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Shape-controlled metal-based nanomaterials provide a special platform to regulate the surface physicochemical properties for optimizing the electrocatalytic performance, due to their homogeneously arranged surface atomic structures. Accordingly, owing to the solely {100} facets-ended surfaces, highly uniform Pt nanocubes (NCs) are utilized in this study, to probe the effects of synergizing with Ir species (a very effective metal for various electrocatalysis) on the electrocatalytic performance for the oxygen reduction reaction (ORR). Electrochemical results present that carbon-supported Pt1Ir1 NCs with surface Ir–O species (Pt1Ir1–O NCs/C) have much enhanced electrocatalytic activity and electrochemical stability than both Pt NCs/C and commercial Pt/C. Physicochemical characterization and theoretical calculation analyses further elucidate the mechanism of the improved electrocatalytic performance: the strong electronic interaction between Pt and Ir, the lowered d-band center of the surface metal atoms, and especially the synergistic effect induced by the surface Ir–O species. This study not only develops a highly active and stable ORR electrocatalyst, but also demonstrates an effective and universal research paradigm to explore the surface engineering effects on the electrocatalytic performance, which can be further applied in other crystalline facets for other (electro)catalytic reactions. © 2023

Readily available N-carbamoyl indolines can be converted into highly valuable 2-alkenyl and 2-alkyl indoles in a one-pot reaction, through an autotandem catalytic cascade promoted by an iridium complex. The process entails a dehydrogenation reaction initiated by an iridium-promoted C(sp3)-H activation, the addition of the resulting indole to an alkyne -or alkene-partner, and a spontaneous loss of the carbamoyl directing group. Interestingly, the resulting C2-alkenyl indoles can participate in a variety of metal-catalyzed annulations initiated by C-H activation, including formal [4 + 1] and [4 + 2] cycloadditions, as well as cross-dehydrogenative cyclizations, thus enabling a divergent access to a collection of functionally rich nitrogen-containing heterocycles.

Readily available N-carbamoyl indolines can be converted into highly valuable 2-alkenyl and 2-alkyl indoles in a one-pot reaction, through an autotandem catalytic cascade promoted by an iridium complex. The process entails a dehydrogenation reaction initiated by an iridium-promoted C(sp3)–H activation, the addition of the resulting indole to an alkyne -or alkene-partner, and a spontaneous loss of the carbamoyl directing group. Interestingly, the resulting C2-alkenyl indoles can participate in a variety of metal-catalyzed annulations initiated by C–H activation, including formal [4 + 1] and [4 + 2] cycloadditions, as well as cross-dehydrogenative cyclizations, thus enabling a divergent access to a collection of functionally rich nitrogen-containing heterocycles.

Proton-exchange-membrane water electrolyzers (PEMWEs) produce high-purity H2, withstand load fluctuations, and operate with a pure-water feed but require platinum-group-metal catalysts for durability, such as IrO2 and Pt, due to the acidic environment. At the anode, the slow oxygen evolution reaction (OER) requires a high overpotential to achieve relevant current densities (>2 A·cm-2) even with a high loading of IrO2. Using a simple commercial 1,5-cyclooctadiene iridium chloride dimer precursor, we synthesized submonolayer-thick IrOx on the surfaces of conductive metal oxides to make every Ir atom available for catalysis and reach the ultimate lower limit for Ir loading. We show that the reaction on Sb/SnO2 and F/SnO2 conductive oxides is surface-limited and that a continuous Ir-O-Ir network provides improved stability and activity. We cover IrOx with a thin layer of acid-stable TiOx by atomic-layer deposition. The effects of TiOx on the catalyst’s performance were assessed by inductively coupled plasma mass spectrometry (ICP-MS) coupled in situ with an electrochemical flow cell and ex situ by X-ray photoelectron spectroscopy. Tuning the binding environment of IrOx by TiOx addition enhances the intrinsic activity of the active sites, simultaneously accelerating the dissolution of the catalyst and the metal-oxide support. We illustrate the interplay between the support, catalyst, and protection-layer dissolution with OER activity, and highlight the effects of annealing to densify the TiOx protection layer on stability/activity. These ultrathin supported Ir-based catalysts do not eliminate the long-standing issue of the catalyst and support instability during OER in acids, but do provide new insight into the catalyst-support interactions and may also be of utility for advanced spectroscopic investigations of the OER mechanism.

Atomically dispersed catalysts have been shown highly active for preferential oxidation of carbon monoxide in the presence of excess hydrogen (PROX). However, their stability has been less than ideal. We show here that the introduction of a structural component to minimize diffusion of the active metal center can greatly improve the stability without compromising the activity. Using an Ir dinuclear heterogeneous catalyst (DHC) as a study platform, we identify two types of oxygen species, interfacial and bridge, that work in concert to enable both activity and stability. The work sheds important light on the synergistic effect between the active metal center and the supporting substrate and may find broad applications for the use of atomically dispersed catalysts.

