A novel structural motif for calix[4]arene dihydrophosphonic acid in its complex with di-methyl ammonium and tetra-methyl ammonium cations

The structure of calix[4]arene dihydrophosphonic acid in its complex with di-methyl ammonium and tetra-methyl ammonium cations shows a novel dimeric structural motifs for the calixarene assembly, with one calixarene unit showing distal aromatic rings inclined into the cavity and then both of the rings partially included into the cavity of a second molecule present in the flattened cone conformation.