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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. [ABSTRACT FROM AUTHOR]

Abstract 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.

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 stability and activity of classical iridium complex for photocatalytic water-splitting. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, solidstate nuclear magnetic resonance, and gel permeation chromatography results indicate that the degree of polymerization (n) of D1-n could be tuned by the synthesis 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 µmol·g-1. Compared with classical 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 spectroscopic 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 suitable length acts as a large steric hindrance to reduce the undesired photoinduced decomposition and prolong its lifetime. The possible coupling of adjacent Ir complexes in D1-2/3 lowers the energy gap and increases the utilization of visible light, which overcomes the adverse effect of large steric hindrance and finally improve the activity. This work first 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. [ABSTRACT FROM AUTHOR]

In this work, we obtained three new phosphorescent iridium complexes (Ir1–Ir3) of general stoichiometry [Ir(N^C)2(N^N)]Cl decorated with oligo(ethylene glycol) fragments to make them water-soluble and biocompatible, as well as to protect them from aggregation with biomolecules such as albumin. The major photophysical characteristics of these phosphorescent complexes are determined by the nature of two cyclometallating ligands (N^C) based on 2-pyridine-benzothiophene, since quantum chemical calculations revealed that the electronic transitions responsible for the excitation and emission are localized mainly at these fragments. However, the use of various diimine ligands (N^N) proved to affect the quantum yield of phosphorescence and allowed for changing the complexes' sensitivity to oxygen, due to the variations in the steric accessibility of the chromophore center for O2 molecules. It was also found that the N^N ligands made it possible to tune the biocompatibility of the resulting compounds. The wavelengths of the Ir1–Ir3 emission maxima fell in the range of 630–650 nm, the quantum yields reached 17% (Ir1) in a deaerated solution, and sensitivity to molecular oxygen, estimated as the ratio of emission lifetime in deaerated and aerated water solutions, displayed the highest value, 8.2, for Ir1. The obtained complexes featured low toxicity, good water solubility and the absence of a significant effect of biological environment components on the parameters of their emission. Of the studied compounds, Ir1 and Ir2 were chosen for in vitro and in vivo biological experiments to estimate oxygen concentration in cell lines and tumors. These sensors have demonstrated their effectiveness for mapping the distribution of oxygen and for monitoring hypoxia in the biological objects studied. [ABSTRACT FROM AUTHOR]

The design, synthesis, and investigation of new molecular oxygen probes for bioimaging, based on phosphorescent transition metal complexes are among the topical problems of modern chemistry and advanced bioimaging. Three new iridium [Ir(N^C)2(N^N)]+ complexes with cyclometallating 4-(pyridin-2-yl)-benzoic acid derivatives and different di-imine chelate ligands have been synthesized and characterized by mass spectrometry and NMR spectroscopy. The periphery of these complexes is decorated with three relatively small "double-tail" oligo(ethylene glycol) fragments. All these complexes exhibit phosphorescence; their photophysical properties have been thoroughly studied, and quantum chemical calculations of their photophysical properties were also performed. It turned out that the changes in the nature of the di-imine ligand greatly affected the character of the electronic transitions responsible for their emission. Two complexes in this series show the desired photophysical characteristics; they demonstrate appreciable quantum yield (14–15% in degassed aqueous solutions) and a strong response to the changes in oxygen concentration, ca. three-fold increase in emission intensity, and an excited state lifetime upon deaeration of the aqueous solution. The study of their photophysical properties in model biological systems (buffer solutions containing fetal bovine serum—FBS) and cytotoxicity assays (MTT) showed that these complexes satisfy the requirements for application in bioimaging experiments. It was found that these molecular probes are internalized into cultured cancer cells and localized mainly in mitochondria and lysosomes. Phosphorescent lifetime imaging (PLIM) experiments showed that under hypoxic conditions in cells, a 1.5-fold increase in the excitation state lifetime was observed compared to aerated cells, suggesting the applicability of these complexes for the analysis of hypoxia in biological objects. [ABSTRACT FROM AUTHOR]

A series of bis-metalated phosphorescent [(N^C)2Ir(bipyridine)]+ complexes with systematic variations in the structure and electronic characteristics of the N^C ligands were synthesized and characterized by using elemental analysis, mass spectrometry, NMR spectroscopy and X-ray crystallography. Investigation of the complexes' spectroscopic properties together with DFT and TD DFT calculations revealed that metal-to-ligand charge transfer (MLCT) and intraligand (LC) transition play key roles in the generation of emissive triplet states. According to the results of theoretical studies, the 3LC excited state is more accurate to consider as an intraligand charge transfer process (ILCT) between N- and C-coordinated moieties of the N^C chelate. This hypothesis is completely in line with the trends observed in the experimental absorption and emission spectra, which display systematic bathochromic shifts upon insertion of electron-withdrawing substituents into the N-coordinated fragment. An analogous shift is induced by expansion of the aromatic system of the C-coordinated fragment and insertion of polarizable sulfur atoms into the aromatic rings. These experimental and theoretical findings extend the knowledge of the nature of photophysical processes in complexes of this type and provide useful instruments for fine-tuning of their emissive characteristics. [ABSTRACT FROM AUTHOR]

