Chemistry Commons^™

Multi-Dimensional Mass Spectrometry For The Characterization Of Glycopolymers, Maria Ganios

Williams Honors College, Honors Research Projects

Several glycopolymers synthesized by Activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP), were characterized by mass spectrometry to elucidate their microstructure and architecture. Analyses were performed using Matrix Assisted Laser Desorption Ionization- Time of Flight/ Time of Flight (MALDI-ToF/ToF) and Electrospray Ionization Mass Spectrometry (ESI-MS) instruments. The linear isopropylidenated glycopolymer (P65B1) analyzed with ESI-MS also was examined with multi-stage mass spectrometry (MSⁿ) using collision induced dissociation (CID) to examine the tetramer parent ion. This glycopolymer was found to be either cyclic or linear (sans end groups) due to the data being fit for both forms …

Research Games In Structural Biology, Nic Vigilante

Alison Scott Ricker Research Award

As problems in structural biology and bioinformatics have become increasingly complex, innovative new com-putational methods have been proposed and implemented. Of these methods, research games are unique in how they privi-lege human intuition over algorithmic verification in certain steps of the research process; researchers in structural biology have developed a number of research games since 2008 to utilize human pattern recognition and spatial manipulation skills. Players are not expected to have any scientific knowledge, as the game interfaces abstract the relevant problems from their biological contexts, and they are not reimbursed or incentivized in any way apart from methods such …

The Fate And One-Dimensional Transport Of Creighton Colloidal Silver Nanoparticles Through Saturated Porous Media, Jessica M. Dagher

Browse all Theses and Dissertations

With the ubiquitous burst of nanotechnology, silver nanoparticles (AgNPs) have become indispensable in numerous industrial, medicinal, and research applications. Consequently, AgNPs have been alarmingly disposed into subsurface water increasing the risk of human and environmental exposure. While mechanisms of AgNP cytotoxicity have been reported, research studies on AgNP transport in subsurface water are needed, according to U.S. Environmental Protection Agency (EPA). The main goal of this study was to investigate the environmental fate and transport of widely-used Creighton colloidal AgNPs in a laboratory transport system simulating a porous, saturated groundwater aquifer. To achieve this, a large volume of AgNPs was …

Redox-Active Silver N-Heterocyclic Carbene Complexes: A Dual Targeting Antibacterial Drug, Kotiba Malek

Browse all Theses and Dissertations

Bacterial resistance to current [beta]-lactam antibiotics necessitates new therapeutic approaches. Silver-based drugs offer a promising alternative because of their antibacterial properties and minimal bacterial resistance. However, many silver-based antibacterial drugs rapidly release silver ions, limiting the bioavailability of silver ions for a longer period of time. Recently, N-heterocyclic carbenes (NHC) containing silver complexes have become a popular subject of research due to their versatility and the slow release of silver ions under biological conditions. To further enhance the efficacy of silver-NHC drugs, we fused redox-active substituents such as naphthoquinone and ferrocenes to NHCs. Both naphthoquinone and ferrocenes have been shown …

Structure-Property Relationships Of N-Heterocycle Functionalized Triphenylphosphine Oxide-Based Poly (Arylene Ether)S, Luke Meyer

Browse all Theses and Dissertations

The synthesis of N-heterocycle functionalized triphenylphosphine oxide based PAEs, utilizing 3,5 difluorinated diphenyl sulfone systems was achieved. 3’-Iodo 3,5-difluorodiphenylsulfone was subjected to copper and palladium catalyzed coupling reactions with carbazole, phenothiazine, and indole. The syntheses of 3’-(9-carbazole) 3,5-difluorodiphenylsulfone, 3’-(9-phenothiazine) 3,5-difluorodiphenylsulfone, and 3’-(9-indole) 3,5-difluorodiphenylsulfone were successfully carried out. Copolymers with 4,4’ difluorotriphenylphosphine oxide, as well as 4,4’ dihydroxydiphenyl ether (DPE), as the nucleophilic partner, were prepared via standard nucleophilic aromatic substitution (NAS) polycondensataion reactions. Incorporation of the monomers containing N-heterocycle units was determined by NMR spectroscopy. All polymers displayed sufficient molecular weights (Mn) to allow for films to be cast from …

