Proton-Coupled Electron Transfer and Substituent Effects in Catechol-Based Deep Eutectic Solvents: Gross and Fine Tuning of Redox Activity

The 1,2-diol moiety in a variety of substituted catechols allows formation of room temperature ionic melts in a 2:1 ratio with choline chloride or choline dihydrogen citrate. These deep eutectic solvents were 4.3-6.6 M in redox active catechols. Substituents on 3- and 4-substituted catechols shift both E° and pKa such that Hammett parameters predict the observed Ep for oxidation in square wave voltammetry. The proton acceptor for the...