(a hydrogen-bond donor). The top panel in Figure demonstrates that sequential additions of H2O to a DMF solution containing C2O4 2-enables fine-tuning of Epa for C2O4 2-oxidation over a 700 mV range. As E 0 (DiMeFc + /DiMeFc) lies between the lower-and upper-limits of this range (Figure , bottom panel, black), we hypothesized that DiMeFc + -mediated C2O4 2-oxidation can be optimized by additions of H2O to the solution, where the driving force for DiMeFc + -mediated were carried out to determine the final products. Details of the electrolysis cell, procedure, product isolation, and product characterization can be found in the Supporting Information. A brief summary of the CPE methodology is presented here.