Cyclodextrin Inclusion Complexes: Studies of the Variation in the Size of Alicyclic Guests

Document Type

Article

Publication Date

1-1-1989

Abstract

We have determined thermodynamic parameters for the interaction of a congener series of alicyclic carboxylic acids (e.g., adamantanecarboxylic acid, bicyclo [2.2.2.] octanecarboxylie acid, etc.) with α and β-cyclodextrin hosts in aqueous solution. The side chains of these guests are roughly spherical and vary in carbon number from 11 to 5. With O-cyclodextrin, we find that 1:1 hosts-guest inclusion complexes are formed with all the guests at both low and high pH, with stronger binding occurring as low pH, where the carboxylic acid forms of the guests predominate. With α-cyclodextrin, 1:1 complexes are formed with the carboxylate forms of the guests, but 2:1 bis(α-cyclodextrin)-guest complexes are formed, in a cooperative manner, with the carboxylic acid forms of the guests. A strong guest-size dependence is found for both the free-energy change and enthalpy change for complex formation. The variation of these thermodynamic parameters with guest size is used to draw inferences about contributions to the overall binding free-energy change from the hydrophobic effect and van der Waals forces. Data were obtained by using flow microcalorimetry, pH potentiometric measurements, and spectral displacement methods. © 1989, American Chemical Society. Alle Rechte vorbehalten.

Identifier

33645955001 (Scopus)

Publication Title

Journal of the American Chemical Society

External Full Text Location

https://doi.org/10.1021/ja00199a041

e-ISSN

15205126

ISSN

00027863

First Page

6765

Last Page

6772

Issue

17

Volume

111

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