Ir(2-phenylpyridine)2(benzene-1,2-dithiolate) anion as a diastereoselective metalloligand and nucleophile: stereoelectronic effect, spectroscopy, and computational study of the methylated and aurated complexes and their oxygenation products

Synthesis and luminescent properties of hetero-bimetallic and hetero-trimetallic Ru(II)/Au(I) or Ir(III)/Au(I) complexes

A series of Ru(II) and Ir(III) based photoluminescent complexes were synthesised that incorporate an ancillary 2,2'-bipyridine ligand adorned with either one or two pendant N-methyl imidazolium groups. These complexes have been fully characterised by an array of spectroscopic and analytical techniques. One Ir(III) example was unequivocally structurally characterised in the solid state using single crystal X-ray diffraction confirming the proposed formulation and coordination sphere. These complexes were then transformed into their heterometallic, Au(I)-containing, analogues in two steps to yield either bi- or trimetallic complexes that integrate {Au(PPh3)}+ units. X-ray diffraction was used to corroborate the solid state structure of the hetero bimetallic complex, based upon a Ru(II)-Au(I) species. The heterometallic complexes all displayed red photoluminescent features (λem = 616-629 nm) that were consistent with the parent Ru(II) or Ir(III) lumophores in each case. The modulation of the emission from the Ru(II)-Au(I) complexes was much more strongly evident than for the Ir(III)-Au(I) analogues, which is ascribed to the inherent differences in the specific triplet excited state character of the emitting states within each heterometallic species.

Simple Synthesis of Red Iridium(III) Complexes with Sulfur-Contained Four-Membered Ancillary Ligands for OLEDs

Phosphorescent iridium(III) complexes have been widely researched for the fabrication of efficient organic light-emitting diodes (OLEDs). In this work, three red Ir(III) complexes named Ir-1, Ir-2, and Ir-3, with Ir-S-C-S four-membered framework rings, were synthesized efficiently at room temperature within 5 min using sulfur-containing ancillary ligands with electron-donating groups of 9,10-dihydro-9,9-dimethylacridine, phenoxazine, and phenothiazine, respectively. Due to the same main ligand of 4-(4-(trifluoromethyl)phenyl)quinazoline, all Ir(III) complexes showed similar photoluminescence emissions at 622, 619, and 622 nm with phosphorescence quantum yields of 35.4%, 50.4%, and 52.8%, respectively. OLEDs employing these complexes as emitters with the structure of ITO (indium tin oxide)/HAT-CN (dipyra-zino[2,3-f,2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile, 5 nm)/TAPC (4,4'-cyclohexylidenebis[N,N-bis-(4-methylphenyl)aniline], 40 nm)/TCTA (4,4″,4″-tris(carbazol-9-yl)triphenylamine, 10 nm)/Ir(III) complex (10 wt%): 2,6DCzPPy (2,6-bis-(3-(carbazol-9-yl)phenyl)pyridine, 10 nm)/TmPyPB (1,3,5-tri(mpyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) achieved good performance. In particular, the device based on complex Ir-3 with the phenothiazine unit showed the best performance with a maximum brightness of 22,480 cd m^-2, a maximum current efficiency of 23.71 cd A^-1, and a maximum external quantum efficiency of 18.1%. The research results suggest the Ir(III) complexes with a four-membered ring Ir-S-C-S backbone provide ideas for the rapid preparation of Ir(III) complexes for OLEDs.

Thermodynamic Resolution and Enantioselective Synthesis of C2-Symmetric Bis-sulfoxides Based on Chiral Iridium(III) Complexes

Enantiopure Λ-[Ir(dfppy)₂(MeCN)₂](PF₆) and Δ-[Ir(dfppy)₂(MeCN)₂](PF₆) (where dfppy is (4,6-difluoropheny)pyridine) were demonstrated to preferentially react with (S,S)-1,2-bis(arylsulfinyl)ethane and (R,R)-1,2-bis(arylsulfinyl)ethane, respectively, under thermodynamic equilibrium. Sequential treatment of Λ-[Ir(dfppy)₂(MeCN)₂](PF₆) and Δ-[Ir(dfppy)₂(MeCN)₂](PF₆) with C₂-symmetric bis-sulfoxides led to diastereoselective formation of the corresponding diastereomers Λ-[Ir(dfppy)₂(R,R)-bis-sulfoxide)](PF₆) in 90-92% and Δ-[Ir(dfppy)₂(S,S)-bis-sulfoxide)](PF₆) in 88-90%, respectively. The uncoordinated (R,S)-bis-sulfoxides were afforded in 45% with >97% de values. Enantiopure (S,S)-bis-sulfoxides and (R,R)-bis-sulfoxides were respectively obtained by the release of sulfoxide ligands from the corresponding complexes in the presence of glycine in yields of 20-21% with 97-99% ee values. The enantioreceptors Λ-[Ir(dfppy)₂(MeCN)₂](PF₆) and Δ-[Ir(dfppy)₂(MeCN)₂](PF₆) can be recycled and reused in the next reaction cycle. Moreover, a protocol for asymmetric oxidation of prochiral bis-sulfide into enantiopure C₂ symmetric bis-sulfoxide was also developed in a high enantioselectivity. The absolute configurations at the metal centers and sulfur atoms were determined by X-ray crystallography.

Fast Synthesis of Iridium(III) Complexes Incorporating a Bis(diphenylphorothioyl)amide Ligand for Efficient Pure Green OLEDs

Bis(diphenylphorothioyl)amide (Stpip) containing phosphor-sulfur (P═S) bonds was used as an ancillary ligand for three pure green iridium(III) emitters Ir1, Ir2, and Ir3, which were synthesized in few minutes at room temperature with high reaction yields above 70%. All these complexes show good thermal stability and excellent sublimation yields of around 80-90%, which are considered beneficial for industry practical production and organic light-emitting diode (OLED) fabrication. The emission profiles of these complexes meet the green standards of CIE1931 with coordinates of (0.33, 0.63), (0.33, 0.62), and (0.34, 0.62), respectively, and high photoluminescence quantum yields of up to 98% are achieved. Utilizing these complexes as emissive dopants, these OLEDs exhibited high current efficiency up to 91.94 cd A^-1, external quantum efficiency up to 26.52%, and power efficiency up to 92.60 lm W^-1 with very small efficiency roll-off, without adopting internal or external out-coupling methods. These results indicate that Stpip is a potentially suitable ligand scaffold for highly efficient phosphorescent Ir(III) emitters that endow corresponding OLEDs with high efficiency and small roll-off.

Photophysical dynamics of the efficient emission and photosensitization of [Ir(pqi)2(NN)]+complexes

Rational photophysical investigation through experimental and theoretical analyses reveals the photophysical dynamics of the highly-emissive [Ir(pqi)₂(NN)]⁺complex series, with remarkable emission quantum yields and efficient generation of singlet oxygen.

Alkynyl bridged cyclometalated Ir2M2 clusters: impact of the heterometal in the photo- and electro-luminescence properties

The distinct photo- and electro-luminescence properties of clusters [Ir₂M₂(ppy)₄(μ-CCC₆H₄-OMe₃)₄] (M = Ag, Cu) provide an example of the role of the CCR groups in modulating metallophillic bonding in the T₁ state.

Heteroleptic iridium(iii) complexes bearing a coumarin moiety: an experimental and theoretical investigation

Three mononuclear heteroleptic Ir(iii) complexes have been synthesized. The electronic structure and the spectral properties of the complexes were calculated applying the DFT-TDDFT method. The chemical shift was also computed by the GIAO-DFT method.