Unveiling Photodeactivation Pathways for a New Iridium(III) Cyclometalated Complex

We report the synthesis and characterization of a neutral heteroleptic Ir^III complex bearing 6‐fluoro‐2‐phenylbenzo[d]thiazole as cyclometalating ligand and (Z)‐6‐(9H‐carbazol‐9‐yl)‐5‐hydroxy‐2,2‐dimethylhex‐4‐en‐3‐one as ancillary ligand. The photodeactivation mechanisms have been elucidated through extensive density functional theory (DFT) calculations. The active role of metal‐centered (³MC) triplet excited states in the nonradiative deactivation pathways is, for first time, confirmed in such complexes.     

Synthesis and Photoluminescence of a New Red PhosphorescentIridium(III) Quinoxaline Complex

Much attention has been paid to the phosphorescent materials in recent years for their potential application as highly efficient electroluminescent (EL) emitters in organic light emitting diodes (OLEDs) 1-2. Heavy metal complexes, particularly those containing Pt and Ir, where strong spin orbit coupling leads to singlet-triplet state mixing, can result in high efficiency electrophosphorescence in OLED 3-5. Among the many kinds of metal complexes, iridium complexes are the most effective …     

Cyclometalated Iridium(III) Complexes with Deoxyribose Substituents

Fundamental study of enzymatic nucleoside transport suffers for lack of optical probes that can be tracked noninvasively. Nucleoside transporters are integral membrane glycoproteins that mediate the salvage of nucleosides and their passage across cell membranes. The substrate recognition site is the deoxyribose sugar, often with little distinction among nucleobases. Reported here are nucleoside analogues in which emissive, cyclometalated iridium(III) complexes are “clicked” to C‐1 of deoxyribose in place of canonical nucleobases. The resulting complexes show visible luminescence at room temperature and 77 K with microsecond‐length triplet lifetimes. A representative complex is crystallographically characterized. Transport and luminescence are demonstrated in cultured human carcinoma (KB3‐1) cells.     

A Novel Method for the Selective Determination of Silver （I） Ion

Semiconductor quantum dots (QDs) present considerable advantages over bulk single-crystal semiconductors1. As a result of quantum confinement, they have unique optical and electronic properties such as broad excitation spectra, narrow, symmetric and tunable emission spectra2. In addition, QDs exhibit high photobleaching threshold and excellent photostability. They are starting to attract considerable attention as novel fluorescence probes in recent years3-6. Recently, Chen and Rosenzwei…     

Cyclometalated Iridium(III) Complexes as Two‐Photon Phosphorescent Probes for Specific Mitochondrial Dynamics Tracking in Living Cells

Five cyclometalated iridium(III) complexes with 2‐phenylimidazo[4,5‐f][1,10]phenanthroline derivatives ( IrL1 – IrL5 ) were synthesized and developed to image and track mitochondria in living cells under two‐photon (750 nm) excitation, with two‐photon absorption cross‐sections of 48.8–65.5 GM at 750 nm. Confocal microscopy and inductive coupled plasma‐mass spectrometry (ICP‐MS) demonstrated that these complexes selectively accumulate in mitochondria within 5 min, without needing additional reagents for membrane permeabilization, or replacement of the culture medium. In addition, photobleaching experiments and luminescence measurements confirmed the photostability of these complexes under continuous laser irradiation and physiological pH resistance. Moreover, results using 3D multicellular spheroids demonstrate the proficiency of these two‐photon luminescent complexes in deep penetration imaging. Two‐photon excitation using such novel complexes of iridium(III) for exclusive visualization of mitochondria in living cells may substantially enhance practical applications of bioimaging and tracking.     

Bimetallic Cyclometalated Iridium(III) Diastereomers with Non‐Innocent Bridging Ligands for High‐Efficiency Phosphorescent OLEDs

Two phosphorescent dinuclear iridium(III) diastereomers (ΛΔ/ΔΛ) and (ΛΛ/ΔΔ) are readily separated by making use of their different solubilities in hot hexane. The bridging diarylhydrazide ligand plays an important role in the electrochemistry and photophysics of the complexes. Organic light‐emitting devices (OLEDs) that use these complexes as the green‐emissive dopants in solution‐processable single‐active‐layer architectures feature electroluminescence efficiencies that are remarkably high for dinuclear metal complexes, achieving maximum values of 37 cd A^?1, 14 lm W^?1, and 11 % external quantum efficiency.     

