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  x  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.