Krebs ist nach wie vor eine der häufigsten Todesursachen weltweit und eine Vielzahl an Krebsarten ist aktuell nicht heilbar (Sung et al., 2021). Trotz der Entdeckung hochwirksamer Pt-basierter Tumortherapeutika wie Cisplatin, Oxaliplatin und Carboplatin ist die Entwicklung metallbasierter Krebsmedikamente mit günstigerem Nebenwirkungsprofil und verminderter Resistenzentwicklung notwendig. Neben Pt-Verbindungen werden auch Ru-, Os-, Rh-, Ir-, Ti-, Au-Komplexe intensiv als Antitumormittel untersucht. Viele Vertreter dieser Substanzklassen scheinen ihre Wirkung nicht primär über Bindung der DNA zu entfalten, wie es bei Cisplatin der Fall ist, sondern durch Interaktion mit Proteinen (Dyson and Sava, 2006). Das Verständnis molekularer Interaktionen von experimentellen Metallkomplexen mit biologischen Strukturen ist entscheidend für die Entwicklung neuer Chemotherapeutika. Besonders massenspektrometrische Verfahren werden zur Charakterisierung molekularer Interaktionen und zur Identifizierung biologischer Targets eingesetzt (Hartinger et al., 2013). In dieser Arbeit wurden 16 ausgewählte Metallkomplexe und ihre molekularen Interaktionen mit verschiedenen Proteinen mittels HPLC-ESI-MS analysiert. Die hierbei gewonnenen Daten liefern wertvolle Erkentnisse zur Ausbildung und Kinetik gebildeter Addukte und können einen Beitrag zur Entwicklung neuer therapeutischer Metallkomplexe leisten. Ziel dieser Arbeit war die Entwicklung einer HPLC-ESI-MS(MS2)-Methode zur Bestimmung von Bindungspräferenzen der Testsubstanzen, welche erstmalig eine simultane Messung von Proteinen und Oligonukleotiden im positiven Modus ermöglicht. Als Oligonukleotid wurde ein 8-mer mit einer internen GG-Sequenz eingesetzt, welche als bekannte Bindungsstelle zu Cisplatin gilt. Durch HCD-Fragmentierung von [8-mer + Pt(NH3)2]-Addukten und anschließender Analyse des erhaltenen Fragmentspektrums mit der Aom2S-Software wurde die Bindung zu dieser Sequenz überprüft. Bei der Methodenentwicklung war die Untersuchu, Cancer remains one of the leading causes of death worldwide and many cancer-types are currently incurable (Sung et al., 2021). Despite the discovery of highly effective Pt-based anticancer drugs such as cisplatin, oxaliplatin and carboplatin, there is a need to develop metal-based anticancer drugs with a more favourable side-effect profile and lower resistance development. In addition to Pt compounds, Ru, Os, Rh, Ir, Ti and Au complexes are also being intensively investigated as antitumour agents. Many representatives of these substance classes do not appear to exert their effect primarily by binding DNA, as is the case with cisplatin, but rather by interacting with proteins (Dyson and Sava, 2006). Understanding the molecular interactions of experimental metal complexes with biological structures is crucial for the development of new chemotherapeutics. Mass spectrometric methods in particular are used to characterize molecular interactions and identify biological targets (Hartinger et al., 2013). In this study, 16 selected metal complexes and their molecular interactions with various proteins were analyzed using HPLC-ESI-MS. The data obtained provide valuable insights into the formation and kinetics of formed adducts and can contribute to the development of new metallodrugs. The aim of this thesis was to determine the binding preferences of the tested metal complexes by developing an HPLC-ESI-MS(MS2) method, which enables for the first time the simultaneous measurement of proteins and oligonucleotides in positive ion mode. The oligonucleotide used was an 8-mer with an internal GG-sequence, which is a known binding site for cisplatin. The ability for cisplatin to bind to this sequence was verified by HCD fragmentation of [8-mer + Pt(NH3)2] adducts and subsequent analysis of the resulting fragment spectrum using the Aom2S software. During method development, the analysis of oligonucleotides in positive ion mode in the presence of other biomolecules was associated with, eingereicht von: Slaviero Daniel, Im Titel ist 2 hochgestellt, in englischer Sprache, Masterarbeit Universität Innsbruck 2023

The synthesis of iridium 1,5-cyclooctadiene and cyclooctene complexes supported by a monoanionic NNN-pincer ligand is described. The 1,5-cyclooctadiene complexes, ArLIr(COD) (L = 2,5-(iPr2P=NAr)2C4H2N, Ar = Pipp, Dipp, Mes, COD = 1,5-cyclooctadiene) did not react with dihydrogen or silanes, precluding further work into catalytic processes, such as alkane dehydrogenation and hydrosilylation. As such, a more reactive species was sought. PippLIr(COE) (COE = cyclooctene) reacted with dihydrogen and silanes, allowing the synthesis of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph). These complexes were characterized by multinuclear (1H, 13C{1H}, 29Si, 31P{1H}) and 2-dimensional NMR spectroscopy, X-ray crystallography, and elemental analysis. Alternatives to PippLIr(COE), including PippLIr(CO), PippLIr(PPh3), and others were investigated. This was undertaken to avoid competing reactivity with free COE in solution. The efficacy of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph) as catalysts for alkene hydrogenation and alkane dehydrogenation, and hydrosilylation, respectively, was explored.

The synthesis of iridium 1,5-cyclooctadiene and cyclooctene complexes supported by a monoanionic NNN-pincer ligand is described. The 1,5-cyclooctadiene complexes, ArLIr(COD) (L = 2,5-(iPr2P=NAr)2C4H2N, Ar = Pipp, Dipp, Mes, COD = 1,5-cyclooctadiene) did not react with dihydrogen or silanes, precluding further work into catalytic processes, such as alkane dehydrogenation and hydrosilylation. As such, a more reactive species was sought. PippLIr(COE) (COE = cyclooctene) reacted with dihydrogen and silanes, allowing the synthesis of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph). These complexes were characterized by multinuclear (1H, 13C{1H}, 29Si, 31P{1H}) and 2-dimensional NMR spectroscopy, X-ray crystallography, and elemental analysis. Alternatives to PippLIr(COE), including PippLIr(CO), PippLIr(PPh3), and others were investigated. This was undertaken to avoid competing reactivity with free COE in solution. The efficacy of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph) as catalysts for alkene hydrogenation and alkane dehydrogenation, and hydrosilylation, respectively, was explored.

The long-term operation of refractory-metal-based metamaterials is crucial for applications such as thermophotovoltaics. The metamaterials based on refractory metals like W, Mo, Ta, Nb, and Re fail primarily by oxidation. Here, the use of the noble metal Ir is proposed, which is stable to oxidation and has optical properties comparable to gold. The thermal endurance of Ir in a 3-layer-system, consisting of HfO2/Ir/HfO2, by performing annealing experiments up to 1240 °C in a pressure range from 2 × 10−6 mbar to 1 bar, is demonstrated. The Ir layer shows no oxidation in a vacuum and inert gas atmosphere. At temperatures above 1100 °C, the Ir layer starts to agglomerate due to the degradation of the confining HfO2 layers. An in situ X-ray diffraction experimental comparison between 1D multilayered Ir/HfO2 and W/HfO2 selective emitters annealed at 1000 °C, 2 × 10−6 mbar, over 100 h, confirms oxidation stability of Ir while W multilayers gradually disappear. The results of this work show that W-based metamaterials are not long-term stable even at 1000 °C. However, the oxidation resistance of Ir can be leveraged for refractory plasmonic metamaterials, such as selective emitters in thermophotovoltaic systems with strong suppression of long wavelength radiation.

