Cyclometalated Iridium(III) Complexes of Azadipyrromethene Chromophores

Abstract

Azadipyrromethenes are bidentate ligands that absorb in the red-orange region of the spectrum, with applications as tags, light harvesters, and sensitizers. Reported here are borontransmetalation reactions that bind azadipyrromethenes to cyclometalated iridium(III). The new species absorb both near 590 nm and into the near-ultraviolet. Two examples have been crystallographically characterized. Both intra-and intermolecular aromatic stacking interactions are found. Cyclic voltammetry experiments show that azadipyrromethene complexes of iridium(III) undergo reduction and oxidation at potentials that depend little on the cyclometalating ligands on iridium. Density functional theory calculations indicate a LUMO that is azadipyrromethene-centered, whereas the HOMO may localize on either the Ir(C ∧ N) 2 + fragment or the azadipyrromethene.

Silver(I) complexes of mono- and bidentate N-heterocyclic carbene ligands: Synthesis, crystal structures, and in vitro antibacterial and anticancer studies

“…3.530 Å [25]. Besides this, hydrogen bonding interactions were observed between complex cations and hexafluorophosphate anions with the bond distances in the range 2.333-2.563 Å.…”

Azadipyrromethenes: from traditional dye chemistry to leading edge applications

“…[36][37][38][39][40][41][42][43][44][45][46] Typically, complexes are formed under mild rt conditions in THF with t-butoxide or DIPEA as base. This points to an ever expanding future for these complexes not just for their own inherent properties but also for catalysis and material applications.…”

Unveiling photophysical properties of cyclometalated iridium(iii) complexes with azadipyrromethene and dipyrromethene ancillary: a theoretical perspective

“…25,26 Unique photophysical properties have rendered them, and are widely applied in biological systems, organic electronic devices and solar energy conversion. 32 Contrary to what was expected, the azadipyrromethene quenches the emission of the resulting complexes, and thus leads to a nonemission at room temperature. [29][30][31] However, the azadipyrromethenes ligands have not been explored as the N^N ancillary ligand in neutral heteroleptic Ir(III) complexes to date.…”

“…32 Herein, we tentatively calculated the phosphorescent characters of 1 to provide an understanding of its experimental observation. 32 Herein, we tentatively calculated the phosphorescent characters of 1 to provide an understanding of its experimental observation.…”

“…23,27,28 The development of azadipyrromethenes evolved from complexation with BF 2 + to transition-metal ions such as d 10 metal ions of copper(I), silver(I) and gold(I), d 8 metal centers of rhodium(I) and platinum(II). 32 Such unusual experimental phenomena encouraged us to deepen the understanding of these L a Br 2 -chelated complexes by theoretical study. A series of neutral Ir(III) azadipyrromethene (L a Br 2 ) ( Fig.…”