Laser Synthesis Of Nanomaterials Incorporated Within High Surface Area Materials: Applications For Heterogeneous Catalysis, Water Treatment, And Photothermal Energy Conversion, Julian A. Bobb

Theses and Dissertations

Chemical methods are generally used for the synthesis of active nanoparticles (metals, semi-metals, metal oxides, and etc) supported on high surface area materials. Chemical methods involve using strong solvents, harmful gases (H₂ & CO), and high temperature techniques such as high boiling solvents, calcination and pyrolysis. The main drawbacks of using this approach, is the prevalence of chemical agents on nanomaterials which tends to negate its applications. Alternatively, photochemical and photothermal methods are widely being considered for the synthesis and design of nanomaterials.

For these studies, the active nanomaterials incorporated within high surface area materials were prepared by the …

Determination Of Local Elastic Modulus Of Soft Biomaterial Samples Using Afm Force Mapping, Faieza Saad Ejweada Bodowara

Theses and Dissertations

Conventional methods of mechanical testing cannot measure properties of soft materials at the nanoscale. In fields such as tissue engineering, it is important to distinguish the bulk elastic modulus from the surface elastic modulus and to characterize the spatial distribution of material with non-uniform stiffness. One of the important new methods of testing is the force mapping using the atomic force microscope. The existing force mapping approaches often suffer from omitting important effects that might result in artifacts. The most important effects include taking into account sample’s adhesion and viscoelasticity and considering more realistic probe shapes. In this work, we …

Physicochemical, Spectroscopic Properties, And Diffusion Mechanisms Of Small Hydrocarbon Molecules In Mof-74-Mg/Zn: A Quantum Chemical Investigation, Gemechis Degaga

Dissertations, Master's Theses and Master's Reports

In petroleum refining industries, the fracturing process allows for the cracking of long-chain hydrocarbons into a mixture of small olefin and paraffin molecules that are then separated via the energetically and monetarily demanding cryogenic distillation process. In an attempt to mitigate both energetic and capital consumptions, selective sorption of light hydrocarbons by tunable sorbents, such as metal-organic frameworks (MOFs), appears to be the most promising alternative for a more efficient gas separation process. MOFs are novel porous materials assembled from inorganic bricks connected by organic linkers. From a crystal engineering stand point, MOFs are advantageous in creating a range …

Direct Measurement Of Rupture Force Of Single Triazole Molecule By Atomic Force Microscope And Solid Phase Synthesis Of Monodisperse Polyethylene Glycols, Ashok Khanal

Dissertations, Master's Theses and Master's Reports

This dissertation includes two topics, which are related to each other: (1) Rupture force measurement of single triazole molecule by atomic force microscope (AFM) and (2) Solid phase stepwise synthesis of polyethylene glycols (PEGs).

The reaction of an alkyne and an azide to form a 1,2,3- triazole has found wide applications. However, the stability of triazole under mechanical stress is unclear. We investigated the cycloreversion at the single molecular level using atomic force microscopy. A mica surface functionalized with a molecule containing a 1,2,3-triazole moiety in the middle and an activated ester at the end was prepared. An AFM tip …

Crystallomagnetic Studies Of First And Third Row Transition Metal Containing Oxides Grown Via The Molten Flux Method, Timothy Ferreira

Theses and Dissertations

The primary objective of this dissertation is to inform about the single crystal growth of complex first and third row transition metal oxides via molten flux methods. Particular focus is given to complex oxides that contain transition metals with unpaired electrons. This fundamental research is motivated by a singular question: What can a critical analysis of chemical structure elucidate about magnetic order in oxide materials? Throughout the eight chapters of this dissertation, including an introductory chapter, this structure-property relationship will be investigated. These seven chapters will be organized into three parts, each corresponding to the general structure type of the …

Tailoring Polybenzimidazole Membranes For Enhanced Performance In Electrochemical Devices, Andrew T. Pingitore

Theses and Dissertations

After approximately 15 years of development, polybenzimidazole (PBI) chemistries and the concomitant manufacturing processes have evolved into commercially produced membrane electrode assemblies (MEAs). PBI MEAs can operate reliably without complex water humidification hardware and are able to run at elevated temperatures of 120-180 OC due to the physical and chemical robustness of PBI membranes. These higher temperatures improve the electrode kinetics and conductivity of the MEAs, simplify the water and thermal management of the systems, and significantly increase their tolerance to fuel impurities. Membranes cast by a newly developed polyphosphoric acid (PPA) Process possessed excellent mechanical properties, higher phosphoric acid …