Eine der Schwierigkeiten bei der Tumorbehandlung mit Cisplatin, ist die hohe Bindung an Serumproteine im Blutkreislauf. Folglich geben die Wechselwirkungen zwischen Biomolekülen und Metallodrugs Auskunft über mögliche Wirkungen und Nebenwirkungen dieser Metall-Komplexe, darum ist es Ziel dieser Arbeit Bindungsstelle und Bindungsstärke mittels energy-resolved Massenspektrometrie (ER-MS) genauer zu untersuchen. Es wurden Metall-Verbindungen, die Osmium-, Ruthenium-, Iridium-, Rhodium-, Platin- oder Gold als zentrales Metallatom besitzen, näher betrachtet. Als Biomoleküle wurden Angiotensin 1, Substanz P und Thioredoxin als Peptide und ein 8mer als Oligonukleotid verwendet. Die verwendeten Metallkomplexe wurden im dreifachen Überschuss mit den Biomolekülen inkubiert und es konnte gezeigt werden, dass die Os-, Ru-, Ir-, und Rh-Verbindungen, im Vergleich zu Peptiden mit Met-Resten, bevorzugt an Peptide mit His-Resten binden und diese Bindung am stärksten ist, wenn mehrere Bindungsstellen zum Peptid ausgebildet werden können. Das verwendete 8mer hat am stärksten an die Platin-Verbindungen, RAPTA-C und eine oxidierte Form von Os(cym)(8-AQ)Cl gebunden. Außerdem konnte gezeigt werden, dass der Austausch des 8-AQ-Liganden mit einem 8-HQ-Liganden die Bindung zum 8mer verstärkt. Die Bindungspräferenzen der Os-,Ru-,Ir- und Rh-Verbindungen folgten der HSAB-Theorie. Die Ergebnisse dieser Arbeit bestätigen nicht nur die Anwendbarkeit der ER-MS-Methode zur Charakterisierung von Metallkomplexen mit Peptiden und Oligonukleotiden, sondern zeigen auch, dass die Prinzipien der HSAB-Theorie zur Vorhersage von Bindungspräferenzen zwischen Metallionen und Biomolekülen herangezogen werden können. Insgesamt tragen die gewonnenen Informationen dazu bei, das Verständnis der Wechselwirkungen zwischen Metallkomplexen und Biomolekülen zu vertiefen und liefern neue Hinweise für neue Targets einiger Metallkomplexe, sowie für das gezielte Design von Metallkomplexen in der medizinischen Chemie., One of the challenges in tumor treatment with Cisplatin is its high binding to serum proteins in the bloodstream. Consequently, the interactions between biomolecules and metal-based drugs provide insights into the potential effects and side effects of these metal complexes. Therefore, the aim of this study is to investigate binding sites and binding strengths more precisely using energy-resolved mass spectrometry (ER-MS). Metal compounds featuring osmium, ruthenium, iridium, rhodium, platinum, or gold as the central metal atom were closely examined. As biomolecules, peptides including Angiotensin 1, Substance P, and Thioredoxin, along with an 8mer oligonucleotide, were utilized. The metal complexes were incubated with biomolecules in a threefold excess, and it was demonstrated that Os-, Ru-, Ir-, and Rh- compounds preferentially bind to peptides with histidine residues compared to peptides with methionine residues. This binding is strongest when the peptide can bind in a multidentate fashion. Among these, platinum compounds, RAPTA-C, and an oxidized form of Os(cym)(8-AQ)Cl exhibited the strongest binding to the 8mer used in the study. Furthermore, it was revealed that substituting the 8-AQ ligand with an 8-HQ ligand enhances binding to the 8mer. The binding preferences of Os-, Ru-, Ir-, and Rh- compounds aligned with HSAB theory. The results of this study not only affirm the applicability of ER-MS for characterizing metal complexes with peptides and oligonucleotides but also demonstrate that the principles of the HSAB theory can be employed to predict binding preferences between metal ions and biomolecules. Overall, the obtained information contributes to a deeper understanding of the interactions between metal complexes and biomolecules, providing new insights into potential targets for certain metal complexes and guiding the targeted design of metal complexes in medicinal chemistry., Carolin Iseler, in englischer Sprache, Masterarbeit Universität Innsbruck 2023

The synthesis of iridium 1,5-cyclooctadiene and cyclooctene complexes supported by a monoanionic NNN-pincer ligand is described. The 1,5-cyclooctadiene complexes, ArLIr(COD) (L = 2,5-(iPr2P=NAr)2C4H2N, Ar = Pipp, Dipp, Mes, COD = 1,5-cyclooctadiene) did not react with dihydrogen or silanes, precluding further work into catalytic processes, such as alkane dehydrogenation and hydrosilylation. As such, a more reactive species was sought. PippLIr(COE) (COE = cyclooctene) reacted with dihydrogen and silanes, allowing the synthesis of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph). These complexes were characterized by multinuclear (1H, 13C{1H}, 29Si, 31P{1H}) and 2-dimensional NMR spectroscopy, X-ray crystallography, and elemental analysis. Alternatives to PippLIr(COE), including PippLIr(CO), PippLIr(PPh3), and others were investigated. This was undertaken to avoid competing reactivity with free COE in solution. The efficacy of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph) as catalysts for alkene hydrogenation and alkane dehydrogenation, and hydrosilylation, respectively, was explored.

The synthesis of iridium 1,5-cyclooctadiene and cyclooctene complexes supported by a monoanionic NNN-pincer ligand is described. The 1,5-cyclooctadiene complexes, ArLIr(COD) (L = 2,5-(iPr2P=NAr)2C4H2N, Ar = Pipp, Dipp, Mes, COD = 1,5-cyclooctadiene) did not react with dihydrogen or silanes, precluding further work into catalytic processes, such as alkane dehydrogenation and hydrosilylation. As such, a more reactive species was sought. PippLIr(COE) (COE = cyclooctene) reacted with dihydrogen and silanes, allowing the synthesis of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph). These complexes were characterized by multinuclear (1H, 13C{1H}, 29Si, 31P{1H}) and 2-dimensional NMR spectroscopy, X-ray crystallography, and elemental analysis. Alternatives to PippLIr(COE), including PippLIr(CO), PippLIr(PPh3), and others were investigated. This was undertaken to avoid competing reactivity with free COE in solution. The efficacy of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph) as catalysts for alkene hydrogenation and alkane dehydrogenation, and hydrosilylation, respectively, was explored.

