The problem of this study was to develop a curriculum based on present destructive testing procedures used in industry dealing with the mechanical properties of ferrous and non-ferrous metals, and to organize the curriculum at the university level.

The oxidative elimination reactions of (5-X-phen)Mo(C0)₄ (X = H, CH₃, Cl, NO₂; phen = o-phenanthroline) and (3,4,7,8-(CH₃)₄-phen)Mo(CO)₄ with mercuric chloride in acetone have been investigated. In these reactions, a carbon monoxide group is replaced by two univalent ligands, accompanied by the corresponding increase in coordination number and formal oxidation state of the central metal atom, to give products of the type, (X-phen)Mo(CO)₃(Cl)HgCl. With the exception of (3,4,7,8-(CH₃)₄-phen), the substituted o-phenanthrolines were selected so as to minimize steric differences from one substrate to another while obtaining the widest range of pKₐ of the ligand.

Thesis advisor: Chia-Kuang (Frank) Tsung / The core-shell hybrid structure is the simplest motif of two-component systems which consists of an inner core coated by an outer shell. Core-shell composite materials are attractive for their biomedical, electronic and catalytic applications in which interface between core and shell is critical for various functionalities. However, it is still challenging to study the exact role that interface plays during the formation of the core-shell structures and in the properties of the resulted materials. By studying the formation mechanism of a well interface controlled one-to-one metal nanoparticle (NP)@zeolite imidazolate framework-8 (ZIF-8) core-shell material, we found that the dissociation of capping agents on the NP surface results in direct contact between NP and ZIF-8, which is essential for the formation of core-shell structure. And the amount of capping agents on the NP surface has a significant effect to the crystallinity and stability of ZIF-8 coating shell. Guided by our understanding to the interface, one-to-one NP@UiO-66 core-shell structure has also been achieved for the first time. We believe that our research will help the development of rational design and synthesis of core-shell structures, particularly in those requiring good interface controls. / Thesis (MS) — Boston College, 2017. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Copper and iron are trace elements that form an indispensable part of many proteins and are crucial for the well-being of all cells. At the same time, the intracellular levels of these metals require careful regulation, as excess or deficiency may be lethal. P1B-ATPases are key players in metal homeostasis. They belong to the superfamily of P-type ATPases, transmembrane proteins present in virtually all life forms, are responsible for solute translocation across biological membranes. The goal of this thesis is to improve our understanding of the structural and functional roles of P1B-ATPases in metal homeostasis by focusing on the host-microbe interaction. The thesis first describes the importance of Cu+ distribution in the outcome of host-microbe interaction. Copper is an important element in host-microbe interactions, acting both as a catalyst in enzymes and as a potential toxin. Cu+-ATPases drive cytoplasmic Cu+ efflux and protect bacteria against metal overload. Many pathogenic and symbiotic bacteria contain multiple Cu+-ATPase genes within particular genetic environments, suggesting alternative roles for each resulting protein. This hypothesis was tested by characterizing five homologous Cu+-ATPases present in the symbiotic organism Sinorhizobium meliloti. Mutation of each gene led to different phenotypes and abnormal nodule development in the alfalfa host. Distinct responses were detected in free-living S. meliloti mutant strains exposed to metal and redox stresses. Differential gene expression was detected under Cu+, oxygen or nitrosative stress. These observations suggest that CopA1a maintains the cytoplasmic Cu+ quota and its expression is controlled by Cu+ levels. CopA1b is also