Preferential axial protonation in a zwitterionic calix[4]arene.
[structure: see text] Calixarene 3, substituted at two methylene bridges by dimethylamino groups, exists in the crystal and in polar solvents as a zwitterion, with the axial dimethylamino group protonated.
Simaan
Samah
S
Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Biali
Silvio E
SE