Emissive Ir(III) complexes bearing thienylamido groups on a 1,10-phenanthroline scaffold

Luminescence properties of [Ir(C^N)2(N^N)]+ complexes: relations between DFT computation results and emission band-shape analysis data

Luminescence properties of two series of [Ir(C^N)₂(N^N)]⁺ complexes bearing deprotonated 1-phenyl-1H-pyrazole or 1-(2,4-difluorophenyl)-1H-pyrazole as cyclometalating C^N ligands and different α-diimines (2,2′-bipyridine, 1,10-phenanthroline and their derivatives) as ancillary N^N ligands have been studied in acetonitrile solutions at room temperature and in 77 K methanol/ethanol (1 : 1) matrices. Ligand and temperature induced changes in the nature of the emissive ³*[Ir(C^N)₂(N^N)]⁺ species result in well-pronounced changes in their emission properties like emission wavelength, emission quantum yields and emission lifetimes. Depending on the nature of the coordinated C^N and N^N ligands and/or the measurement temperature, the investigated luminophores exhibit emissions arising from the intraligand transitions localized within the N^N ligand or from the metal-to-ligand charge-transfer transitions involving the Ir(C^N)₂⁺ and N^N moieties as confirmed by means of the DFT computations. The computed DFT energies of the excited ³*[Ir(C^N)₂(N^N)]⁺ states and outer/inner reorganization energies associated with the S₀ ← ³*[Ir(C^N)₂(N^N)]⁺ transitions remain in nice agreement with those available from the performed emission band-shape analyses. The observed agreement implies ordinary DFT computations at the B3LYP/LANL2DZ/6-31G(d,p) level of theory, even performed neglecting the spin–orbit phenomena, as enough accurate in the quantitative prediction of the most important parameters characterizing the investigated [Ir(C^N)₂(N^N)]⁺ luminophores.

For two series of [Ir(C^N)₂(N^N)]⁺ luminophores, the computed DFT quantities remain in nice agreement with those available from the emission band-shape analyses.

Synthesis and crystal structure of (1,10-phenanthroline-κ2 N,N')[2-(1H-pyrazol-1-yl)phenyl-κ2 N 2,C 1]iridium(III) hexa-fluorido-phosphate with an unknown number of solvent mol-ecules

The cationic cyclo­metallated iridium(III) complex [Ir(C₉H₇N₂)₂(C₁₂H₈N₂)](PF₆) has been synthesized and crystallized by the inter-diffusion method. It contains an unknown number of solvent mol­ecules and has a different space-group symmetry (C2/c) structure than its solvatomorph (P2₁/c).

The cationic complex in the title compound, [Ir(C₉H₇N₂)₂(C₁₂H₈N₂)]PF₆, comprises two phenyl­pyrazole (ppz) cyclo­metallating ligands and one 1,10-phenanthroline (phen) ancillary ligand. The asymmetric unit consists of one [Ir(ppz)₂(phen)]⁺ cation and one [PF₆]⁻ counter-ion. The central Ir^III ion is six-coordinated by two N atoms and two C atoms from the two ppz ligands as well as by two N atoms from the phen ligand within a distorted octa­hedral C₂N₄ coordination set. In the crystal structure, the [Ir(ppz)₂(phen)]⁺ cations and PF₆⁻ counter-ions are connected with each other through weak inter­molecular C—H⋯F hydrogen bonds. Additional C—H⋯π inter­actions between the rings of neighbouring cations consolidate the three-dimensional network. Electron density associated with additional disordered solvent mol­ecules inside cavities of the structure was removed with the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown solvent mol­ecule(s). The title compound has a different space-group symmetry (C2/c) from its solvatomorph (P2₁/c) comprising 1.5CH₂Cl₂ solvent mol­ecules per ion pair.

Synthesis and crystal structure of (1,8-naphth-yridine-κ2 N,N')[2-(1H-pyrazol-1-yl)phenyl-κ2 N 2,C 1]iridium(III) hexa-fluorido-phosphate di-chloro-methane monosolvate

The solvated title salt, [Ir(C9H7N2)2(C8H6N2)]PF6·CH2Cl2, was obtained from the reaction between 1,8-naphthyridine (NAP) and an orthometalated iridium(III) precursor containing a 1-phenyl-pyrazole (ppz) ligand. The asymmetric unit comprises one [Ir(ppz)2(NAP)]+ cation, one PF6 - counter-ion and one CH2Cl2 solvent mol-ecule. The central IrIII atom of the [Ir(ppz)2(NAP)]+ cation is distorted-octa-hedrally coordinated by four N atoms and two C atoms, whereby two N atoms stem from the NAP ligand while the ppz ligands ligate through one N and one C atom each. In the crystal, the [Ir(ppz)2(NAP)]+ cations and PF6 - counter-ions are connected with each other through weak inter-molecular C-H⋯F hydrogen bonds. Together with an additional C-H⋯F inter-action involving the solvent mol-ecule, a three-dimensional network structure is formed.

Toward fluorine-free blue-emitting cationic iridium complexes: to generate emission from the cyclometalating ligands with enhanced triplet energy

Generating emission from cyclometalating ligands with enhanced triplet energy is an efficient avenue toward fluorine-free blue-emitting cationic iridium complexes.