Kinetics of formation of the host-guest complex of a viologen with cucurbit[7]uril

Org Lett. 2012 Jul 6;14(13):3248-51. doi: 10.1021/ol300911a. Epub 2012 Jun 12.

Abstract

Host-guest complexation between the dicationic viologen 1-tri(ethylene glycol)-1'-methyl-m-xylyl-4,4'-bipyridinium and cucurbit[7]uril (CB7) was studied at pH = 4.5 in water. The stability constants of the mono- and bis-CB7 adducts were determined at 25 °C by UV-vis spectroscopy. Stopped-flow kinetic experiments were performed to measure the formation and dissociation rate constants of the monoadduct: k(1) = (6.01 ± 0.03) × 10(6) M(-1)s(-1) and k(-1) = 52.7 ± 0.4 s(-1), respectively. Possible mechanisms of complexation are discussed in view of the kinetic results.

Publication types

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

MeSH terms

  • Bridged-Ring Compounds / chemistry*
  • Imidazoles / chemistry*
  • Kinetics
  • Models, Molecular
  • Molecular Structure
  • Viologens / chemistry*

Substances

  • Bridged-Ring Compounds
  • Imidazoles
  • Viologens
  • cucurbit(7)uril