The behavior of water in a benzene solution of C-undecylcalixresorcinarene (UR) is studied by 1H 2D NMR exchange spectroscopy and by 1D NMR. The rate constants for exchange of the UR hydroxyl protons, Ha, with water over the temperature range 298-338 K are 0.7-4.6 s-1 and those for the exchange of UR hydroxyl protons, Hb, over the temperature range 298-328 K are 1.8-8.1 s-1. Activation energies calculated for these exchange processes are 9.0 ± 0.5 kcal/mol and 10.2 ± 1.0 kcal/mol, respectively. The chemical shift of dissolved water is largely dependent upon the concentration of UR. An upper limit for the critical aggregation concentration of UR is 10-5 M as shown by 1H NMR.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry