Synthesis and Characterization of Novel Orange-emitting Iridium(Ⅲ)Complexes with Diphenylquinoline Ligands Containing Fluorinated Substituent

Three new cyclometalated iridium（m） complexes based on ligands of diphenylquinoline with fluorinated subsfituents were prepared, and characterized by elemental analysis （EA）, ^1H NMR, and mass spectroscopy （MS）. The photophysical and electrophosphorescent properties of the complexes were briefly discussed.

Synthesis and Luminescent Properties of Iridium Complexes with Reduced Concentration Quenching Effect

Three novel cyclometalated ligands 1-benzyl-2-phenyl-lH-benzoimidazole（BPBM）, 1-（4-methoxy- benzyl）-2-（4-methoxy-phenyl）-lH-benzoimidazole（MBMPB） and 4-[2-（4-dimethylamino-phenyl）-benzoinidazol-1- ylmethyl]-phenyl-dimethyl-amine（DBPA） were designed and synthesized, and the corresponding highly efficiency green-emitting phosphorescent iridium complexes Ir（BPBM）2（acac）（1）, Ir（MBMPB）2（acac）（2） and Ir（DPBA）2（acac） （3） with acetylacetone（acac） as auxiliary ligand were also synthesized. The ligands are functionalized by bulky non-planarity substituents, thus the phosphorescent concentration quenching is substantially suppressed, and all the complexes exhibit bright photoluminescence（PL） in solid state. The photo-physical properties of the three iridium complexes were researched in detail. The results indicate that they have potential application in fabricating non-doped electrophosphorescence device.

Understanding AIE and ACQ phenomenon of organometallic iridium(Ⅲ) complexes by simple cationization engineering

Understanding the relationship between structure and properties is critical to the development of solidstate luminescence materials with desired characteristics and performance optimization. In this work, we elaborately designed and synthesized a pair of mononuclear iridium(Ⅲ) complexes with similar structures but different degrees of cationization. [Ir2-f][2PF_(6)] with two counterions is obtained by simple Nmethylation of the ancillary ligand of [Ir1-f][PF_(6)] which is a classic cationic iridium(Ⅲ) complex. Such a tiny modification results in tremendously different optical properties in dilute solutions and powders.[Ir1-f][PF_(6)] exhibits weak light in solution but enhanced emission in solid-state as well as poly(methyl methacrylate) matrix, indicative of its aggregation-induced emission(AIE) activity. On the sharp contrary, [Ir2-f][2PF_(6)] is an aggregation-caused quenching(ACQ) emitter showing strong emission in the isolated state but nearly nonemissive in aggregation states. Benefiting from the appealing characteristics of mechanochromic luminescence and AIE behavior, [Ir1-f][PF_(6)] has been successfully applied in reversible re-writable data recording and cell imaging. These results might provide deep insights into AIE and ACQ phenomenon of iridium(Ⅲ) complexes and facilitate the development of phosphorescent materials with promising properties.

Review on the study of Nonlinear Optics of Iridium Metal Organic Complex

Nonlinear optical materials are one of the key research objects in the field of optics, which mainly research the nonlinear effects of the interaction between luminesce and matter. Compared with inorganic nonlinear optical materials, organic nonlinear materials have outstanding advantages: strong adaptability, high flexibility, low cost, easy modification and damage resistance. In this review, the electric field induced second harmonic generation (EFISH) experimental technology is used to measure and research the nonlinearity of iridium metal complexes. And because of its structural diversity, people can design molecules according to their needs to get the best nonlinear optical response. Organic molecules with large nonlinear coefficients should have the following characteristics: asymmetric charge distribution, the delocalized nature of π electrons, and easy polarization by external electric fields, and a large π conjugated system. In recent years, metal organic compounds have become a leader in the field of optics, mainly because of their very good nonlinear optical properties. In the future, people will do more investigation on the nonlinearity of metal organic complexes. Researchers have shown great interest in iridium metal organic complexes due in particular to their attractive stability and nonlinear activity. This review mainly studies the nonlinear principle, performance test and Measurement of nonlinearity of iridium metal complexes. The nonlinear properties of other metal-metal organic complexes will not be discussed.

Solid-state electrochemiluminescence of a novel iridium(Ⅲ) complex

The solid-state ECL behavior of a water-insoluble bis-cyclometalated （pq）2Ir（N-phMA） complex is presented, in which pq is a 2-phenylquinoline anion and N-phMA is N-phenyl methacrylamide, a monoanionic bidentate ligand. The MWNTs/（pq）2Ir（N-phMA） film, MWNTs/Ru（bpy）3^2＋ film and （pq）2Ir（N-phMA） directly modified glassy carbon electrode were fabricated; only the MWNTs/（pq）2Ir（N-phMA） film can produce steady ECL in the presence of tri-n-propylamine as a coreactant.

Blue-green Phosporescent Iridium Complex with Terdentate Ligand

An ionic iridium（Ⅲ） complex[Ir（F2dpyb）（bzdpp）2Cl][OTf]with 1,3-difluoro-4,6-di（2-pyridinyl） benzene（F2dpybH） terdentate ligand and benzyldiphenylphosphine（bzdpp）ligand was synthesized and characterized.The structure of iridium complex was verified by single-crystal X-ray crystallography.It crystallizes in monoclinic,space group P21/n with a =14.3654（7）,b = 23.0026（10）,c = 15.7964（7） A°,β = 97.6029（11）,V= 5173.9（4） A°3,Z = 4,F（000） =2552,Dc = 1.645 Mg/m^3,Mr = 1281.49 and μ = 0.071 mm^-1.The UV-vis absorption and phosphorescence of the complex were discussed.The complex was ＇aggregation induced emission（AIE）＇ active.It exhibited no emission in CH2Cl2 solution but strong blue-green emission in solid state under ultraviolet light excitation.The complex emitted a strong phosphorescence centered at493 nm when doped in PMMA.Its lifetime is 0.755 μs and quantum yield is approximately 0.134.

Novel Iridium Complex with Carbazol-2-yl-β-diketone Derivative:Low-energy Excitation and Red Electrophosphorescent Devices

A novel iridium-complex,（BPPBI） 2 Ir（2-TFDBC）[BPPBI=2-（biphenyl-4-yl）-1-phenyl-1H-benzo[d]imidazole,2-TFDBC=1-（9-ethyl-9H-carbazol-2-yl）-4,4,4-trifluorobutane-1,3-dione],was synthesized,and its structure and component were confirmed by 1 H NMR and element analysis,respectively.UV-Vis absorption and photoluminescent（PL） spectra of（BPPBI） 2 Ir（2-TFDBC） in dichloromethane were investigated.The Ir-complex exhibited a long wavelength excitation of 470 nm,i.e.,low-energy excitation.So,it is a promising candidate for phosphorescent probe and PL material.（BPPBI） 2 Ir（2-TFDBC）-based electroluminescent devices,ITO/MoO 3（10 nm）/NPB（80 nm）/CBP：x（BPPBI） 2 Ir（2-TFDBC）（20 nm）/TPBi（45 nm）/LiF/Al,were fabricated,where x（%） was of 4% or 8% doping concentration（mass fraction）;ITO=indium tin oxides;NBP=N,N＇-bis-（1-naphthalenyl）-N,N＇-bis-phenyl-（1,1＇-biphenyl）4,4＇-diamine,CBP=4,4＇-bis（N-carbazolyl）-1,1＇-biphenyl,TPBi=1,3,5-tris（1-phenyl-1H-benzimidazol-2-yl）benzene.The devices showed a red emission of 620 nm.The maximum current efficiency and brightness were 1.7 cd/A and 4063 cd/m 2 for a device of 8%（mass fraction） doping level,respectively.The moderate luminous efficiency was due to the inadequate energy transfer from the host material to the guest material.

Synthesis and Luminescent Properties of Cationic Ir(Ⅲ) Complexes of 2-Phenylquinoline Derivatives

Two cationic iridium（Ⅲ） complexes, [（pqcm）2Ir（pybz）]（PF6） （Ir1） and [（pqcm）2Ir（apybz）]（PF6） （Ir2） （pqcmH = 2-phenyl-quinoline-4-carboxylic acid methyl ester, pybz = 2-pyridyl-benzimidazole, apybz = 1-allyl-2-pyridyl-benzimidazole）, were readily synthesized from the reaction of IrⅢ-μ-chloro-bridged dimer [Ir（pqcm）2（Cl）]2 and corresponding ancillary ligands, and characterized by NMR and mass spectroscopies. The structure of It2 was also confirmed by single-crystal X-ray diffraction. The photophysical properties of the two complexes were also investigated. Irl shows deep red emission peaked at around 652 nm with the phosphorescence quantum yield of ca. 0.29 and the emission lifetime of 233 ns, while Ir2 shows red emission peaked at around 615 nm with the phosphorescence quantum yield of ca. 0.13 and the emission lifetime of 430 ns. The active hydrogen on pybz ligand is believed to have a great influence on the photophysical properties of Ir1.

