Cyclodextrin Derivatives as Chiral Selectors—Investigation of the Interaction with (<i>R,S</i>)‐Methyl‐2‐chloropropionate by Enantioselective Gas Chromatography, NMR Spectroscopy, and Molecular Dynamics Simulation

Köhler, Jutta; Hohla, Manfred; Richters, Martina; König, Wilfried Α.

doi:10.1002/anie.199203191

Cited by 65 publications

(13 citation statements)

References 16 publications

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“…11,12 A source of irreproducible chromatographic separation consists of the traces of water or moisture, the content of which is very difficult to control and, in general, constitutes an undesired presence. 27, 28 The investigation of enantiodiscrimination processes in the presence and absence of traces of water was conducted by using methyl-2-chloropropionate (MCP, Scheme 1), which is differentiated by the selector, [26][27][28][29]31,32 as probe 30,33 of enantiodiscrimination processes. [13][14][15][16] This aspect may become notably relevant in the case of chiral selectors able to encapsulate small molecules, such as cyclodextrins [17][18][19] and resorcinarenes.…”

Section: Introductionmentioning

confidence: 99%

“…20 With the aim of going into detail on this subject, an accurate spectroscopic and computational study was carried out on the effect of the presence of trace amounts of water on the enantiodiscriminating potency of octakis(3-Obutanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex E, Scheme 1), 21 which represents one of the most popular cyclodextrinic selectors employed in gas chromatography [22][23][24][25][26] and in sensors. 27,28 The investigation of enantiodiscrimination processes in the presence and absence of traces of water was conducted by using methyl-2-chloropropionate (MCP, Scheme 1), which is differentiated by the selector, [26][27][28][29]31,32 as probe 30,33 of enantiodiscrimination processes.…”

Section: Introductionmentioning

confidence: 99%

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Synergistic Effects of Trace Amounts of Water in the Enantiodiscrimination Processes by Lipodex E: A Spectroscopic and Computational Investigation

et al. 2014

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Nuclear magnetic resonance (NMR) investigations on mixtures containing octakis(3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex E) and each enantiomer of methyl-2-chloropropionate (MCP) ascertained the role of trace amounts of water in the enantiodiscrimination processes. Water is deeply included into the cyclodextrin and favors the formation of the inclusion complex with (S)-MCP, whereas (R)-MCP is only slightly affected, thus causing a significant increase of NMR differentiation. Molecular dynamics simulations were performed to shed light on the possible behavior of Lipodex E in different conditions (i.e., solvent, inclusion complexes), providing energetic and atomistic details that are in agreement with NMR observations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synergistic Effects of Trace Amounts of Water in the Enantiodiscrimination Processes by Lipodex E: A Spectroscopic and Computational Investigation

et al. 2014

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“…Yet unexpected large enantioseparation factors α has been observed with enflurane, [124] with α ¼ 2.02 corresponding to ÀΔ S,R ΔG ¼ 2.1 kJ/mol at 60 C, whereby the (S)-enantiomer is eluted after the (R)-enantiomer, and NMR studies and molecular dynamics calculations were carried out for this efficient enantioselective system [125,126]. Methyl 2-chloropropanoate was also enantioseparated on octakis(3-Obutanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex E) with α ¼ 2.27 corresponding to ÀΔ S,R ΔG ¼ 2.34 kJ/mol, ÀΔ S,R ΔH ¼ 13.8 kJ/mol, and ÀΔ S,R ΔS ¼ 33.5 J/mol K at 70…”

Section: An Extraordinary Enantiomeric Differentiationmentioning

confidence: 98%

Salient Features of Enantioselective Gas Chromatography: The Enantiomeric Differentiation of Chiral Inhalation Anesthetics as a Representative Methodological Case in Point