Dually Modified Transmembrane Proteoglycan Tβriii/Betaglycan In Cell Signaling And Cancer, Laura M. Jenkins

Theses and Dissertations

During tumor progression, cancer cells undergo a number of alterations to evade tumor inhibitory mechanisms, proliferate, invade surrounding tissues and metastasize to distant sites. These properties reflect changes in their cell signaling pathways that, in normal cells, control aberrant cell proliferation, motility, and survival. Over the past few decades, hyperactive Wnt/β-catenin signaling has been linked to the formation of multiple cancers, including malignant ovarian cancer, making identification of molecules regulating Wnt/β-catenin signaling crucial to the development of early detection methods and cancer treatment strategies. Proteoglycans, which regulate transmission of cellular signals, are implicated in the pathophysiology of diseases, including cancer, …

Investigation Of Gold(Iii) Complexes With Hiv-Ncp7 And Models, James Beaton

Theses and Dissertations

The medicinal uses of gold date as far back as 2500 B.C. in China. In modern times, gold has been used in the treatment of a number of different human diseases including rheumatoid arthritis, cancer, and viral infections. This dissertation will focus on the development of gold complexes for the purpose of selective inhibition of HIV NCp7, a 55 amino acid zinc finger protein with two Cys₃His zinc binding domains.

NCp7 is involved in a number of viral life cycle processes including activation of reverse transcription, integration, DNA recognition, RNA packaging, and formation of the viral envelope. The …

Modification Of Wheat Gluten For Improvement Of Binding Capacity With Keratin In Hair, Shukun Wang, Danyang Meng, Sisi Wang, Zhong Zhang, Ruijin Yang, Wei Zhao

Department of Food Science and Technology: Faculty Publications

In this study, enzymatic hydrolysis and cationization with epoxypropyldodecyldimethylammonium chloride of wheat protein, an economic protein complex containing great amount of disulfide bonds, were conducted to improve properties such as solubility and disassociation behaviour for recovery of damaged hair when used in shampoo. The optimal conditions for enzymatic hydrolysis were pH 8.2, 55°C with Alcalase for 60min. After the selected hydrolysis, the degree of hydrolysis, nitrogen solubility index, foaming capacity index, foam stability index, emulsifying activity index and emulsion stability index of hydrolysate with 58.71% of shortchain peptides (less than 1000 Da) were 8.81%, 39.07%, 225%, 56.67%, 9.62m² g …

Changes In Enzymatic Activities And Functionality Of Whole Wheat Flour Due To Steaming Of Wheat Kernels, Rachana Poudel, Devin J. Rose

Department of Food Science and Technology: Faculty Publications

The effects of steaming wheat kernels on lipolytic degradation of resulting whole flour was studied by quantifying enzyme activities and lipid degradation products during storage. Lipase, lipoxygenase, polyphenol oxidase, and peroxidase activities were decreased by up to 81%, 63%, 22%, and 34%, respectively, as the time of steaming increased up to 90 s. Steaming had no effect on starch and gluten properties. Upon storage free fatty acids decreased with respect to time of steaming. Time of steaming did not affect lipid oxidation in flour; however, total carbonyls produced in dough made from stored flour were decreased with the increase in …

Abnormal Phase Transition Between Two-Dimensional High-Density Liquid Crystal And Low-Density Crystalline Solid Phases, Wenbin Li, Longjuan Kong, Baojie Feng, Huixia Fu, Hui Li, Xiao Cheng Zeng, Kehui Wu, Lan Chen

Xiao Cheng Zeng Publications

Some two-dimensional liquid systems are theoretically predicted to have an anomalous phase transition due to unique intermolecular interactions, for example the first-order transition between two-dimensional high-density water and low-density amorphous ice. However, it has never been experimentally observed, to the best of our knowledge. Here we report an entropy-driven phase transition between a high-density liquid crystal and low-density crystalline solid, directly observed by scanning tunneling microscope in carbon monoxide adsorbed on Cu(111). Combined with first principle calculations, we find that repulsive dipole–dipole interactions between carbon monoxide molecules lead to unconventional thermodynamics. This finding of unconventional thermodynamics in two-dimensional carbon monoxide …

Fabrication Of Mnox/Mwcnts-Gc Nanocatalyst For Oxygen Evolution Reaction, Islam M. Al-Akraa Dr., Yaser M. Asal Mr, Amr M. Arafa Eng.

