title: Mono- and dinuclear cationic iridium(III) complexes bearing a 2,5-dipyridylpyrazine (2,5-dpp) ligand.
abstract: The synthesis, X-ray structures, photophysical, and electrochemical characterization of mono- (1) and dinuclear (2) cationic iridium(III) complexes bearing a 2,5-dipyridylpyrazine (2,5-dpp) ancillary ligand are reported. Upon the complexation of a first equivalent of iridium, the photoluminescence shifts markedly into the deep red (λem = 710 nm, ΦPL = 0.9%) compared to other cationic iridium complexes such as [Ir(ppy)2(bpy)]PF6. With the coordination of a second equivalent of iridium, room temperature luminescence is completely quenched. Both 1 and 2 are luminescent at low temperatures but with distinct excited state decay kinetics; the emission of 2 is significantly red-shifted compared to 1. Emission both at 298 and 77 K results from a mixed charge-transfer state. Density functional theory (DFT) calculations and electrochemical behavior point to an electronic communication between the two iridium complexes.
authors.affiliation: Département de Chimie, Université de Sherbrooke, 2500 Boul. de l'Université, Sherbrooke, QC, Canada J1K 2R1.
authors.forename: Loïc
authors.initials: L
authors.lastname: Donato
authors.forename: Catherine E
authors.initials: CE
authors.lastname: McCusker
authors.forename: Felix N
authors.initials: FN
authors.lastname: Castellano
authors.forename: Eli
authors.initials: E
authors.lastname: Zysman-Colman
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011719:Pyrazines / Q000737:chemistry*
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D011719:Pyrazines; D007495:Iridium