Successive Inclusion of Water, [H3NCH2CH2NH3]2+ and [H3NCH2CH2NH2]+ in the Aromatic Cavity of (p-Sulfonato)calix[4]arene

Titration of the sulfonic protons of (p-sulfonato) calix [4] arene (H8L) with two equivalents of ethylenediamine affords [H3NCH2CH2NH3](2)[H4L(H2O)(3)].H2O, a molecular complex in which water is included inside the macrocycle. Deprotonation of one of the phenolic groups expels the water molecules from the aromatic cavity, leading to the formation of [H3NCH2CH2NH3](1.5)[(H3L) (H3NCH2CH2NH3)].(H2O)(5.5), which represents an unprecedented example of the inclusion of a dication in a calixarene. Further addition of ethylenediamine affords the mixed salt [H3NCH2CH2NH3](2)-[(H3L) (H3NCH2CH2NH2)].(H2O)(4.5) in which the monocation [H3NCH2CH2NH2](+) is preferentially bound to the cavity through a non-classical hydrogen bond involving an N-H...pi facial aromatic contact. Inclusion phenomena are indicated both by NMR and X-ray structure determinations. In the same way as their inorganic-organic counterparts, these clay-like materials are organised into parallel organic-organic layers.