Chemical Engineering

Manganese oxide (MnOx) and multiwalled carbon nanotubes (MWCNTs) are intended to modify the GC electrode for oxygen evolution reaction (OER). Optimization of MnOx loading is carried out and the deposition of 55 cycles was sufficient to obtain the highest activity toward OER. The stability of the catalyst is enhanced by the addition of MWCNTs. As a result, an amount of 22 kWh/Kg of O2 of energy is saved. Several techniques including cyclic voltammetry, linear sweep voltammetry, chronoamperometry, chronopotentiometry, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy will be combined to track the catalyst activity and to determine its morphology …

Assembling Of Niox/Mwcnts-Gc Anodic Nanocatalyst For Water Electrolysis Applications, Islam M. Al-Akraa Dr., Yaser M. Asal Mr, Saher D. Khamis Eng

Chemical Engineering

Glassy carbon (GC) electrode is intended to be modified with nickel oxide (NiOx) and multiwalled carbon nanotubes (MWCNTs) in the anodic reaction of water electrolysis. NiOx deposition time is optimized and a 5 min was enough to attain the maximum activity. A further modification of the catalyst with MWCNTs could greatly enhance its stability during continuous electrolysis. As an outcome, an energy amount of 21.7 kWh/KgO2 is minimized. Several electrochemical and materials characterization setups will be utilized to test the catalyst activity and to know its geometry and structure.

Fabrication Of Cuox-Pd Nanocatalyst Supported On A Glassy Carbon Electrode For Enhanced Formic Acid Electro-Oxidation, Islam M. Al-Akraa Dr., Ahmad M. Mohammad Prof, Mohamed S. El-Deab Prof, Bahgat E. El-Anadouli Prof

Chemical Engineering

Formic acid (FA) electro-oxidation (FAO) was investigated at a binary catalyst composed of palladium nanoparticles (PdNPs) and copper oxide nanowires (CuOxNWs) and assembled onto a glassy carbon (GC) electrode. /e deposition sequence of PdNPs and CuOxNWs was properly adjusted in such a way that could improve the electrocatalytic activity and stability of the electrode toward FAO. Several techniques including cyclic voltammetry, chronoamperometry, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction were all combined to report the catalyst’s activity and to evaluate its morphology, composition, and structure. /e highest catalytic activity and stability were obtained at the CuOx/Pd/GC …

Toward The Detection Of The Triatomic Negative Ion Spn−: Spectroscopy And Potential Energy Surfaces, Tarek Trabelsi, Majdi Hochlaf, Joseph S. Francisco

Department of Chemistry: Faculty Publications

High level theoretical calculations using coupled-cluster theory were performed to provide an accurate description of the electronic structure, spectroscopic properties, and stability of the triatomic negative ion comprising S, N, and P. The adiabatic electron affinities (AEAs) and vertical detachment energies

(VDEs) of PNS, SPN, PSN, and cyc-PSN were calculated. The predicted AEA and VDE of the linear SPN isomer are large: 2.24 and 3.04 eV, respectively. The potential energy surfaces (PESs) of the lowest-lying electronic states of the SPN isomer along the PN and SP bond lengths and bond angle were mapped. A set of spectroscopic parameters for …

Characterization Of Solution-Phase Drug-Protein Interactions By Ultrafast Affinity Extraction, Sandya Beeram, Xiwei Zheng, Kyungah Suh, David S. Hage

Department of Chemistry: Faculty Publications

A number of tools based on high-performance affinity separations have been developed for studying drug-protein interactions. An example of one recent approach is ultrafast affinity extraction. This method has been employed to examine the free (or non-bound) fractions of drugs and other solutes in simple or complex samples that contain soluble binding agents. These free fractions have also been used to determine the binding constants and rate constants for the interactions of drugs with these soluble agents. This report describes the general principles of ultrafast affinity extraction and the experimental conditions under which it can be used to characterize such …

