Synthesis and characterization of luminescent orthometallated iridium(III) polypyridine complexes

CHED 1255

Lindsay M. Hinkle, lhinkle@austincollege.edu, Kari A. McGee, mcgee@chem.umn.edu, and Kent R. Mann. Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455
Recently, there has been an increased interest in the development of sensors utilizing emissive transition metal complexes, especially those with predictable and consistent emission sites. The use of crystalline materials ensures this consistent emission site. Small molecules can reach the emissive metal site and quench the emission via energy transfer. This emission quenching allows the quencher concentration to be determined spectroscopically. Six iridium(III) complexes were synthesized with the general formula [Ir(C^N)2(L)]Cl or [Ir(C^N)2(L′)2]Cl, where (C^N) is an orthometallating ligand, L is a bidentate phosphine or polypyridine, and L′ is an isocyanide. To generate void space within the crystal, each chloride salt was metathesized to a tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (TFPB) salt. TFPB salts generate void space due to poor anion packing and the fluorines allow the small molecules to diffuse into the crystal lattice. One particular complex, [Ir(ppy)2(bpy)]TFPB was completely characterized through measurements of quantum yield, lifetime, and emission spectroscopy.