New heteroleptic cyclometalated iridium(III) complexes containing 2-(2′,4′-difluorophenyl)-4-methylpyridine for organic light-emitting diode applications

Seo, Hoe-Joo; Heo, Young-Min; Jin, Sung‐Ho; Yook, Kyoung Soo; Lee, Jun Yeob; Kang, Sung Kwon; Kim, Young-Inn

doi:10.1016/j.jlumin.2010.03.034

Cited by 9 publications

(1 citation statement)

References 40 publications

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“…7). At the center of this chain is an offset π•••π stacking interaction between the pyrazine regions of symmetry-equivalent Ir2 complexes (plane-to-plane distance of 3.29 Å) similar to that observed in the bis(3,5-difluoro-2-(4-methylpyridin-2-yl)phenyl)-pyrazine-2-carboxylato)-Ir(III) complex [52]. The exposed nitrogen atom of the pyrazine region of the second unique complex, Ir1, forms the C-H•••N interaction with the Ir2 complex.…”

Section: Structural Characterization Of Iridium(iii) Complexes With A...supporting

confidence: 52%

Synthesis and Crystallographic Characterization of Heteroleptic Ir(III) Complexes Containing the N-oxide Functional Group and Crystallographic Characterization of Ir(III) N-oxide Precursors

Stumbo,

Hodge,

Williams

et al. 2024

Crystals

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The N-oxide functional group has been exploited for synthetic strategies and drug design, and it has been utilized in imaging agents. Herein, we present rare examples of neutral heteroleptic cyclometallated Ir(III) compounds that contain an uncoordinated N-oxide functional group. These species, along with others described within, were verified by NMR, EA, HRMS, and single-crystal X-ray analysis. N-oxide-containing Ir(III) species were prepared selectively in high yields > 66% from chloro-bridged Ir(III) dimers with Acipimox, a picolinate-type ligand containing the N-oxide functional group. Non-N-oxide analogs were synthesized in a similar fashion (yields > 77%). Electrochemical comparison (cyclic voltammetry) indicates that the presence of an N-oxide functional group anodically shifts the reduction potential, suggesting that the N-oxide is acting as an electron-withdrawing group in these species. Crystallographic studies were pursued to examine the coordination behavior of these N-oxides compared to their non-oxidized congeners. The Ir(III) complexes with Acipimox indeed leave the N-oxide uncoordinated and exposed on the complexes. The uncoordinated N-oxide group is influential in directing the packing structures of these complexes directly through C-H···O and O···π interactions at the N-oxide. The crystallographic characterization of cationic Ir(III) compounds with uncoordinated nitrogen atoms is also presented. The C-H···N interactions between these complexes form a variety of dimers, finite chains, and continuous chains. Future work will focus on functionalizing the cationic Ir(III) species into their corresponding N-oxide derivatives and rigorously characterizing how the N-oxide functional group impacts the optical properties of transition metal compounds in both cationic and neutral complexes.

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Section: Structural Characterization Of Iridium(iii) Complexes With A...supporting

confidence: 52%

Synthesis and Crystallographic Characterization of Heteroleptic Ir(III) Complexes Containing the N-oxide Functional Group and Crystallographic Characterization of Ir(III) N-oxide Precursors

Stumbo,

Hodge,

Williams

et al. 2024

Crystals

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Orange–Yellow Phosphorescent Iridium(III) Complex for Solution‐processed Organic Light‐Emitting Diodes: Structural, Optical and Electroluminescent Properties of Bis(2‐phenylbenzothiazole)[2‐(2‐hydroxyphenyl)benzothiazole]iridium(III)