New organometallic iridium compounds with phosphorus modified glucose ligands containing isopropylidene protection group or bearing uracil, thymine, and 5-fluorouracil (3,5,6-bicyclophosphite-1,2-O-isopropylidene-α-d-glucofuranoside, 3,5,6-bicyclophosphite-1-β-D-glucofuranosyluracil, 3,5,6-bicyclophosphite-1-β-D-glucofuranosylthymine, 3,5,6-bicyclophosphite-1-β-D-glucofuranosyl-5-flurouracil) were prepared. The structure of the new complexes was confirmed by the spectroscopic technique (1H, 31P{1H} NMR) and mass spectrometry, and purity by elemental analysis. The molecular structure of the complex with the isopropylidene protection group was established by the X-ray analysis. The antiproliferative activity of the new iridium compounds was evaluated against several cancer cell lines of human origin, and all compounds showed low toxicity independent of the pyrimidine base nature, attached to the sugar unit. [ABSTRACT FROM AUTHOR]

• Synthesis and characterization of half-sandwich imino pyridine iridium catalysts. • The structure of an iridium complex was confirmed by X-ray diffraction. • One-pot amidation reaction of aldehyde to amide was investigated. • Excellent conversion, with catalytic turnover number > 850. A series of stable mononuclear half-sandwich iridium(III) complexes of the general formula [(η5-C 5 Me 5)Ir(L)Cl](BPh 4) has been synthesized in dry methanol using different imino pyridine ligands (L 1 –L 6) and [(η5-C 5 Me 5) 2 Ir 2 (µ-Cl) 2 Cl 2 ] in a 2:1 molar ratio. All complexes were fully characterized by melting point, CHN analysis, FT-IR, UV–visible, 1H NMR, 13C NMR spectroscopy and mass spectrometry. The structure of complex 3 [(η5-C 5 Me 5)Ir(L 3)Cl](BPh 4) was determined by single crystal X-ray structure analysis, showing a chelating coordination mode of the imino pyridine L 3. One pot organic transformations of aldehyde to amide were carried out by complexes 1–6 in toluene at 110 °C in the presence of hydroxyl amine hydrochloride and sodium bicarbonate. The catalytic activity of complex 3 was found to be excellent, showing high conversion with catalytic turnover frequency up to 500. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel tetrahydroquinoxaline-dioxiridium complexes (Ir/Ln) are synthesized. • Ir/L8 exhibits high efficiency for additive-free formic acid dehydrogenation. • Structural engineering of Ir/Ln elucidates the structure-efficiency relationship. • DFT calculations provide insight on dehydrogenation mechanism. Formic acid (FA), as a promising hydrogen storage carrier, plays a key role in the implementation of a hydrogen economy with its efficient hydrogen evolution, especially for additive-free systems. To this end, we construct a series of tetrahydroquinoxaline-dioximino iridium complexes (Ir/Ln) that meet the above criteria. After optimization of the ligand structure, Ir/L8 (L8 = 6,7-dimethyl-2,3-dioxo-1,2,3,4-tetrahydroquinoxaline) exhibits an initial TOF of 80,000 h−1 at 60 °C (337,500 h−1 at 80 °C), outperforming the previous reported counterparts for additive-free systems. Besides, a possible dehydrogenation mechanism, i.e. the synergistic auxiliary effect of β-NH units, water and HCOOH molecules favored Ir/L8-driven FA decomposition, is adequately elucidated by experimental and theoretical studies, filling the gap in the existing mechanism system. In brief, the ingenious design and systematic research lay the foundation for the efficient release of hydrogen from FA, promising the overall implementation of "green hydrogen economy". [ABSTRACT FROM AUTHOR]

In this work, we obtained three new phosphorescent iridium complexes (Ir1–Ir3) of general stoichiometry [Ir(N^C)2(N^N)]Cl decorated with oligo(ethylene glycol) fragments to make them water-soluble and biocompatible, as well as to protect them from aggregation with biomolecules such as albumin. The major photophysical characteristics of these phosphorescent complexes are determined by the nature of two cyclometallating ligands (N^C) based on 2-pyridine-benzothiophene, since quantum chemical calculations revealed that the electronic transitions responsible for the excitation and emission are localized mainly at these fragments. However, the use of various diimine ligands (N^N) proved to affect the quantum yield of phosphorescence and allowed for changing the complexes’ sensitivity to oxygen, due to the variations in the steric accessibility of the chromophore center for O2 molecules. It was also found that the N^N ligands made it possible to tune the biocompatibility of the resulting compounds. The wavelengths of the Ir1–Ir3 emission maxima fell in the range of 630–650 nm, the quantum yields reached 17% (Ir1) in a deaerated solution, and sensitivity to molecular oxygen, estimated as the ratio of emission lifetime in deaerated and aerated water solutions, displayed the highest value, 8.2, for Ir1. The obtained complexes featured low toxicity, good water solubility and the absence of a significant effect of biological environment components on the parameters of their emission. Of the studied compounds, Ir1 and Ir2 were chosen for in vitro and in vivo biological experiments to estimate oxygen concentration in cell lines and tumors. These sensors have demonstrated their effectiveness for mapping the distribution of oxygen and for monitoring hypoxia in the biological objects studied.

