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  Adsorption behavior of the (±)-Tröger’s base enantiomers in the phase system of a silica-based packing coated with amylose tri(3,5-dimethyl carbamate) and 2-propanol and molecular modeling interpretation

Mihlbachler, K., De Jesus, M. A., Kaczmarski, K., Sepaniak, M. J., Seidel-Morgenstern, A., & Guiochon, G. (2006). Adsorption behavior of the (±)-Tröger’s base enantiomers in the phase system of a silica-based packing coated with amylose tri(3,5-dimethyl carbamate) and 2-propanol and molecular modeling interpretation. Journal of Chromatography A, 1113(1-2), 148-161. doi:10.1016/j.chroma.2006.02.001.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0013-9A48-7 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0025-BA69-2
Genre: Journal Article

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 Creators:
Mihlbachler, K.1, 2, 3, Author
De Jesus, M. A.1, Author
Kaczmarski, K.4, Author
Sepaniak, M. J.1, Author
Seidel-Morgenstern, A.3, 5, Author              
Guiochon, G.1, 2, Author
Affiliations:
1University of Tennessee, Department of Chemistry, Knoxville, TN, USA, ou_persistent22              
2Division of Chemical Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA, ou_persistent22              
3Otto-von-Guericke-Universität Magdeburg, External Organizations, ou_1738156              
4Rzeszów University of Technology, Rzeszów, Poland, ou_persistent22              
5Physical and Chemical Foundations of Process Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Max Planck Society, ou_1738150              

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Free keywords: Tröger’s base; Enantioseparation; Adsorption energy; Adsorption isotherm; Multi-layer adsorption; Equilibrium-dispersive model; Molecular modeling: Molecular mechanics and molecular dynamics
 Abstract: The binary adsorption isotherms of the enantiomers of Tröger’s base in the phase system made of Chiral Technologies ChiralPak AD [a silica-based packing coated with amylose tri(3,5-dimethyl carbamate)] as the chiral stationary phase (CSP) and 2-propanol as the mobile phase were measured by the perturbation method. The more retained enantiomer exhibits a S-shaped adsorption isotherm with a clear inflection point, the concentration of the less retained enantiomer having practically no competitive influence on this isotherm: In the entire range of concentrations studied, dq2/dC1≈0. By contrast, the less retained enantiomer has a Langmuir adsorption isotherm when pure. At constant mobile phase concentrations, however, its equilibrium concentration in the adsorbed phase increases with increasing concentration of the more retained enantiomer and dq1/dC2>0. This cooperative adsorption behavior, opposed to the classical competitive behavior, is exceedingly rare but was clearly demonstrated in this case. Two adsorption isotherm equations that account for these physical observations were derived. They are based on the formation of an adsorbed multi-layer, as suggested by the isotherm data. The excellent agreement between the experimental overloaded elution profiles of binary mixtures and the profiles calculated with the equilibrium-dispersive model validates this binary isotherm model. The adsorption energies calculated by molecular mechanics (MM) and by molecular dynamics (MD) indicate that the chiral recognition arising from the different interactions between the functional groups of the CSP and the molecules of the Tröger’s base enantiomers are mainly driven by their Van der Waals interactions. The MD data suggest that the interactions of the (−)-Tröger’s base with the CSP are more favored by 8±(5) kJ/mol than those of (+)-Tröger’s base. This difference seems to be a contributing factor to the increased retention of the − enantiomer on this chromatographic system. The modeling of the data also indicates that both enantiomers can form high stoichiometry complexes while binding onto the stationary phase, in agreement with the results of the equilibrium isotherm studies.

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Language(s): eng - English
 Dates: 2006
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: eDoc: 268135
DOI: 10.1016/j.chroma.2006.02.001
Other: 49/06
 Degree: -

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Title: Journal of Chromatography A
Source Genre: Journal
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Publ. Info: Amsterdam : Elsevier
Pages: - Volume / Issue: 1113 (1-2) Sequence Number: - Start / End Page: 148 - 161 Identifier: ISSN: 0021-9673
CoNE: https://pure.mpg.de/cone/journals/resource/954925527837_1