Bone analysis using an aggregation-induced emission-active iridium complex

Fluorescent analysis of bone provides valuable insights into bone structures.However,conventional dyes suffer from low specificity on bone tissue,small stokes shift,short fluorescent lifetime,and aggregation-caused quenching effect,which result in low efficacy and artifacts.In this work,we design an aggregation-induced emission(AIE)-active iridium(III)complex(Ir-BP2)as a highly selective,convenient,nondestructiveness,and dual-mode staining agent for bone analysis.Ir-BP2 containing phosphonate groups selectively binds to hydroxyapatites,the main component of bone matrix,and exhibits turn-on AIE phosphorescence with prolonged lifetime.Ir-BP2 exhibits promising biosafety and offers higher accuracy in staining calcium deposits than conventional Alizarin Red S staining assay when it is employed in real-time monitoring of osteogenesis differentiation process.A ready-to-use staining spray of Ir-BP2 is fabricated.By using fluorescent imaging and lifetime imaging,Ir-BP2 staining provides valuable insights into bone microstructure analysis,microdamage diagnosis,and bone growth state identification.Further,Ir-BP2 is successfully applied on a human spine vertebra for diagnosing bone invasiveness of eosinophilic granuloma,validating its clinical practice.This work presents a powerful tool in bone analysis and will lead to new approaches for the diagnosis and treatment of bone-related diseases.

A simple strategy to simultaneously improve the lifetime and activity of classical iridium complex for photocatalytic water-splitting

Herein,we design and synthesize a series of oligomers[Ir(ppy)2(dabpy)-ODPA]n(D1-n)by copolymerization of[Ir(ppy)2(dabpy)][PF6](D2)with 4,4′-Oxydiphthalic anhydride(ODPA),to resolve the problem of simultaneous improvement of sta-bility and activity of classical iridium complex for photocatalytic water-splitting.Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,solid-state nuclear magnetic resonance,and gel permeation chromatography results indicate that the degree of polymerization(n)of D1-n could be tuned by the syn-thesis method.The best photocatalytic performance is reached by D1-n with n at of 2 and/or 3(D1-2/3),which exhibits a photocatalytic lifetime up to 676 h and a photocatalytic hydrogen evolution of 162055.1 Compared with classicalμmol⋅g-1.iridium complex D2,the photocatalytic lifetime of D1-2/3 is about 38 times longer and the photocatalytic activity is 1.3 times higher.Further increase of n leads to a decrease in both photocatalytic lifetime and activity.According to the spectro-scopic characterizations,photoelectrochemical experiments,and density functional theory calculation,the significantly enhanced photocatalytic performance of D1-2/3 originates from the oligomeric structure.The oligomer chain of D1-2/3 with suit-able length acts as a large steric hindrance to reduce the undesired photoinduced decomposition and prolong its lifetime.The possible coupling of adjacent Ir com-plexes in D1-2/3 lowers the energy gap and increases the utilization of visible light,which overcomes the adverse effect of large steric hindrance andfinally improve the activity.This workfirst provides a simple strategy for constructing oligomeric Ir photosensitizers to simultaneously achieve long lifetime and high activity,it will lay the foundation for the design of highly efficient photosensitizers in the future.