The synthesis of iridium 1,5-cyclooctadiene and cyclooctene complexes supported by a monoanionic NNN-pincer ligand is described. The 1,5-cyclooctadiene complexes, ArLIr(COD) (L = 2,5-(iPr2P=NAr)2C4H2N, Ar = Pipp, Dipp, Mes, COD = 1,5-cyclooctadiene) did not react with dihydrogen or silanes, precluding further work into catalytic processes, such as alkane dehydrogenation and hydrosilylation. As such, a more reactive species was sought. PippLIr(COE) (COE = cyclooctene) reacted with dihydrogen and silanes, allowing the synthesis of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph). These complexes were characterized by multinuclear (1H, 13C{1H}, 29Si, 31P{1H}) and 2-dimensional NMR spectroscopy, X-ray crystallography, and elemental analysis. Alternatives to PippLIr(COE), including PippLIr(CO), PippLIr(PPh3), and others were investigated. This was undertaken to avoid competing reactivity with free COE in solution. The efficacy of PippLIr(H)2 and PippLIr(H)(SiR3) (R3 = Et3, HPh2, H2Ph) as catalysts for alkene hydrogenation and alkane dehydrogenation, and hydrosilylation, respectively, was explored.

Despite their outstanding properties as potential photosensitizers for photodynamic therapy (PDT), Ir(III) biscyclometalated complexes need both further developments to overcome remaining limitations and in-depth investigations into their mechanisms of action to reach clinic application in the treatment of cancer. This work describes the synthesis of a family of Ir(III) complexes of general formula [Ir(C^N)2(N^N′ )]Cl (N^N′ = thiabendazole-based ligands; C^N = ppy (2-phenylpyridinate) (Series A), or dfppy (2-(2,4-difluorophenyl)pyridinate) (Series B)) and their evaluation as potential PDT agents. These complexes are partially soluble in water and exhibit cytotoxic activity in the absence of light irradiation versus several cancer cell lines. Furthermore, the cytotoxic activity of derivatives of Series A is enhanced upon irradiation, particularly for complexes [1a]Cl and [3a]Cl, which show phototoxicity indexes (PI) above 20. Endocytosis was established as the uptake mechanism for [1a]Cl and [3a]Cl in prostate cancer cells by flow cytometry. These derivatives mainly accumulate in the mitochondria as shown by colocalization confocal microscopy experiments. Presumably, [1a]Cl and [3a]Cl induce death on cancer cells under irradiation through apoptosis triggered by a multimodal mechanism of action, which likely involves damage over mitochondrial DNA and mitochondrial membrane depolarization. Both processes seem to be the result of photocatalytic oxidation processes., We acknowledge the financial support provided by the Spanish Ministerio de Ciencia, Innovacion ´ y Universidades (RTI2018-100709-BC21, RTI2018-100709-B-C22) and CTQ (QMC)-RED2018-102471-T), Junta de Castilla y Leon ´ (BU087G19), Junta de Comunidades de CastillaLa Mancha-FEDER (JCCM) (grant SBPLY/19/180501/000260) and UCLM-FEDER (grants 2019-GRIN-27183 and 2019-GRIN-27209). I. Echevarría wants to acknowledge his fellowship to both the European Social Fund and Consejería de Educacion ´ de la Junta de Castilla y Leon ´ (EDU/1100/2017). E. Zafon wants to acknowledge her predoctoral fellowship to the Generalitat de Catalunya (AGAUR; 2021 FI_B 01036). We are also indebted to Jacinto Delgado, Pilar Castroviejo and Marta Mansilla (PCT of the Universidad de Burgos) for technical support and Jos´e Vicente Cuevas Vicario for advice and support with theoretical calculations and Gabriel García-Herbosa for providing us access to CV equipment.

Piperazine rings are essential motifs frequently found in commercial drugs. However, synthetic methodologies are mainly limited to N-substituted piperazines, preventing structural diversity. Disclosed herein is a straightforward catalytic method for the synthesis of complex C-substituted piperazines based on an uncommon head-to-head coupling of easily prepared imines. This 100% atom-economic process allows the selective formation of a sole diastereoisomer, a broad substrate scope, and a good functional group tolerance employing a bench-stable iridium catalyst under mild reaction conditions. Key to the success is the addition of N-oxides to the reaction mixture, as they notably enhance the catalytic activity and selectivity.

The synthesis, characterization, and catalytic performance of an iridium(III) catalyst with an electron-deficient cyclopentadienyl ligand ([(CpIrI2)-Ir-E](2)) are reported. The [(CpIrI2)-Ir-E](2) catalyst was synthesized by complexation of a precursor of the Cp-E ligand with [Ir(cod)OAc](2), followed by oxidation, desilylation, and removal of the COD ligand. The electron-deficient [(CpIrI2)-Ir-E](2) catalyst enabled C-H amidation reactions assisted by a weakly coordinating ether directing group. Experimental mechanistic studies and DFT calculations suggested that the high catalytic performance of [(CpIrI2)-Ir-E](2) is due to its electron-deficient nature, which accelerates both C-H activation and Ir-V-nitrenoid formation.

In this work, catalytic alkane metathesis has been evaluated as a suitable approach to upcycle hydrocarbons (polyolefins) at moderate temperatures. To this end, a pincer-ligated iridium complex (dehydrogenation catalyst) has been combined with a rhenium-based (metathesis) catalyst, being the effect of immobilizing the Ir complex over different supports deeply investigated. FTIR spectroscopy has been used to confirm the complex grafting and to elucidate the anchoring site to the support. Additionally, the supports have been dehydroxylated at different conditions to evaluate its possible impact in both the complex grafting and the catalytic activity. The influence of the support nature and its participation in the catalytic reaction have been clearly evidenced.

