Electrochemical Properties of Cationic Complexes of Molecular Containers from Cucurbituril Family

Electrochemical properties of cationic complexes of supramolecular cavitands from the cucurbit[n]uril (CBn s ) family are studied. Based on the analysis of a complex of systematic data on these compounds, basic regularities characterizing their adsorption behavior are formulated, in particular, the extremely high surface activity and unusually wide adsorption potential region over which the adsorption layer structure is transformed upon changes of the electrode charge value and sign. The varying of concentrations of reactants involved in the complex-formation reaction (the cavitand and inorganic cation) in the studied systems is shown to change significantly the observed picture of adsorption phenomena. The comparative analysis of adsorption data for systems containing supramolecular complexes of cucurbiturils with different cations can back qualitative estimating of their strength constants. It has been established by example of systems containing inclusive complexes of the СВ7 cavitand with organic cation (the cation of 3,3′-diethylthiocarbocyanine iodide dye) and with organic molecules (super-tough complexes with 1-hydroxyadamantan and ferrocene, the strength constants K of 10 9 –10 10 М –1 by order of magnitude), that including of neutral organic molecule into the cavitand cavity does not prevent the formation of an exclusive complex with sodium cation and that such a complex is not formed in the presence of organic cation in the cavitand cavity. It was demonstrated by example of the cobaltocene(Сос)/cobaltocenium(Сос + ) redox-system studied in the solutions added with СВ7 and СВ7-free ones that the formation of adsorption layer of the Сос + ⊂ СВ7 supramolecular complex particles preceding an electrode process leads to changing of the electrode reaction rate and mechanism.