Rational Design of Cyclometalated Iridium(III) Complexes for Three-Photon Phosphorescence Bioimaging

Compared to 2PE (two-photon excitation) microscopy, 3PE microscopy has superior spatial resolution, deeper tissue penetration, and less defocused interference. The design of suitable agents with a large Stokes shift, good three-photon absorption (3PA), subcellular targeting, and fluorescence lifetime imaging (FLIM) properties, is challenging. Now, two Ir^III complexes (3PAIr1 and 3PAIr2) were developed as efficient three-photon phosphorescence (3PP) agents. Calculations reveal that the introduction of a new group to the molecular scaffold confers a quadruple promotion in three-photon transition probability. Confocal and lifetime imaging of mitochondria using Ir^III complexes as 3PP agents is shown. The complexes exhibit low working concentration (50 nm ), fast uptake (5 min), and low threshold for three-photon excitation power (0.5 mW at 980 nm). The impressive tissue penetration depth (ca. 450 μm) allowed the 3D imaging and reconstruction of brain vasculature from a living specimen.     

Highly Sensitive and Selective Amperometric Detection of Periodate at Glassy Carbon Electrode Modified with a Cyclometalated Iridium(III) Complex and Single‐Wall Carbon Nanotubes

Single‐wall carbon nanotubes (SWCNTs) were used as an immobilization matrix to incorporate [Ir(ppy)₂(phen‐dione)](PF₆) complex onto a glassy carbon electrode for the study of electrocatalytic reduction of periodate ion. Detailed preliminary electrochemical data for the Ir(III)‐complex in acetonitrile solution and for the modified GCE/SWCNTs/[Ir(ppy)₂(phen‐dione)](PF₆)/CGE are presented. The modified electrode was applied to selective amperometric detection of periodate through its electrocatalytic reduction to iodide at 0.200 V and pH 2.0. The use of amperometry resulted in two calibration plots over the concentration ranges of 1‐20 μM and 20‐450 μM, with a detection limit of 0.6 μM and sensitivity of 198 nA μM^?1.     

含螺环位阻铱(III)配合物的共轭结构调控及其电致发光性能研究

基于螺[芴-9,9'-氧杂蒽]的位阻结构,在其芴端连接苯并噻唑构成共轭扩展的环金属配体,并成功合成了相应的均配、面式构型铱（III）配合物fac-Ir（SFXbtz）₃.配合物的最强发射峰位于587 nm,在635 nm处伴有肩峰发射;其在溶液中的磷光寿命为316 ns,光致发光量子产率达到64.7%.以fac-Ir（SFXbtz）₃为发射材料,在高掺杂浓度下分别制备了橙光电致发光器件及与蓝光材料FIrpic（双（4,6-二氟苯基吡啶-N,C²）吡啶甲酰合铱）组合的二元白光器件.以CBP（4,4'-二（9-咔唑）联苯）为主体材料的橙光器件最高电流效率和功率效率为10.8 cd·A^-1和8.4 lm·W^-1,最大亮度为7217 cd·m^-2.二元白光器件最高电流效率和功率效率为11.6 cd·A^-1和8.0 lm·W^-1,最大亮度为8763 cd·m^-2,在3~9 V操作电压下CIE1931色坐标稳定.结果表明：协同利用螺环芳烃的共轭结构和位阻结构优势,是获得低成本、本征光电性质良好及可高浓度掺杂的磷光铱（III）配合物的便捷方法.     

