Supramolecular crystal structures of per(3,6-anhydro)-α-cyclodextrin grown from KCl or NaI solutions

Crystals of per(3,6-anhydro)-α-cyclodextrin{hexakis(3,6- anhydro)cyclomaltohexaose} (1) grown in presence of KCl or NaI evidence the similar distorted conformation of macrocycle and provide the same supramolecular scaffolding of cyclodextrins based on CH⋯O hydrogen bonds. Infinite tubes parallel to symmetry axis 6 are filled by water molecules or by iodine atoms in 1/KCl and 1/NaI crystals, respectively. In 1/KCl crystals an inclusion complex of stoichiometry 1:2 has been found. Coordination polyhedra of the dimeric K units fuse with the coordination polyhedra of one pentacoordinated chloride atom to form an infinite helix along the c direction crossing over a helical organic envelope of cyclodextrin molecules.