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Garcia C, Humilière D, Riva N, et al. Kinetic and thermodynamic consequences of the substitution of SMe for OMe substituents of cryptophane hosts on the binding of neutral and cationic guests. Org Biomol Chem. 2003;1(12):2207-16doi: 10.1039/b211363e.
Garcia, C., Humilière, D., Riva, N., Collet, A., & Dutasta, J. P. (2003). Kinetic and thermodynamic consequences of the substitution of SMe for OMe substituents of cryptophane hosts on the binding of neutral and cationic guests. Organic & biomolecular chemistry, 1(12), 2207-16. https://doi.org/10.1039/b211363e
Garcia, Chantal, et al. "Kinetic and thermodynamic consequences of the substitution of SMe for OMe substituents of cryptophane hosts on the binding of neutral and cationic guests." Organic & biomolecular chemistry vol. 1,12 (2003): 2207-16. doi: https://doi.org/10.1039/b211363e
Garcia C, Humilière D, Riva N, Collet A, Dutasta JP. Kinetic and thermodynamic consequences of the substitution of SMe for OMe substituents of cryptophane hosts on the binding of neutral and cationic guests. Org Biomol Chem. 2003 Jun 21;1(12):2207-16. doi: 10.1039/b211363e. PMID: 12945915.
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Org Biomol Chem. 2003 Jun 21;1(12):2207-16. doi: 10.1039/b211363e.

Kinetic and thermodynamic consequences of the substitution of SMe for OMe substituents of cryptophane hosts on the binding of neutral and cationic guests.

Organic & biomolecular chemistry

Chantal Garcia, Delphine Humilière, Nathalie Riva, André Collet, Jean-Pierre Dutasta

Affiliations

  1. Stéréochimie et Interactions Moléculaires, Ecole Normale Supérieure de Lyon, UMR CNRS No 5532, 46 Alleé d'Italie, F-69364 Lyon 07, France.

PMID: 12945915 DOI: 10.1039/b211363e

Abstract

To investigate the origin of the high selectivity of cryptophane-E (1) towards Me3NH+, Me4N+, and CHCl3, and particularly to discriminate the different contributions that stabilize the supramolecular complexes, we have synthesized the new cryptophane 2 bearing six MeS groups instead of MeO groups in 1. This led to a decrease of the negative charge density in the equatorial region of 2 without affecting notably the size of the molecular cavity. The binding properties of 1 and 2 towards the three guests were examined in solution and showed a slight decrease of the deltaGa favoring the complexes of 1, accompanied by a significant modification of the deltaHa vs. deltaSa balance. The binding of the ammonium guests to 1 and 2 was strongly entropy driven, while that of CHCl3 was purely enthalpy driven. A combination of spectroscopic and computational techniques was used to assign the main intermolecular interactions that occurred during the inclusion process. The neutral CHCl3 molecule is more stabilized in the less negatively charged CTV cap of 1. The different behavior towards the ammonium cations can be explained in term of interactions with the electronegative heteroatoms and cation-pi interactions. Moreover, this study revealed a considerable slowing down of the guest exchange kinetics with host 2, for which the association and dissociation rates are reduced by a factor 10(3) to 10(4) with respect to 1. For example, at room temperature, the Me4N+@2 complex exhibits a half-life of ca. 2 years, instead of a few hours for the corresponding complex of 1.

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