Clean production of renewable fuels is a great challenge of our scientific community. Iridium complexes have demonstrated a superior catalytic activity in the water oxidation (WO) reaction, which is a crucial step in water splitting process. Herein we have used a defective zirconium MOF with UiO-66 structure as support of a highly active Ir complex based on EDTA with formula [Ir(HEDTA)Cl]Na. The defects are induced by the partial substitution of tereftalic acid with smaller formiate groups. Anchoring of the complex occurs through a post-synthetic exchange of formiate anions, coordinated at the zirconium clusters of the MOF, with the free carboxylate group of the [Ir(HEDTA)Cl]-complex. The modified material was tested as heterogenous catalyst for the WO reaction by using Cerium Ammonium Nitrate as sacrificial agent. Although TOF and TON values are comparable to those of other iridium heterogenized catalysts, the MOF exhibits iridium leaching not limited at the first catalytic run, as usually observed, suggesting a lack of stability of the hybrid system under strong oxidative conditions.

A facile iridium/graphene-catalyzed methodology providing an efficient synthetic route for C-N bond formation is reported. This catalyst can directly promote the formation of C-N bonds, without pre-activation steps, and without solvents, alkalis and other additives. This protocol provides a direct N -alkylation of amines using a variety of primary and secondary alcohols with good selectivity and excellent yields. Charmingly, the use of diols resulted in intermolecular cyclization of amines, and such products are privileged structures in biologically active compounds. Two examples illustrate the advantages of this catalyst in organic synthesis: the tandem catalysis to synthesize hydroxyine, and the intermolecular cyclyzation to synthesize cyclizine. Water is the only by-product, which makes this catalytic process sustainable and environmentally friendly.

Polymer electrolyte membrane water electrolyser suffers mainly from slow kinetics regarding oxygen evolution reaction (OER). Noble metal oxides, like IrO2, RuO2, are generally more active for OER than metal electrodes, exhibiting low anodic overpotentials and high catalytic activity. However, issues like electrocatalyst stability under continuous operation and cost minimization through reduction of the catalyst loading are of great importance for the research community. In the present study, unsupported IrO2 of various particle sizes (different calcination temperatures) were evaluated for the OER and as anode electrodes for PEM water electrolyzers [1]. The elec-trocatalysts were synthesized by the modified Adams method [2][3] and the effect of calcination temperature on the properties of IrO2 electrocatalysts is investigated. Physicochemical charac-terization was conducted using X-ray Diffraction, BET, High-Resolution TEM and XPS analyses. For the electrochemical performance of synthesized electrocatalysts in the OER, cyclic voltammetry and linear sweep voltammetry were conducted in a typical 3-cell electrode configuration, using glassy carbon as working electrode, where the synthesized electrocatalysts were casted on, in 0.5 M H2SO4 solution. The materials, as anode PEM water electrolysis electrodes, were further evaluated in a typical electrolytic cell using Nafion®115 membrane as electrolyte and Pt/C as cathode elec-trocatalyst. The IrO2 electrocatalyst calcined at 400°C shows high crystallinity with 1.24 nm particle size, high specific surface area (185 m2 g-1) and a high OER activity of 177 mA cm-2 at 1.8 V as anode electrocatalyst for PEM water electrolyzer.

Two novel neutral phosphorescent iridium(III) complexes (Ir1 and Ir2) were rationally designed and synthesized with high yields using 10,11,12,13-tetrahydrodibenzo[a,c]phenazine as the main ligand. The two complexes showed bright red phosphorescence (625 nm for Ir1, and 620 nm for Ir2, in CH2Cl2), high luminescence quantum efficiency (0.32 for Ir1, and 0.35 for Ir2), obvious solvatochromism and good thermostability. Then, they were used to fabricate high-efficiency red OLEDs via vacuum evaporation, the maximum CE, PE, and EQE of the red devices based on Ir1 and Ir2 are 13.47/15.22 cd/A, 10.35/12.26 lm/W, and 10.08/7.48%, respectively.

A series of chiral complexes of the form Ir(NHC)2(aa)(H)(X) (NHC = N-heterocyclic carbene, aa = chelated amino acid, X = halide) was synthesized by oxidative addition of -amino acids to iridium(I) bis-NHC compounds and screened for asymmetric transfer hydrogenation of ketones. Following optimization of the reaction conditions, NHC, and amino acid ligands, high enantioselectivity was achieved when employing the Ir(IMe)2(l-Pro)(H)(I) catalyst (IMe = 1,3-dimethylimidazol-2-ylidene), which asymmetrically reduces a range of acetophenone derivatives in up to 95% enantiomeric excess.

