Cyclic voltammetry with cyclic iminium ions: Implications for charge transfer with biomolecules (metabolites of nicotine, phencyclidine, and spermine)

Abstract

Recently, the theory was advanced that the iminium species plays a widespread role in living systems as a charge transfer agent. Cyclic voltammetry was applied to model compounds, 3,4-dihydro-1,5-dimethyl-2H-pyrrolium perchlorate 2 and 3,4-dihydro-1-methyl-5-phenyl-2H-pyrrolium chloride 3, in order to provide reference data. Compounds 2 and 3 gave reductions with E p = −1.11 and −0.98 V, respectively, vs SCE (DMF). Reactions were also carried out in water and benzonitrile. Resonance and inductive effects are used to rationalize the data. Iminium ions 5, 12, and 18 are intermediary oxidative metabolites of nicotine 6, the hallucinogenic drug phencyclidine 8, and spermine 17a, respectively. Reduction potentials are −1.04, −0.93, and −1.10 V, respectively. It is suggested that electon transfer mediated by iminium moieties may be related to biological activity. Examples are presented of electrochemically reducible iminium compounds which exhibit physiological activity in a variety of areas.