Synthesis and photophysical properties of yellow-emitting iridium complexes. Effect of the temperature on the character of triplet emission.

The parent study includes synthesis end photophysical characterization of four new phosphorescent cyclometalated iridium (III) complexes. The cyclometaled ligands used here are 2-(4-chlorophenyl)benzo[d]thiazole, 2(4isopropylphenyl)benzo[d] thiazole, 2-(4-methoxyphenyl)benzo[d]thiazole, 4-(benzo[d]thiazol-2-yl)-N,N-dimethylaniline. The auxiliary ligand is acetylacetone (Hacac). The photometric analyses show temperature dependence on phosphorescent spectra and the nature of the emitting state of the synthesized complexes. Using fluorescent and absorption spectroscopy we suggest an explanation of the observed effect points out the transition from ligand centered (LC) to MLCT main character of the emitting state. The quantitative photometric analysis states high phosphorescent quantum yields of the complexes in solution.