High Order in a Self-Assembled Iridium (III) Complex Gelator Towards Nanostructured IrO2 Thin Films

The preparation and characterization of a new metallogelator based on the Ir(III) discrete cyclometallated complex [(ppy)2Ir(bpy)](CH3CH2OCH2CO2) are reported, where H(ppy) is 2-phenylpiridine and bpy is 2,2'-bipyridine, used as ancillary ligand. The compound is able to self-assemble in water in a range of concentrations between 3% and 6 % w/w, creating a luminescent ordered supramolecular gel. The gel and xerogel architectures were investigated through POM, SEM and TEM microscopies coupled with Powder X-Ray Diffraction. The gel supramolecular organization is characterized by columnar tetragonal strands, already present at high dilution conditions, of cations surrounded by counteranions. These strands, in turn, are self-assembled in an oblique columnar cell upon gelification. The xerogel thin films obtained upon complete dehydration maintained the gel supramolecular order and can be used as precursor for the preparation of nanostructured IrO2 thin films.