Electron Transfer Kinetics in Ethaline/Water Mixtures: An Apparent Non?Marcus Behavior in a Deep Eutectic Solvent

Effects of water on the charge-transfer (CT) kinetics in deep eutectics solvents (DES) have been investigated ethaline (1 : 2 choline chloride+ethylene glycol), taken as a prototypical example hydrophilic DES. Standard heterogeneous CT rate constants ks were measured for two redox couples: 1,1’-ferrocene-dimethanol/1,1’-ferrocenium-dimethanol and ferro-/ferricyanide glassy carbon electrode function amount Contrarily to behavior reported classical apparent contradiction with Marcus Theory, values show very little or no variation DES changes viscosities diffusion coefficients that are observed. This unexpected phenomenon is discussed known physical-chemistry parameters ethaline.