Inclusion of methylviologen in cucurbit[7]uril

Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5007-11. doi: 10.1073/pnas.062656699. Epub 2002 Mar 26.

Abstract

The inclusion behavior of methylviologen (N,N'-dimethyl-4,4'-bipyridinium, MV) dication in cucurbit[7]uril (CB[7]) has been studied by using various spectroscopic and electrochemical methods. The inclusion complex of MV dication in CB[7] is stable thermodynamically and kinetically. The electrochemical study reveals that unlike beta-cyclodextrin, CB[7] prefers the charged species, MV dication (MV(2+)), and cation radical (MV(+)*) to the fully reduced neutral (MV(0) species as guests. Dimerization of MV(+)* is suppressed effectively by forming a stable complex with CB[7] in aqueous solution as confirmed by spectroelectrochemical experiments. Furthermore, the first redox process (MV(2+)/MV(+)*) of the MV(2+)-CB[7] complex occurs predominantly via the direct electron transfer pathway, whereas the second redox process (MV(+)*/MV(0)) occurs via both the direct and indirect pathway because of the low affinity of the fully reduced species MV(0) to CB[7].

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bridged-Ring Compounds / chemistry*
  • Calorimetry
  • Cations
  • Circular Dichroism
  • Cyclodextrins / pharmacology
  • Electrochemistry
  • Electrons
  • Herbicides / pharmacology
  • Imidazoles / chemistry*
  • Kinetics
  • Models, Chemical
  • Oxidation-Reduction
  • Paraquat / pharmacology*
  • Spectrophotometry
  • Thermodynamics
  • beta-Cyclodextrins*

Substances

  • Bridged-Ring Compounds
  • Cations
  • Cyclodextrins
  • Herbicides
  • Imidazoles
  • beta-Cyclodextrins
  • cucurbit(7)uril
  • betadex
  • Paraquat