The importance of electrochemical analysis for charge-transfer
science cannot be overstated. Interfaces in electrochemical cells
present certain challenges in the interpretation and the utility of
the analysis. This publication focuses on: (1) the medium polarity
that redox species experience at the electrode surfaces that is smaller
than the polarity in the bulk media and (2) the liquid-junction potentials
from interfacing electrolyte solutions of different organic solvents,
namely, dichloromethane, benzonitrile, and acetonitrile. Electron-donor–acceptor
pairs of aromatics with similar structures (i.e., 1-naphthylamine
and 1-nitronaphthalene, 10-methylphenothiazine and 9-nitroanthracene,
and 1-aminopyrene and 1-nitropyrene) serve as redox analytes for this
study. Using the difference between the reduction potentials of the
oxidized donors and the acceptors eliminates the effects of the liquid
junctions on the analysis of charge-transfer thermodynamics. This
analysis also offers a means for evaluating the medium polarity that
the redox species experience at the surface of the working electrode
and the effects of the liquid junctions on the measured reduction
potentials. While the liquid-junction potentials between the dichloromethane
and acetonitrile solutions amount to about 90 mV, for the benzonitrile-acetonitrile
junctions, the potentials are only about 30 mV. The presented methods
for analyzing the measured electrochemical characteristics of donors
and acceptors illustrate a means for improved evaluation of the thermodynamics
of charge-transfer systems.