Cyclometalated iridium complexes are widely used in optoelectronic technologies,but creating efficient red emitters remains challenging.Prior investigations have demonstrated the efficiency of electron-rich salicylald...Cyclometalated iridium complexes are widely used in optoelectronic technologies,but creating efficient red emitters remains challenging.Prior investigations have demonstrated the efficiency of electron-rich salicylaldimine and 2-picolinamide ligands in promoting red to deep red luminescence.This work introduces a series of ten new red or deep-red emitting heteroleptic bis-cyclometalated iridium(Ⅲ)complexes supported by eight different ancillary ligands,including some from the salicylaldimine and 2-picolinamide families.Our study reveals that the effectiveness of salicylaldimine ligands at supporting efficient red phosphorescence is dependent on the cyclometalating ligand they are paired with.A more significant finding is that the 2-picolinamide ligands can adopt three different coordination modes.Firstly,the N-propyl-substituted 2-picolinamide proligand can bind to the iridium center in its neutral,protonated form through the pyridyl N and amide O atoms,forming five-membered metallacycles.Furthermore,N-aryl-substituted ligands can coordinate with the iridium center in either N,N’or N(pyridyl),O modes,yielding two structurally distinct isomers.Notably,the change in coordination mode minimally influences emission wavelength while significantly modulating the photoluminescence quantum yield.This study advances our comprehension of how ligand coordination impacts cyclometalated iridium complexes,offering invaluable insights into the design of high-performance red phosphors for potential optoelectronic applications.展开更多
In this work,we describe bis-cyclometalated iridium complexes with efficient deep-red luminescence.Two different cyclometalating(C^N)ligands-1-phenylisoquinoline(piq)and 2-(2-pyridyl)benzothiophene(btp)-are used with ...In this work,we describe bis-cyclometalated iridium complexes with efficient deep-red luminescence.Two different cyclometalating(C^N)ligands-1-phenylisoquinoline(piq)and 2-(2-pyridyl)benzothiophene(btp)-are used with five strongπ-donating ancillary ligands(L^X)to furnish a suite of nine new complexes with the general formula Ir(C^N)_(2)(L^X).Improvements in deep-red photoluminescence quantum yields were accomplished by the incorporation of sterically encumbering substituents onto the ancillary ligand,which can enhance the radiative rate constant(k_(r))and/or reduce the non-radiative rate constant(k_(nr)).Five of the complexes were characterized by X-ray crystallography,and all of them were investigated by in-depth spectroscopic and electrochemical measurements.展开更多
The design of deep-red to near-infrared(DR-NIR)phosphorescent compounds with high photoluminescence quantum yields(Φ_(PL))is a significant fundamental challenge that impacts applications including optoelectronic devi...The design of deep-red to near-infrared(DR-NIR)phosphorescent compounds with high photoluminescence quantum yields(Φ_(PL))is a significant fundamental challenge that impacts applications including optoelectronic devices,imaging,and sensing.Here we show that bis-cyclometalated iridium complexes with electron-rich ancillary ligands can have exceptional quantum yields for DR-NIR phosphorescence(peak λ>700 nm).Six bis-cyclometalated iridium(Ⅲ)complexes with DR-NIR phosphorescence are described in this work,pairing highly conjugated cyclometalating ligands with electron-rich and sterically encumbered β-ketoiminate(acNac),β-diketiminate(NacNac),and N,N’-diisopropylbenzamidinate(dipba)ancillary ligands.The photoluminescence spectra and quantum yields are solventdependent,consistent with significant charge-transfer character in the emissive excited state.The ancillary ligands perturb the excited-state kinetics relative to closely related compounds,which can lead to enhanced Φ_(PL) values in the DR-NIR region,particularly in toluene solution and in doped polymer films.展开更多
A series of bis-cyclometalated iridium complexes were prepared which combine triazole or NHC-based cyclometalating ligands with substitutedβ-diketiminate(NacNac)ancillary ligands.The HOMO is localized on the NacNac l...A series of bis-cyclometalated iridium complexes were prepared which combine triazole or NHC-based cyclometalating ligands with substitutedβ-diketiminate(NacNac)ancillary ligands.The HOMO is localized on the NacNac ligand and its energy and associated redox potential are determined by the NacNac substitution pattern.The effect of the cyclometalating ligand,relative to the more common 2-phenylpyridine derivatives.展开更多
基金the Welch Foundation(Grant E-1887)the National Science Foundation(Grant CHE-1846831)for funding this work.
