Ionic luminescent cyclometalated Ir(III) complexes with polypyridine co-ligands

Two novel ligands containing a functionalized N ∧ N chelating moiety (pbpy-OBut and tpy-COOH, respectively) were treated with [Ir(ppy)2(μ-Cl)]2 (ppy = 2-(2-pyridyl)phenyl), leading to the cationic cyclometalated complexes [Ir(ppy)2(pbpy-OBut)]+ (2) (pbpy-OBut = 4-{4′-(4-phenyloxy)-6′-phenyl-2,2′-bipyridyl}butene) and [Ir(ppy)2(tpy-COOH)]+ (3) (tpy-COOH = 4′-(4-carboxyphenyl)-2,2′:6′,2″-terpyridine). Complexes 2 and 3 exhibit intense room temperature luminescence both in solution and as solid films. Assignment of the emissive behavior to a 3LLCT (ppy-to-N ∧ N) excited state is proposed.