Synthesis and characterization of green-to-yellow emissive Ir(III) complexes of pyridylbenzothiadiazine ligand

Abstract

Reaction of Tetrakis(2-phenylpyridinato-C2,N')(μ-dichloro)di-iridium with 3-(pyridin-2-yl)-4H-benzo[e][1,2,4]thiadiazine ( L1 ) under neutral and basic media afforded the charged and neutral Ir-complexes, 1 and 2 , respectively, in good yields (63 – 79%). Single crystal XRD analysis confirms that the ancillary ligands in both 1 and 2 binds to the iridium via coordination of N2 of the benzo[e][1,2,4]thiadiazine. Upon isolation of the neutral complex, the sulfur atom rapidly oxidizes to form 2 . The UV-vis absorption spectra of the complexes exhibit both ligand-centered and mixed metal-to-ligand and ligand-to-ligand charged transfer (CT) transitions that are typical of many heteroleptic iridium complexes. Complexes 1 and 2 were found to be emissive at room temperature in the green and yellow region of the electromagnetic spectrum, respectively, albeit with poor photoluminescence quantum yield (ΦPL = 1.1 – 2.5%).