Studies are presented showing that N,N’-dimethyl-2,7-diazapyrenium, DAP(2+), acts as a redox-dependent receptor for aromatic carboxylates in aqueous solution. Cyclic voltammetric studies of DAP(2+) by itself indicate that its one-electron reduction to DAP(+) is only quasi-reversible in both aqueous and acetonitrile solutions due to the slow oxidation of DAP(+) back to DAP(2+). In aqueous solution, the oxidation is very sensitive to other conditions such as pH and the presence of small amounts of iodide, However, in pH 7 phosphate buffer, fairly reversible voltammetry is observed at slow scan rates. Under these conditions, addition of excess aromatic carboxylate results in large negative shifts in the E(1/2) of DAP(2+/+). Similar changes are observed in the H-1 NMR spectrum of DAP(2+) in the presence of the different carboxylates, indicating that the potential shift is due to strong interactions between the carboxylates and DAP(2+). Upon reduction, the favorable coulombic interactions between the anionic carboxylates and the cationic pyrenium are weakened, resulting in the observed negative shifts in E(1/2). Although the perturbation of electrostatic interactions causes the potential shifts, the magnitude of the shifts correlates more with the strength of pi-stacking interactions between the carboxylates and DAP(2+). Those carboxylates whose pi system can come into maximum close contact with the DAP(2+) pi system give the largest potential shifts.