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The goal of this research was to develop alternate economic routes for the synthesis of functionalised triarylphosphines. Such species are employed as catalysts ligands in chemical synthesis and can be incorporated into designed-ylides for olefination reactions. The synthesis of the SHOP ligand, the key constituent of the Shell Higher Olefins Process for making linear alpha olefins via ethylene oligomerisation and olefin metathesis, is described using four totally new approaches. These include a Directed Ortho Metalation (DOM) approach, Copper iodide catalyzed cross-coupling, Halogen-Magnesium Exchange reaction and Diazonium salt approaches. The efficiency, in terms of overall yield and mild process conditions, make some of the routes potentially commercialisable. Additionally, a series of ortho-substitued triarylphosphines were derived to probe and modulate the reactivity of the Wittig reaction. We report that non-stabilized ortho-P-alkoxy-substituted ylides react with aromatic and aliphatic aldehydes providing (E)-olefins with high stereocontrol employing an intramolecular phenoxy and alkoxy substituent to promote (E)-olefination through betaine interconversion. In one particular case; removal of phosphoine oxide was also achieved. Extension of this methodology was also carried out on semi-stabilized benzylic ylides, which are known for producing 1:1 mixtures of (E):(Z) olefins under classical condition. Potential applications of the methodology are also described. / Thesis / Master of Science (MSc)

This dissertation summarizes my efforts and research in the Roy group to study the tunability of superatoms through ligand effects, create microporous structures from molecular cluster precursors to act as battery materials, and understand the electronic structure governing the interesting magnetic properties of Fe₆S₈(CN)₆, as well as efforts to design novel extended structures utilizing Fe₆S₈(CN)₆. Chapter 1 serves as an introduction to superatoms. It briefly discusses the quantum nature of small materials and how this gives rise to properties exhibited by superatoms. Properties which will prove important to this dissertation and methods of altering those properties through core composition and ligand choice are explored. Next, an overview of many methods to create extended structures is provided. Select examples of how superatomic clusters have already been used to increase our knowledge of fundamental concepts in science are then discussed. Finally, a brief summary and explanation of how these concepts will be explored in later chapters is given. This chapter is meant to serve as a targeted review with plenty of further reading cited for any incoming students with interest in continuing my projects. Chapter 2 discusses studies to understand the effects of either replacing PEt₃ ligands with CO ligands or the removal of PEt₃ ligands in the Co₆S₈(PEt₃)ₓ(CO)₆₋ₓ and Co₆S₈(PEt₃)ₓ systems, respectively. It presents a collaborative approach to synthesize a series of clusters for analysis by anion photoelectron spectroscopy and evaluation of results using computational chemistry. A drastic change in the donor/acceptor behavior of the cluster is observed, but surprisingly little change in the HOMO-LUMO gap is observed as the HOMO and LUMO experience similar energetic changes upon ligand removal or substitution. Chapter 3 presents a practical application for ligand removal of superatomic clusters. I present a synthesis of microspherical, highly porous materials derived from superatomic clusters. These microsphere materials display very different morphology from typical materials made using the same elemental ratio. This altered morphology results in a material which is favorable for use as a battery electrode. Its increased porosity improves its capacity retention upon cycling and at high power. The Co₆S₈(PEt₃)₆ derived material also shows promise as a Na+ ion battery material. In this chapter I also discuss unfinished studies on mixed chalcogenide materials. Chapter 4 explores the electronic basis for the high magnetic moment of the Fe₆S₈(CN)₆ cluster. Through collaboration with computational chemists, I present evidence of a phenomenon known as dual-subshell filling allowing for two spin channels holding different number of electrons resulting in many unpaired electrons. This cluster is also uniquely prepared for use as an extended material due to its cyanide ligands which may readily be used to form Prussian blue analogs. Chapter 5 describes efforts to design extended structures using the Fe₆S₈(CN)₆ cluster. Attempts towards Prussian blue analogs, covalently bound clusters using DCNQI, and EDT-TTF-CONH2 utilizing structures are discussed. Detailed notes on the synthesis of [NEt₄]₅[Fe₆S₈(CN)₆] are also provided. 2 structures which have successfully been synthesized, a 4 bridging ligand and a 2 bridging ligand “wire” are described in detail. In Chapter 6, collaborative efforts to increase our understanding of the cluster building blocks which can function as nanoscale atoms that assemble to form superatomic solids are described. We characterize a representative superatomic cluster, Co₆S₈(PEt₃)₆, in terms of structural, electronic, and magnetic properties using Solid State Nuclear Magnetic Resonance (SSNMR), Density Function Theory (DFT) calculations, and Superconducting Quantum Interference Device (SQUID) measurements. Evidence of delocalized HOMO orbitals and a delocalized spin in the oxidize cluster is shown. The findings presented in this chapter will assist the design of superatomic clusters and state-of-the-art applications, such as single-electron devices. Finally, Chapter 7 is much shorter than the other chapters as it is used to describe smaller projects which do not fit in the scope of the overall thesis. Magnetic measurements on a compound designed in the Norton lab are described.

