Cyclodextrins enantiomers using

Recently, two examples of the separation of enantiomers using CCC have been published (Fig. 1-2). The complete enantiomeric separation of commercial d,l-kynurenine (2) with bovine serum albumin (BSA) as a chiral selector in an aqueous-aqueous polymer phase system was achieved within 3.5 h [128]. Moreover, the chiral resolution of 100 mg of an estrogen receptor partial agonist (7-DMO, 3) was performed using a sulfated (3-cyclodextrin [129, 130], while previous attempts with unsubstituted cyclodextrin were not successful [124]. The same authors described the partial resolution of a glucose-6-phosphatase inhibitor (4) with a Whelk-0 derivative as chiral selector (5) [129]. 

FIGURE 9 Electropherograms of the chiral resolution of (I) l-cyanobenz[/]isoindole (CBI)-selenomethionine and (II) CBI-selenoethionine enantiomers using a mixture of boric acid (10 mM) and phosphate buffer (30 mM, pH 7) as the mobile phase containing [i-cyclodextrin (30 mM) and taurodeoxycholic acid (50 mM) as CMPAs with sodium dodecyl sulfate (50 mM) as the mobile phase modifier (from Ref. 97). 

Chirality of derivatized cyclodextrin was used for recognition of stereoisomers. Phenylazobenzoyl modified y-cyclodextrin was anchored onto silica gel used as stationary phase in HPLC and photoresponsive chromatographic behavior of dansyl amino acid enantiomers was studied [64],... 

Yoshida, K. Nakagama, T. Uchiyama, K. and Hobo, T. (1998) Photo responsive chromatographic behavior of dansyl amino acid enantiomers using azobenzene-modified cyclodextrin stationary phases in... 

This method is based on the fact that molecular association may lead to an efficient chiral recognition leading to enantiomeric separation when a chiral stationary phase (e.g. cyclodextrins) is used in GC. The gas (mobile phase, e.g. hydrogen, helium, nitrogen) is carrying the chiral analyte through the stationary phase. The enantiomers to be analyzed... 

Using the native cyclodextrin, the enantiomers of amino acid derivatives were enantioselectively complexed [21]. Further, for a more detailed analysis, zwitterionic tryptophan was employed [22]. For the complexation studies performed on this molecule the a-cyclodextrin was used, as its inner cavity is the smallest. The H NMR measurements showed that (R)-tryptophan formed a stronger complex with a-cyclodextrin compared with the (S) enantiomer. This is due to the number of hydrogen bonds which can be formed between each enantiomer and the host molecule. The NMR studies showed another very interesting fact the amino acid is very likely forming no intracavity complex. It has been suggested that it is coordinated near the rim of the cyclodextrin. 

Octakis (2,3,6-tri-0-methyl-gamma-cyclodextrin) was used to separate enantiomers of methyl esters of deltametrinic acid and permetrinic acid the positional isomers of nitrotoluene were also separated on the same column [17,18]. Various alkyl- and dialkyl-benzenes have been separated on beta- and gamma-cyclodextrin [19]. A complete review of the use of cyclodextrins in chromatography has been published by Hinze [20]. Cyclo-dextrins have been analyzed by packed-column gas chromatography as their dimethylsilyl ethers [21]. 

This review will illustrate examples of computer projected models of inclusion complexes of structural isomers (ortho, meta, para nitrophenol), enantiomers (d- and 1- propranolol) and diastereomers [cis and trans. l(p-B-dimethylaminoethoxy-phenyl-butene), tamoxifen] in either a- or B-cyclodextrin. The use of these computer projections of the crystal structures of these complexes allows for the demonstration and prediction of the chromatographic behavior of these agents on immobilized cyclodextrin. 

Even the higher homologues of 5-lactones (C 3-C g) were resolved into their enantiomers, using a thin film capillary coated with modified P-cyclodextrin [86] (Fig. 6.32). 

Figure 4.16. Resolution of enantiomers using BioRad Biofocus 3000 capillary electrophoresis 36 cm x 50p,m capillary column at 20 °C, 100 mM aqueous p-cyclodextrin in pH 2.5 phosphate buffer (Busacca et al., 1996).