regulated by Cu+ concentrations and is required during symbiosis for bacteroid maturation. CopA2-like proteins, FixI1 and FixI2, are necessary for the assembly of two different cytochrome c oxidases at different stages of bacterial life. CopA3 is a phylogenetically distinct Cu+-ATPase that does not contribute to Cu+ tolerance. It is regulated by redox stress and required during symbiosis. We postulated a model where non-redundant homologous Cu+-ATPases, operating under distinct regulation, transport Cu+ to different target proteins. In its second part, the thesis describes the novel Fe2+-ATPases and their influence in the host-microbe interaction. Little is known about iron efflux transporters in bacterial systems. Recently, the participation of Bacillus subtilis PfeT, a P1B4-ATPase, in cytoplasmic Fe2+ efflux has been proposed. We report here the distinct roles of mycobacterial P1B4-ATPases in the homeostasis of Co2+ and Fe2+. Mutation of Mycobacterium smegmatis ctpJ affects the homeostasis of both ions. Alternatively, a M. tuberculosis ctpJ mutant is more sensitive to Co2+ than Fe2+, while mutation of the homologous M. tuberculosis ctpD leads to Fe2+ sensitivity but no alterations in Co2+ homeostasis. In vitro, the three enzymes are activated by both Fe2+ and Co2+ and bind one equivalent of either ion at their transport site. However, equilibrium binding affinities and activity kinetics show that M. tuberculosis CtpD has higher affinity for Fe2+ and twice the Fe2+ stimulated activity than the CtpJs. These parameters are accompanied by a lower activation by and affinity for Co2+. Analysis of Fe2+ and Co2+ binding to CtpD by X-ray spectroscopy shows that both ions are coordinated by 5-6 O/N atoms with similar geometry. Mutagenesis studies suggest the involvement of invariant Ser, His and Glu in metal coordination. Interestingly, replacement of Cys in the conserved CPS sequence at the metal binding pocket leads to a large reduction in Fe2+ but not Co2+ binding affinity. We propose that CtpJ ATPases participate in the control of steady state Fe2+ levels. CtpD, required for M. tuberculosis virulence, is a high affinity Fe2+ transporter involved in the rapid response to iron dyshomeostasis generated upon redox stress. These studies provide significant insights into the metal selectivity, regulation, transport kinetics and functional diversity of homologous P1B-ATPases in Cu+ and Fe2+ homeostasis. Moreover, these biochemical characterizations can be integrated with the structural-functional analysis to elucidate the complex metal distribution networks.

Guo-cong Guo. / "June 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Chapter 1 focuses on the computational study of Zr(CH2Ph)4 and chapter 2 discusses synthesis, characterization and density functional study of 2-imidazolethione. Chapters 3 - 6 describe the synthesis, structural characterization several multidentate tripodal ligands, namely tris(mercaptoimidazolyl)-hydroborato ligand, [TmR], tris(2-pyridylseleno)methyl ligand, [Tpsem], bis(2-pyridonyl)(pyridine-2-yloxy)methyl ligand, [O-poBpom] and allyl-tris(3-t-butylpyrazolyl)borato ligand, [allylTpBut], and their application to main group and transition metals. Chapter 1 describes the analysis of a monoclinic modification of Zr(CH2Ph)4 by single crystal X-ray diffraction, which reveals that the Zr-CH2-Ph bond angles in this compound span a range of 25.1°; that is much larger than previously observed for the orthorhombic form (12.1°;). In accord with this large range, density functional theory calculations demonstrate that little energy is required to perturb the Zr-CH2-Ph bond angles in this compound. Furthermore, density functional theory calculations on Me3ZrCH2Ph indicate that bending of the Zr-CH2-Ph moiety in the monobenzyl compound is also facile, thereby demonstrating that a benzyl ligand attached to zirconium is intrinsically flexible, such that its bending does not require a buffering effect involving another benzyl ligand. Chapter 2 describes the structure of 