Nitrogen oxide trifluoride was prepared in trace quantities by the reaction of nitric oxide and fluorine. Low, but improved yields were obtained when nitrosyl fluoride and fluorine were heated together at 220°. It was found that (NO)₂2NiF₆ was formed by the reaction of the walls of the Monel reaction vessels, with nitrosyl fluoride, and fluorine, and that pyrolysis of this salt (in 70 p.s.i. fluorine at 350°) gave the new compound in good yield. The reactions of platinum and iridium hexafluoride with nitrosyl fluoride were investigated as routes to ONF₃. Nitrogen oxide trifluoride was colourless in the solid, liquid, and gaseous phases, melting at -161° and boiling at -87.5°. The vapour pressure was determined over the range -128° to -78°. The empirical formula was established by elemental analysis, and by determination of its molecular weight. The structural formula ONF₃ was established from the ¹⁹F n.m.r., and the infrared spectrum of the compound. Nitrogen oxide trifluoride was found to be only moderately reactive. There was no evidence that ONF₃ could be protonated by strong acids. A 1:1 adduct was formed with AsF₅. The chemical behaviour and infrared spectrum of ONF3,AsF₅ was consistent with the formulation ONF₂⁺AsF₆⁻. The empirical formula of (NO)₂^NiF₆ was established by elemental analysis. Its infrared spectrum, and magnetic susceptibility showed that it contained the (NO)⁺ and (NiF₆)²⁻ ions, and a low spin d⁶ arrangement for Ni(IV). The X-ray powder diffraction patterns of (NO)₂NiF₆ could be indexed on the basis of a hexagonal unit cell a = 5.524 Å, c = 5.097 Å, except for five diffuse lines that varied in intensity from sample to sample. Weissenberg (h k 0, h k 1,h k 2, h k 3) photographs showed two sets of reflections. One sharp strong set that could be indexed on the basis of the same hexagonal cell as the lines of the powder photograph, and a weak diffuse set of reflections that together with the strong reflections could be indexed on the hexagonal unit cell, a = 4x5.524, c = 5.097 Å. A structure determination was carried out using the strong sharp set of reflections. The diffraction data were consistent with various models, but the most likely model consisted of (NiF₆)²⁻ groups with the fluorine atoms in a regular octahedron around the nickel atom and the Ni-F bond distance equal to 1.76 Å. The N-O bond distance was very short, 0.88Å, and had associated with it regions of electron density normal to the axis defined by the nitrogen and oxygen atoms. A similar situation for the O2⁺ ion in O₂PtF₆ was reported by Ibers and Hamilton.(108) At 200° chlorine pentafluoride and iridium hexafluoride reacted to give small quantities of a yellow compound which was characterised as ClF₂⁺IrF₆⁻ from elemental analysis, magnetic susceptibility measurements, and its infrared spectrum. A structural determination was attempted from single crystal X-ray data. Preliminary results suggest that the iridium atoms form an ab face centred array, and the chlorine atoms are situated almost in the centre of the square pyramidal holes defined by the iridium atoms. / Arts, Faculty of / Philosophy, Department of / Graduate

This thesis reports the spectroscopic studies of two gaseous molecules, niobium nitride (NbN) and vanadium oxide (VO). The ³∏ — ³∆ electronic transition of NbN was recorded by laser-induced fluorescence at Doppler-limited resolution as well as at sub-Doppler resolution. Two almost identical branch features are observed in the ³∏₀ — ³∆₁ sub-band because the A-doubling in the ³∏₀ sub-state is large and almost J-independent. The ³∏₁ — ³∆₂ transition is shifted 600 cm⁻¹ to the red of its central first-order position as a result of very large second-order spin-orbit