文摘Cyclometalated iridium complexes are widely used in optoelectronic technologies,but creating efficient red emitters remains challenging.Prior investigations have demonstrated the efficiency of electron-rich salicylaldimine and 2-picolinamide ligands in promoting red to deep red luminescence.This work introduces a series of ten new red or deep-red emitting heteroleptic bis-cyclometalated iridium(Ⅲ)complexes supported by eight different ancillary ligands,including some from the salicylaldimine and 2-picolinamide families.Our study reveals that the effectiveness of salicylaldimine ligands at supporting efficient red phosphorescence is dependent on the cyclometalating ligand they are paired with.A more significant finding is that the 2-picolinamide ligands can adopt three different coordination modes.Firstly,the N-propyl-substituted 2-picolinamide proligand can bind to the iridium center in its neutral,protonated form through the pyridyl N and amide O atoms,forming five-membered metallacycles.Furthermore,N-aryl-substituted ligands can coordinate with the iridium center in either N,N’or N(pyridyl),O modes,yielding two structurally distinct isomers.Notably,the change in coordination mode minimally influences emission wavelength while significantly modulating the photoluminescence quantum yield.This study advances our comprehension of how ligand coordination impacts cyclometalated iridium complexes,offering invaluable insights into the design of high-performance red phosphors for potential optoelectronic applications.
基金the National Science Foundation(CHE-1846831)the Welch Foundation(grant no.E-1887)for funding this research.
文摘In this work,we describe bis-cyclometalated iridium complexes with efficient deep-red luminescence.Two different cyclometalating(C^N)ligands-1-phenylisoquinoline(piq)and 2-(2-pyridyl)benzothiophene(btp)-are used with five strongπ-donating ancillary ligands(L^X)to furnish a suite of nine new complexes with the general formula Ir(C^N)_(2)(L^X).Improvements in deep-red photoluminescence quantum yields were accomplished by the incorporation of sterically encumbering substituents onto the ancillary ligand,which can enhance the radiative rate constant(k_(r))and/or reduce the non-radiative rate constant(k_(nr)).Five of the complexes were characterized by X-ray crystallography,and all of them were investigated by in-depth spectroscopic and electrochemical measurements.
基金the National Science Foundation(Grant No.CHE-1846831)the Welch Foundation(Grant No.E-1887)for funding this research.
文摘The design of deep-red to near-infrared(DR-NIR)phosphorescent compounds with high photoluminescence quantum yields(Φ_(PL))is a significant fundamental challenge that impacts applications including optoelectronic devices,imaging,and sensing.Here we show that bis-cyclometalated iridium complexes with electron-rich ancillary ligands can have exceptional quantum yields for DR-NIR phosphorescence(peak λ>700 nm).Six bis-cyclometalated iridium(Ⅲ)complexes with DR-NIR phosphorescence are described in this work,pairing highly conjugated cyclometalating ligands with electron-rich and sterically encumbered β-ketoiminate(acNac),β-diketiminate(NacNac),and N,N’-diisopropylbenzamidinate(dipba)ancillary ligands.The photoluminescence spectra and quantum yields are solventdependent,consistent with significant charge-transfer character in the emissive excited state.The ancillary ligands perturb the excited-state kinetics relative to closely related compounds,which can lead to enhanced Φ_(PL) values in the DR-NIR region,particularly in toluene solution and in doped polymer films.
基金the National Science Foundation(Grant Number CHE-1846831)the Welch Foundation(Grant Number E-1887)for funding this workComputations performed at CWRU were supported by the Air Force Office of Scientific Research,contract number FA9550-18-1-0247 to T.G.G。
文摘A series of bis-cyclometalated iridium complexes were prepared which combine triazole or NHC-based cyclometalating ligands with substitutedβ-diketiminate(NacNac)ancillary ligands.The HOMO is localized on the NacNac ligand and its energy and associated redox potential are determined by the NacNac substitution pattern.The effect of the cyclometalating ligand,relative to the more common 2-phenylpyridine derivatives.
