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Kinetics and mechanism of cyclodextrin inclusion complexation incorporating bidirectional inclusion and formation of orientational isomers

Title
Kinetics and mechanism of cyclodextrin inclusion complexation incorporating bidirectional inclusion and formation of orientational isomers
Authors
Park J.W.
Ewha Authors
박준우
SCOPUS Author ID
박준우scopusscopus
Issue Date
2006
Journal Title
Journal of Physical Chemistry B
ISSN
1520-6106JCR Link
Citation
vol. 110, no. 49, pp. 24915 - 24922
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
The kinetics of cyclodextrin (CD) inclusion complexation has been usually analyzed in terms of a one-step reaction or a consecutive two-step reaction involving intracomplex structural transformation as a second step. These schemes presume the inclusion of guest molecules through only one side of the CD cavity and the formation of unidirectional CD complexes. However, there has been increasing experimental evidence for the inclusion of guests through both sides of the CD cavity and the formation of orientational isomers for noncentrosymmetric guest molecules. This article presents a novel parallel reaction scheme for CD inclusion complexation, incorporating bidirectional inclusion and the formation of orientational isomers into the scheme. It is shown that the parallel reaction scheme gives the same concentration versus reaction time relationship as the consecutive two-step reaction scheme. The experimental methods for determining the microscopic directional rate constants are presented. The kinetic parameters of the two-step reaction scheme are expressed as functions of the directional rate constants. The ratios of orientational isomers of α-CD-based [2]-pseudorotaxanes and the microscopic directional rate constants of the threading and dethreading reactions are estimated from the reported thermodynamic and kinetics data obtained by using either the one-step or two-step reaction scheme. It is shown that the thermodynamic preference of an isomer over the other is mainly due to the slow dethreading rate of the isomer. © 2006 American Chemical Society.
DOI
10.1021/jp065238
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자연과학대학 > 화학·나노과학전공 > Journal papers
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