Coordination of fully substituted cyclopentano cucurbit[5]uril with alkali cation in the presence of tetrachloridezicate anion

Abstract

Coordination of fully substituted cyclopentano cucurbit[5]uril (CyP5Q[5]) with an alkali cation (A+) in the presence of tetrachloridezicate anions was investigated. Single-crystal X-ray diffraction analysis revealed that the CyP5Q[5]–Na+ and K+–[ZnCl4]2−–HCl interaction systems yielded an A+/Cl−@CyP5Q[5]/A+-type molecular capsule, and that a chloride anion was included in the cavity of the CyP5Q[5] molecule. [ZnCl4]2− anions were not involved in direct coordination with the A+/Cl−@CyP5Q[5]/A+ capsule. The CyP5Q[5]–Rb+ and Cs+–[ZnCl4]2−–HCl interaction systems yielded an A+/CyP5Q[5]/A+-type molecular capsule shell, and no chloride anions were included in the cavity of the CyP5Q[5] molecule. [ZnCl4]2− anions directly interacted with coordinated Rb+ or Cs+ cations through electrostatic interaction, and [ZnCl4]2− anions in particular played the role of linkers, resulting in the formation of a linear supramolecular assembly ⋯[ZnCl4]2−–A+/Cl−@CyP5Q[5]/A+–[ZnCl4]2−–A+/Cl−@CyP5Q[5]/A+⋯. Close inspection revealed that the obtained CyP5Q[5]/A+-based supramolecular assemblies (A=Na, K, Rb, Cs) presented different porous conformation and could show different absorption properties.