interaction effects. The shift is believed to be caused principally by the coupling of the ³∏₁ component with the ¹∏ state from the same electron configuration, with a smaller contribution from coupling of the ³∆₂ component of the ground state with the low-lying ¹∆ state. The ³∏ and ¹∏ states are unusual in that their zero-order energies are calculated to be within 100 cm⁻¹, based on the newly observed ¹∏₁ - ³∆₂ (1,0) transition; this means that they form a very fine example of a "super-multiplet", where the spin-orbit effects within and between the states of a particular electron configuration are larger than their separations. The spin-orbit interactions are so extensive that the fine structure can only be fitted using effective rotational and hyperfine Hamiltonians for the individual sub-states, as in case (c) coupling. From the determined hyperfine constants h and C⍳ for the three ³∏(v — 0) components, the Fermi contact constant b was found to be negative, which is consistent with the configuration πδ. Rotational analysis gave the ³∏ and ³∆ bond lengths as 1.6705 Å and 1.6622 Å, respectively. The near-infrared electronic system of VO has been recorded in emission at Doppler-limited resolution with the 1-m FT spectrometer at Kitt Peak National Observatory. The spectrum in the 4000-14000 cm⁻¹ region consists of numerous transitions with most of them extensively analyzed. Two isolated sub-bands at 7200 cm⁻¹ have been assigned as the two spin components of a ²∏ — ²∆ transition and rotationally analyzed. The rotational constant for the lower state is found to be larger than that for the σδ² X ⁴∑⁻ ground state, indicating that the ²∆ state arises from the electron configuration σ²δ. The configuration assignment was confirmed by the derived spin-orbit coupling constant for the ²∆ state. Similar reasoning applied to the ²∏ upper state suggests that it may arise from the configuration σ²π, though the preliminary study of the hyperfine structure argues against this assignment. / Science, Faculty of / Chemistry, Department of / Graduate

Bibliography: pages 83-90. / Beta alumina solid electrolyte material is conventionally synthesized by the high temperature solid state reaction of α-Al₂O₃ with soda and a stabilizer ion such as lithia or magnesia. This reaction requires a reconstructive transformation of the α-Al₂O₃ oxygen sublattice and results in a two-phase mixture of β and β"-Al₂O. In order to maximize the preferred β"-Al₂O₃ phase an additional peak heat treatment schedule is required. This work investigated the replacement of the α-Al ₂O₃ component of the reaction mixture with a range of synthetic aluminium hydroxide precursor materials. Four different aluminium hydroxide precursors were synthesized by the controlled hydrolysis of a common aluminium isopropoxide parent material. The oxygen sublattice of each aluminium hydroxide precursor was engineered by varying the alkoxide hydrolysis conditions. These precursors were used to synthesize beta alumina powders by the high temperature solid state reaction with soda and lithia, resulting in powders with a nominal composition of Li₀.₃₈Na₁.₆₅Al₁₀.₆₆O₁₇. The solid state reactions were monitored by differential thermal analysis and thermogravimetric analysis. The structural development of the reaction products with increasing temperature, was monitored by powder X-ray diffraction. A significant observation was the direct formation of single phase β"-Al₂O₃ at 1200 °C by the solid state reaction of soda and lithia with certain aluminium hydroxides. The work concludes with the proposal of a generalized mechanism relating the aluminium hydroxide precursor oxygen sublattice to the nature of the beta alumina reaction product.