Schurig

2013

Topics in Current Chemistry

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The enantiomeric differentiation of the volatile chiral inhalation anesthetics enflurane, isoflurane, and desflurane by analytical and preparative gas chromatography on various modified cyclodextrins is described. Very large enantioseparation factors α are obtained on the chiral selector octakis(3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex E). The gas-chromatographically observed enantioselectivities are corroborated by NMR-spectroscopy using Lipodex E as chiral solvating agent and by various sensor devices using Lipodex E as sensitive chiral coating layer. The assignment of the absolute configuration of desflurane is clarified. Methods are described for the determination of the enantiomeric distribution of chiral inhalation anesthetics during narcosis in clinical trials. The quantitation of enantiomers in a sample by the method of enantiomeric labeling is outlined. Reliable thermodynamic parameters of enantioselectivity are determined by using the retention-increment R' approach for the enantiomeric differentiation of various chiral halocarbon selectands on diluted cyclodextrin selectors.

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“…The enantioselectivity of modified cyclodextrins has been studied, successively separating enantiomers of 2-haloalkanes [9], 2-haloalkanoates [10,11] and various haloge-nated ethers [12]. Indeed, in one of the first papers dealing with studies of interaction mechanism on alkylated CD stationary phases Venema, et al [13] used 2-X-alkyl derivatives (where X = Cl, Br, I, OH, O-CH 3 , CN and NH 2 ) with various alkyl chain lengths.…”

Section: Introductionmentioning

confidence: 98%

GC separation of 2‐substituted ethyl propionate enantiomers on permethylated and 2,6‐dimethyl‐3‐pentyl β‐ and γ‐cyclodextrin stationary phases

S̆pánik¹,

Zebrowski²,

Májek³

et al. 2005

J of Separation Science

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In this work, the capillary gas chromatographic enantiomer separation of eight congeneric compounds with general formulae CH3-HCX-COOC2H5 (where X = Cl, Br, I, CN, OH, OC2H5, OC6H5 and NHCOCF3) on four different permethyl- and 2,6-di-O-methyl-3-O-pentyl- beta- and gamma-CD stationary phases has been studied. The separation of enantiomers was evaluated in terms of the interactions of the X substituent of studied derivatives, as well as the nature of the 3-O-alkyl group in the 2,6-di-O-methyl-3-O-alkyl-CDs and the CDs cavity size. The differences in thermodynamic data [deltaH and -deltaS] obtained for studied compounds and the selectivity of modified beta- and gamma-cyclodextrin phases in gas chromatographic separation were evaluated. deltaH values were compared with a deltaH value of an achiral standard (ethyl propionate, where X = H) in order to obtain the contribution of a particular substituent to the overall interaction energy. It was shown that the variation in the enantiomeric separation with temperature and the retention order of these compounds on a given cyclodextrin capillary column depends on the nature of the substituents bonded to stereogenic carbon atom. It was found that the temperature dependencies of selectivity factors, In a on 1/T, were both linear as well as non-linear, inter alia depending on the number of glucopyranose units of the CD derivatives. The enantiospecific thermodynamic data [delta21(deltaH)] and [-delta21(deltaS)] which characterize the chiral recognition in the separation system were used to gain more insight into the mechanistic aspects of the enantioseparations on permethylated and 2,6-di-O-methyl-3-O-pentyl-beta- and gamma-cyclodextrins.

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Cyclodextrin Derivatives as Chiral Selectors—Investigation of the Interaction with (R,S)‐Methyl‐2‐chloropropionate by Enantioselective Gas Chromatography, NMR Spectroscopy, and Molecular Dynamics Simulation

Cited by 65 publications

References 16 publications

Synergistic Effects of Trace Amounts of Water in the Enantiodiscrimination Processes by Lipodex E: A Spectroscopic and Computational Investigation

Synergistic Effects of Trace Amounts of Water in the Enantiodiscrimination Processes by Lipodex E: A Spectroscopic and Computational Investigation

Salient Features of Enantioselective Gas Chromatography: The Enantiomeric Differentiation of Chiral Inhalation Anesthetics as a Representative Methodological Case in Point

GC separation of 2‐substituted ethyl propionate enantiomers on permethylated and 2,6‐dimethyl‐3‐pentyl β‐ and γ‐cyclodextrin stationary phases

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