Proton exchange membrane water electrolysis (PEMWE) technology is especially advantageous for green H2 production as a clean energy vector. During the water electrolysis process, the oxygen evolution reaction (OER) requires a large amount of iridium (2-3 mgIr cm−2) as catalyst. This material is scarce and expensive, representing a major bottleneck for large-scale deployment of electrolyzers. This work develops an anode with 10-fold reduction of Ir loading (0.2 mgIr cm−2) compared to what it is used in commercial PEMWE for more than 1000 h. An advanced catalyst based on an Ir mixed oxide (Sr2CaIrO6) is used for this purpose. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) analyses show that the unconventional structure of the reconstructed catalyst can contribute to the reduction of Ir in the catalyst layer. The reconfiguration of the ionomer in the catalyst layer is also observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), results in almost the full coverage of the catalytic layer with ionomer. The results presented herein demonstrate that it is possible to achieve high performance and stability in PEMWE with low Ir loading in the anode without showing significant degradation.

The catalytic hydroarylation of alkynes has emerged as an excellent methodology for the synthesis of functionalized alkenes with excellent levels of regio- and stereocontrol (syn). However, in spite of the great progress in this field, the number of asymmetric methodologies is still scarce. Herein, we report an atroposelective Ir-catalyzed C–H hydroarylation of alkynes, which enables the asymmetric synthesis of axially chiral heterobiaryl trisubstituted olefins in good to high yields and enantioselectivities up to 98% ee.

Proton exchange membrane water electrolysis (PEMWE) is the technology of choice for the large-scale production of green hydrogen from renewable energy. Current PEMWEs utilize large amounts of critical raw materials such as iridium and platinum in the anode and cathode electrodes, respectively. In addition to its high cost, the use of Ir-based catalysts may represent a critical bottleneck for the large-scale production of PEM electrolyzers since iridium is a very expensive, scarce, and ill-distributed element. Replacing iridium from PEM anodes is a challenging matter since Ir-oxides are the only materials with sufficient stability under the highly oxidant environment of the anode reaction. One of the current strategies aiming to reduce Ir content is the design of advanced Ir-mixed oxides, in which the introduction of cations in different crystallographic sites can help to engineer the Ir active sites with certain characteristics, that is, environment, coordination, distances, oxidation state, etc. This strategy comes with its own problems, since most mixed oxides lack stability during the OER in acidic electrolyte, suffering severe structural reconstruction, which may lead to surfaces with catalytic activity and durability different from that of the original mixed oxide. Only after understanding such a reconstruction process would it be possible to design durable and stable Ir-based catalysts for the OER. In this Perspective, we highlight the most successful strategies to design Ir mixed oxides for the OER in acidic electrolyte and discuss the most promising lines of evolution in the field. © 2023 The Authors. Published by American Chemical Society.

The Ir-MaxPHOX-type catalysts demonstrated high catalytic performance in the hydrogenation of a wide range of nonchelating olefins with different geometries, substitution patterns, and degrees of functionalization. These air-stable and readily available catalysts have been successfully applied in the asymmetric hydrogenation of di-, tri-, and tetrasubstituted olefins (ee ' s up to 9996). The combination of theoretical calculations and deuterium labeling experiments led to the uncovering of the factors responsible for the enantioselectivity observed in the reaction, allowing the rationalization of the most suitable substrates for these Ircatalysts.

Herein, we report a chiral phosphine-triazole ligand for the Ir-catalyzed asymmetric hydrogenation of exocyclic benzofused alkenes. Overcoming previous limitations, the catalytic system is able to successfully hydrogenate exocyclic olefins bearing a benzofused five- and six-membered ring motif (ee's between 92 to 99%). The catalyst tolerates well the presence of several substituents and substitution patterns at both aromatic rings. The absence of a competing isomerization process together with the perfect fit of the olefins in the catalyst chiral pocket are key to surpass the previous limitations in the hydrogenation of both 5- and 6-membered ring benzofused exocyclic olefins.

C-H activations have over the recent decades risen from a mere curiosity to a viable synthetic strategy. However, challenges in terms of accessible transformations, selectivity and functional group tolerance limit the widespread applicability of this approach. The aim of the work presented in this thesis was to develop directed ortho C-H activation methodologies specifically designed for applications in drug discovery. The [Cp*Ir(III)] catalytic system was key for the herein described transformations. Chapter 2 covers the development of selective monoiodination of benzoic acids. A mono/di selectivity >20:1 was observed throughout a range of diversely functionalized substrates. Mechanistic investigations revealed the key role of the Ag(I) additive in controlling selectivity. Chapter 3 discusses C-H methylations applied to a wide range of benzoic acids, including examples of late-stage functionalization of marketed drugs. The methodology also allows for introduction of CD3 groups. Biological studies demonstrated positive effect on biological and physical properties of pharmaceuticals as the result of methylation. In chapter 4 the C-H amination and sulfonamidation of benzoic acids is described, with applications for the synthesis of aminated analogues of drug-like molecules. Rapid synthesis of conjugates relevant to drug discovery is also demonstrated. Chapter 5 is dedicated to the development of a general C-H amination protocol, successfully applied to 21 distinct directing groups. The utility of the method is demonstrated by the functionalization of 11 complex drugs and natural products. Directing group informer libraries and functional group tolerance studies enabled the generation of guidelines for reaction outcome prediction.

Poisoning tolerance of Pt-based catalyst is an important parameter for the designing of direct electrochemical fuel cells (EFCs) based on electrooxidation of alcohols (i.e. methanol, ethanol). Applicability of direct ethanol EFCs is still challenging taking into account the lack of effective electrocatalysts which are able to produce high faradic current densities and high stability towards strong adsorption of C1 and C2 oxidation products. As we present here, mono- and bimetallic Pt-based electrocatalysts have been synthesized on a carbon black support for the elecotrooxidation of ethanol in acidic media. Depending of the molar ratio between poly-n-vinylpyrrolidone (PVP, acting as protecting agent) and Pt, nanoparticle size distribution has been controlled, obtaining an optimal condition of Pt loading and electroactive surface area (ECSA) for the PVP/Pt ratio = 1. The electrochemical behavior of electrocatalyst Pt/Re/CB-1 shows a negligible variation in the ECSA (98.3 m2 g−1) in comparison with the monometallic electrodes (90.2 m2 g−1). In contrast, addition of Ir tends to reduce the ECSA by agglomeration of some nanoparticles and decreasing its electrochemical performance. Incorporation of Re in the alloy promotes bond breaking of the intermediates adsorbed on surface, specifically adsorbed C2 molecules, releasing great number of the active sites from the Pt surface, minimizing the deactivation with cycling and providing remarkable stable catalyst with high specific current densities with the addition of small amounts of Re.

