title: Photochemical Tuning of Tris-Bidentate Acridine- and Phenazine-Based Ir(III) Complexes.
abstract: Five new Ir(III) complexes of the type [Ir(ppy)2L]+(where ppy = 2-phenylpyridine, L = bidentate N^N ligand) bearing linear and elbow-shaped acridine- and phenazine-based extended planar aromatic ligands have been successfully synthesized and characterized. The electrochemical and photochemical studies revealed that all complexes allow emission in the range 589-601 nm from excited states corresponding to a charge transfer between an Ir-ppy fragment and the extended planar ligand. Luminescence quenching occurs in water for [Ir(ppy)2dpac]+(Ir-DPAC), [Ir(ppy)2dpacF2]+(Ir-DPACF2), [Ir(ppy)2dpacF4]+(Ir-DPACF4) and [Ir(ppy)2bdppz]+(Ir-BDPPZ), while solely partial quenching is observed for [Ir(ppy)2npp]+(Ir-NPP). This "light-switch" effect has been ascribed to the possible formation of a non-emissive mono-hydrogen-bonded excited state for the four complexes. The "elbow shaped" of Ir-NPP is believed to prevent the non-chelating nitrogen atom of the npp ligand to form H-bond with solvent molecules. The results emphasized the potential of small chemical modifications of the extended planar ligand on the properties of the corresponding Ir(III) complexes. Their tunable properties make them ideal candidates for applications such as DNA photoprobes.
authors: Institute of Condensed Matter and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST), Université catholique de Louvain, Place Louis Pasteur 1/L4.01.02, 1348, Louvain-la-Neuve, Belgium.
authors: Quentin
authors: Q
authors: Deraedt
authors: Département de Chimie Moléculaire, Université Grenoble-Alpes, CNRS UMR 5250, BP53, 38041, Grenoble, France.
authors: Frédérique
authors: F
authors: Loiseau
authors: Institute of Condensed Matter and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST), Université catholique de Louvain, Place Louis Pasteur 1/L4.01.02, 1348, Louvain-la-Neuve, Belgium. Benjamin.Elias@uclouvain.be.
authors: Benjamin
authors: B
authors: Elias
keywords: Acridine; Iridium; Luminescence; Polypyridyl complexes