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

Alkynyl ligands stabilize dimers [Ir(-X)(3b) 2 ] 2 with a cis disposition of the heterocycles of the 3b ligands, in contrast to chloride. Thus, the complexes of this classcis-[Ir( 2 - 2 -CCPh){ 2 -C,N-(C 6 H 4 -Isoqui)} 2 ] 2 (Isoqui = isoquinoline) and cis-[Ir( 2 - 2 -CCR){ 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(-OH){ 2 -C,N-(C 6 H 4 -Isoqui)} 2 ] 2 and trans-[Ir(-OH){ 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{ 2 -C,N-[C(CH 2 Ph)Npy]}{ 2 -C,N-(C 6 H 4 -Isoqui)} 2 and Ir{ 2 -C,N-[C(CH 2 R)Npy]}{ 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{ 2 -C,N-[C(CH 2 t Bu)Npy]}-{ 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.