[EN] An unprecedented quantum tunneling effect has been observed in catalytic Si-H bond activations at room temperature. The cationic hydrido-silyl-iridium(III) complex, {Ir[SiMe(o-C6H4SMe)(2)](H)(PPh3)(THF)}[BAr4F], has proven to be a highly efficient catalyst for the hydrolysis and the alcoholysis of organosilanes. When triethylsilane was used as a substrate, the system revealed the largest kinetic isotopic effect (KIESi-H/Si-D=346 +/- 4) ever reported for this type of reaction. This unexpectedly high KIE, measured at room temperature, together with the calculated Arrhenius preexponential factor ratio (A(H)/A(D)=0.0004) and difference in the observed activation energy [(EaD -EaH )=34.07 kJ mol(-1)] are consistent with the participation of quantum tunneling in the catalytic process. DFT calculations have been used to unravel the reaction pathway and identify the rate-determining step. Aditionally, isotopic effects were considered by different methods, and tunneling effects have been calculated to be crucial in the process.

C-H activations have over the recent decades risen from a mere curiosity to a viable synthetic strategy. However, challenges in terms of accessible transformations, selectivity and functional group tolerance limit the widespread applicability of this approach. The aim of the work presented in this thesis was to develop directed ortho C-H activation methodologies specifically designed for applications in drug discovery. The [Cp*Ir(III)] catalytic system was key for the herein described transformations. Chapter 2 covers the development of selective monoiodination of benzoic acids. A mono/di selectivity >20:1 was observed throughout a range of diversely functionalized substrates. Mechanistic investigations revealed the key role of the Ag(I) additive in controlling selectivity. Chapter 3 discusses C-H methylations applied to a wide range of benzoic acids, including examples of late-stage functionalization of marketed drugs. The methodology also allows for introduction of CD3 groups. Biological studies demonstrated positive effect on biological and physical properties of pharmaceuticals as the result of methylation. In chapter 4 the C-H amination and sulfonamidation of benzoic acids is described, with applications for the synthesis of aminated analogues of drug-like molecules. Rapid synthesis of conjugates relevant to drug discovery is also demonstrated. Chapter 5 is dedicated to the development of a general C-H amination protocol, successfully applied to 21 distinct directing groups. The utility of the method is demonstrated by the functionalization of 11 complex drugs and natural products. Directing group informer libraries and functional group tolerance studies enabled the generation of guidelines for reaction outcome prediction.

C-H activations have over the recent decades risen from a mere curiosity to a viable synthetic strategy. However, challenges in terms of accessible transformations, selectivity and functional group tolerance limit the widespread applicability of this approach. The aim of the work presented in this thesis was to develop directed ortho C-H activation methodologies specifically designed for applications in drug discovery. The [Cp*Ir(III)] catalytic system was key for the herein described transformations. Chapter 2 covers the development of selective monoiodination of benzoic acids. A mono/di selectivity >20:1 was observed throughout a range of diversely functionalized substrates. Mechanistic investigations revealed the key role of the Ag(I) additive in controlling selectivity. Chapter 3 discusses C-H methylations applied to a wide range of benzoic acids, including examples of late-stage functionalization of marketed drugs. The methodology also allows for introduction of CD3 groups. Biological studies demonstrated positive effect on biological and physical properties of pharmaceuticals as the result of methylation. In chapter 4 the C-H amination and sulfonamidation of benzoic acids is described, with applications for the synthesis of aminated analogues of drug-like molecules. Rapid synthesis of conjugates relevant to drug discovery is also demonstrated. Chapter 5 is dedicated to the development of a general C-H amination protocol, successfully applied to 21 distinct directing groups. The utility of the method is demonstrated by the functionalization of 11 complex drugs and natural products. Directing group informer libraries and functional group tolerance studies enabled the generation of guidelines for reaction outcome prediction.

Herein, we report an iridium-catalyzed directed C–H amination methodology developed using a high-throughput experimentation (HTE)-based strategy, applicable for the needs of automated modern drug discovery. The informer library approach for investigating the accessible directing group chemical space, in combination with functional group tolerance screening and substrate scope investigations, allowed for the generation of reaction application guidelines to aid future users. Applicability to late-stage functionalization of complex drugs and natural products, in combination with multiple deprotection protocols leading to the desirable aniline matched pairs, serve to demonstrate the utility of the method for drug discovery. Finally, reaction miniaturization to a nanomolar range highlights the opportunities for more sustainable screening with decreased material consumption.

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor is described. The reduction of enones proceeded smoothly under mild conditions to afford ketones or alcohols. The reaction occurred chemoselectively with the use of different cathode catalysts (Pd/C or Ir/C).

This is an Accepted Manuscript of an article published by Taylor & Francis in Phosphorus, Sulfur, and Silicon and the Related Elements on 6 Dec 2022, available at https://doi.org/10.1080/10426507.2022.2152815., Sulfur-containing functional groups, among various coordinating functions, have recently attracted attention as useful directing groups for the direct catalytic C-H transformation of aromatic and heteroaromatic compounds. Herein we briefly summarize our recent work on the site-selective substitution on indole and naphthalene skeletons using thioether directing groups under either Cp*Rh(III) or Cp*Ir(III) catalysis. The thioether groups can readily be removed and transformed to other functional groups. The reactions developed appear to be of importance in pharmaceutical and materials chemistry.

