Alkynyl Ligands as Building Blocks for the Preparation of Phosphorescent Iridium(III) Emitters: Alternative Synthetic Precursors and Procedures.

Alkynyl ligands stabilize dimers [Ir(μ-X)(3b)] with a cis disposition of the heterocycles of the 3b ligands, in contrast to chloride. Thus, the complexes of this class─[Ir(μ-η-C≡CPh){κ-,-(CH-Isoqui)}] (Isoqui = isoquinoline) and [Ir(μ-η-C≡CR){κ-,-(MeCH-py)}] (R = Ph, Bu)─have been prepared in high yields, starting from the dihydroxo-bridged dimers [Ir(μ-OH){κ-,-(CH-Isoqui)}] and [Ir(μ-OH){κ-,-(MeCH-py)}] and terminal alkynes. Subsequently, the acetylide ligands have been employed as building blocks to prepare the orange and green iridium(III) phosphorescent emitters, Ir{κ-,-[C(CHPh)Npy]}{κ-,-(CH-Isoqui)} and Ir{κ-,-[C(CHR)Npy]}{κ-,-(MeCH-py)} (R = Ph, Bu), respectively, with an octahedral structure of carbon and nitrogen atoms. The green emitter Ir{κ-,-[C(CHBu)Npy]}{κ-,-(MeCH-py)} reaches 100% of quantum yield in both the poly(methyl methacrylate) (PMMA) film and 2-MeTHF at room temperature. In organic light-emitting diode (OLED) devices, it demonstrates very saturated green emission at a peak wavelength of 500 nm, with an external quantum efficiency (EQE) of over 12% or luminous efficacy of 30.7 cd/A.