1-t-butyl-1,3-dihydro-2H-benzimidazole-2-thione which has been determined by X-ray diffraction. The compound exists in the chalcogenone form instead of chalcogenol form, which is similar to its oxo and selone counterparts. Comparison of 2-imidazolone, 2-imidazolethione and 2-imidazoleselone compounds shows that two N-C-E bond angles in the chalcogenone forms are not symmetric. This trend can be reproduced by density functional theory calculations. Additionally, H(mbenzimBut) has intermolecular hydrogen bonding interactions, whereas its selenium counterpart does not. The C-E bond lengths of 2-imidazolone, 2-imidazolethione and 2-imidazoleselone compounds are intermediate between those of formal C-E single and double bonds, which is in accord with the notion that zwitterionic structures that feature single C+-E- dative covalent bonds provide an important contribution in such molecules. Furthermore, NBO analysis of the bonding in H(ximBut) derivatives demonstrates that the doubly bonded C=E resonance structure is most significant for the oxygen derivative, whereas singly bonded C+-E- resonance structures dominate for the tellurium derivative. This result appears to be counterintuitive, based on the fact that it opposes the trend that one would expect on the basis of electronegativity difference, however, studies on XC(E)NH2 derivatives provide solid support for it. In this regard, the C~E bonding in these compounds is significantly different to that in chalcogenoformaldehyde derivatives for which the bonding is well represented by a H2C=E double bonded resonance structure. Chapter 3 describes the computational study on [TmMeBenz] anion and the synthesis and characterization of [TmButBenz]Na, [TmButBenz]Tl and [TmButBenz]Tl. It is worth noting that the two thallium compounds are the first structurally characterized monovalent monomeric [TmR]Tl complexes. Chapter 4 describes the synthesis and characterization of a few [TmR]M (M = Ti, Zr, Hf) complexes, including (i) Cp[TmBut]TiCl2 and Cp[TmBut]ZrCl2, which are analogues of Cp2TiCl2 and Cp2ZrCl2; (ii) [TmBut]Zr(CH2Ph)3 and (iii) [TmBut]Hf(CH2Ph)3 and [TmAd]Hf(CH2Ph)3, which are the first structurally characterized [TmR]Hf complexes. Chapter 5 describes two multidentate, L3X type ligands, which feature [CN3] and [CNO2] donors, namely tris(2 pyridylseleno)methane, [Tpsem]H, and bis(2-pyridonyl)(pyridin-2-yloxy)methane, [O-poBpom]H. They have been synthesized, characterized, and employed in the synthesis of zinc and cadmium complexes. Chapter 6 describes the synthesis and structural characterization of a new [Tp] ligand featuring an allyl substituent on the central boron atom, namely [allylTpBut]Li is reported. The compound reacts steadily with CH3CH2SH under 350 nm UV light via a thiol-ene click reaction. The resulting [CH3CH2S(CH2)3TpBut]Li complex can further react with metal halide. For example, the reaction of [CH3CH2S(CH2)3TpBut]Li with ZnI2 produced [CH3CH2S(CH2)3TpBut]ZnI at room temperature. This study provides a simple model on the immobilization of [Tp] metal complexes to the polymer chains with -SH terminals.

The molecular structures of [κ³-S₂H-Tmᴮᵘᵗ]Na(THF)₃ and [κ³-S₂H-Tmᴬᵈ]Na(THF)₃ have been obtained, which is significant as these are the first two examples of monomeric κ³-S₂H coordinate sodium compounds to be reported. Based on an extensive structural analysis of all of the [Tmᴿ]M compounds listed in the Cambridge Structural Database, a set of criteria has been generated that can be used to classify [Tmᴿ] ligands according to their coordination modes. Compounds exhibiting κ³-S₃ coordination are found to be the most prevalent, as are compounds exhibiting 0:3 conformation modes. A series of [Tmᴮᵘᵗ]CdO₂CR complexes (R = C₆H₄-4-Me; C₆H₄-4-F; C₆H₃-3,5-F₂; C₆H₃-2,6-F₂; C₃H₆Ph; 9-An; and tridecyl) has been prepared via the reaction of [Tmᴮᵘᵗ]CdMe with the corresponding carboxylic acids. [Tmᴮᵘᵗ]ZnO₂CR (R = C₆H₄-4-Me; C₆H₄-4-F; C₆H₃-3,5-F₂; C₆H₃-2,6-F₂; 9-An) have been prepared by an analogous method. In addition, two thiobenzoate