Influence of π-Stacking on the Redox Properties of Oligothiophenes:  (α-Alkyloligo-thienyl)para[2.2]cyclophanes

[structure: see text] Oligothienyl-substituted paracyclophanes bearing alpha-thienyl substituents, which block polymerization at these sites, undergo oxidation to form stable radical cations and dications. Splitting of the first voltammetric oxidation wave of stacked dimers into two single-electron processes corresponding to formation of the stacked mono(radical cation) and the stacked bis(radical cation) illustrates the influence of pi-stacking on the behavior of conjugated chains, which serve as models for stacked polarons in conjugated polymers.