Selective Hydrogenation of Avermectin Catalyzed by Iridium-Phosphine Complexes

A series of new iridium complexes, IrCl（COD）（TMOPP） （1） [COD=1,5-cyclooctadiene, TMOPP=tris（4- methoxyphenyl）phosphine], IrCl（COD）（TFMPP） （2） [TFMPP = tris（4-trifluoromethylphenyl）phosphine], IrCl（COD）（BDNA） （3） [BDNA= 1,8-bis（diphenylphosphinomethyl）naphthalene], IrCl（COD）（BISBI） （4） [BISBI= 2,2＇-bis（diphenylphosphinomethyl）biphenyl] and IrCl（COD）（BDPB） （5） [BDPB= 1,2-bis（diphenylphosphinomethyl）benzene], were synthesized and characterized by NMR spectra and elemental analyses. In order to obtain the relationships between complex structures and their catalytic properties, IrCl（COD）（DPPM） （6） [DPPM = bis（diphenylphosphino）methane], IrCl（COD）（DPPE） （7） [DPPE= 1,2-bis（diphenylphosphino）ethane], IrCl（COD）（DPPP） （8） [DPPP=1,3-bis（diphenylphosphino）propane] and IrCl（COD）（TPP） （9） [TPP=triphenylphosphine], were also synthesized according to the reported methods. The hydrogenation results showed that the low electronic density at the central metal was favorable to increase the catalytic activity for the hydrogenation of avermectin, but decrease the selectivity to ivermectin. The complex with a large chelating ring and a bulky chelating backbone would easily cause the cleavage of C-O bond in avermectin to give a byproduct avermectin aglycon.

Mitochondria-localized iridium(Ⅲ) complexes with anthraquinone groups as effective photosensitizers for photodynamic therapy under hypoxia

Photodynamic therapy(PDT)is a potential way for the tumor treatment.However,it notably suffers the limitation of hypoxia in solid tumors.Thus,it is significant to develop effective photosensitizers which can exhibit excellent therapeutic performance under both normoxia and hypoxia.Herein,we reported four ionic iridium(Ⅲ)complexes(Irl-Ir4)with anthraquinone groups which can regulate their excited state energy levels effectively.Among them,the energy gap of Ir1 was between 1.63 and 2.21 eV,which can match well with that of O2,and the HOMO energy of Ir1 is less than-5.51 eV.Compared with Ir2-Ir4,the luminescent quantum efficiency of Irl was the highest.Particularly,Ir1 can specifically target the mitochondria of the tumor cells.Meanwhile,Ir1 showed high singlet oxygen quantum yields(Ф△)in both solutions and living cells with low cytotoxicity.The results of PDT experiments revealed that Irl,as a photosensitizer,exhibited excellent therapeutic effect not only in normoxia but also in hypoxia condition.We believe that this work is meaningful for developing excellent PDT agents based on cyclometalated Ir(III)complexes via rational ligand modification.

New luminescent cyclometalated iridium(Ⅲ) complexes containing fluorinated phenylisoquinoline-based ligands: Synthesis, structures,photophysical properties and DFT calculations

Two new fluorinated phenylisoquinoline-based iridium（Ⅲ） complexes,[Ir（f2piq）2（bipy）][PF6]（3a） and[Ir（fmpiq）2（bipy）][PF6]（3b）（f2piq = l-（2,4-difluorophenyl）isoquinoline,fmpiq = 1-（4-fluoro-2-methylphenyl）isoquinoline,bipy = 2,2＇-bipyridine）,have been synthesized and fully characterized.Single crystal X-ray diffraction study has been undertaken on complexes 3a and 3b,which show that each adopts the distorted octahedral coordination geometry with the cis-C,C＇ and trans-N,N＇ configuration.The photoluminescence spectra of 3a and 3b exhibit yellow and orange emission maxima at 584 and 600 nm,respectively.The frontier molecular orbital diagrams and the lowest-energy electronic transitions of 3a-3b have been calculated with density functional theory（DFT） and time-dependent DFT（TD-DFT）.The absorption and emission spectra of complex 3b is red-shifted relative to those of complex 3a,as a consequence of the nature of the methyl group.

Recent progress in functionalized electrophosphorescent iridium(Ⅲ) complexes

Iridium（Ⅲ） complexes are one of the most important electrophosphorescent dyes with tunable emissions in the range of visible and near infrared lights,high photoluminescence yields and short lifetimes for high-efficiency organic light-emitting diodes（OLED） with 100% exciton harvesting.This review summarizes the recent development of electroluminescent Ir^（3＋） complexes functionalized with host-featured carrier-transporting groups,with emphasis on correlations between functionalization,optoelectronic properties and device performance.According to the introducing approaches,the complexes were sorted with conjugated and aliphatic linkages,as well as the types of functional groups.The modification effect on physical properties and the state-of-the-art device performances were discussed.