Conventional liquid lubricants are faced with limitations under extreme cyclic operating conditions, such as in applications that require lubrication when changing from atmospheric pressure to ultrahigh vacuum and ambient air to dry nitrogen (e.g., satellite components), and room to elevated (>500°C) temperatures (e.g., aerospace bearings). Alternatively, solid lubricant coatings can be used in conditions where synthetic liquid lubricants and greases are not applicable; however, individual solid lubricant phases usually perform best only for a limited range of operating conditions. Therefore, solid lubricants that can adequately perform over a wider range of environmental conditions are needed, especially during thermal cycling with temperatures exceeding 500°C. One potential material class investigated in this dissertation is lubricious oxides, because unlike other solid lubricant coatings they are typically thermodynamically stable in air and at elevated temperatures. While past studies have been focused on binary metal oxide coatings, such as ZnO, there have been very few ternary oxide and no reported quaternary oxide investigations. The premise behind the addition of the third and fourth refractory metals Ti and Zr is to increase the number of hard and wear resistant phases while maintaining solid lubrication with ZnO. Therefore, the major focus of this dissertation is to investigate the processing-structure-tribological property relations of composite ZnO, TiO2 and ZrO2 phases that form ternary (ZnTi)xOy and quaternary (ZnTiZr)xOy nanocrystalline coatings. The coatings were processed by atomic layer deposition (ALD) using a selective variation of ALD parameters. The growth structure and chemical composition of as-deposited and ex situ annealed ternary and quaternary oxide coatings were studied by combined x-ray diffraction/focused ion beam microscopy/cross-sectional transmission electron microscopy, and x-ray photoelectron spectroscopy/Auger electron spectroscopy, respectively. It was determined that the structure varied from purely nanocrystalline (ternary oxides) to composite amorphous/nanocrystalline (quaternary oxides) depending on ALD parameters and annealing temperatures. In particular, the ZnTiO3 ilmenite phase with (104) textured nanocolumnar grains, exhibiting high stacking fault/partial dislocation densities >1012/cm2, was responsible for the excellent tribological behavior. Steady-state sliding friction coefficients down to 0.12 in humid air and 0.2 in dry nitrogen were measured along with sliding and fretting wear factors in the range of 10-6 to 10-7 mm3/N·m, even after ex situ annealing to 550°C. Additionally, the quaternary oxide phase Zn(Ti,Zr)O3 in solid solution exhibited a low fretting wear rate of 1x10-6 mm3/N·m. In contrast, certain phases, such as Zn2TiO4 cubic spinel, that form at annealing temperatures >550°C were responsible for high friction and wear. Mechanistic studies using the above techniques revealed low friction and wear-reducing surfaces and subsurfaces were due to different velocity accommodation modes (VAM). In the case of the ternary system, sliding-induced plastic deformation was possible when ZnTiO3 (104) stacking faults, bordered by partial dislocations, serve as a pathway for the dislocations to glide parallel to the sliding direction and hence achieve low friction and wear via an intrafilm shear VAM. It was evident that the individual nanocolumnar ZnTiO3 grains were plastically sheared as opposed to being fractured during wear. Conversely for the quaternary system, an interfacial sliding VAM between the counterface and a mechanically mixed layer (tribofilm) composed of the refined coating and counterface material, that also served as a source for the formation of cylindrical rolls, was responsible for wear reduction. Therefore, these lubricious oxides are a potential candidate for solid lubrication at high temperatures (up to 550 °C) and in space environments.

The adsorption of different fractions of organic matter on the surface of Al2O3 and ZrO2 were investigated. The aim was to study the affinity of these fractions on the surface of metal oxide and the effect of several factors. Batch adsorption experiments were conducted with Low molecular weight oxygenated compounds. These chemical compound have been chosen to investigate:1) the aliphatic and aromatic structurer;2)contribution of hydroxyl group and; 3) the number of carboxyl group. HPLC and IC analysis used for determent the concentration of these chemical in the working solution. ATR-FTIR used to distinguish the type of coordination structure with the surface of metal oxide. The results fitted with Langmuir equation. The results showed that the chemical structure and the type and number of attached functional have an impact on the adsorption. Which it was proved via ATR-FTIR where the result showed that each chemical have different coordination structure on the surface of ZrO2 and Al2O3. Different fractions and sources of NOM were used (hydrophobic fraction of Suwannee and Colorado River, biopolymers extracted for the exuded of 2 species of algae, and low molecular acids that do not adsorb in XAD-8 resin). Results showed that these different fractions have different affinity with the surface of Al2O3 and ZrO2. These adsorption behaviors were varying according to the difference in the component of each NOM. Biopolymers showed significant adsorption at acidic pH. These biopolymers are mainly comprised of polysaccharides and this result proved that polysaccharide adsorb on the surface of ZrO2 more than Al2O3.

