Supramolecular Ladder Assemblies as a Model for Probing Electronic Interactions between Multiple Stacked π-Conjugated Systems.

A series of mono-, di-, and tri-topic receptors in which H-bonding sites, complementary to those of barbituric acid (BA), are fused is used to induce the supramolecular assembly of n×m ladders containing 1, 2, or 3 triphenylenevinylene units appended with BA. The topological constraint enforced by the architectures induces through-space interactions between the electroactive moieties that are reflected in the electronic absorption and emission spectrum. The n=2, m=2 or m=3 architectures undergo two single electron oxidation events, indicative of the formation of the corresponding mono- and di-radical cation species with comproportionation constants of 340 and 70, respectively. Comparison of the electrochemical potentials suggests that the charges are delocalized over the electroactive units in the assembly.