SYNTHESIS AND ASSEMBLY OF SELF-COMPLEMENTARY CALIX[4]ARENES

A calix[4]arene was designed to reversibly dimerize and form an egg-sh aped enclosure. Adhesive interactions in the assembly were provided by four self-associating ureas, which form a cyclic array containing 16 hydrogen bonds. The synthesis was completed in four steps from the pre viously described O,O',O '',O '''-tetrabenzylcalix[4] arene. Evidence for dimerization of the calixarene tetraurea was provided by H-1 NMR, mass spectrometry, and the observation of encapsulated molecules. The resulting cavity was of sufficient size to capture guests such as ethy l benzene and p-xylene.