Issue 4, 2015

γ-Cyclodextrin modulates the chemical reactivity by multiple complexation

Abstract

Multiple complexation by γ-CD has been studied by self-diffusion coefficients (DOSY) and chemical kinetics experiments in which 4-methoxybenzenesulfonyl chloride (MBSC) solvolysis was used as a chemical probe. The addition of a surfactant as a third component to the reaction mixture induced a very complex reactivity pattern that was explained on the basis of multiple complexation phenomena and surfactant self-assembly to form micelles. A cooperative effect that yielded a ternary complex formed by cyclodextrin–surfactant–MBSC was observed. The larger cavity of γ-CD in comparison with β-CD is responsible for the change from the competitive complexation mechanism predominant with β-CD to a cooperative/competitive mixed mechanism operating for the larger derivative. The cavity size in γ-CD is large enough to bind two surfactant alkyl chains with a cooperative effect. Water molecules released by the formation of 1 : 1 host–guest complexes made the cavity more hydrophobic and promoted further inclusion. A reduction in the available volume of the cavity should be considered on binding a second guest.

Graphical abstract: γ-Cyclodextrin modulates the chemical reactivity by multiple complexation

Supplementary files

Article information

Article type
Paper
Submitted
03 Here 2014
Accepted
12 Du 2014
First published
12 Du 2014

Org. Biomol. Chem., 2015,13, 1213-1224

Author version available

γ-Cyclodextrin modulates the chemical reactivity by multiple complexation

J. Fernández-Rosas, M. Pessêgo, M. Cepeda-Plaza, N. Basilio, M. Parajó, P. Rodríguez-Dafonte and L. García-Río, Org. Biomol. Chem., 2015, 13, 1213 DOI: 10.1039/C4OB02113D

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