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.

Electroluminescence from Spontaneously Generated Single-Vesicle Aggregates Using Solution-Processed Small Organic Molecules

Self-assembled aggregates offer great potential for tuning the morphology of organic semiconductors, thereby controlling their size and shape. This is particularly interesting for applications in electroluminescent (EL) devices, but there has been, to date, no reports of a functional EL device in which the size and color of the emissive domains could be controlled using self-assembly. We now report a series of molecules that spontaneously self-organize into small EL domains of sub-micrometer dimensions. By tailoring the emissive chromophores in solution, spherical aggregates that have an average size of 300 nm in diameter and emit any one color, including CIE D65 white, are spontaneously formed in solution. We show that the individual aggregates can be used in EL devices built either using small patterned electrodes or using a sandwich architecture to produce devices emitting in the blue, green, red, and white. Furthermore, sequential deposition of the three primary colors yields an RGB device in which single aggregates of each color are present in close proximity.