The design, synthesis, and investigation of new molecular oxygen probes for bioimaging, based on phosphorescent transition metal complexes are among the topical problems of modern chemistry and advanced bioimaging. Three new iridium [Ir(N^C)2(N^N)]+ complexes with cyclometallating 4-(pyridin-2-yl)-benzoic acid derivatives and different di-imine chelate ligands have been synthesized and characterized by mass spectrometry and NMR spectroscopy. The periphery of these complexes is decorated with three relatively small “double-tail” oligo(ethylene glycol) fragments. All these complexes exhibit phosphorescence; their photophysical properties have been thoroughly studied, and quantum chemical calculations of their photophysical properties were also performed. It turned out that the changes in the nature of the di-imine ligand greatly affected the character of the electronic transitions responsible for their emission. Two complexes in this series show the desired photophysical characteristics; they demonstrate appreciable quantum yield (14–15% in degassed aqueous solutions) and a strong response to the changes in oxygen concentration, ca. three-fold increase in emission intensity, and an excited state lifetime upon deaeration of the aqueous solution. The study of their photophysical properties in model biological systems (buffer solutions containing fetal bovine serum—FBS) and cytotoxicity assays (MTT) showed that these complexes satisfy the requirements for application in bioimaging experiments. It was found that these molecular probes are internalized into cultured cancer cells and localized mainly in mitochondria and lysosomes. Phosphorescent lifetime imaging (PLIM) experiments showed that under hypoxic conditions in cells, a 1.5-fold increase in the excitation state lifetime was observed compared to aerated cells, suggesting the applicability of these complexes for the analysis of hypoxia in biological objects.

New organometallic iridium compounds with phosphorus modified glucose ligands containing isopropylidene protection group or bearing uracil, thymine, and 5-fluorouracil (3,5,6-bicyclophosphite-1,2-O-isopropylidene-α-d-glucofuranoside, 3,5,6-bicyclophosphite-1-β-D-glucofuranosyluracil, 3,5,6-bicyclophosphite-1-β-D-glucofuranosylthymine, 3,5,6-bicyclophosphite-1-β-D-glucofuranosyl-5-flurouracil) were prepared. The structure of the new complexes was confirmed by the spectroscopic technique (1H, 31P{1H} NMR) and mass spectrometry, and purity by elemental analysis. The molecular structure of the complex with the isopropylidene protection group was established by the X-ray analysis. The antiproliferative activity of the new iridium compounds was evaluated against several cancer cell lines of human origin, and all compounds showed low toxicity independent of the pyrimidine base nature, attached to the sugar unit.

A series of bis-metalated phosphorescent [(N^C)2Ir(bipyridine)]+ complexes with systematic variations in the structure and electronic characteristics of the N^C ligands were synthesized and characterized by using elemental analysis, mass spectrometry, NMR spectroscopy and X-ray crystallography. Investigation of the complexes’ spectroscopic properties together with DFT and TD DFT calculations revealed that metal-to-ligand charge transfer (MLCT) and intraligand (LC) transition play key roles in the generation of emissive triplet states. According to the results of theoretical studies, the 3LC excited state is more accurate to consider as an intraligand charge transfer process (ILCT) between N- and C-coordinated moieties of the N^C chelate. This hypothesis is completely in line with the trends observed in the experimental absorption and emission spectra, which display systematic bathochromic shifts upon insertion of electron-withdrawing substituents into the N-coordinated fragment. An analogous shift is induced by expansion of the aromatic system of the C-coordinated fragment and insertion of polarizable sulfur atoms into the aromatic rings. These experimental and theoretical findings extend the knowledge of the nature of photophysical processes in complexes of this type and provide useful instruments for fine-tuning of their emissive characteristics.

A series of [Ir(N^C)2(N^N)]+ NIR-emitting orthometalated complexes (1–7) has been prepared and structurally characterized using elemental analysis, mass-spectrometry, and NMR spectroscopy. The complexes display intense phosphorescence with vibrationally structured emission bands exhibiting the maxima in the range 713–722 nm. The DFT and TD DFT calculations showed that the photophysical characteristics of these complexes are largely determined by the properties of the metalating N^C ligands, with their major contribution into formation of the lowest S1 and T1 excited states responsible for low energy absorption and emission, respectively. Emission lifetimes of 1–7 in degassed methanol solution vary from 1.76 to 5.39 µs and show strong quenching with molecular oxygen to provide an order of magnitude lifetime reduction in aerated solution. The photophysics of two complexes (1 and 7) were studied in model physiological media containing fetal bovine serum (FBS) and Dulbecco's Modified Eagle Medium (DMEM) to give linear Stern-Volmer calibrations with substantially lower oxygen-quenching constants compared to those obtained in methanol solution. These observations were interpreted in terms of the sensors' interaction with albumin, which is an abundant component of FBS and cell media. The studied complexes displayed acceptable cytotoxicity and preferential localization, either in mitochondria (1) or in lysosomes (7) of the CHO-K1 cell line. The results of the phosphorescence lifetime imaging (PLIM) experiments demonstrated considerable variations of the sensors' lifetimes under normoxia and hypoxia conditions and indicated their applicability for semi-quantitative measurements of oxygen concentration in living cells. The complexes' emission in the NIR domain and the excitation spectrum, extending down to ca. 600 nm, also showed that they are promising for use in in vivo studies. [ABSTRACT FROM AUTHOR]

