Synthesis and characterization of phosphorescent iridium complexes of 6-chloro-3-phenylpyridazine and 3-chloro-6-(3′-methoxy-phenyl)-4-methyl-pyridazine

The preparation and photophysics of organometallic Ir(III) complexes with 3-phenylpyridazine (H6Clppdz) and its derivative are reported. IrCl3 · nH2O reacts with H6Clppdz, and 3-chloro-6-(3′-methoxyphenyl)-4-methyl-pyridazine (MCOMppdz) to give the corresponding chloride-bridged dimers, (6Clppdz)2Ir(μ-Cl)2Ir(6Clppdz)2 and (MCOMppdz)2Ir(μ-Cl)2Ir(MCOMppdz)2 in good yields. These chloride-bridged dimers are cleaved with 2-pyrazinecarboxylic acid (Hpyzc), 2-picolinic acid (Hpic), acetylacetone (Hacac), and 2,2,6,6-tetramethyl-3,5-heptanedione (Htmd) to give the corresponding monomer, (6Clppdz)2Ir(pyzc), (6Clppdz)2Ir(pic), (6Clppdz)2Ir(acac), (6Clppdz)2Ir(tmd), (MCOMppdz)2Ir(acac), and (MCOMppdz)2Ir(tmd), respectively. The complexes show bright orange to red luminescence at room temperature and the emission wavelenghts are affected by the ancillary ligands as well as cyclometalating ligands (593-664 nm).