Yes / Half-sandwich metal complexes are of considerable interest in medicine, material, and nanomaterial chemistry. The design of libraries of such complexes with particular reactivity and properties is therefore a major quest. Here, we report the unique and peculiar reactivity of eight apparently 16-electron half-sandwich metal (ruthenium, osmium, rhodium, and iridium) complexes based on benzene-1,2-dithiolato and 3,6-dichlorobenzene-1,2-dithiolato chelating ligands. These electron-deficient complexes do not react with electron-donor pyridine derivatives, even with the strong σ-donor 4-dimethylaminopyridine (DMAP) ligand. The Ru, Rh, and Ir complexes accept electrons from the triphenylphosphine ligand (σ-donor, π-acceptor), whilst the Os complexes were found to be the first examples of non-electron-acceptor electron-deficient metal complexes. We rationalized these unique properties by a combination of experimental techniques and DFT/TDFT calculations. The synthetic versatility offered by this family of complexes, the low reactivity at the metal center, and the facile functionalization of the non-innocent benzene ligands is expected to allow the synthesis of libraries of pseudo electron-deficient half-sandwich complexes with unusual properties for a large range of applications.

Hybrid inorganic-organic networks have been studied in both chemistry and materials science due to properties, (e.g. porosity, magnetic and electronic behaviors) that may lead to applications in catalysis, gas absorption and storage. It is important to understand the different structural topologies shown by hybrid networks to help develop practical applications for these materials. The research is focused on the design and synthesis of well-defined hybrid network structures that have potential to contain molecular size cavities that can be used for catalysis and gas storage. In the field of organic-inorganic hybrid networks, the goals are to design and synthesize 1D, 2D and 3D networks with cavities, and to characterize them by X-ray, TGA and surface area measurements. Twenty-six networks have been successfully made with interesting structure topologies. These hybrid network structures are classified into three series based on their ligands. Series I contains ten hybrid networks constructed from the flexible ligand, 4, 4′-trimethylenedipyridine (TMDP), Zn2+ ions, and H3PO3, and with aromatic alcohols as templates to direct the formation of various hybrid network structures. Series II consists of five structures constructed from the relatively rigid ligand, 4, ′-bisimidazolelybipyridine (BIB) with metal ions (Cu2+, Ni2+) and the conjugated bases of H3PO3 and H3PO4. The BIB ligand is not commercially available so is produced and characterized by NMR, mass spectrometry and TGA. Rigid network structures were expected to construct with pores of molecular dimensions with the BIB ligand. To date, the BIB ligand has not yield the desired porous network, however, these 3D hybrid networks have interesting topologies, one of which is an interdigitated network that is the precursor for 3D interpenetrated networks. Series III contains five hybrid structures constructed from various organic ligands, such as tartaric acid, picolinic acid and 1, 2, 4-triazole. In addition to the hybrid networks, six hydrogen bonded networks were prepared. Graph-Analysis is applied to study these hydrogen bonded network structures. The Ï â ¦.Ï interaction is also discussed within the hydrogen bonded networks. / Ph. D.