Six novel Ir(CˆN)2 (LˆX)-type heteroleptic iridium complexes with deep-red and nearinfrared region (NIR)-emitting coverage were constructed through the cross matching of various cyclometalating (CˆN) and ancillary (LX) ligands. Here, three novel CˆN ligands were designed by introducing the electron-withdrawing group CF3 on the ortho (o-), meta (m-), and para (p-) positions of the phenyl ring in the 1-phenylisoquinoline (piq) group, which were combined with two electron-rich LX ligands (dipba and dipg), respectively, leading to subsequent iridium complexes with gradually changing emission colors from deep red (≈660 nm) to NIR (≈700 nm). Moreover, a series of phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated by employing these phosphors as dopant emitters with two doping concentrations, 5% and 10%, respectively. They exhibited efficient electroluminescence (EL) with significantly high EQE values: >15.0% for deep red light0 (λmax = 664 nm) and >4.0% for NIR cases (λmax = 704 nm) at a high luminance level of 100 cd m−2. This work not only provides a promising approach for finely tuning the emission color of red phosphors via the easily accessible molecular design strategy, but also enables the establishment of an effective method for enriching phosphorescent-emitting molecules for practical applications, especially in the deep-red and near-infrared region (NIR). [ABSTRACT FROM AUTHOR]

The reactions of [Ir(H)2(PPh3)2(tptz)]PF6 (1) (tptz = 2,4,6-tris(2-pyridyl)-s-triazine) with {Cu(I), Ag(I)} salts under Ar afforded heterometallic trinuclear {Cu(I), Ag(I)}-Ir(III)-tptz hydride complexes [CuIr2(H)4(PPh3)4(tptz)2](PF6)3·2Me2CO (2), [AgIr2(H)4(PPh3)4(tptz)2](PF6)3·4Me2CO·H2O (3a) and [AgIr2(H)4(PPh3)4(tptz)2](CF3SO3)2(PF6)·4Me2CO (3b). We have demonstrated that Ir(III)-tptz complex 1 can serve as a potentially bridgeable Ir metalloligand. X-ray analyses showed that meaningful intramolecular π-π stacking interactions exist in {Cu(I), Ag(I)}-Ir(III)-tptz hydride complexes 2, 3a and 3b. These intramolecular π-π stacking interactions could be contributed to the structural stabilization of the distorted boat-shaped structure. 1H and 31P NMR analyses showed that the structures of {Cu(I), Ag(I)}-Ir(III)-tptz hydride complexes 2 and 3a are kept in solution. The significant 1H NMR upfield shifts could be induced by the ring current effect from the phenyl groups of adjacent PPh3 ligands.

Abstract Two novel N‐embedded polycyclic units functionalized phosphorescent iridium(III) complexes (Ir‐1 and Ir‐2) with substituents in different positions have been prepared. Complex Ir‐1 bearing the substituent at the 3‐position shows a distinct blue shift single‐peak emission (524 nm) with a higher luminescence efficiency (ΦPL=42 %) and shorter emission lifetime (τ=282 ns) by comparison with 4‐position substitution based complex Ir‐2 (ΦPL=23 %, τ=562 ns), which exhibits a dual‐peak emission (564 nm and 602 nm), and phosphorescence color can be tuned from green to yellow. In addition, DFT calculations demonstrate that unusual ligand‐to‐metal charge transfer (3LMCT) excited state property can be found in Ir‐2, which is in contrast to metal‐to‐ligand charge transfer (3MLCT) excited state character in Ir‐1. This result can be attribute to strong electron‐donating character and 4‐position substitution effect of the unit.

A series of [Ir(N^C)2(N^N)]+ NIR-emitting orthometalated complexes (1–7) has been prepared and structurally characterized using elemental analysis, mass-spectrometry, and NMR spectroscopy. The complexes display intense phosphorescence with vibrationally structured emission bands exhibiting the maxima in the range 713–722 nm. The DFT and TD DFT calculations showed that the photophysical characteristics of these complexes are largely determined by the properties of the metalating N^C ligands, with their major contribution into formation of the lowest S1 and T1 excited states responsible for low energy absorption and emission, respectively. Emission lifetimes of 1–7 in degassed methanol solution vary from 1.76 to 5.39 µs and show strong quenching with molecular oxygen to provide an order of magnitude lifetime reduction in aerated solution. The photophysics of two complexes (1 and 7) were studied in model physiological media containing fetal bovine serum (FBS) and Dulbecco’s Modified Eagle Medium (DMEM) to give linear Stern-Volmer calibrations with substantially lower oxygen-quenching constants compared to those obtained in methanol solution. These observations were interpreted in terms of the sensors’ interaction with albumin, which is an abundant component of FBS and cell media. The studied complexes displayed acceptable cytotoxicity and preferential localization, either in mitochondria (1) or in lysosomes (7) of the CHO-K1 cell line. The results of the phosphorescence lifetime imaging (PLIM) experiments demonstrated considerable variations of the sensors’ lifetimes under normoxia and hypoxia conditions and indicated their applicability for semi-quantitative measurements of oxygen concentration in living cells. The complexes’ emission in the NIR domain and the excitation spectrum, extending down to ca. 600 nm, also showed that they are promising for use in in vivo studies.

