Interlocked host anion recognition by an indolocarbazole-containing [2]rotaxane

J Am Chem Soc. 2009 Apr 8;131(13):4937-52. doi: 10.1021/ja809905x.

Abstract

The design, synthesis, structure, and anion-binding properties of the first indolocarbazole-containing interlocked structure are described. The novel [2]rotaxane molecular structure incorporates a neutral indolocarbazole-containing axle component which is encircled by a tetracationic macrocycle functionalized with an isophthalamide anion recognition motif. (1)H NMR and UV-visible spectroscopies and X-ray crystallography demonstrated the importance of pi-donor-acceptor, CH...pi, and electrostatic interactions in the assembly of pseudorotaxanes between the electron-deficient tetracationic macrocycle and a series of pi-electron-rich indolocarbazole derivatives. Subsequent urethane stoppering of one of these complexes afforded a [2]rotaxane, which was shown by (1)H NMR spectroscopic titration experiments to exhibit enhanced chloride and bromide anion recognition compared to its non-interlocked components. Computational molecular dynamics simulations provide further insight into the mechanism and structural nature of the anion recognition process, confirming it to involve cooperative hydrogen-bond donation from both macrocycle and indolocarbazole components of the rotaxane. The observed selectivity of the [2]rotaxane for chloride is interpreted in terms of its unique interlocked binding cavity, defined by the macrocycle isophthalamide and indolocarbazole N-H protons, which is complementary in size and shape to this halide guest.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anions / chemistry*
  • Binding Sites
  • Carbazoles / chemical synthesis
  • Carbazoles / chemistry*
  • Computer Simulation
  • Crystallography, X-Ray
  • Hydrogen Bonding
  • Indoles / chemical synthesis
  • Indoles / chemistry*
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Molecular Structure
  • Rotaxanes / chemical synthesis*
  • Rotaxanes / chemistry

Substances

  • Anions
  • Carbazoles
  • Indoles
  • Rotaxanes
  • carbazole