The peptidyl prolyl cis/trans isomerase, PPIase, has been the focus of numerous studies in the field of cell cycle regulation since proline-directed phosphorylation is an essential signaling mechanism that might arrest cancer proliferation. Pin1 is the first phosphorylation-dependent PPIase enzyme to be discovered. The Pin1 regulatory mechanism, acting on other mitotic proteins in vivo and in vitro, remains largely unknown. For the study of Pin1 function, two types of assays were used to identity ligands for Pin1: (1) The Enzyme-Linked Enzyme Binding Assay (ELEBA) for the identification of WW domain ligands, (2) a catalytic assay to identified inhibitors of Pin1 catalytic activity. The ELEBA offers a selective approach for detecting ligands that bind to the Pin1 WW domain from chemical libraries. By using the ELEBA, a pSer-Pro peptidomimetic library of 315 ligands was screened, identifying three promising ligands cis-D2, O2, and M18. Competitive Kd values for cis-D2, O2, and M18 were determined to be 263 ± 6.4, 206 ± 3.4, and 130 ± 3.0μM, respectively. Furthermore, we screened the pSer-Pro peptidomimetic library using a Pin1 discontinuous-catalytic assay to identify inhibitors of Pin1. Ligands D20 and K7 were identified to decrease more than 90% of the Pin1 catalytic activity. To investigate the nature of the Pin1 interaction with c-Myc, we synthesized and characterized four peptides corresponding to the c-Myc sequence. These peptides were used in NMR isomerization studies of Pin1 by our collaborator Dr. Jeffry Peng (University of Notre Dame). Preliminary work shows that Pin1 binds and isomerizes the Ac–LLPpTPPLSPS–NH₂ peptide at the cMyc pThr58 position. Finally, we measured a secondary kinetic isotope effect (2º KIE) to study the Pin1 catalytic mechanism of proline isomerization. The ratio of kH/kD for unlabeled and [d₃]Ser-labeled substrate gave a SKIE value of 1.34 ± 0.01. The normal 2º KIE value indicates that carbonyl-serine hybridization is not changing from sp² to sp³. This result supports substrate analogue inhibitor studies, and previous solvent and SKIE results on Pin1, that suggest a twisted amide mechanism assisted by a transient hydrogen bond in the transition state. / Ph. D.

Organoboron compounds have shown a wide variety of applications in both organic synthesis and the pharmaceutical field in the past decades. Transition metal-catalyzed boration of unsaturated compounds has been studied extensively as an efficient method to install C-B bonds. Most of the previous examples employed symmetrical diboron reagents such as B₂(pin)₂ (pin = pinacolate) and B₂(cat)₂ (cat = catecholate). There are, however, limited examples of boration using unsymmetrical diboron reagents. This dissertation discloses two transition metal-catalyzed borations of unsaturated compounds with unsymmetrical diboron compounds. A Cu-catalyzed β-boration of electrophilic allenoates with a novel sp²-sp³ hybridized diboron reagent (PDIPA) is described. This unsymmetrical diboron reagent is preactivated and allows the boration to go smoothly under mild reaction conditions. The reaction provides β-borylated β,γ- unsaturated esters with exclusive (Z)-double bond geometry. These borylated products are useful intermediates for subsequent Suzuki-Miyaura cross-coupling reaction. In order to install two C-B bonds in one reaction, a Pt-catalyzed diboration of allenes with a differentially protected diboron reagent (PDAN) is presented. This unsymmetrical diboron reagent is prepared from the sp²-sp³ hybridized diboron compound, and it reacts with a series of 1,1- disubstituted allenes chemo- and regioselectively. Steric control ensures that both boryl moieties add to the terminal double bond, and the pinacol boronate preferentially attaches to the sp-hybridized carbon. The bis-boronyl products can be further converted to other functional groups as well as cross-coupling reactions. A collaborative project with Department of Physics and Department of Chemical Engineering is also discussed. In this project, a series of 𝑜-nitrobenzyl ligands containing a disulfide group as the anchor to gold surfaces are synthesized. The 𝑜-nitrobenzyl group uncages an amine upon photoexcitation. Attempts to make a water soluble analog failed, however, the mixture of methanol and water as the solvent was sufficient to attach them on gold surfaces. / Ph. D.

