Organogel formation by a cholesterol-stoppered bistable [2]rotaxane and its dumbbell precursor

J Am Chem Soc. 2008 May 21;130(20):6348-50. doi: 10.1021/ja800731k. Epub 2008 Apr 30.

Abstract

The switching properties, gelation behavior, and self-organization of a cholesterol-stoppered bistable [2]rotaxane containing a cyclobis(paraquat-p-phenylene) ring and tetrathiafulvalene/1,5-dioxynaphthalene recognition units situated in the rod portion of the dumbbell component have been investigated by electrochemical, spectroscopic, and microscopic means. The cyclobis(paraquat-p-phenylene) ring in the [2]rotaxane can be switched between the tetrathiafulvalene and 1,5-dioxynaphthalene recognition units by addressing the redox properties of the tetrathiafulvalene unit. The organogels can be prepared by dissolving the [2]rotaxane and its dumbbell precursor in a CH2Cl2/MeOH (3:2) mixed solvent and liquified by adding the oxidant Fe(ClO4)3. Direct evidence for the self-organization was obtained from AFM investigations which have shown that both of the [2]rotaxane and its dumbbell precursor form linear superstructures which we propose are helical in nature.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cholesterol / chemistry*
  • Circular Dichroism
  • Gels / chemistry
  • Heterocyclic Compounds / chemistry
  • Microscopy, Atomic Force
  • Models, Molecular
  • Oxidation-Reduction
  • Paraquat / analogs & derivatives
  • Paraquat / chemistry
  • Rotaxanes / chemistry*
  • Spectrophotometry, Ultraviolet

Substances

  • Gels
  • Heterocyclic Compounds
  • Rotaxanes
  • Cholesterol
  • tetrathiafulvalene
  • Paraquat