Orotate containing anionic luminescent iridium(iii) complexes and their use in soft salts

Abstract

Two anionic iridium complexes [(R-ppy)₂Ir(O^N)]TBA with R-ppy = 2-phenylpyridine or 4,5′-dimethyl-2-phenylpyridine, O^N = dianionic form of orotic acid and TBA = tetrabutylammonium have been synthesised and fully characterised by UV-Vis, emission, IR, NMR and cyclic voltammetric studies. These cyclometallated luminescent complexes containing a dianionic bidentate ancillary ligand show bright emission (60–70% PLQY) with maxima in the green region of the visible spectrum. Coupled with the ionic iridium complexes [(ppy)₂Ir(N^N)]X, where N^N = 2-picolylamine or 2,2′-bipyridyl, and X = Cl⁻ or CH₃CO₂⁻, a series of new soft salts of general formula [(ppy)₂Ir(N^N)][(R-ppy)₂Ir (O^N)] have been obtained and fully characterized, with enhanced luminescent properties up to ca. 80% of phosphorescence quantum yields.