The pink color defect in cooked, uncured turkey is a sporadic problem which can result in consumer dissatisfaction. Nicotinamide hemochrome may be one of the major pigments responsible for this defect. Reflectance (400-700 nm) methodology was developed to reliably and easily quantify (%R 537 nm/%R 553 nm; r = 0.993) the presence of nicotinamide hemochrome. Fourteen ligands were tested in a ground turkey system to determine their ability to reduce pinking in control samples and in the presence of pinking agents (1.0% nicotinamide or 150 ppm sodium nitrite). Trans 1,2-diaminocyclohexane-N,N,N’,N’ tetraacetic acid monohydrate (CDTA); diethylenetriamine pentaacetic acid (DTPA), ethylenedinitrilo-tetraacetic acid disodium salt (EDTA), and calcium reduced non-fat dry milk (NFDM) were the most effective at reducing pinking with and without pinking agents. These four ligands were evaluated in intact turkey breasts with and without added pinking agents (1.0% nicotinamide or 20 ppm, 100 ppm sodium nitrite). Ligands were evaluated at various levels (50, 100, 200 ppm; except NFDM 1.0% or 2.0%), over three storage times (1, 14, 21 days), and after two minutes of exposure to light and air. When ligands were evaluated without pinking agents, samples were generally lighter and less pink than controls. In the presence of added pinking agents, the ligands were more successful at reducing nicotinamide pink than nitrite pink. As storage time increased, samples became more pink and the addition of ligands was only successful in delaying this affect. One of the most effective ligands, DTPA, reduced the sample CIE a* value 31.7% when tested alone and 30.8% in the presence of nicotinamide. NICHEM was also effectively reduced by DTPA. In general, 50 ppm of added ligand was sufficient to produce a significant reduction in pinking. / Master of Science

Complexes of the general formula M(X-SALDAPE) and M(X-SALDAPS) formed by the reaction of substituted salicylaldehydes and bis(3,3'-aminopropyl)ether or bis(3,3'-aminopropyl)sulfide with nickel(II) and cobalt(II) have been isolated. The complexes have been characterized by elemental analysis, mass spectra, infrared spectra, magnetic susceptibility measurements, and ultraviolet-visible-near infrared spectra. In the solid state the nickel(II) complexes, Ni(X-SALDAPE) and Ni(X-SALDAPS), where X = H, 5-Br, 3-(CH₃)₂CH, or 3-CH₃O, are speculated as pseudo-square planar or weak low-spin five-coordinate structures. The complexes exhibit anomalous magnetic behavior explained in terms of a spin state isomerism between singlet and triplet spin states. In a non-coordinating solvent, the nickel complexes are pseudo-square planar losing all five-coordinate structural features due to salvation. When dissolved in a coordinating solvent, the complexes are high-spin pseudo-octahedral. The cobalt(II) complexes, Co(H-SALDAPE) and Co(X-SALDAPS) where X = H, or 3-(CH₃)₂CH, were found to be high-spin pseudo-tetrahedral in the solid state with magnetic moments of approximately 3.4 B.M. The olive green nickel complexes are stable to air and moisture. The brownish cobalt complexes are stable as dry solids, but very easily oxidized when wet. / Master of Science