Highly branched phosphorescent dendrimers

Abstract

A simple convergent procedure, involving the Diels-Alder reaction between 2,3,4,5-tetraphenylcyclopentadienone with an acetylene-substituted 2-phenylpyridine and subsequent complexation with iridium(III), has been developed for the formation of highly branched phosphorescent dendrimers. The procedure is demonstrated with the preparation of a first generation dendrimer composed of a fac -tris(2-phenylpyridyl)iridium(III) core with a single dendron attached to phenyl ring of each of the ligands. Each dendron is comprised of a branching phenyl unit with a further four phenyl groups attached. The lack of surface groups on the dendrons was found to reduce solubility of the dendrimers and allow strong intermolecular interactions of the emissive and electroactive cores in neat films. This was evidenced by a decrease in the photoluminescence quantum yield in going from solution to the solid state.