Systems And Methods For Actuating Soft Robotic Actuators, Robert F. Shepherd, Adam Stokes, Stephen A. Morin, Ludovico Cademartiri, Jacob Freake, Rui Nunes, Xin Chen, George M. Whitesides

Department of Chemistry: Faculty Publications

Systems and methods for providing a soft robot is provided. In one system , a robotic device includes a flexible body having a fluid chamber, where a portion of the flexible body includes an elastically extensible material and a portion of the flexible body is strain limiting relative to the elastically extensible material. The robotic device can further include a pressurizing inlet in fluid communication with the fluid chamber, and a pressurizing device in fluid communication with the pressurizing inlet, the pressurizing device including a reaction chamber configured to accommodate a gas producing chemical reaction for providing pressurized gas to …

Tin Nanoparticles Encapsulated Carbon Nanoboxes As High-Performance Anode For Lithium-Ion Batteries, Ziming Yang, Hong-Hui Wu, Zhiming Zheng, Yong Cheng, Pei Li, Qiaobao Zhang, Ming-Sheng Wang

Department of Chemistry: Faculty Publications

One of the crucial challenges for applying Sn as an anode of lithium-ion batteries (LIBs) is the dramatic volume change during lithiation/delithiation process, which causes a rapid capacity fading and then deteriorated battery performance. To address this issue, herein, we report the design and fabrication of Sn encapsulated carbon nanoboxes (denoted as Sn@C) with yolk@shell architectures. In this design, the carbon shell can facilitate the good transport kinetics whereas the hollow space between Sn and carbon shell can accommodate the volume variation during repeated charge/discharge process. Accordingly, this composite electrode exhibits a high reversible capacity of 675 mAh g^{−1 …}

Anatomy Of Stem Teaching In American Universities: A Snapshot From A Large-Scale Observation Study, Marilyne Stains, Jordan Harshman, Megan K. Barker, Stephanie V. Chasteen, Renee Cole, Sue Ellen Dechenne-Peters, M. Kevin Eagan Jr., Joan M. Esson, Jennifer K. Knight, Frank A. Laski, Marc Levis-Fitzgerald, Christopher J. Lee, Stanley M. Lo, Lisa M. Mcdonnell, Timothy A. Mckay, Nicole Michelotti, Michael S. Palmer, Kathryn M. Plank, Tamara M. Rodela, Erin R. Sanders, Natalie G. Schimpf, Patricia M. Schulte, Michelle Smith, Mackenzie Stetzer, Jackie Stewart, Blaire Van Valkenburgh, Erin Vinson, Laura K. Weir, Paul J. Wendel, Lindsay B. Wheeler, Anna M. Young

Department of Chemistry: Faculty Publications

National and local initiatives focused on the transformation of STEM teaching in higher education have multiplied over the last decade. These initiatives often focus on measuring change in instructional practices, but it is difficult to monitor such change without a national picture of STEM educational practices, especially as characterized by common observational instruments. We characterized a snapshot of this landscape by conducting the first large scale observation-based study. We found that lecturing was prominent throughout the undergraduate STEM curriculum, even in classrooms with infrastructure designed to support active learning, indicating that further work is required to reform STEM education. Additionally, …

Reductive Cleavage Of Organic Peroxides By Iron Salts And Thiols, Anderw Olson, Abigail J. Jameson, Shiva K. Kyasa, Boone W. Evans, Patrick H. Dussault

Department of Chemistry: Faculty Publications

Despite the low bond strength of the oxygen− oxygen bond, organic peroxides are often surprisingly resistant to cleavage by nucleophiles and reductants. As a result, achieving decomposition under mild conditions can be challenging. Herein, we explore the reactivity of a selection of peroxides toward thiolates, phenyl selenide, Fe(II) salts, and iron thiolates. Peroxides activated by conjugation, strain, or stereoelectronics are rapidly cleaved at room temperature by thiolate anions, phenylselenide, or Fe(II) salts. Under the same conditions, unhindered dialkyl peroxides are only marginally reactive; hindered peroxides, including triacetone triperoxide and diacetone diperoxide (DADP), are inert. In contrast, all but the most …

The Secant Rate Of Corrosion: Correlating Observations Of The Uss Arizona Submerged In Pearl Harbor, Donald L. Johnson, Robert J. Deangelis, Dana J. Medlin, Jon E. Johnson, James D. Carr, David L. Conlin

Department of Chemistry: Faculty Publications

Contrary to previous linear projections of steel corrosion in seawater, analysis of an inert marker embedded in USS Arizona concretion since the 7 December 1941 attack on Pearl Harbor reveals evidence that the effective corrosion rate decreases with time. The secant rate of corrosion, or SRC correlation, derived from this discovery could have a significant impact on failure analysis investigations for concreted shipwrecks or underwater structures. The correlation yields a lower rate of metal thinning than predicted. Development of the correlation is described.