The development of an iridium(Ⅲ) complex functionalized G-quadruplex probe for the stability of G-quadruplex and lifetime image in cytoplasm

G-quadruplex(G4) is widely known as a non-classical secondary structure of nucleic acid. With the indepth study of G4, it is an urgent need for a phosphorescent probe with a high G4 binding ability to evaluate the level of G4 in the cytoplasm. Thus, this study designed and synthesized Ir-PDP where an Ir(Ⅲ)complex was used as a phosphorescent emitter. Meanwhile, two installed PDPs(pyridostatin derivatives)were used to improve the combination ability with G4 and reduced the cytotoxicity of the Ir(Ⅲ) complex.Compared with other nucleic acid secondary structures, Ir-PDP produced a higher phosphorescence lifetime after interacting with G4. Ir-PDP was distributed in the cytoplasm of living cells, and two-photon phosphorescence lifetime imaging can detect the binding events of the probe in the cytoplasm. The addition of G4 binder PDS significantly regulated cytoplasmic phosphorescence lifetime. The project explored a new sensing pathway to observe the binding manners of probes in the cytoplasm through the phosphorescence lifetime of probes.

pH-responsive aldehyde-bearing cyclometalated iridium(Ⅲ) complex for tracking intracellular pH fluctuations under external stimulation

Intracellular p H undertakes critical functions in various biological and pathological processes. It is important to monitor intracellular p H fluctuations for understanding physiological and pathological processes.Here, one aldehyde-bearing cyclometalated iridium(Ⅲ) complex([(4-pba)_(2)Ir(dcphen)]PF_(6), 4-pba = 4-(2-pyridyl) benzaldehyde, dcphen = 4,7-dichloro-1,10-phenanthroline, probe 1) was synthesized and used to track intracellular p H fluctuations. Probe 1 displayed p H-dependent luminescence property in p H range of 1.81–6.81 with an evaluated p Kavalue of 4.30 in BR buffer-DMSO(v:v = 99:1). An intramolecular hydrogen bonds assisted p H-responsive mechanism was proposed for the p H-responsive behavior of probe1. Probe 1 was successfully applied for imaging and tracking p H fluctuations in He La cells under external stimulation with fast response time, good photostability as well as low cytotoxicity and high cell permeability. This work demonstrates that aldehyde-bearing cyclometalated iridium(Ⅲ) complex can be used as alternative p H-responsive probe for real-time tracking intracellular p H fluctuations, which provides a strategy for the design of p H-responsive probe in versatile applications.

Metal-ligand cooperative iridium complex catalyzed C-alkylation of oxindole and 1,3-dimethylbarbituric acid using alcohols

A general and high-efficiency C-alkylation of oxindoles and barbituric acids has been developed by a Cp*Ir complex[Cp*Ir(2,20-bpyO)(OH)]Na with a bipyridine-based functional ligand.In particular,H_(2)O was selected as the solvent instead of the organic solvent in this catalytic system.Through mild reaction conditions gave a variety of corresponding alkylated heterocyclic compounds with good to excellent yields.More importantly,the gramscale C-alkylation reaction was successfully carried out with good yield using a common route with only a single purification by column chromatography.

Sensitizing photoactive metal-organic frameworks via chromophore for significantly boosting photosynthesis

Photosensitization related to energy/electron transfer process is of great importance to natural photosynthesis.Herein,we proposed a promising strategy to improve the sensitizing ability of the typical photoactive MOFs(UiO-Ir)by engineering its metal coordination center with NBI(1,8-naphthalenebenzimidizole)chromophore.The resulting MOFs(UiO-Ir-NBI)exhibited a strong sensitizing ability for significantly boosting photosynthesis.Impressively,the catalytic yield of 2-chloroethyl ethyl sulfoxide with UiO-Ir-NBI can reach 99%,over 6 times higher than that with UiO-Ir(16.4%).Moreover,UiO-Ir-NBI exhibited an excellent catalytic stability and a broad substrate tolerance,highlighting its great application prospect.Systematic investigations revealed that the strong visible light absorption,long excited state lifetime and efficient electron-hole separation of UiO-Ir-NBI greatly contributed to harvesting visible light and facilitating interface electron/energy transfer for efficient solar energy utilization.This work provides a new horizon to boost photosythesis of MOFs by engineering their metal sensitizing centers at a molecular level.

BODIPY@Ir(Ⅲ)Complexes Assembling Organic Nanoparticles for Enhanced Photodynamic Therapy

We present a new cyclometalated Ir（III） complexes IrBDP, which could self-assemble into organic nanoparticles （IrBDP NPs）. IrBDP NPs show enhanced photodynamic effect and can be engulfed by HeLa cells for cell imaging as well as photodynamic therapy （PDT） upon low energy irradiation.