Kang

Jeon

Jin

et al. 2017

Bulletin Korean Chem Soc

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New orange–yellow phosphorescent cyclometalated iridium(III) complex, (bt)2Ir(btz), where btH = 2‐phenylbenzothiazole and btzH = 2‐(2‐hydroxyphenyl)benzothiazole, was synthesized, and its structural, photophysical and electroluminescence properties were investigated to apply for organic light‐emitting diodes (OLEDs) applications. The coordination geometry around iridium metal ion was distorted octahedral, exhibiting cis‐C, C′ and trans‐N, N′ chelate dispositions with narrow ligand bite angles ranging from 79.7° (2) to 84.5° (1). The optical properties revealed that the π‐conjugated nature of bt ligand caused a bathochromic shift in emission and btz ligand played a role in fine color tuning. The synthesized (bt)2Ir(btz) was soluble in common organic solvents and the emitting layer was readily spin‐coated in chlorobenzene solution onto substrate. The OLED fabricated with the configuration of ITO/PEDOT:PSS/PVK:TCTA:OXD‐7: (bt)2Ir(btz) (32:32:28:8)/Bphen/LiF/Al exhibited a maximum external quantum efficiency (EQE) of 4.67% and a maximum luminance efficient (LE) of 8.61 cd/A with CIE (x, y) coordinates of (0.54,0.45).

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Synthesis, Structure, and OLEDs Application of Cyclometalated Iridium(III) Complexes Utilizing Substituted 2‐Phenylpyridine

Yun

Jeon

Jin

et al. 2017

Bulletin Korean Chem Soc

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The syntheses, structures, photophysical, and electroluminescent properties of three green emitting heteroleptic cyclometalated iridium(III) complexes, (ptfmppy) 2Ir(pic) (Ir1), (dfptfmppy) 2Ir(pic) (Ir2), and (tfptfmppy) 2Ir(pic) (Ir3) [ptfmppy = 5‐(trifluoromethyl)‐2‐(phenyl)pyridine, dfptfmppy = 5‐(trifluoromethyl)‐2‐(2,4‐difluorophenyl) pyridine, tfptfmppy = 5‐(trifluoromethyl)‐2‐(2,3,4‐difluorophenyl)pyridine, and picH = picolinic acid] and the results of an investigation on their suitabilities for phosphorescent organic light‐emitting diodes (phOLEDs) applications are reported. X‐ray single crystal structures showed that iridium(III) cations in Ir1 and Ir2 adopted six‐coordinated geometries involving two C and two N atoms from substituted‐ppy, and one N and one O atom from pic, which produced a distorted octahedral geometry. Photoluminescence (PL) spectra revealed that the synthesized iridium(III) complexes exhibited emissions at 497 ~ 534 nm in dichloromethane with high photoluminescence quantum yield (PLQY) ranging from 60 to 67%, and TGA experiments showed that they had good thermal stabilities. In Ir3, the conjugation effect rather than the electronic effect of the 3‐positioned fluorine atom on phenyl ring of ppy increased the HOMO energy level causing bathochromic shifts. Electroluminescent devices of ITO(110 nm)/PEDOT:PSS (40 nm)/PVK:TCTA:OXD‐7:Ir (80 nm)/TmPyPB (20 nm)/Al (100 nm) were fabricated using the iridium(III) complexes as phosphors in an emitting layer, and their electroluminescent performances were investigated.

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New heteroleptic cyclometalated iridium(III) complexes containing 2-(2′,4′-difluorophenyl)-4-methylpyridine for organic light-emitting diode applications

Cited by 9 publications

References 40 publications

Synthesis and Crystallographic Characterization of Heteroleptic Ir(III) Complexes Containing the N-oxide Functional Group and Crystallographic Characterization of Ir(III) N-oxide Precursors

Synthesis and Crystallographic Characterization of Heteroleptic Ir(III) Complexes Containing the N-oxide Functional Group and Crystallographic Characterization of Ir(III) N-oxide Precursors

Orange–Yellow Phosphorescent Iridium(III) Complex for Solution‐processed Organic Light‐Emitting Diodes: Structural, Optical and Electroluminescent Properties of Bis(2‐phenylbenzothiazole)[2‐(2‐hydroxyphenyl)benzothiazole]iridium(III)

Synthesis, Structure, and OLEDs Application of Cyclometalated Iridium(III) Complexes Utilizing Substituted 2‐Phenylpyridine

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