complexes, [Tmᴮᵘᵗ]MSC(O)Ph (M = Zn, Cd), have been obtained via the treatment of [Tmᴮᵘᵗ]MR (R = Me) with thiobenzoic acid. An extensive structural analysis of the [Tmᴮᵘᵗ]MO₂CR and [Tmᴮᵘᵗ]MSC(O)Ph complexes has been provided, based on single crystal X-ray diffraction and NMR spectroscopy. In addition, degenerate benzoate exchange between [Tmᴮᵘᵗ]MO₂C(4-C₆H₄-F) and 4-fluorobenzoic acid has been investigated by ¹⁹F-NMR lineshape analysis over a large temperature range (195-262 K). The acid concentration dependence of the rate for the exchange process supports an associative exchange mechanism. [Tmᴮᵘᵗ]MO₂C(4-C₆H₄-F) benzoate exchange is extremely rapid on the 19F NMR timescale at 25˚, and has been observed to be faster for [Tmᴮᵘᵗ]CdO₂C(4-C₆H₄-F) than for [Tmᴮᵘᵗ]ZnO₂C(4-C₆H₄-F). The reactivity of [Tmᴮᵘᵗ]CdS(C₆H₄-4-F) towards different thiols, ArSH (Ar = C₆H₄-4-F, C₆H₄-4-Buᵗ, C₆H₄-4-OMe, C₆H₄-3-OMe), has been investigated using various NMR techniques. In contrast to the results of our degenerate benzoate exchange studies, thiolate exchange between [Tmᴮᵘᵗ]CdS(C₆H₄-4-F) and ArSH is slow on the ¹H NMR timescale. Even at elevated temperatures, the NMR signals for the reaction species remain resolved with minimal linebroadening. The equilibrium constants for the reactions of [Tmᴮᵘᵗ]CdS(C₆H₄-4-F) with ArSH (Ar = C₆H₄-4-But, C₆H₆-4-OMe, C₆H₄-3-OMe) have been calculated and determined to be indistinguishable, with equilibrium favoring the [Tmᴮᵘᵗ]CdS(C₆H₄-4-F) and ArSH species. Additionally, the reactivity of [Tmᴮᵘᵗ]CdS(C₆H₄-4-F) toward phenols, ArOH (Ar = Ph, 2,6-diphenylphenol), has been investigated. While [Tmᴮᵘᵗ]CdS(C₆H₄-4-F) has been found to be unreactive toward ArOH, [Tmᴮᵘᵗ]CdSOAr (Ar = 2,6-diphenylphenol) reacts immediately (C₆H₄-4-F)SH, resulting in complete conversion to [Tmᴮᵘᵗ]CdS(C₆H₄-4-F). Two monomeric [Tmᴮᵘᵗ]CdE(2-C₅H₄N) complexes (E = S, Se) have also been prepared, and structurally characterized. A monomeric, terminal zinc hydride complex, [Tmᴮᵘᵗ]ZnH, has been prepared via the reaction of [Tmᴮᵘᵗ]ZnOPh with phenylsilane. The molecular structure of [Tmᴮᵘᵗ]ZnH has been obtained by single crystal X-ray diffraction techniques, and the reactivity of [Tmᴮᵘᵗ]ZnH towards various reagents has been investigated. [Tmᴮᵘᵗ]ZnH reacts rapidly with ArEH (EAr = OPh, S(C₆H₄-4-F), SePh) to form [Tmᴮᵘᵗ]ZnEA via H₂ elimination. [Tmᴮᵘᵗ]ZnH reacts with CO₂ to form [Tmᴮᵘᵗ]ZnO₂CH via CO₂ insertion into the Zn-H bond. [Tmv]ZnO₂CH can also be prepared by the reaction of [Tmᴮᵘᵗ]ZnH with formic acid. [Tmᴮᵘᵗ]ZnH reacts rapidly with ZnEt₂ to form [Tmᴮᵘᵗ]ZnEt. The reaction of [Tmᴮᵘᵗ]ZnH with CpMo(CO)₃H resulted in the formation of a metal-metal bonded complex, namely [Tmᴮᵘᵗ]Zn-MoCp(CO)₃. A series of [Tmᴮᵘᵗ]M-M'Cp(CO)₃ heterobimetallic complexes (M = Zn, Cd; M' = Cr, Mo, W) has been prepared via the reaction of [Tmᴮᵘᵗ]MR (R = Me) with CpM'(CO)₃H. An extensive structural analysis of these complexes is provided, based on X-ray diffraction and NMR spectroscopy. Each of these complexes features a direct M-M' bond, which is supported by two partially bridging carbonyl ligands. Only a few complexes featuring an M-M' bond have been structurally characterized, and the molecular structures of [Tmᴮᵘᵗ]Zn-CrCp(CO)₃ and [Tmᴮᵘᵗ]Cd-WCp(CO)₃ represent the first two structures reported for compounds featuring either a Zn-Cr or Cd-W bond. The coordination chemistry of [tpyᴬʳ] (Ar = p-tolyl, mesityl) and [bppᴮᵘᵗ] with various main group and transition metals has been investigated. [tpyᴬʳ]MX₂ complexes (M = Co, Zn; X = Cl, I) are prepared by the reaction of [tpyᴬʳ] with the dihalide MX2 complex. [bppᴮᵘᵗ]MX2 (M = Fe, Co, Zn, Cd; X = Cl, I) complexes are prepared by an analogous method. Each of these [tpyᴬʳ]MX₂ and [bppᴮᵘᵗ]MX₂ complexes have been characterized by single crystal X-ray diffraction. The [bppᴮᵘᵗ]LiI compound was unexpectedly obtained from the reaction of [bppᴮᵘᵗ]FeCl₂ with MeLi, which is significant as it is the first example of an alkali metal complex featuring a [bppᴮᵘᵗ] ligand that has been structurally characterized.

