Chromatography–voltammetry studies on the interaction between alkali metal cations and acyclic polyethers

The complexation and ion-association behavior of acyclic polyethers having anthraquinone terminal groups in acetonitrile are studied with chromatography–voltammetry. Polydispersed acyclic polyethers are separated into monodispersed components with chromatography according to their complexation ability with ammonium ions anchored on the silica gel surface; separation of polyethers gives the information on the complexation of electrically neutral (unreduced) polyethers. After chromatographic separation, monodispersed components are fed into a voltammetric cell, where cyclic voltammetric studies are carried out to obtain the information on the interaction between metal ions and polyethers having anion-radical terminals. Their interaction constants are determined based on the measurements of reduction currents. The comparison of the ion-association constants of anion radicals with the complexation constants of the neutral polyethers allows us to infer the differences in structures between Li+- and Na+-anion radical ion-associates.