Rational Design of Mono- and Bi-Nuclear Cyclometalated Ir(III) Complexes Containing Di-Pyridylamine Motifs: Synthesis, Structure, and Luminescent Properties.

Heteroleptic cyclometalated iridium (III) complexes ( 1 - 3 ) containing di-pyridylamine motifs were prepared in a stepwise fashion. The presence of the di-pyridylamine ligands tunes their electronic and optical properties, generating blue phosphorescent emitters at room temperature. Herein we describe the synthesis of the mononuclear iridium complexes [Ir(ppy) 2 (DPA)][OTf] ( 1 ), (ppy = phenylpyridine; DPA = Dipyridylamine) and [Ir(ppy) 2 (DPA-PhI)][OTf] ( 2 ), (DPA-PhI = Dipyridylamino-phenyliodide). Moreover, the dinuclear iridium complex [Ir(ppy) 2 ( L )Ir(ppy) 2 ][OTf] 2 ( 3 ) containing a rigid angular ligand " L = 3,5-bis[4-(2,2'-dipyridylamino)phenylacetylenyl]toluene" and displaying two di-pyridylamino groups was also prepared. For comparison purposes, the related dinuclear rhodium complex [Rh (ppy) 2 ( L )Rh(ppy) 2 ][OTf] 2 ( 4 ) was also synthesized. The x-ray molecular structure of complex 2 was reported and confirmed the formation of the target molecule. The rhodium complex 4 was found to be emissive only at low temperature; in contrast, all iridium complexes 1 - 3 were found to be phosphorescent in solution at 77 K and room temperature, displaying blue emissions in the range of 478-481 nm.