Electrochemical characterization of hydrogen-bonding complexation between indoline and nitrogen containing bases

The electrochemical behavior of indoline in non-aqueous media in the presence of nitrogen-containing bases was studied. Electrooxidation of indoline with strong bases displayed behavior consistent with the formation of a non-covalent hydrogen-bonding complex prior to the electrooxidation. This behavior was studied by cyclic voltammetry and 1H NMR spectroscopy, and a 1:1 interaction between indoline and the base has been proposed. Electrochemistry experiments using a rotating ring disk electrode (RRDE) were performed to further understand the electrooxidation mechanism in the presence of bases. When the electrooxidation experiments were conducted using weak bases, different behavior was observed; in this case complexation of the electrogenerated radical cation with the base is proposed.