Luminescent bis-tridentate iridium(III) complexes: Overcoming the undesirable reactivity of trans-disposed metallated rings using –N^N^N-coordinating bis(1,2,4-triazolyl)pyridine ligands

• Nine new iridium(III) complexes are synthesised featuring two tridentate ligands. One ligand is cyclometallating and the other a bis(triazolyl)pyridine. These stable, unlike their tris-cyclometallated analogues. All luminescent in solution at room temperature with quantum yields up to 3% Three analogues prepared bidentate triazolylpyridine non-emissive. ligands have been of form Ir( N^C^N )( – N^N^N ), where represents based on 1,3-di(2-pyridyl)benzene doubly deprotonated bis(1,2,4-triazolyl)pyridine. examples each used, different substituents central aryl ring former para -substituted groups 5-positions triazole rings latter. Two structurally characterised solid-state by X-ray diffraction, confirming mutually orthogonal arrangement Unlike related type C^N^C which unstable respect photoactivated cleavage trans -disposed Ir–C bonds, show no evidence instability. They phosphorescent green region spectrum lifetimes around 200 ns 3%, apparently limited non-radiative decay processes particular. Although there some variation performance substitution pattern, only discernible trend that 4-methoxy-substituted better emitters. N^N )Cl incorporating 1,2,4-triazolylpyridine also prepared. room-temperature emission but properties 77 K similar those bis-tridentate systems.