稠杂环化合物在红色磷光铱配合物中的应用

在过去的几十年里, 有机发光二极管(OLED)由于潜在的优势, 在全彩显示领域引起了高度重视. 电致磷光材料因其优异的发光性能, 引起了人们广泛关注. 对于实际应用的平板显示器, 蓝、绿、红三基色是必不可少的. 相对于高效的绿光材料, 红光磷光材料仍然存在色纯度差、效率低和亮度不足等问题, 因此设计合适的红光材料成为具有挑战性的问题. 稠杂环化合物因发光量子效率高、发光颜色可调、平衡电荷注入及迁移等优越性能而广泛应用于红色磷光铱配合物. 本文综述了近几年稠杂环化合物在小分子、树枝状及高分子红色磷光铱配合物中的应用, 阐述了铱配合物分子结构对材料光电性质及器件性能的影响, 最后展望了稠杂环化合物在红光磷光材料中的应用前景.     

Spin–Orbit Coupling in Phosphorescent Iridium(III) Complexes

We study the excited states of two iridium(III) complexes with potential applications in organic light‐emitting diodes: fac‐tris(2‐phenylpyridyl)iridium(III) [Ir(ppy)₃] and fac‐tris(1‐methyl‐5‐phenyl‐3‐n‐propyl‐[1,2,4]triazolyl)iridium(III) [Ir(ptz)₃]. Herein we report calculations of the excited states of these complexes from time‐dependent density functional theory (TDDFT) with the zeroth‐order regular approximation (ZORA). We show that results from the one‐component formulation of ZORA, with spin–orbit coupling included perturbatively, accurately reproduce both the results of the two‐component calculations and previously published experimental absorption spectra of the complexes. We are able to trace the effects of both scalar relativistic correction and spin–orbit coupling on the low‐energy excitations and radiative lifetimes of these complexes. In particular, we show that there is an indirect relativistic stabilisation of the metal‐to‐ligand charge transfer (MLCT) states. This is important because it means that indirect relativistic effects increase the degree to which SOC can hybridise singlet and triplet states and hence plays an important role in determining the optical properties of these complexes. We find that these two compounds are remarkably similar in these respects, despite Ir(ppy)₃ and Ir(ptz)₃ emitting green and blue light respectively. However, we predict that these two complexes will show marked differences in their magnetic circular dichroism (MCD) spectra.     

Heterometallation of Photoluminescent Silver(I) Sulfide Nanoclusters Protected by Octahedral Iridium(III) Thiolates

The recently-increasing interest in coinage metal clusters stems from their photophysical properties, which are controlled via heterometallation. Herein, we report homometallic Ag^I₄₆S₁₃ clusters protected by octahedral fac-[Ir(aet)₃] (aet=2-aminoethanethiolate) molecules and their conversion to heterometallic Ag^I₄₃M^I₃S₁₃ (M=Cu, Au) clusters. The reactions of fac-[Ir(aet)₃] with Ag⁺ and penicillamine produced [Ag₄₆S₁₃{Ir(aet)₃}₁₄]²⁰⁺ ([ 1 ]²⁰⁺), where a spherical Ag^I₄₆S₁₃ cluster is covered by fac-[Ir(aet)₃] octahedra through thiolato bridges. [ 1 ]²⁰⁺ was converted to [Ag₄₃M₃S₁₃{Ir(aet)₃}₁₄]²⁰⁺ ([ 1^M ]²⁰⁺) with an Ag^I₄₃M^I₃S₁₃ cluster by treatment with M⁺, retaining its overall structure. [ 1 ]²⁰⁺ was photoluminescent and had an emission band ca. 690 nm that originated from an S-to-Ag charge transfer. While [ 1^Cu ]²⁰⁺ showed an emission band with a slightly higher energy of ca. 650 nm and a lower quantum yield, the emission band for [ 1^Au ]²⁰⁺ shifted to a much higher energy of ca. 590 nm with an enhanced quantum yield.     