Study Of The Oxidation Kinetics Of Nitrite Ions By Potassium Ferrate(Vi), J. Carr, I. Goncharova, D. Golovko, C. Mclaughlin, I. Golovko, J. Erickson

Department of Chemistry: Faculty Publications

Вивчено кiнетику окиснення нiтрит до нiтрат йонiв калiй фератом(VI) в широкому дiапазонi рН, вiд нейтрального до лужного сере- довища. Проведено двi серiї кiнетичних експе- риментiв, заснованих на рiзних технологiях одержання калiй ферату(VI). В першiй серiї експериментiв кристалiчний калiй ферат(VI) отримували хiмiчним синтезом. В дiапазонi рН 6.5–11 твердий K₂FeO₄ додавали до роз- чинiв нiтрит йонiв при вiдомiй концентрацiї та рН. Експерименти проводили пiд контролем рН та йонної сили. Кiнетичнi дослiдження коливалися вiд мiлiсекунд до декiлькох хви- лин. В другiй серiї експериментiв розчини K₂FeO₄ було отримано електрохiмiчним син- тезом. Лужнi розчини калiй ферату(VI) в 8.0 М …

Microstructural Changes To Proso Millet Protein Bodies Upon Cooking And Digestion, Paridhi Gulati, You Zhou, Christian Elowsky, Devin J. Rose

Department of Food Science and Technology: Faculty Publications

Cooking results in a drastic decline in digestibility of proso millet proteins, panicins. Scanning electron and confocal microscopy were used to observe morphological changes in proso millet protein bodies upon cooking and digestion that could be associated with the loss in digestibility. Spherical protein bodies (1–2.5 mm) were observed in proso millet flour and extracted protein. Cooking did not result in any noticeable change in the size or shape of the protein bodies. However, upon digestion with pepsin the poor digestibility of cooked proso millet protein was clearly evident from the differences in microstructure of the protein bodies: large cavities …

Free-Base Nicotine Determination In Electronic Cigarette Liquids By 1H Nmr Spectroscopy, Anna K. Duell, James F. Pankow, David H. Peyton

Chemistry Faculty Publications and Presentations

E-liquids usually contain significant nicotine, which will exist primarily in two forms, monoprotonated and free-base, the proportions of which are alterable through the effective pH of the medium. The fraction of nicotine in the free-base form is α_fb, with 0 ≤ α_fb ≤ 1. When dosed via aerosol, the two nicotine forms have different mechanisms and kinetics of delivery, as well as differing implications for harshness of the inhaled aerosol, so α_fb is relevant regarding abuse liability. Previous attempts to determine α_fb in electronic cigarette liquids and vapor have been flawed. We employed the exchange-averaged …

Facile Synthesis Of Ligand-Free Iridium Nanoparticles And Their In Vitro Biocompatibility, Anna L. Brown, Hayden Winter, Andrea M. Goforth, Gaurav Sahay, Conroy Sun

Chemistry Faculty Publications and Presentations

High-density inorganic nanoparticles have shown promise in medical applications that utilize radiation including X-ray imaging and as radiation dose enhancers for radiotherapy. We have developed an aqueous synthetic method to produce small (~ 2 nm) iridium nanoparticles (IrNPs) by reduction of iridium(III) chloride using a borohydride reducing agent. Unlike other solution-based synthesis methods, uniform and monodispersed IrNPs are produced without the use of surfactants or other solubilizing ligands. These nanoparticles are highly crystalline as observed by X-ray diffraction and high-resolution transmission electron microscopy (TEM). In vitro metabolic toxicity assays using hepatocyte and macrophage cells demonstrate that both IrNPs and iridium(III) …