (raw)
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Molecules
This work reviews the literature of chiral capillary electrokinetic chromatography from January 2016 to March 2021. This is done to explore the state-of-the-art approach and recent developments carried out in this field. The separation principle of the technique is described and supported with simple graphical illustrations, showing migration under normal and reversed polarity modes of the separation voltage. The most relevant applications of the technique for enantioseparation of drugs and other enantiomeric molecules in different fields using chiral selectors in single, dual, or multiple systems are highlighted. Measures to improve the detection sensitivity of chiral capillary electrokinetic chromatography with UV detector are discussed, and the alternative aspects are explored, besides special emphases to hyphenation compatibility to mass spectrometry. Partial filling and counter migration techniques are described. Indirect identification of the separated enantiomers and the dete...
Analytical Letters, 2006
Three enantioselective, potentiometric carbon paste electrodes (EPCPEs) based on carbon paste impregnated with (1,2-methanofullerene C60)-61-carboxylic acid (I), diethyl (1,2-methanofullerene C60)-61-61-dicarboxylate (II), and tert-butyl (1,2-methanofullerene C60)-61-carboxylic acid (III) are reported. Response characteristics showed that the proposed electrodes could be reliably used in the assay of S-clenbuterol raw material and in serum samples. The surfaces of the electrodes are stable and easily renewable by simply polishing on an alumina paper.
ELECTROPHORESIS, 2003
Enantioselective strong cation-exchange molecular recognition materials: Design of novel chiral stationary phases and their application for enantioseparation of chiral bases by nonaqueous capillary electrochromatography New chiral stationary phases derived from enantiomerically pure derivatives of cysteine carrying sulfonic acid groups are synthesized and evaluated for enantiomer separation of chiral bases by non aqueous capillary electrochromatography after bonding to a linker and grafting upon thiol-modified silica particles. Structural modifications of these low molecular weight chiral selectors are investigated and discussed in terms of apparent enantioselectivities and resolution factors based on the enantiomeric separations of a set of chiral bases including b-blockers, b-sympathomimetics and other basic drugs. The influence of the mobile phase constitution and its flow velocity on the enantioseparation by nonaqueous capillary electrochromatography is also briefly evaluated and discussed for the chiral substances investigated.
Electrochimica Acta, 2011
An electrochemical method for chiral polyaniline synthesis has been optimised to develop voltammetric sensors capable of target enantiomer recognition. The methodologies for both R-and S-specific sensor development have been carefully optimised in order to obtain the highest chiral discrimination capacity. R and S specific sensors were synthesised potentiostatically at 0.5 V and 0.6 V, respectively in 0.28 M R-or S-camphorsulphonic acid, which acted as a chiral inducing agent. Higher potential values led to polymer degradation. The proposed methodology allows the generation of sensors which are able to bind the different enantiomers of the pesticide dinoseb with good sensitivity and repeatability (RSD < 10%). Thereby the resulting R-and S-sensors showed a very high capability to bind selectively the target enantiomer from a racemic mixture. The proposed method could be also extended easily to selective recognition of enantiomers of other chiral compounds.
A CHROMATOGRAPHIC METHOD FOR MEASURING K F OF ENANTIOMER-CHIRAL SELECTOR COMPLEXES
Journal of Liquid Chromatography & Related Technologies, 1999
The method uses high-speed countercurrent chromatography to retain a given concentration of the chiral selector (CS) in the liquid stationary phase. A minute amount of an enantiomeric analyte is eluted through the column to measure its retention time from which the distribution ratio of the analyte is computed. The experiment is repeated by varying the CS concentration in the stationary phase. Using a set of data thus obtained, plotting the CS concentration in the stationary phase against the relative distribution ratio of the analyte produces a straight line whose slope corresponds to the formation constant (K f ) of the CS-analyte complex. The validity of the method is demonstrated on a set of dinitrobenzoyl amino acids using N-dodecanoyl-L-proline-3,5-dimethylanilide as CS. The method will be useful for understanding the basic mechanism of enantioselectivity and designing effective chiral selectors.
Angewandte Chemie International Edition, 2008
Many biologically active molecules are chiral, and the enantiomeric composition of pharmacologically relevant chiral substances should be known to exclude unwanted side effects. [1-3] A reliable and fast chiral discrimination still represents a major challenge in sensorics because of the identical physicochemical properties (with the exception of chiroptics) of the respective enantiomers in an achiral environment. [4-6] The signals of sensors coated with chiralrecognition structures usually vary only in the magnitude of their response to the different enantiomers. [4-8] Herein, we demonstrate the principle of a capacitive chiral sensor, which provides antipode signals upon exposure to the enantiomers of methyl propionate compounds, so that it is possible to unambiguously determine the enantiomer identity. The dielectric coefficient of the analyte-receptor complex of one enantiomer is significantly different from that of its counterpart. The results disclosed herein show that simple sensor techniques can be used to detect the subtle effects of the different molecular orientations. Chiral separation techniques, such as electrophoresis and chromatograpy, are widely used and established methods. [9-12] Chiral sensors for the liquid phase (for example, potentiometric sensors) [7, 8] have been more extensively studied [4, 6, 8,13] than the sensors for the gas phase. [5, 6] Separation and sensor methods predominantly rely on the use of matrices that contain enantioselective receptor structures, [6, 9-16] such as cyclodextrins, [5, 6, 11, 16] or molecularly imprinted polymers. [17, 18] The chiral recognition is then based on the formation of a more stable diastereomeric complex with one of the enantiomers. The larger the Gibbs-energy difference between the diastereomeric complexes, the higher the enantioselectivity.
2018
A rapid and simple method for separation of enantiomers of a variety of compounds is desirable as information regarding the enantiomeric composition may not be provided by the chemical suppliers especially chemical drug compounds. These drugs are commercially available with no information regarding whether they are pure enantiomers or racemic mixtures. Each enantiomer may have different pharmacological activity. Thus the information of chirality is important. This work aims to employ a capillary electrophoresis with UV detection as a simple and rapid method for separation of enantiomers to determine the compound chirality. The developed method has been applied for separation of different functional chemicals of drugs, such as β-blockers and neurotransmitter, by using a single capillary electrophoresis method. The buffer conditions for the capillary method were optimized with regards to the chiral selector type and concentration for improving the efficiency of enantiomer separation. ...