Solid state voltammetry of an anthraquinone molten salt

The solid-state voltammetries of the two reduction steps of a novel redox polyether hybrid - an anthraquinone molten salt (triethyl(MePEG350)ammonium anthraquinone sulfonate, (Et₃NMePEG350⁺)(AQSO₃^-)) - and its disulfonated analogue, are reported. Multiple effects on charge transport rates are encountered. Currents for the first reduction step are enhanced by electron self-exchange charge transport, whereas currents for the second reduction wave are greater than 10-fold smaller. The relative charge transport rates of the two reductions are examined as a function of temperature and of incrementally replacing the AQSO₃^- anion in the melt with the electroinactive BF₄^- anion. An analysis that includes ionic conductivity measurements shows that the apparent charge transport rate of the second anthraquinone reduction is attenuated primarily as a result of ionic migration of the products of comproportionation reactions occurring in the diffusion layer.