Homooxacalix[3]arene is related to calix[4]arene and 18-crown-6 ether with unique structural features, such as a cavity composed of an 18-membered ring, C 3 -symmetry, and a limited number of possible conformations (ie, cone and partial cone). 1 The most striking structural difference between homooxacalix[3]arene and 18-crown-6 ether is that homooxacalix[3]arene has a three-dimensional cavity. These features have awakened supramolecular chemists to ...