Complexation of potassium ions by nonactin was studied by cyclic voltammetr
y in several non-proton-donating media. It was found that the stability con
stants, K-s, are strongly influenced by the solvents, and the corresponding
logK(s) values vary inversely with the Guttmann donicity scale. Based on t
he results of a simulated annealing procedure, the possible structure of th
e complex with regard to the molecules of acetonitrile microsolvating the b
ound cation is proposed. Accordingly, there are four carbonyl oxygens, two
ether oxygens and two acetonitrile nitrogens coordinating the potassium cat
ion and this results in a net coordination number of eight.