E. Coutouli-argyropoulou et al., Electrochemical studies of ferrocene derivatives and their complexation bybeta-cyclodextrin, J ELEC CHEM, 477(2), 1999, pp. 130-139
The voltammetric behaviour of (ferrocenylmethyl)trimethylammonium hexafluor
ophosphate, 2-ferrocenylacrylic acid, N-ferro-cenylmethyl-N-methyl-4.4'-bip
yridium hexafluorophosphate and 9-ferrocenylmethyladenine was studied in aq
ueous and/or acetonitrile solutions by means of cyclic voltammetry and rota
ting-disc electrode voltammetry. The influence of beta-cyclodextrin on the
voltammetric behaviour of the compounds was also studied in aqueous solutio
ns. (Ferrocenylmethyl)trirmethylammonium hexafluomphosphate and 2-ferroceny
lacrylic acid, studied in aqueous solutions at pH 9.2, exhibit typical reve
rsible one electron transfer behaviour. whereas the redox reaction of 9-fer
rocenylmethyladenine, studied in acetonitrile, is strongly affected by adso
rption. N'-ferrocenylmethyl-N'-methyl-4,4'-bipyridinium hexafluorophosphate
gives voltammetric responses for both ferrocene and viologen redox centres
In acetonitrile. In aqueous solutions it is hydrolyzed to ferrocenylmethyl
alcohol and N-methylbipyridyl, a process facilitated by the neighbouring gr
oup participation of the iron atom. In all cases beta-cyclodextrin causes a
decrease in the currents and shifts the potentials positively. The formati
on constants of the inclusion complexes of compounds with beta-cyclodextrin
were determined by quantitative evaluation of E-1.2 values and possible ex
planations about their differentiation are discussed. In the case of N-ferr
ocenylmethyl-N'-methyl-4,4'-bipyridinium hexafluorophosphate it was found t
hat beta-cyclodextrin decreases the rate of Its hydrolysis substantially. (
C) 1999 Elsevier Science S.A. All rights reserved.