Coordination of alkaline earth metal ions in the inverted cucurbit[7]uril supramolecular assemblies formed in the presence of [ZnCl4]2- and [CdCl4]2-

Qing Li; Yun-Qian Zhang; Qian-Jiang Zhu; Sai-Feng Xue; Zhu Tao; Xin Xiao

doi:10.1002/asia.201500003

Coordination of alkaline earth metal ions in the inverted cucurbit[7]uril supramolecular assemblies formed in the presence of [ZnCl4]2- and [CdCl4]2-

Chem Asian J. 2015 May;10(5):1159-64. doi: 10.1002/asia.201500003. Epub 2015 Feb 26.

Authors

Qing Li¹, Yun-Qian Zhang, Qian-Jiang Zhu, Sai-Feng Xue, Zhu Tao, Xin Xiao

Affiliation

¹ Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Department of Chemistry, Guizhou University, Guiyang 550025 (China).

PMID: 25627326
DOI: 10.1002/asia.201500003

Abstract

A convenient method to isolate inverted cucurbit[7]uril (iQ[7]) from a mixture of water-soluble Q[n]s was established by eluting the soluble mixture of Q[n]s on a Dowex (H(+) form) column so that iQ[7] could be selected as a ligand for coordination and supramolecular assembly with alkaline earth cations (AE(2+)) in aqueous HCl solutions in the presence of [ZnCl(4)](2-) and [CdCl(4)](2-) anions as structure-directing agents. Single-crystal X-ray diffraction analysis revealed that both iQ[7]-AE(2+) -[ZnCl(4)](2-) -HCl and iQ[7]-AE(2+) -[CdCl(4)](2-) -HCl interaction systems yielded supramolecular assemblies, in which the [ZnCl(4)](2-) and [CdCl(4)](2-) anions presented a honeycomb effect, and this resulted in the formation of linear iQ[7]/AE(2+) coordination polymers through outer-surface interactions of Q[n]s.

Keywords: alkaline earth metals; coordination modes; inverted cucurbiturils; outer-surface interaction; supramolecular chemistry.