The potential applications afforded by the generation and reactivity of artificial metalloenzymes (ArMs) in microorganisms are vast. We show that a non-pathogenic E. coli strain, Nissle 1917 (EcN), is a suitable host for the creation of ArMs from cytochrome P450s and artificial heme cofactors. An outer-membrane receptor in EcN transports an iridium porphyrin into the cell, and the Ir-CYP119 (CYP119 containing iridium porphyrin) assembled in vivo catalyzes carbene insertions into benzylic C-H bonds enantioselectively and site-selectively. The application of EcN as a whole-cell screening platform eliminates the need for laborious processing procedures, drastically increases the ease and throughput of screening, and accelerates the development of Ir-CYP119 with improved catalytic properties. Studies to identify the transport machinery suggest that a transporter different from the previously assumed ChuA receptor serves to usher the iridium porphyrin into the cytoplasm.

The use of Constellations for weather science, security and disaster monitoring is a major challenge for space application services. Satellite to satellite communication using existing constellations has not been extensively explored yet. It can improve the communication times for small-satellite missions which have limited access to ground stations. Thus, a mission to demonstrate the feasibility of this link is required. Another element of interest in space application is Earth Observation, especially in the context of Climate Change. Gravimetry allows an understanding of mass transport in the Earth System through the remote sensing of the time variation of the Earth gravity field. CubeSats are low-cost small-scale and hence lower risk solutions to Earth Observation missions. University CubeSats have shown their success in demonstration and scientific missions, and have a great potential in providing students with practice and application on real space systems. In this context, the student associations ASTRE and SUPAERO CubeSat Club have joined in a CubeSat program called TOLOSAT, with the hope of demonstrating such technologies. Gathering 70 students from Toulouse, the team was split into subsystems in accordance with the concurrent engineering principles. The work performed followed recommendations from experts from the French National Centre for Space Studies (CNES) and the industry. The TOLOSAT payloads have to test and demonstrate new means of measuring gravity and addressing communication issues. Firstly, for the gravimetry mission, our approach relies solely on GNSS to compute the gravity field, avoiding expensive gravimeters. For the communication mission: the Iridium constellation will be used as an intermediate between the CubeSat and the ground station. Off-the-shelf components such as patch antennas are planned to prove their efficiency in orbit. This would improve the coverage and the communication window. The preliminary design was completed. TOLOSAT

A heterogenized iridium catalyst was employed to perform photoredox catalysis for a collection of mechanistically orthogonal reactions using very low quantities of iridium (0.01-0.1 mol %). The heterogenized construct consists of an organometallic iridium coordination complex bonded to an aluminum metal oxide solid-state support via an anchoring group. The solid-state support allows for easy recovery and reusability of the catalyst. Evaluation of the catalytic activity was performed with five different reactions, showing broad applicability and demonstrating the general potential for a heterogenized strategy. Moreover, the heterogenized catalyst was shown to be reusable up to five times and also mediated the reactions with much higher efficiency than the original processes by employing the corresponding homogeneous catalyst. As a result of the low catalyst loadings employed, the feasibility of reusage, and faster reaction times, this catalyst offers a more sustainable option when precious metal catalysts are used in organic synthesis. Finally, the catalyst was successfully applied to a gram-scale reaction, showing it is susceptible to scalability.

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor is described. The reduction of enones proceeded smoothly under mild conditions to afford ketones or alcohols. The reaction occurred chemoselectively with the use of different cathode catalysts (Pd/C or Ir/C).

This is an Accepted Manuscript of an article published by Taylor & Francis in Phosphorus, Sulfur, and Silicon and the Related Elements on 6 Dec 2022, available at https://doi.org/10.1080/10426507.2022.2152815., Sulfur-containing functional groups, among various coordinating functions, have recently attracted attention as useful directing groups for the direct catalytic C-H transformation of aromatic and heteroaromatic compounds. Herein we briefly summarize our recent work on the site-selective substitution on indole and naphthalene skeletons using thioether directing groups under either Cp*Rh(III) or Cp*Ir(III) catalysis. The thioether groups can readily be removed and transformed to other functional groups. The reactions developed appear to be of importance in pharmaceutical and materials chemistry.

The organometallic chemistry of 4d and 5d transition metals has been vastly dominated by closed-shell states. The reactivity of their metalloradical species is though remarkable, albeit yet poorly understood and with limited mechanistic investigations available. In this work we report the synthesis and characterization of two mononuclear IrII species, including the first dinitrogen adduct. These compounds activate dihydrogen at a dissimilar rate, in the latter case several orders of magnitude faster than its IrI precursor. A combined experimental/computational investigation to ascertain the mechanism of this transformation in IrII compounds is reported.

A heterogenized iridium catalyst was employed to perform photoredox catalysis for a collection of mechanistically orthogonal reactions using very low quantities of iridium (0.01-0.1 mol %). The heterogenized construct consists of an organometallic iridium coordination complex bonded to an aluminum metal oxide solid-state support via an anchoring group. The solid-state support allows for easy recovery and reusability of the catalyst. Evaluation of the catalytic activity was performed with five different reactions, showing broad applicability and demonstrating the general potential for a heterogenized strategy. Moreover, the heterogenized catalyst was shown to be reusable up to five times and also mediated the reactions with much higher efficiency than the original processes by employing the corresponding homogeneous catalyst. As a result of the low catalyst loadings employed, the feasibility of reusage, and faster reaction times, this catalyst offers a more sustainable option when precious metal catalysts are used in organic synthesis. Finally, the catalyst was successfully applied to a gram-scale reaction, showing it is susceptible to scalability.

The organometallic chemistry of 4d and 5d transition metals has been vastly dominated by closed-shell states. The reactivity of their metalloradical species is though remarkable, albeit yet poorly understood and with limited mechanistic investigations available. In this work we report the synthesis and characterization of two mononuclear IrII species, including the first dinitrogen adduct. These compounds activate dihydrogen at a dissimilar rate, in the latter case several orders of magnitude faster than its IrI precursor. A combined experimental/computational investigation to ascertain the mechanism of this transformation in IrII compounds is reported.

Figure S1. XRD patterns of fresh Ir/Nb/Ti catalysts. Figure S2. Figure S3. Cs-corrected STEM-HAADF. Figure S4. O(1s) XPS core-level spectra.

