Preparation of Phosphorescent Iridium(III) Complexes with a Dianionic C,C,C,C-Tetradentate Ligand

Abstract

The preparation and photophysical properties of heteroleptic iridium(III) complexes containing a dianionic C,C,C,C-tetradentate ligand and a cyclometalated phenylpyridine group are described. Complex [Ir(μ-OMe)(COD)] (1, COD = 1,5-cyclooctadiene) reacts with 1,1-diphenyl-3,3-butylenediimidazolium iodide ([PhIm(CH)ImPh]I), in the presence NaOBu, to give [Ir(μ-I){κ- C, C, C, C-[CHIm(CH)ImCH]}] (2), which leads to {[Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}](μ-OH)(μ-OMe)} (3) by treatment first with silver trifluoromethanesulfonate (AgOTf) in acetone-dichloromethane and subsequently with KOH in methanol. The reaction of 2 with AgOTf and acetonitrile affords the bis(solvento) complex [Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}(CHCN)]OTf (4). The latter promotes the pyridyl-supported heterolytic ortho-CH bond activation of the phenyl group of 2-phenylpyridine, 2-(2,4-difluorophenyl)pyridine, 2-( p-tolyl)pyridine, and 5-methyl-2-phenylpyridine to yield Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}{κ- C, N-[Ar-py]} (Ar-py = CH-py (5), CHF-py (6), CHMe-py (7), CH-Mepy (8)) using (piperidinomethyl)polystyrene as an external base. Complexes 5-8 are blue-green emitters, which display short lifetimes (0.6-4.8 μs) and quantum yields close to unity in both doped poly(methyl methacrylate) films at 5 wt % and in 2-methyltetrahydrofuran at room temperature.

Preparation via a NHC Dimer Complex, Photophysical Properties, and Device Performance of Heteroleptic Bis(tridentate) Iridium(III) Emitters

“…Their synthesis took place through the dimer [Ir(μ-I){κ 4 -C,C,C,C-[C6H4Im(CH2)4ImC6H4]}]2, which was obtained from [Ir(μ-OMe)( 4 -COD)]2 and 1,1'-diphenyl-3,3'-butylenediimidazolium diiodide (Scheme 2). 19 The success in the preparation of this family of compounds, encouraged us to apply the same concept to the preparation of [5t + 4t'] iridium(III) emitters, bearing monoanionic 5t and dianionic 4t' ligands based on a 1,3bis(imidazolylidene)phenyl group and a pincer with a 2-pyridylimidazolate or -benzimidazolate moiety, respectively. This paper describes the synthesis of a [IrI(μ-I)(5t)]2 dimer, which is an efficient entry to the target emitters.…”

Luminescent Platinum(IV) Complexes Bearing Cyclometalated 1,2,3‐Triazolylidene and Bi‐ or Terdentate 2,6‐Diarylpyridine Ligands

“…[42,43] We anticipated that the donor properties of the triazolylidene moiety would benefit the emission efficiencies of cyclometalatedP t IV complexes by increasing the energy of deactivating excited states of LMCT character to ag reater extent than in the case of 2-arylpyridines. Cyclometalating aryl-NHC ligands have previously been employed for the synthesis of luminescentc omplexes of Ir III , [44][45][46][47][48][49][50][51][52] Pt II , [53][54][55][56] and Au III [57] with enhanced emission properties, often as non-chromophorics upporting ligands. However, most of them are normal 2-imidazolylidene-typea ryl-NHCs, whereas mesoionic aryl-NHCs have only been employed to prepare a limited number of luminescent Pt II complexeso ft he type [Pt(C^C*)(O^O)] (O^O = b-diketonate).…”

Deacylative Alkylation vs. Photoredox Catalysis in the Synthesis of 3,3'‐Bioxindoles

“…Ruthenium(II) complex 19 , as well as organophotocatalyst Eosin B (this last example is not shown in the Table ) did not promote the reaction at all. In view of this situation, we decided to employ recently reported organometallic phosphorescent compounds as new photocatalysts (Table , entries 3–6): the homoleptic osmium(II) complex 20 bearing two equal 5‐electron donor C,C,C‐pincer ligands based on bis‐NHC systems, the heretoleptic iridium(III) derivatives 21 and 22 containing a 6‐electron donor C,C,C,C‐tetradentate group and a 3‐electron donor orthometalated phenylpyridine, and the heteroleptic compound 23 stabilized by a 5‐electron donor N,C,N‐pincer ligand and a 4‐electron donor C,N,C‐group . The osmium complex 20 is a blue emitter in 2‐methyl tetrahydrofuran, which displays a quantum yield of 0.62 in the solid state.…”