Leading iridium photosensitizers of the form [Ir(ppy)2(bpy)]+ (ppy=2-phenylpyridine and bpy=2,2'-bipyridine) are vulnerable to decomposition through dissociation of their bidentate bipyridine ligand. Here, a new architecture is explored in which bpy is replaced with a more stable, tridentate ligand while cyclometalation is maintained to create a long-lived mixed excited state. Straightforward modification of all ligand sites in the new architecture has been achieved, and the geometric arrangement of the ligands is unambiguously assigned via X-ray crystallography. The rich electrochemistry of the complexes is presented via cyclic voltammetry and shows that ligand modification affords control of electrochemical behavior and electronic structure. Effects of ligand tuning are also shown in solution-based photophysical measurements. These measurements reveal intense room temperature phosphorescence with quantum yields ranging from 3-28 % and emission lifetimes in the ????s range. Electrochemical and photophysical trends are elucidated through DFT calculations. Meanwhile, oxygen quenching and photocatalytic hydrogen generation studies highlight the robustness of the new materials and their potential for broad future application.

New iridium luminophores combining tunability and enhanced photostability

247th National Meeting (2014)

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