The Underestimated Role of Counter Ions in Electrostatic Self-Assembly:[1+1] Cavitand-Calix[4]arene Capsules Based on Azinium–Sulfonate Interactions
✍ Scribed by Gennady V. Oshovsky; David N. Reinhoudt; Willem Verboom
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 226 KB
- Volume
- 2006
- Category
- Article
- ISSN
- 1434-193X
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✦ Synopsis
Abstract
The apparent K~a~ values of the formation of [1+1] cavitand‐calix[4]arene capsules, based on azinium–sulfonate electrostatic interactions, obtained by direct titration experiments are concentration dependent due to the influence of the interaction of the charged capsule components with their initial counterions. ^1^H NMR and UV dilution experiments, in which this ion‐pairing is excluded, gave K~a~‐values larger than 2**·**10^6^ M^–1^ in methanol and methanol/water (1:1) for the capsule formation. The capsule encapsulates small guests like methanol, ethanol, etc., as proven by ESI‐MS. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)