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The Underestimated Role of Counter Ions in Electrostatic Self‐Assembly:[1+1] Cavitand‐Calix[4]arene Capsules Based on Azinium–Sulfonate Interactions
Author(s) -
Oshovsky Gennady V.,
Reinhoudt David N.,
Verboom Willem
Publication year - 2006
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200600163
Subject(s) - chemistry , cavitand , counterion , sulfonate , methanol , titration , ion , supramolecular chemistry , dilution , polymer chemistry , medicinal chemistry , organic chemistry , inorganic chemistry , molecule , sodium , physics , thermodynamics
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)