| Abstract
| - Wide rim tetraurea derivatives (2a,b) have been prepared from a calix[4]arene rigidified in thecone conformation by two diethyleneglycol ether bridges between adjacent oxygens. In comparisonto the analogous tetraurea derivatives (3a,b) of a tetrapentoxy calix[4]arene, 2a,b show an increasedthermodynamic stability in mixtures of CDCl3 and DMSO-d6. Their kinetic stability as expressedby the rate of guest exchange (benzene or cyclohexane against the solvent benzene-d6) is also stronglyincreased by factors of 30−38. Noticeable differences for the inclusion of selected guests are found.
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