title: Calix[n]imidazolium as a new class of positively charged homo-calix compounds.
abstract: Macrocycles based on neutral calixarenes and calixpyrroles have been extensively explored for ion binding, molecular assembly and related applications. Given that only these two types of calix compounds and their analogs are available, the introduction of new forms of widely usable calix macrocycles is an outstanding challenge. Here we report the quadruply/quintuply charged imidazole-based homo-calix compounds, calix[4/5]imidazolium. The noncovalent (C-H)(+)/π(+)-anion interactions of the imidazolium rings with anions inside and outside the cone are the stabilizing factors for crystal packing, resulting in self-assembled arrays of cone-shaped calix-imidazolium molecules. Calix[4]imidazolium senses fluoride selectively even in aqueous solutions. Calix[5]imidazolium recognizes neutral fullerenes through π(+)-π interactions and makes them soluble in water, which could be useful in fullerene chemistry. Not only derivatization and ring expansion of calix[n]imidazolium, but also their utilization in ionic liquids, carbene chemistry and nanographite/graphene exfoliation could be exploited.
authors: Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, Pohang 790 784, Korea.
authors: Young
authors: Y
authors: Chun
authors: N Jiten
authors: NJ
authors: Singh
authors: In-Chul
authors: IC
authors: Hwang
authors: Jung Woo
authors: JW
authors: Lee
authors: Seong Uk
authors: SU
authors: Yu
authors: Kwang S
authors: KS
authors: Kim
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