23749-58-8Relevant articles and documents
Synthesis of a highly phosphorescent emitting iridium(III) complex and its application in OLEDs
Hu, Jiawei,Zhang, Guanghui,Shih, Hung-Hsin,Jiang, Xiaoqing,Sun, Peipei,Cheng, Chien-Hong
, p. 2798 - 2802 (2008)
A rigid ligand benzo[de]benzo[4,5]imidazo[2,1-α]isoquinolin-7-one (biio) was designed and conveniently synthesized, and the corresponding bis-cyclometalated iridium complex (biio)2Ir(acac) (acac = acetylacetone) was prepared. The light emitting and electrochemical properties of this complex were studied. The complex has the characters of simply synthetic procedure and strong phosphorescence. The electroluminescent device using this complex as dopant was fabricated. The device had the structure of ITO/NPB (40 nm)/Ir complex:CBP (7%, 30 nm)/BCP (15 nm)/Alq3 (30 nm)/LiF (1 nm)/Al (100 nm). The maximum emission of the device was at 496 nm. The maximum brightness of the device can reach 79640 cd m-2 with an external quantum efficiency of 12.1% and a maximum current efficiency of 31.7 cd A-1.
Naphthalene Benzimidazole Based Neutral Ir(III) Emitters for Deep Red Organic Light-Emitting Diodes
Kim, Hyung Suk,Kumar, Ajay,Lee, Min Hyung,Lee, Woochan,Rajakannu, Palanisamy,Yoo, Seunghyup
, p. 12461 - 12470 (2020)
Rigid naphthalene benzimidazole (NBI) based ligands (L1 and L2) are synthesized and utilized to make deep red phosphorescent cyclometalated iridium(III) complexes ([Ir(NBI)2(PyPzCF3)] (1) and [Ir(DPANBI)2(PyPzCF3)] (2)). Complexes 1 and 2 are prepared from the reaction of L1/L2 with the aid of ancillary ligands (PyPzCF3, 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine) in a two step method. The complexes are characterized by analytical and spectroscopic methods, as well as X-ray diffraction for 1. These complexes show a strong emission in the range of 635-700 nm that extends up to the near-infrared region (800 nm). The introduction of the diphenylamino (DPA) donor group on the naphthalene unit leads to a further red-shift in the emission. The complexes exhibit radiative quantum efficiency (φPL) of 0.27-0.29 in poly(methylmethacrylate) film and relatively short phosphorescence decay lifetimes (τ = 1.1-3.5 μs). The structural, electronic, and optical properties are investigated with the support of density functional theory (DFT) and time-dependent-DFT calculations. The calculation results indicate that the lowest-lying triplet (T1) excited state of 1 has a mixed metal-to-ligand charge transfer (3MLCT) and ligand-centered (3LC) character, while 2 shows a dominant 3LC character. Deep red-emitting organic light-emitting diodes fabricated using 1 as a dopant display a maximum external quantum efficiency of 10.9% with the CIE color coordinates of (0.690, 0.294), with an emission centered at 644 and 700 nm. Similarly, the emitter 2 also shows a maximum external quantum efficiency of 6.9% with emissions at 657 and 722 nm.
Efficient Phosphorescence from Naphthalenebenzimidizole-Coordinated Iridium(III) Chromophores
Yarnell, James E.,De La Torre, Patricia,Castellano, Felix N.
, p. 5238 - 5245 (2017)
The electronic structure and photophysical properties of two phosphorescent iridium(III) cyclometalated complexes are presented. The molecules were synthesized by cyclometalating the ligand 1,8-naphthalenebenzimidizole (NBI), to an iridium(III) metal center. Two NBI ligands were covalently attached along with a 1,10-phenanthroline (phen) ligand producing the [Ir(NBI)2(phen)](PF6) complex and three NBI ligands were used to prepare the corresponding tris-cyclometalate fac-Ir(NBI)3. The optical properties of these new IrIII molecules were investigated using DFT calculations, photoluminescence spectroscopy, and transient absorption spectroscopy. The molecules at the heart of this study were found to contain long-lived ligand-localized triplet excited states on the NBI species, featuring energies suitable for bimolecular photochemical reactions. Both iridium(III) chromophores possess excellent light absorptivity in the visible region of the spectrum with high photoluminescence quantum efficiencies approaching 30 %.
Electrochemical Activation of Diverse Conventional Photoredox Catalysts Induces Potent Photoreductant Activity**
Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.
supporting information, p. 21418 - 21425 (2021/08/25)
Herein, we disclose that electrochemical stimulation induces new photocatalytic activity from a range of structurally diverse conventional photocatalysts. These studies uncover a new electron-primed photoredox catalyst capable of promoting the reductive cleavage of strong C(sp2)?N and C(sp2)?O bonds. We illustrate several examples of the synthetic utility of these deeply reducing but otherwise safe and mild catalytic conditions. Finally, we employ electrochemical current measurements to perform a reaction progress kinetic analysis. This technique reveals that the improved activity of this new system is a consequence of an enhanced catalyst stability profile.
Understanding the influence of geometric and electronic structure on the excited state dynamical and photoredox properties of perinone chromophores
Castellano, Felix N.,Chakraborty, Arnab,Favale, Joseph M.,Garakyaraghi, Sofia,Palmer, Jonathan R.,Pemberton, Barry C.,Valchar, Mary Katharine,Wells, Kaylee A.,Yarnell, James E.
, p. 24200 - 24210 (2021/11/16)
In this work, a series of eight similarly structured perinone chromophores were synthesized and photophysically characterized to elucidate the electronic and structural tunability of their excited state properties, including excited state redox potentials and fluorescence lifetimes/quantum yields. Despite their similar structure, these chromophores exhibited a broad range of visible absorption properties, quantum yields, and excited state lifetimes. In conjunction with static and time-resolved spectroscopies from the ultrafast to nanosecond time regimes, time-dependent computational modeling was used to correlate this behavior to the relationship between non-radiative decay and the energy-gap law. Additionally, the ground and excited state redox potentials were calculated and found to be tunable over a range of 1 V depending on the diamine or anhydride used in their synthesis (Ered* = 0.45-1.55 V;Eox* = ?0.88 to ?1.67 V), which is difficult to achieve with typical photoredox-active transition metal complexes. These diverse chromophores can be easily prepared, and with their range of photophysical tunability, will be valuable for future use in photofunctional applications.