Master of Science / Department of Chemistry / Tendai Gadzikwa / Molecular architecture involves the assembly of molecular building blocks to form supramolecular structures and the decoration of their interiors. The evolution and gathering of molecular building blocks into supramolecular constructs include examples such as co-crystals, micelles, nanoparticles, etc. These cases offer novel and advantageous pathways for research in supramolecular chemistry, however, a class of materials known as metal-organic frameworks (MOFs) materials has emerged as a prime candidate for molecular construction and interior design. MOFs are highly tunable materials because they can be synthesized from a wide range of metals cations and organic linkers. The organic linkers can also be functionalized after the MOF material has been synthesized through a process known as post-synthetic modification (PSM). These materials can be synthesized using two different organic linkers, resulting in a mixed-ligand MOF. If these ligands are modifiable and react independently, the resulting MOF structure will be orthogonally functionalized. Upon PSM we hypothesize that our porous, mixed-ligand MOF will contain homogenous bifunctionality as a blueprint for the construction of a uniformly orthogonally functionalized MOF. The synthesis of the first metal-organic framework, KSU-1, is the first of its kind to be developed at Kansas State University. PSM strategies used in this research show successful functionalization of each organic linker leading to uniform bifunctionality throughout our material. Characterization studies commonly used with MOFs verifies the synthesis and PSM of KSU-1.

A well designed runner and feeding system should produce castings with minimal defects and low pour weight. This thesis investigates how the filling regime and solidification of the mould influences defects in the castings produced from that mould. Design guidelines to reduce such defects are proposed and tested. An existing shrinkage fault in a Grey Iron disc brake casting is simulated using a commercial finite-difference computer program. Three criteria are used to predict the defect and the effect of changes to the feeder geometry. Critical Fraction Solidification analysis is used to determine whether the feeder remains in liquid contact with the casting during solidification and this approach is shown to correctly predict the presence or absence of porosity* The feeder block is extended below the ingate of the casting to improve liquid contact between the casting and feeder without significantly increasing the feeder mass. Plant trials confirm the change to the feeder eliminates the porosity defect. The runner system and mould venting for a thin walled Ductile Iron casting are investigated. Trials show that by setting the total mould vent area to be greater than the net ingate area of the castings, the cold-shut frequency is halved. A method for runner system design based on peak linear flow velocity in the runner during mould filling is proposed. A new pressurised runner system produces castings with significantly fewer defects and reduced pour weight when runner areas are designed to maintain peak velocity below 1 m/s. Peak velocity and magnesium levels are demonstrated to be critical factors in the elimination of cold-shut defects. A pressurised runner system is also shown to isolate inclusion defects from castings more effectively than an unpressurised system. From this work, a technique is proposed which allows the yield of an existing runner and feeder system for iron castings to be improved with confidence in the results.

Thesis (M.A.)--University of North Carolina at Wilmington, 2006. / Includes bibliographical references (leaves: 96-97)