Abstract A series of iridium and rhodium complexes [M(COD)(PhPNHP)]Cl {M = Ir (1), Rh (2)}, [MH 2 Cl(PhPNHP)] {M = Ir (3), Rh (4)} and [IrH 3 (PhPNHP)] (6) supported by pincer ligand H N(CH 2 CH 2 PPh 2) 2 {PhPNHP} have been synthesized and characterized. All complexes were isolated in good yields. The iridium trihydride complex [IrH 3 (PhPNHP)] (6) was found to be an active catalyst for the hydrogenation of CO 2 in 1 M aqueous KOH solution. It also acts as a catalyst for the base-free hydrogenation of carbonyl and imine substrates in MeOH. Under similar hydrogenation conditions, 2-cyclohexen-1-one undergoes solvent assisted tandem Michael addition-reduction mediated by bifunctional Lewis-acid-catalyst [IrH 3 (PhPNHP)] in ROH (R = Me, Et) at room temperature. The complexes 1, 3, 4, and 6 were characterized by X-ray crystallography. Extensive hydrogen bonding interactions N H⋯H Ir (2.15 Å), N H⋯Cl (2.370 Å) were noted in the crystal structures of these complexes. Graphical abstract Image 1 Highlights • [M(COD)(PhPNHP)]Cl {M = Ir (1), Rh (2)}, [MH 2 Cl(PhPNHP)] {M = Ir (3), Rh (4)} and [IrH3(PhPNHP)] (6) complexes bearng pincer ligand H=N(CH 2 CH 2 PPh 2) 2 {PhPNHP} have been synthesized and characterized. • Extensive hydrogen bonding interactions N-H⋯H=Ir (2.15 Å), N=H⋯Cl (2.370 Å) were noted in their crystal structures. • Iridium trihydride complex [IrH 3 (PhPNHP)] (6) is an active catalyst for hydrogenation of CO 2 in 1 M aqueous KOH solution. • Base free hydrogenation of carbonyl and imine substrates in MeOH was also achieved using [IrH 3 (PhPNHP)] (6) as a catalyst. [ABSTRACT FROM AUTHOR]

Two novel N‐embedded polycyclic units functionalized phosphorescent iridium(III) complexes (Ir‐1 and Ir‐2) with substituents in different positions have been prepared. Complex Ir‐1 bearing the substituent at the 3‐position shows a distinct blue shift single‐peak emission (524 nm) with a higher luminescence efficiency (ΦPL=42 %) and shorter emission lifetime (τ=282 ns) by comparison with 4‐position substitution based complex Ir‐2 (ΦPL=23 %, τ=562 ns), which exhibits a dual‐peak emission (564 nm and 602 nm), and phosphorescence color can be tuned from green to yellow. In addition, DFT calculations demonstrate that unusual ligand‐to‐metal charge transfer (3LMCT) excited state property can be found in Ir‐2, which is in contrast to metal‐to‐ligand charge transfer (3MLCT) excited state character in Ir‐1. This result can be attribute to strong electron‐donating character and 4‐position substitution effect of the unit. Ir radiation! Photophysical and excited properties of phosphorescent Iridium(III) complexes can be effectively tuned via functionalization with N‐embedded polycyclic units located in different positions of the complex. [ABSTRACT FROM AUTHOR]

Abstract Two orange phosphorescent iridium complexes decorated by dibenzo-24-crown-8 unit as the dopants were used into polymer light-emitting diodes (PLEDs) with a configuration of ITO/PEDOT:PSS/emission layer (EML)/CsF/Al. Monochromic orange-emitting PLEDs using complex 2 as dopant and poly(N-vinylcarbazole) (PVK) as host exhibit best device performance with a peak luminous efficiency (LE) of 8.94 cd/A at a current density of 1.3 mA/cm2 and a Commission Internationale de L'Eclairage (CIE) coordinate of (0.52, 0.41). More importantly, several white polymer light-emitting diodes (WPLEDs) were also fabricated with the skyblue–orange dual emitters system. The WPLEDs combination of the orange phosphor complex 2 with skyblue phosphor iridium(III)bis(2-(4,6-difluorophenyl)-pyridinato-N,C2′)picolinate (FIrpic) in a single-emissive-layer exhibit best electroluminescent performances with a maximal LE of 5.12 cd/A at a current density of 2.63 mA/cm2, a turn on voltage of 6.5 V and a CIE coordinates of (0.33, 0.39), which is very close to the ideal CIE coordinate of (0.33, 0.33) for pure white color. Graphical abstract Both yellow and white PLEDs are fabricated with a simple single-emission-layer configuration based on dibenzo-24-crown-8 unit decorated iridium complexes. The WPLED combination of complex 2 with FIrpic exhibits a CIE coordinates of (0.33, 0.39), which is very close to the pure white color. Image 1 Highlights • Iridium complexes decorated by dibenzo-24-crown-8 possess good thermal properties. • Both yellow and white PLEDs are fabricated with a single-emission-layer configuration. • The WPLEDs based on complex 2 show an LE max of 5.12 cd/A, a CIE of (0.33, 0.39). [ABSTRACT FROM AUTHOR]

