Fine Tuning of the Cavity Size in Calixarene-Like Cyclophanes: A Complete Series of Homooxacalix[4]arene Ligands for Quaternary Ammonium Ions

The few oxygenated homologues of calixarenes which appear from time to time in the literature are members of a large family of cyclophanes. In the case of calix[4]arene and oxygenated homologues with mixed CH2 and CH2OCH2 units (X in the figure), a complete series of these cyclophanes is now synthetically available; conformational behavior and binding properties are discussed in the light of the continuous change in the ligand structure. Dioxa- to tetraoxa- compounds appear to be good ligands for quats, even in the absence of bridging and other cavity-preorganizing features.