Synthesis, photophysical properties, and DFT calculation of yellow‐red phosphorescent iridium(III) complexes based on thiophen‐pyrimidine/pyridine derivatives

Abstract

AbstractA series of heteroleptic phosphorescent iridium(III) complexes [Ir(C^N)2(O^O)] (C^N = 2‐(thiophen‐2‐yl)pyrimidine (tppm), 2‐(benzo[b]thiophen‐2‐yl)pyrimidine (btppm), 2‐(thiophen‐2‐yl)‐4‐(trifluoromethyl)pyridine (cf3thp), 2‐(benzo[b]thiophen‐2‐yl)‐4‐(trifluoromethyl)pyridine (cf3btp); O^O = acetylacetonate (acacH)) have been synthesized and characterized, and their photophysical properties are reported. All of these complexes emit yellow‐red color in the spectral range of 558–647 nm in CH2Cl2 solution at room temperature with quantum yields of 20.1–50.9% and emission lifetimes of 0.23–0.33 μs. Density functional theory (DFT) and time‐dependent‐DFT (TD‐DFT) calculations on these complexes facilitate a detailed assignment of the excited states involved in the absorption and emission processes, that is, metal‐to‐ligand and ligand‐centered charge‐transfer (MLCT/LC) transitions. These charge‐transfer‐type bands are dominated by C^N ligands more than O^O ligand.