Correlation of the formation constant of ferrocene–cyclodextrin complexes with dielectric properties of the aqueous DMSO solution

The host–guest interactions between ferrocene and α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), Heptakis(2,6-di-O -methyl)-β-cyclodextrin (2-β-CD) and Heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (3-β-CD) in aqueous DMSO solution were studied by means of cyclic voltammetry. The complex formation constant K was determined in the solutions of various values of the relative permittivity ɛ r of DMSO:water mixture. The dependence of K on dielectric properties of the mixtures ɛ r for all type of cyclodextrin utilized was found. Furthermore, the dependence of K on the cyclodextrin type was also found. As an additional feature the different dependencies of the Gibbs energy of the complex formation, View the MathML sourceΔGCF0 for different CDs on the volume ratio of DMSO, φDMSO were observed.