Tunable Emission of Iridium(III) Complexes Bearing Sulfur-Bridged Dipyridyl Ligands.

A series of six new cyclometalated iridium(III) complexes [Ir(ppy)(NN)][PF] (ppy = 2-phenylpyridine) is reported herein. Proligands bis(pyridin-2-yl)sulfane (1a), 2,2'-sulfinyldipyridine (1b), 2,2'-sulfonyldipyridine (1c), bis(4-methylpyridin-2-yl)sulfane (2a), 2,2'-sulfinylbis(4-methylpyridine) (2b), and 2,2'-sulfonylbis(4-methylpyridine) (2c) were synthesized, characterized, and employed as the NN ancillary ligand. Changing the oxidation state of the sulfur atom serves as a switch to alter the emissive state from that of mainly LC character (blue-green emission) to one of MLCT/LLCT character (yellow emission).