Herein we report the synthesis of 4-aryl-1-benzyl-1H-1,2,3-triazoles (atl), made via "Click chemistry" and their incorporation as cyclometallating ligands into new heteroleptic iridium(III) complexes containing diimine (N(^)N) ancillary ligands 2,2'-bipyridine (bpy) and 4,4'-di-tert-butyl-2,2'-bipyridine (dtBubpy). Depending on decoration, these complexes emit from the yellow to sky blue in acetonitrile (ACN) solution at room temperature (RT). Their emission energies are slightly blue-shifted and their photoluminescent quantum efficiencies are markedly higher (between 25 and 80%) than analogous (C(^)N)(2)Ir(N(^)N)(+) type complexes, where C(^)N is a decorated 2-phenylpyridinato ligand. This increased brilliance is in part due to the presence of the benzyl groups, which act to sterically shield the iridium metal center. X-ray crystallographic analyses of two of the atl complexes corroborate this assertion. Their electrochemistry is reversible, thus making these complexes amenable for inclusion in light-emitting electrochemical cells (LEECs). A parallel computational investigation supports the experimental findings and demonstrates that for all complexes included in this study, the highest occupied molecular orbital (HOMO) is located on both the aryl fragment of the atl ligands and the iridium metal while the lowest unoccupied molecular orbital (LUMO) is located essentially exclusively on the ancillary ligand.

The synthesis of a family of 4'-functionalized 5,5'-diaryl-2,2'-bipyridines (bpy*; 6a-6g) is reported. These ligands were reacted with the dimer [(ppy)(2)IrCl](2) (ppyH = 2-phenylpyridine) and afforded, after subsequent counterion exchange, a new series of luminescent cationic heteroleptic iridium(III) complexes, [(ppy)(2)Ir(bpy*)]PF(6) (8a-8g). These complexes were characterized by electrochemical and spectroscopic methods. The crystal structures of two of these complexes (8a and 8g) are reported. All of the complexes except for 8c and 8f exhibit intense and long-lived emission in both 2-MeTHF and ACN at 77 K and room temperature. The origin of this emission has been assigned by computational modeling to be an admixture of ligand-to-ligand charge-transfer [(3)LLCT; pi(ppy) --> pi*(bpy*)] and metal-to-ligand charge-transfer [(3)MLCT; dpi(Ir) --> pi*(bpy*)] excited states that are primarily composed of the former. The luminescent properties for 8a-8c are dependent upon the functionalization at the 4' position of the aryl substituents affixed to the diimine ligand, while those for 8d-8g are essentially independent because of an electronic decoupling of the aryls and bpy due to the substitution of o,o-dimethyl groups on the aryls, causing a near 90 degrees angle between the aryl and bipyridyl moieties. A combined density functional theory (DFT)/time-dependent DFT study was conducted in order to understand the origin of the transitions in the absorption and emission spectra and to predict accurately emission energies for these complexes.

The useful optoelectronic properties of cationic iridium(III) complexes have been exploited in diverse applications, from visual displays to biological probes to analytical sensors. It is thus not surprising to note the increased recent efforts to document, understand, and ultimately control the photophysical and electrochemical properties of the archetypal cationic iridium(III) complex [(ppy) 2 Ir(bpy)] + , in which ppyH = 2phenylpyridine and bpy = 2,2Ј-bipyridine, and decorated versions thereof. Of the ligand architectures explored, the [a] Département 2986with N-heterocyclic carbenes (NHCs) are also included within the survey. We also wish to direct the reader to other recent review articles on other facets of Ir III chemistry, property evaluation, and applications. [1] This Review commences with a historical overview of iridium(III) chemistry, an account of the properties of iridium, and a comprehensive description of the photophysical properties of [(ppy) 2 Ir(bpy)] + (1), supported by a detailed DFT study. Following this perspective, the survey is then organized by type of heterocycle. The properties of these complexes are compared and contrasted with the archetype complex 1 and fluorinated congener [(dFppy) 2 Ir(bpy)] + (2), which in this Review act as benchmarks. Finally, optoelectronic data from complexes with structurally similar ligands are collated together to elucidate more clearly the salient structure-property relationships.

Improved luminophore: The electrochemiluminescence (ECL) of an iridium complex self-enhanced up to 16 times is reported. Three excited states were observed in the emission spectra (see picture). The ECL efficiency of this complex is the highest reported for an iridium complex.

Electrochemiluminescence (ECL) of four bright iridium(III) complexes containing aryltriazole cyclometallated ligands is reported. The ECL mechanisms, spectra and high efficiencies via annihilation and coreactant paths have been investigated.