Improved deep-red phosphorescence in cyclometalated iridium complexes via ancillary ligand modification

Abstract

Bis-cyclometalated iridium complexes with electron-rich ancillary ligands exhibit high phosphorescence quantum yields in the deep red region.

A Roadmap Towards Visible Light Mediated Electron Transfer Chemistry with Iridium(III) Complexes

“…Nevertheless, NacNac complexes ( Ir32 – 35 ) bearing other cyclometalated ligands well‐known to improve light absorption, i. e . 1‐phenylisoquinoline (1‐piq) and 2‐(benzo[ b ]‐thiophen‐2‐yl)pyridine (btpy), were also recently reported (Figure 10B) [62–63] . Unfortunately, the substitution of the C−N ligand led to a dramatic decrease of their photo‐reducing power, due to the decreased free energy stored in the excited‐state (E 0‐0 ) (Table 6).…”

Deep-Red Luminescence from Platinum(II) Complexes of N^N–^N-Amido Ligands with Benzannulated N-Heterocyclic Donor Arms

“…The non-radiative rate constants, meanwhile, show a trend that is in line with that expected from the energy gap law, with the lowest-energy emitters subject to the most rapid non-radiative decay. Efforts to improve deep red phosphorescence further by addressing the relative rates of radiative vs. non-radiative decay through ligand design 60 are now underway.…”

Iridium(III) Sensitisers and Energy Upconversion: The Influence of Ligand Structure upon TTA‐UC Performance

“…Other recent examples of red phosphorescence from Ir III species have been achieved through the use of conjugated triazole, [27] conjugated phenazine, [28] and cyclometallating phenylquinazoline [29] ligands. Teets and co‐workers have also described a systematic study of a series of anionic ancillary ligands which facilitate excellent control over the emitting state energies of their Ir III complexes [30] . The addition of bulky groups to the ancillary ligand was shown as a useful strategy for improving the quantum yields of these deep red phosphorescing species.…”

“…Te ets and coworkers have also described as ystematic study of as eries of anionic ancillary ligands which facilitatee xcellent control over the emitting state energieso ft heir Ir III complexes. [30] The addition of bulky groups to the ancillary ligand was shown as a useful strategy for improving the quantum yields of these deep red phosphorescing species. We have also reportedt he use of substituted2 -phenylquinoline [31] cyclometallating (C^N) ligandsf or red emitting Ir III complexes.…”