Halogen bonding-based anion coordination in calixarene/inorganic halide/diiodoperfluorocarbon assemblies

Abstract

Self-assembly of ternary mixtures composed of cation segregating agent/inorganic halide (penta-tert-butyl-pentakis(ethoxycarbonylmethoxy)calix[5]arene (1)/NaI or 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8,8,8]hexacosane (4)/BaI₂) and diiodoperfluorocarbon (1,8-diiodoperfluorooctane (2)) produces crystalline supramolecular salts 3 and 5, respectively, whose structural characteristics in the solid state have been elucidated by single-crystal X-ray analyses. Encapsulation of alkali or alkaline-earth metal ions inside the complexing pocket of the appropriate receptor generates naked iodide anions, which effectively drive the self-assembly of diiodoperfluorooctane 2 into halogen-bonded supramolecular anions with a comb-like copolymer structure.

Keywords:

• anion coordination
• calixarenes
• comb-like copolymer
• halogen bonding
• X-ray

Notes

^1. Upon addition of NaI (1 equiv.) to a CDCl₃ (5 mM) of 1, the aromatic and ethereal OCH₂ signals underwent a 0.11 and 0.10 ppm downfield complexation induced shift, respectively. Similarly, positive ESI-MS analysis of a 10 μM CHCl₃/CH₃OH solution of 1:NaI (1:1) showed a peak at m/z = 1263.7, consistent with the formation of a [1·Na]⁺ complex.

^2. t and g stand for trans and gauche, respectively.