Rational Design of Cyclometalated Iridium(III) Complexes for Three‐Photon Phosphorescence Bioimaging

Compared to 2PE (two‐photon excitation) microscopy, 3PE microscopy has superior spatial resolution, deeper tissue penetration, and less defocused interference. The design of suitable agents with a large Stokes shift, good three‐photon absorption (3PA), subcellular targeting, and fluorescence lifetime imaging (FLIM) properties, is challenging. Now, two Ir^III complexes (3PAIr1 and 3PAIr2) were developed as efficient three‐photon phosphorescence (3PP) agents. Calculations reveal that the introduction of a new group to the molecular scaffold confers a quadruple promotion in three‐photon transition probability. Confocal and lifetime imaging of mitochondria using Ir^III complexes as 3PP agents is shown. The complexes exhibit low working concentration (50 nm ), fast uptake (5 min), and low threshold for three‐photon excitation power (0.5 mW at 980 nm). The impressive tissue penetration depth (ca. 450 μm) allowed the 3D imaging and reconstruction of brain vasculature from a living specimen.     

Microwave Assisted Synthesis of a New Triplet Iridium(III) Pyrazine Complex

A new cyclometalated iridium(III) complex Ir(DPP)₃ (DPP=2,3-diphenylpyrazine) was pre-pared by reaction of DPP with iridium trichloride hydrate under microwave irradiation. The structure of the complex was confirmed by elemental analysis, ¹H NMR, and mass spec-troscopy. The UV-Vis absorption and photoluminescent properties of the complex were investigated. The complex shows strong ¹MLCT (singlet metal to ligand charge-transfer) and ³MLCT (triplet metal to ligand charge-transfer) absorption at 382 and 504 nm, respec-tively. The complex also shows strong photoluminescence at 573 nm at room temperature.These results suggest the complex to be a promising phosphorescent material.     

Strongly Phosphorescent Iridium(III)-Porphyrins - New Oxygen Indicators with Tuneable Photophysical Properties and Functionalities

Synthesis and characterization of four iridium(III)-octaethylporphyrins and a π-extended iridium(III)-benzoporphyrin are presented. Strong room-temperature phosphorescence was observed for all of the complexes with quantum yields of up to 30 %. Axial ligands were introduced to tune the photophysical properties and the solubility. Complexes bearing lipophilic ligands such as pyridine or N-(n-butyl)imidazole were incorporated into polystyrene to obtain optical oxygen sensors. Covalent coupling of the dye is possible by introduction of ligands with binding domains (1-imidazoleacetic acid). This enabled preparation of a water-soluble oxygen probe (by staining bovine serum albumin) and a trace oxygen sensor (by coupling to amino-modified silica gel).     

Development of Strong Visible-Light-Absorbing Cyclometalated Iridium(III) Complexes for Robust and Efficient Light-Driven Hydrogen Production

Weak light absorption of common Ir(III) complexes (e. g., using phenylpyridine as the ligand) has hindered their applications in photocatalytic hydrogen generation from water as an efficient photosensitizer. To address this issue, a series of cyclometalated Ir(III) complexes (Ir1–Ir5), featuring different electron-donating substituents to enhance the absorptivity, have been synthesized and studied as photosensitizers (PSs) for light-driven hydrogen production from water. Ir6–Ir7 were prepared as fundamental systems for comparisons. Electron donors, including 9-phenylcarbazole, triphenylamine, 4,4′-dimethoxytriphenylamine, 4,4′-di(N-hexylcarbazole)triphenylamine moieties were introduced on 6-(thiophen-2-yl)phenanthridine-based cyclometalating (C^N) ligands to explore the donor effect on the hydrogen evolution performance of these cationic Ir(III) complexes. Remarkably, Ir4 with 4,4′-dimethoxytriphenylamine achieved the highest turn-over number (TON) of 12 300 and initial turnover frequency (TOF_i) of 394 h⁻¹, with initial activity (activity_i) of 547 000 μmol g⁻¹ h⁻¹ and initial apparent quantum yield (AQY_i) of 9.59 %, under the illumination of blue light-emitting diodes (LEDs) for 105 hours, which demonstrated a stable three-component photocatalytic system with high efficiency. The TON (based on n(H₂)/n(PSr)) in this study is the highest value reported to date among the similar photocatalytic systems using Ir(III) complexes with Pt nanoparticles as catalyst. The great potential of using triphenylamine-based Ir(III) PSs in boosting photocatalytic performance has also been shown.