We investigated new anodic coloring materials that are used as ion storage layers in complementary energy storage electrochromic devices (ESECDs) to enhance their electrochromic storage performance. In this study, we fabricated counter electrodes (ion storage layers) using IrO2 doping NiO (Ir: NiO) film through cathodic arc plasma (CAP) with varying surface charge capacities. We investigated the influence of MoO3-doped WO3 (Mo: WO3) film by various Ar/O2 gas flow ratios (1/4, 1/5, and 1/6). The ESECDs used in the demonstration were 10×10 cm2 in size. They achieved optical transmittance modulation of Ir: NiO- ESECDs (glass/ITO/ Mo: WO3/gel-polymer electrolytes/ Ir: NiO /ITO/glass), ΔT=53.3% (from Tbleaching (66.6%) to Tcoloration (13.1%)). The ESECDs had a quick coloration time of 3.58 seconds, a rapid bleaching time of 1.24 seconds, and high cycling durability. It remained at 45% transmittance modulation even after 3000 cycles. New anodic materials can provide an alternative to traditional active materials for bi-functional electrochromic batteries.

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 allows 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 possible to tune the biocompatibility of the resulting compounds. The wavelengths of the Ir1-Ir3 emission maxima fall in the range of 630-650 nm, the quantum yields reach 17% (Ir1) in deaerated solution and sensitivity to molecular oxygen, estimated as ratio of emission lifetime in deaerated and aerated water solution, displays the highest value 8.2 for Ir1. The obtained complexes feature 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 have been chosen for in vitro and in vivo biological experiments aimed at estimation of oxygen concentration in cell lines and tumors. These sensors have demonstrated their effectiveness for mapping the distribution of oxygen and for monitoring hypoxia in biological objects studied.

Photodynamic therapy (PDT) has garnered significant attention in the fields of cancer treatment and drug-resistant bacteria eradication due to its non-invasive nature and spatiotemporal controllability. Iridium complexes have captivated researchers owing to their tunable structure, exceptional optical properties, and substantial Stokes displacement. However, most of these complexes suffer from aggregation-induced quenching, leading to diminished luminous efficiency. In contrast to conventional photosensitizers, photosensitizers exhibiting aggregation-induced luminescence (AIE) properties retain the ability to generate a large number of reactive oxygen species when aggregated. To overcome these limitations, we designed and synthesized a novel iridium complex named Ir-TPA in this study. It incorporates quinoline triphenylamine cyclomethylated ligands that confer AIE characteristics for Ir-TPA. We systematically investigated the photophysical properties, AIE behavior, spectral features, and reactive oxygen generation capacity of Ir-TPA. The results demonstrate that Ir-TPA exhibits excellent optical properties with pronounced AIE phenomenon and robust capability for producing singlet oxygen species. This work not only introduces a new class of metal iridium complex photosensitizer with AIE attributes but also holds promise for achieving remarkable photodynamic therapeutic effects in future cellular experiments and biological studies.

Proton exchange membrane water electrolyzers (PEMWEs) for water electrolysis have received tremendous attention due to their immediate response, high proton conductivity, low ohmic losses and gas crossover rate. However, design high activity, economical and long-term durable electrocatalysts in an acidic environment is still the bottleneck to realize the large-scale commercialization of PEMWEs. Iridium-based materials represent one of the most promising classes of oxygen evolution reaction (OER) catalysts due to their intrinsic stability in acid media over ruthenium-based counterparts. However, only a few innovative approaches have been developed to synthesizing iridium-based catalysts (IBCs) in the past decade, mainly due to achieving high activity may deteriorate the stability of IBCs. Accordingly, various engineering strategies of optimizing IBCs have been proposed to address this issue, including doping engineering, morphology engineering, crystal phase engineering and support engineering. Herein, a critical overview focusing on various synthesis and modulation strategies of IBCs is presented, based on an in-depth understanding of the relationship between electronic structures, charge redistribution and activity as well as stability of the electrocatalysts. In addition, the unprecedented achievements in PEMWEs are summarized. The reaction mechanisms and future perspectives are critically discussed to inspire more rational design of IBCs toward practical applications.

We have developed IrO_x/M-SnO₂ (M = Nb, Ta, and Sb) anode catalysts, IrO_x nanoparticles uniformly dispersed on M-SnO₂ supports with fused-aggregate structures, which make it possible to evolve oxygen efficiently, even with a reduced amount of noble metal (Ir) in proton exchange membrane water electrolysis. Polarization properties of IrO_x/M-SnO₂ catalysts for the oxygen evolution reaction (OER) were examined at 80 °C in both 0.1 M HClO₄ solution (half cell) and a single cell with a Nafion^® membrane (thickness = 50 μm). While all catalysts exhibited similar OER activities in the half cell, the cell potential (E_cell) of the single cell was found to decrease with the increasing apparent conductivities (σ_{app, catalyst}) of these catalysts: an E_cell of 1.61 V (voltage efficiency of 92%) at 1 A cm^-2 was achieved in a single cell by the use of an IrO_x/Sb-SnO₂ anode (highest σ_{app, catalyst}) with a low Ir-metal loading of 0.11 mg_Ir cm^-2 and Pt supported on graphitized carbon black (Pt/GCB) as the cathode, with 0.35 mg_Pt cm⁻². In addition to the reduction of the ohmic loss in the anode catalyst layer, the increased electronic conductivity contributed to decreasing the OER overpotential due to the effective utilization of the IrO_x nanocatalysts on the M-SnO₂ supports, which is an essential factor in improving the performance with low noble metal loadings.