[Display omitted] • Iridium complexes of 2,3-diaryl quinolines with electron rich and electron deficient substituents were synthesized and their electronic properties were studied. • The photoluminescence (PL) spectra of the Ir4 complex exhibited a bright yellow phosphorescent emission at 589 nm. • The complex Ir3 and Ir1 showed intensive red phosphorescence near 603 and 611 nm, respectively due to metal-to-ligand and ligand-to-ligand (MLCT/LLCT) charge transfer characteristics. • The PL spectra of Ir2 blue-shifted to 489 nm, which is attributed to a ligand-centered (LC) transition. • The DFT approach was employed to optimise the geometry of Ir (III) complexes and NBO analyses were also carried out to assess the molecule's overall stability. Phosphorescent transition–metal complexes have received considerable interest in the development of efficient organic light-emitting diodes (OLEDs). Iridium complexes derived from heterocyclic ligands have brought a paradigm shift in the optoelectronic materials. Quinoline-based molecular architectures offer excellent materials for such applications due to their exceptional electronic properties, extended π-conjugation and strong ligand–metal binding. Iridium complexes of 2,3-diaryl quinolines with electron rich and electron deficient substituents were synthesized and their electronic properties were studied. Iridium complexes Ir1 and Ir2 bearing the electron withdrawing (-CF 3) and electron donating (–OCH 3) groups, respectively at the para position of the 2-phenyl ring of 2,3-diarylquinoline exhibited prominent absorption bands in the UV range. Further, the complex Ir3 with unsubstituted 2,3-diarylquinoline ligand and CF 3 containing Ir1 showed intensive red phosphorescence near 603 and 611 nm, respectively due to metal-to-ligand and ligand-to-ligand (MLCT/LLCT) charge transfer characteristics. The photoluminescence (PL) spectra of the Ir4 complex derived from 2-phenylquinoline ligand exhibited a bright yellow phosphorescent emission at 589 nm. An additional C3 aryl group on the quinoline ring resulted in a red shift in the emission wavelength of Ir1 and Ir3 complexes compared to Ir4. The PL spectra of Ir2 on the other hand was weak, and blue-shifted to 489 nm, which can be attributed to a ligand-centered (LC) transition. The complexes showed photoluminescence quantum yield (PLQY) in the range of 0.004 to 0.17 and fluorescence lifetime ranged from 1.5 ns to 399 ns, implying the significant effect of the ligand structure on the properties of the complexes. Photophysical investigation of the complexed affirms these complexes to be potent materials for OLEDs fabrication. Cyclic voltammetry was used to investigate the electrochemical characteristics of Ir1-Ir4 complexes in acetonitrile. All of the complexes Ir1-Ir4 exhibited irreversible oxidation waves at 0.44 V, 0.23 V, 0.25 V, and 0.24 V respectively. Ir1-Ir4 complexes showed a reduction potential at −0.98 V, −0.96 V, −1.02 V and −0.97 V respectively. The DFT calculations were used to explore HOMO-LUMO energies, and NBO characteristics by B3LYP level of theory using ECP type double zeta (DZ) quality basis set LanL2DZ for metal and 6-311G(d) basis sets for non-metal atoms. The theoretical calculations were in significant agreement with the experimental studies of these complexes. [ABSTRACT FROM AUTHOR]

Starting from the chiral 5,6,7,8-tetrahydroquinolin-8-ol core, a series of amino-phosphorus-based ligands was realized. The so-obtained amino-phosphine ligand (L1), amino-phosphinite (L2) and amino-phosphite (L3) were evaluated in iridium complexes together with the heterobiaryl diphosphines tetraMe-BITIOP (L4), Diophep (L5) and L6 and L7 ligands, characterized by mixed chirality. Their catalytic performance in the asymmetric hydrogenation (AH) of the model substrate 6,7-dimethoxy-1-phenyl-3,4-dihydroisoquinoline 1a led us to identify Ir-L4 and Ir-L5 catalysts as the most effective. The application of these catalytic systems to a library of differently substituted 1-aryl-3,4-dihydroisoquinolines afforded the corresponding products with variable enantioselective levels. The 4-nitrophenyl derivative 3b was obtained in a complete conversion and with an excellent 94% e.e. using Ir-L4, and a good 76% e.e. was achieved in the reduction of 2-nitrophenyl derivative 6a using Ir-L5.

Two novel tricyclometalated heteroleptic iridium complexes, namely Ir(dfbpy) 2 (pt) and Ir(dfbpy) 2 (dfppy), were designed and synthesized for application as blue phosphors in optoelectronic devices. 2′,6′-difluoro-2,3′-bipyridine (dfbpy) was used as the cyclometalating ligand. In comparison with the parent homoleptic Ir(dfbpy) 3 , the newly developed 3-(1-benzyl-1 H -1,2,3-triazol-4-yl)pyridine (pt) with higher triplet energy than dfbpy or 2-(2,4-difluorophenyl)pyridine (dfppy) was used as the ancillary ligands to tune the electronic properties of these heteroleptic complexes. Both complexes emit strong blue phosphorescence with high quantum yields. The incorporation of high-energy ancillary ligand pt in Ir(dfbpy) 2 (pt) makes the highest-energy sub-band intensity in the phosphorescence spectrum increase relative to those of the parent Ir(dfbpy) 3 , and leads to narrower phosphorescence spectrum than the analogue Ir(dfbpy) 2 (dfppy) as well, which may provide a practical method to adjust the phosphorescence spectra and color purity of the complexes. [ABSTRACT FROM AUTHOR]

