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)(2)](2) with a cis disposition of the heterocycles of the 3b ligands, in contrast to chloride. Thus, the complexes of this class─cis-[Ir(μ(2)-η(2)-C≡CPh){κ(2)-C,N-(C(6)H(4)-Isoqui)}(2)](2) (Isoqui = isoquinoline) and cis-[Ir(μ(2)-η(2)-C≡CR){κ(2)-C,N-(MeC(6)H(3)-py)}(2)](2) (R = Ph, (t)Bu)─have been prepared in high yields, starting from the dihydroxo-bridged dimers trans-[Ir(μ-OH){κ(2)-C,N-(C(6)H(4)-Isoqui)}(2)](2) and trans-[Ir(μ-OH){κ(2)-C,N-(MeC(6)H(3)-py)}(2)](2) 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(2)-C,N-[C(CH(2)Ph)Npy]}{κ(2)-C,N-(C(6)H(4)-Isoqui)}(2) and Ir{κ(2)-C,N-[C(CH(2)R)Npy]}{κ(2)-C,N-(MeC(6)H(3)-py)}(2) (R = Ph, (t)Bu), respectively, with an octahedral structure of fac carbon and nitrogen atoms. The green emitter Ir{κ(2)-C,N-[C(CH(2)(t)Bu)Npy]}{κ(2)-C,N-(MeC(6)H(3)-py)}(2) 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.