Substituent effects on the redox properties and structure of substituted triphenylamines. An experimental and computational study

The peak oxidation potentials of a series of polysubstituted triphenylamines were found to be highly linearly correlated (R=0.995) with their ionization potentials as computed by density functional theory. The computations, as well as confirming previous experiments demonstrating the planar geometry of such substances around the central nitrogen atom, also demonstrate substantial resonance interactions between the central nitrogen atom and a nitro group located para or ortho to it; no such interaction is involved in the corresponding amine cation radicals. On the other hand, a methoxy group located para to the central nitrogen atom interacts strongly with the central nitrogen in the cation radical, but not in the neutral amine.