Preparation and photophysical properties of mixed-ligand cyclometallated complexes of Ir(III) with a dendritic bipyridine ligand

Complexes [Ir((CN)-N-boolean AND)(2)(G1-bpy)]PF6, where (CN)-N-boolean AND is a cyclometallating ligand derived from 2-(2'-thienyl)pyridine and 2-phenylpyridine, and G1-bpy is a dendritic bipyridine ligand of the first generation, 4,4'-bis[3",5"-bis(benzyioxy)phenylethyl]-2,2'-bipyridine, were prepared and characterized by H-1 NMR, electronic absorption, and emission spectroscopy. The polyether dendritic substituents exert a "soft" effect on the spectral and luminescence properties of the complexes, manifested as slight destabilization of the electronically excited charge-transfer state involving the bipyridine ligand, as compared to the model complexes [Ir((CN)-N-boolean AND)(2)(bpy)]PF6.