The electronic structures and spectroscopic properties of two complexes [M(pic)] (M = Ir, Rh) containing picolinate as bidentate ligands have been calculated by means density functional theory (DFT) and time-dependent DFT/TD-DFT using three hybrid functionals B3LYP, PBE0 and mPW1PW91. The PBE0 and mPW1PW91 functionals, which have the same HF exchange fraction (25%), give similar results and do not differ drastically from B3LYP results. Calculated geometric parameters of the complexes are in good agreement with the available experimental data. The UV absorptions observed in acetonitrile were assigned on the basis of singlet state transitions. The most intense band observed in the UV-C region corresponds to ligand-to-ligand charge transfer states (LLCT) in both complexes. The theoretical spectrum of the rhodium complex is characterized by a large degree of mixing between metal-to-ligand-charge-transfer (MLCT), LLCT and metal centered (MC) states in the UV-A region. The presence of low-lying excited states with MC character affects the absorption spectrum under spin-orbit coupling (SOC) effects and play important roles in the photochemical properties. [ABSTRACT FROM AUTHOR]

We present here synthesis and crystal structure of a neutral IrIII complex, [Ir(C19H13N2)2(C15H11O2)]·2CH2Cl2 or [Ir(C^N)2O^O]·2CH2Cl2, where C^N is 1,2-diphenyl-1H-benzimidazole and O^O is 2-benzoyl-1-phenylethenolate. The coordination sphere of the IrIII atom, located on a twofold rotation axis, is that of a slighlty distorted C2N2O2 octahedron, with the N atoms in a trans configuration. In the crystal, complex molecules assemble through weak C—H...π interactions in the range 2.699 (3)–2.892 (3) Å. The solvent CH2Cl2 molecules reside in channels aligned along the a axis and are connected to the complex molecules by C—H...O interactions.

An ultra-thin hybrid film of amphiphilic iridium(III) complexes and synthetic saponite was manipulated by means of the modified Langmuir-Blodgett method. In the film deposited onto a quartz substrate, the external mixed molecular layer of amphiphilic iridium(III) complexes was reinforced by the inner layer of exfoliated synthetic saponite. As components of the molecular layer, two iridium(III) complexes were used: [Ir(dfppy)2(dc9bpy)]+ (dfppyH = 2-(40,60-difluorophenyl) pyridine; dc9bpy = 4,40-dinonyl-2,20-bipyridine) (denoted as DFPPY) and [Ir(piq)2(dc9bpy)]+ (piqH = 1-phenyisoquinoline)) denoted as PIQ). The emission spectra from the films changed from blue to red maxima with the decrease of a ratio of DFPPY/PIQ due to the energy transfer from excited DFPPY to PIQ. The intensity of red decreased with the increase of oxygen pressure through the quenching of excited iridium(III) complexes, promising a possibility as an oxygen-sensing film. [ABSTRACT FROM AUTHOR]

A sensitive electrochemiluminescent (ECL) sandwich immunosensor was proposed herein based on the tris (2-phenylpyridine) iridium [Ir(ppy) 3 ] doped silica nanoparticles (SiO 2 @Ir) with improved ECL emission as signal probes and glucose oxidase (GOD)-based in situ enzymatic reaction to generate H 2 O 2 for efficiently quenching the ECL emission of SiO 2 @Ir. Typically, the SiO 2 @Ir not only increased the loading amount of Ir(ppy) 3 as ECL indicators with high ECL emission, but also improved their water-solubility, which efficiently enhanced the ECL emission. Furthermore, by the efficient quench effect of H 2 O 2 from in situ glucose oxidase (GOD)-based enzymatic reaction on the ECL emission of SiO 2 @Ir, a signal-off ECL immunsensor could be established for sensitive assay. With N-terminal of the prohormone brain natriuretic peptide (BNPT) as a model, the proposed ECL assay performed high sensitivity and low detection limit. Importantly, the proposed sensitive ECL strategy was not only suitable for the detection of BNPT for acute myocardial infarction, but also revealed a new avenue for early diagnosis of various diseases via proteins, nucleotide sequence, microRNA and cells. [ABSTRACT FROM AUTHOR]

