Strongly Phosphorescent Iridium(III)–Porphyrins – New Oxygen Indicators with Tuneable Photophysical Properties and Functionalities

Synthesis and characterization of four iridium(III)–octaethylporphyrins and a π‐extended iridium(III)–benzoporphyrin are presented. Strong room‐temperature phosphorescence was observed for all of the complexes with quantum yields of up to 30 %. Axial ligands were introduced to tune the photophysical properties and the solubility. Complexes bearing lipophilic ligands such as pyridine or N‐(n‐butyl)imidazole were incorporated into polystyrene to obtain optical oxygen sensors. Covalent coupling of the dye is possible by introduction of ligands with binding domains (1‐imidazoleacetic acid). This enabled preparation of a water‐soluble oxygen probe (by staining bovine serum albumin) and a trace oxygen sensor (by coupling to amino‐modified silica gel).