Synthesis and electron transfer studies of anthraquinones

Electron transfer reactions of anthraquinone at a modified electrode interface and the role hydrogen bonds play in the electron transfer reaction were investigated. Two classes of redox active anthraquinones were synthesized, first to probe electronic communication through hydrogen bonds and second to form redox-active self-assembled monolayers (SAMs). The synthesized compounds were subjected to cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments. Formation of the SAMs on Au electrodes was confirmed by a surface FTIR method. Electrochemical studies involving variable temperature and pH provided evidence that SAMs of anthraquinones undergo proton-coupled electron transfer with electron transfer rates of approximately 7 s -1 in acidic media. The formal potential of an anthraquinone SAM at different pH follows the Nernst equation with 60 mV·pH -1 gradient consistent with a 2 electron, 2 proton redox mechanism.