The results of a systematic investigation on the photocatalytic water oxidation activity of eight Ir complexes are reported. In particular, [Cp*IrL n ]X m [ 1 , L n = (H 2 O) 3 , X − m = (NO 3 − ) 2 ; 2 , L n = N -dimethylimidazolin-2-ylidene and (Cl − ) 2 ; 4 , L n = 1,1′-dimethyl-3,3′-ethylene-diimidazol-2,2′- diylidene and Cl − X − = PF 6 − ; 5 , L n = 2-phenylpyridine (ppy) and NO 3 − ; 6 , L n = 2-benzoylpyridine (bzpy) and NO 3 − ; 8 , L n = 2,2′-bipyridine (bpy) and Cl − ], [Ir(HEDTA)Cl]Na ( 3 ) and [Ir(ppy) 2 (OH 2 ) 2 ]OTf ( 7 ), whose water oxidation activity driven by chemical oxidants was already proved, were tested as mediators (10 μM–100 μM) in photocatalytic experiments exploiting [Ru(bpy) 3 ]Cl 2 (1 mM) as photosensitizer and Na 2 S 2 O 8 (2.5 mM–30 mM) as electron acceptor, at pH 5.2 and pH 8 by Na 2 SiF 6 /NaHCO 3 and Na 2 B 4 O 7 buffers, respectively. All complexes showed to be competent catalysts for the photolytic water oxidation. Best performances were obtained with 2 at pH 5.2, where TOF > 2.5 min −1 , TON > 80 and quantum yield > 0.1. H/D kinetic isotopic effect was evaluated for 1 , 2 and 8 and related to their tendency to undergo oxidative transformation as deduced by 1 H NMR studies, using CH 3 COOH as molecular probe. [ABSTRACT FROM AUTHOR]

A series of half-sandwich rhodium and iridium complexes containing carboxylate ligands were synthesized and characterized. Reactions between [Cp ∗ MCl 2 ] 2 (M = Ir or Rh) and 1,3,6-bis(2-pyridyl)-1,2,4,5-tetrazine ( L1 ) gave binuclear complexes 1 and 2 under different conditions. The half-sandwich iridium and rhodium metallamacrocycles complexes 3 – 5 were constructed in a stepwise manner by the addition of carboxylate ligands (sodium acetate or the conjugate bases of pyrazine-2,3-dicarboxylic acid or 3-(2-pyridyl)acrylic acid) to the solution of the binuclear precursors prepared from the reactions of [Cp ∗ MCl 2 ] 2 (M = Rh or Ir) with linear N,N′-donor ligands (4,4′-bipyridine or trans -1,2-bis(4-pyridyl)ethylene), respectively. The structures of bi nuclear complexes and tetranuclear macrocycles were confirmed by elemental analysis, IR, 1 H NMR spectroscopy and single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Nowadays, the design and development of novel phosphorescent iridium(III) complexes for various optoelectronic applications is a well-recognized area of research. The fascinating photophysical properties of iridium(III) compounds are strongly influenced by the spin-orbit coupling exerted by the iridium(III) core, usually resulting in intense emissions with short excited-state lifetimes, which can be precisely controlled with the aid of molecular engineering of the chelating ligand. This review focuses on the recent developments and state of the art knowledge on phosphorescent iridium(III) compounds, especially on heteroleptic complexes derived from 2,3′-bipyridine class of cyclometalating and ancillary ligands, highlighting the excited state phenomenon behind their emission behavior. [ABSTRACT FROM AUTHOR]

The photodegradation behavior of four well-established iridium emitters was investigated. Irradiation of the samples in different solvents and under atmospheric as well as inert conditions helped to identify several pathways that can contribute to the deterioration of these compounds. Degradation via singlet oxygen or the excited states of the emitters as well as the detrimental influence of halogenated solvents are discussed for the different investigated iridium complexes. Some of the resulting degradation products could be identified by using LC–MS or other analytical techniques. The results show how even small structural changes can have a huge influence on rate and mechanism of the photodegradation. The observations from this study may help to better understand degradation processes occurring during the handling of the materials, but also during device processing and operation.

Platelets play a major role in hemostatic events and are associated with various pathological events, such as arterial thrombosis and atherosclerosis. Iridium (Ir) compounds are potential alternatives to platinum compounds, since they exert promising anticancer effects without cellular toxicity. Our recent studies found that Ir compounds show potent antiplatelet properties. In this study, we evaluated the in vitro antiplatelet, in vivo antithrombotic and structure⁻activity relationship (SAR) of newly synthesized Ir complexes, Ir-1, Ir-2 and Ir-4, in agonists-induced human platelets. Among the tested compounds, Ir-1 was active in inhibiting platelet aggregation induced by collagen; however, Ir-2 and Ir-4 had no effects even at their maximum concentrations of 50 μM against collagen and 500 μM against U46619-induced aggregation. Similarly, Ir-1 was potently inhibiting of adenosine triphosphate (ATP) release, calcium mobilization ([Ca2+]i) and P-selectin expression induced by collagen-induced without cytotoxicity. Likewise, Ir-1 expressively suppressed collagen-induced Akt, PKC, p38MAPKs and JNK phosphorylation. Interestingly, Ir-2 and Ir-4 had no effect on platelet function analyzer (PFA-100) collagen-adenosine diphosphate (C-ADP) and collagen-epinephrine (C-EPI) induced closure times in mice, but Ir-1 caused a significant increase when using C-ADP stimulation. Other in vivo studies revealed that Ir-1 significantly prolonged the platelet plug formation, increased tail bleeding times and reduced the mortality of adenosine diphosphate (ADP)-induced acute pulmonary thromboembolism in mice. Ir-1 has no substitution on its phenyl group, a water molecule (like cisplatin) can replace its chloride ion and, hence, the rate of hydrolysis might be tuned by the substituent on the ligand system. These features might have played a role for the observed effects of Ir-1. These results indicate that Ir-1 may be a lead compound to design new antiplatelet drugs for the treatment of thromboembolic diseases.