How to blue-shift phosphorescence color of iridium(III) complexes

We achieve a 20–58 nm (610–1890 cm−1) blue-shift of the phosphorescence maximum of iridium(III) complexes [(C^N)2Ir(N^N)](PF6) of 1,10-phenanthrolines (N^N) by modifying the cyclometalating 2-phenylpyridine ligand (C^N = ppy) with an electron-withdrawing 4′-fluoro or 4′-trifluoromethyl group or by replacing the pyridine in ppy with a pyrazole. New complexes exhibit green or yellow phosphorescence in argon-saturated 10−5 M dichloromethane solution at room temperature with a maximum at 525–563 nm, quantum yield of 54–68%, and excited-state lifetime of 1.1–2.7 μs.