A review of enantiomeric separations by CE using polysaccharides as chiral selectors has been reported (217). Ionic and neutral polysaccharides (e.g., heparin, chondroitin sulfate, dextrin, and maltodextrins) have been used to resolved enantiomers. Racemic acidic drugs were resolved with maltodextrins (218), while heparins and cyclodextrins were used to resolve oxamigue (219). A large number of drugs have been found to bind enantioselectively to proteins. 

JB Vincent, G Vigh. Systematic approach to methods development for the capillary electrophoretic analysis of a minor enantiomer using a single-isomer sulfated cyclodextrin. A case study of L-carbidopa analysis. J Chromatogr A 817 105-111,... 

JB Vincent, G Vigh. Nonaqueous capillary electrophoretic separation of enantiomers using the single-isomer heptakis(2,3-di-acetyl-6-sulfato)- 3-cyclodextrin as chiral resolving agent. J Chromatogr A 816 233-241, 1998. 

FIGURE 24.16 Packed capillary FCCE electropherogram showing the separation of fenoprofen enantiomers using P-cyclodextrin as a chiral selector. (Reprinted from Henley, W. H., et al., Analytical Chemistry 2005, 77, 7024-7031. Copyright 2005 American Chemical Society. With permission.)... 

Zakaiia, R, Macka, M., and Haddad, P. R., Optimisation of selectivity in the separation of aromatic amino acid enantiomers using sulfated fi-cyclodextrin and dextran sulfate as pseudostationary phases. Electrophoresis, 25, 270, 2004. 

Huang, MB, HK Li, GL Li, CT Yan and LP Wang (1996). Planar chromatographic direct separation of some aromatic amino acids and aromatic amino alcohols into enantiomers using cyclodextrin mobile phase additives. Journal of Chromatography A, 742, 289-294. 

The Effect of pH on the Separation of Duloxetine Enantiomers Using Hydroxypropyl-P-Cyclodextrin Additives... 

D.W. Armstrong, W. DeMond, A. Alak, W.L. Hinze, T.E. Riehl and T. Ward, Liquid Chromatographic Separation of Enantiomers Using a Chiral P-Cyclodextrin-Bonded Stationary Phase and Conventional Aqueous-Organic Mobile Phases, Anal. Chem., 57(1985)237. 

Vigh, Gy. Sokolowski, A.D. Capillary electrophoretic separations of enantiomers using cyclodextrin-containing background electrolytes. Electrophoresis 1997,18, 2305-2310. 

A number of enantiomers (aminoglutethimide, chlorpheniramine, chlorthalidone, fluoxetine, ibuprofen, ketoprofen, methylphenidate, metoprolol, phensuximide, propranolol, suprofen and mephenytoin) were separated on a -cyclodextrin column using 40/60 to 20/80 acetonitrile/water (0.1% triethylammonium acetate pH 4.1 or 7.1) mobile phase (analyte dependent) [1550]. 

Takahisa, E. and K. H. Engel, 2005a. 2,3-Di-0-methoxyethyl-6-0-rerf-butyl-dimethylsilyl-(3-cyclodextrin, a useful stationary phase for gas chromatographic separation of enantiomers. 

A few reports are available on chiral separations of pollutants using this modality of liquid chromatography. The separated chiral pollutants are 2-(2-chlorophenoxy)propionic acid and 2-(4-chlorophenoxy)propionic acid on n-alkyl-)8-D-glucopyranoside [17], ibuprofens on vancomycin [18] and PCBs on y-cyclodextrin [19]. Marina etal. [20] reported chiral separations of polychlorinated biphenyls (PCBs) 45, 84, 88, 91, 95, 132, 136, 139, 149, 171, 183 and 196 by MEKC using cyclodextrin chiral selectors. Mixtures of and y-cyclodextrins were used as chiral modifiers in a 2-(yV-cyclohexylamino)ethanesulfonic acid (CHES) buffer containing urea and sodium dodecyl sulfate (SDS) micelles. A mixture of PCBs 45, 88, 91, 95, 136, 139, 149 and 196 was separated into all 16 enantiomers in an... 

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