An effective visible-light-promoted iridium(III)-catalyzed hydrogen production from N-heterocycles is described. A single iridium complex constitutes the photocatalytic system playing a dual task, harvesting visible-light and facilitating C–H cleavage and H2 formation at room temperature and without additives. The presence of a chelating C–N ligand combining a mesoionic carbene ligand along with an amido functionality in the IrIII complex is essential to attain the photocatalytic transformation. Furthermore, the IrIII complex is also an efficient catalyst for the thermal reverse process under mild conditions, positioning itself as a proficient candidate for liquid organic hydrogen carrier technologies (LOHCs). Mechanistic studies support a light-induced formation of H2 from the Ir–H intermediate as the operating mode of the iridium complex.

Iridium(I) compounds featuring bridge-functionalized bis-NHC ligands (NHC = N-heterocyclic carbene), [Ir(cod)(bis-NHC)] and [Ir(CO)2(bis-NHC)], have been prepared from the appropriate carboxylate- or hydroxy-functionalized bis-imidazolium salts. The related complexes [Ir(cod)(NHC)2]+ and [IrCl(cod)(NHC)(cod)] have been synthesized from a 3-hydroxypropyl functionalized imidazolium salt. These complexes have been shown to be robust catalysts in the oxidative dehydrogenation of glycerol to lactate (LA) with dihydrogen release. High activity and selectivity to LA were achieved in an open system under low catalyst loadings using KOH as a base. The hydroxy-functionalized bis-NHC catalysts are much more active than both the carboxylate-functionalized ones and the unbridged bis-NHC iridium(I) catalyst with hydroxyalkyl-functionalized NHC ligands. In general, carbonyl complexes are more active than the related 1,5-cyclooctadiene ones. The catalyst [Ir(CO)2{(MeImCH2)2CHOH}]Br exhibits the highest productivity affording TONs to LA up to 15,000 at very low catalyst loadings.

The multifunctional radioligand [H-3]T0901317 ([H-3]1) has been employed as a powerful autoradiographic tool to target several receptors, such as liver X, farnesoid X, and retinoic acid-related orphan receptor alpha and gamma subtypes at nanomolar concentrations. Although [H-3]1 is commercially available and its synthesis via tritiodebromination has been reported, the market price of this radioligand and the laborious synthesis of corresponding bromo-intermediate potentially preclude its widespread use in biochemical, pharmacological, and pathological studies in research lab settings. We exploit recent reports on hydrogen-isotope exchange (HIE) reactions in tertiary benzenesulfonamides where the sulfonamide represents an ortho-directing group that facilitates C-H activation in the presence of homogenous iridium(I) catalysts. Herein, we report a time- and cost-efficient method for the tritium late-stage labeling of compound 1-a remarkably electron-poor substrate owing to the tertiary trifluoroethylsulfonamide moiety. Under a straightforward HIE condition using a commercially available Kerr-type NHC Ir(I) complex, [(cod)Ir (NHC)Cl], the reaction with 1 afforded a specific activity of 10.8 Ci/mmol. Additionally, alternative HIE conditions using the heterogeneous catalyst of Ir-black provided sufficient 0.72 D-enrichment of 1 but unexpectedly failed while repeating with tritium gas.

The future Athena observatory will feature optics with unprecedented collecting area enabled by silicon pore optics technology. In order to achieve the telescope effective area requirements at 1 keV and 7 keV, thin film coatings of iridium with a low-density overcoat are deposited onto the mirror substrates. Assembling the coated silicon pore optics plates into mirror modules for the Athena optics requires wet chemical processing and thermal annealing. While iridium appears to be compatible with the post-coating processes, previous studies have shown degradation of the low-density material. The overcoat layer is particularly critical for the low-energy telescope performance, so several candidate materials (boron carbide, silicon carbide and carbon) have been studied to identify a compatible thin film design. We present the characterisation of x-ray mirror performance using x-ray reflectometry, as well as the measurements of residual film stress with stylus profilometry. Furthermore, we evaluate the effects of post-coating treatment in order to recommend the most suitable overcoat material for the telescope.

Poisoning tolerance of Pt-based catalyst is an important parameter for the designing of direct electrochemical fuel cells (EFCs) based on electrooxidation of alcohols (i.e. methanol, ethanol). Applicability of direct ethanol EFCs is still challenging taking into account the lack of effective electrocatalysts which are able to produce high faradic current densities and high stability towards strong adsorption of C1 and C2 oxidation products. As we present here, mono- and bimetallic Pt-based electrocatalysts have been synthesized on a carbon black support for the elecotrooxidation of ethanol in acidic media. Depending of the molar ratio between poly-n-vinylpyrrolidone (PVP, acting as protecting agent) and Pt, nanoparticle size distribution has been controlled, obtaining an optimal condition of Pt loading and electroactive surface area (ECSA) for the PVP/Pt ratio = 1. The electrochemical behavior of electrocatalyst Pt/Re/CB-1 shows a negligible variation in the ECSA (98.3 m2 g−1) in comparison with the monometallic electrodes (90.2 m2 g−1). In contrast, addition of Ir tends to reduce the ECSA by agglomeration of some nanoparticles and decreasing its electrochemical performance. Incorporation of Re in the alloy promotes bond breaking of the intermediates adsorbed on surface, specifically adsorbed C2 molecules, releasing great number of the active sites from the Pt surface, minimizing the deactivation with cycling and providing remarkable stable catalyst with high specific current densities with the addition of small amounts of Re.

[EN] An unprecedented quantum tunneling effect has been observed in catalytic Si-H bond activations at room temperature. The cationic hydrido-silyl-iridium(III) complex, {Ir[SiMe(o-C6H4SMe)(2)](H)(PPh3)(THF)}[BAr4F], has proven to be a highly efficient catalyst for the hydrolysis and the alcoholysis of organosilanes. When triethylsilane was used as a substrate, the system revealed the largest kinetic isotopic effect (KIESi-H/Si-D=346 +/- 4) ever reported for this type of reaction. This unexpectedly high KIE, measured at room temperature, together with the calculated Arrhenius preexponential factor ratio (A(H)/A(D)=0.0004) and difference in the observed activation energy [(EaD -EaH )=34.07 kJ mol(-1)] are consistent with the participation of quantum tunneling in the catalytic process. DFT calculations have been used to unravel the reaction pathway and identify the rate-determining step. Aditionally, isotopic effects were considered by different methods, and tunneling effects have been calculated to be crucial in the process.