The primary objective of this research was to develop a new and efficient pathway for well-defined multicomponent homo/co/terpolymers of cyclic esters/ethers using an organocatalytic approach with an emphasis on the macromolecular engineering aspects of the overall synthesis. Macromolecular engineering (as discussed in the first chapter) of homo/copolymers refers to the specific tailoring of these materials for achieving an easy and reproducible synthesis that results in precise molecular characteristics, i.e. molecular weight and polydispersity, as well as specific structure and end?group choices. Precise control of these molecular characteristics will provide access to new materials that can be used for pre-targeted purposes such as biomedical applications. Among the most commonly used engineering materials are polyesters (biocompatible and biodegradable) and polyethers (biocompatible), either as homopolymers or when or copolymers with linear structures. The ability to create non-linear structures, for example stars, will open new horizons in the applications of these important polymeric materials. The second part of this thesis describes the synthesis of aliphatic polyesters, particularly polycaprolactone and polylactide, using a metal-free initiator/catalyst system. A phosphazene base (t?BuP2) was used as the catalyst for the ring-opening copolymerization of ?-aprolactone (??CL) and L,Lactide (LLA) at room temperature with a variety of protic initiators in different solvents. These studies provided important information for the design of a metal-free route toward the synthesis of polyester?based (bio) materials. The third part of the thesis describes a novel route for the one?pot synthesis of polyether-b polyester block copolymers with either a linear or a specific macromolecular architecture. Poly (styrene oxide)?b?poly(caprolactone)?b?poly(L,lactide) was prepared using this method with the goal of synthesizing poly(styrene oxide)-based materials since this styrene oxide (SO) monomer has been less investigated than other well-known epoxide monomers. The new one?pot synthesis of polyether?b?polyester block copolymers allowed a high degree of control with respect to the molecular weight and molecular weight distribution. It also eliminates the need for a multi-step process in which the first block must be isolated and purified prior to its subsequent use as a macroinitiator for the second block. It is also worth noting that this approach is based primarily on the use of organocatalyst because this class of block copolymers has greater potential in biomedical and pharmaceutical applications and because organocatalysts are believed to be less toxic than their metallic counterparts. The fourth part of the thesis describes the extension of the scope of the newly developed catalyst?switching approach in the synthesis of different macromolecular architectures, with a special focus on styrene oxide as a monomer, which had not previously been explored either as a linear copolymer with other monomers (except with EO) or with a macromolecular architecture such as block star or mikto arm star. The results detailed in Chapter 4 demonstrate the validity of extending the newly developed strategy to the synthesis of a variety of polymers with different macromolecular architectures. Since organic catalysts (phoshazene bases) have been utilized in this work for the synthesis of polyethers and polyesters with the aim of alleviating the toxic properties associated with metal-based catalysts, it was necessary to investigate the toxicity of this class of organocatalyst since, until now, no evidence has appeared of any attempt to address this issue. The objective of the work presented in the fifth part of this thesis was therefore to assess whether this class of organocatalysts are safe with respect to human health and whether their structure and concentration are dependent on an evaluation of the level of cytotoxicity or on other parameters. Both the pure catalyst and the polymers synthesized using this class of catalysts were tested using a CKK?8 assay, which is a very well?known protocol for measuring cytotoxicity.

Our previous studies indicate that 3, 4-(methylenedioxy)-1-(2′, 3′-epoxypropyl)-benzene (safrole oxide), a newly synthesized compound, induces apoptosis in vascular endothelial cells (VECs) and A549 lung cancer cells. To our knowledge, the inhibition of angiogenesis by safrole oxide has not been reported yet. We report here that cultured rat aorta treated with safrole oxide exhibited a significant microvessel reduction as determined by counting the number of microvessels in a phase contrast microscope. There were more microvessels formed in the presence of A549 lung cancer cells in rat aorta model, while a dramatic inhibition of angiogenesis was obtained by adding 220-450 μmol l- 1 of safrole oxide to the growth medium (P <. 01). The culture of rat aorta treated with safrole oxide produced only some abortive endothelial cells but not microvessels. Furthermore, safrole oxide induced antiangiogenic effect in the chorioallantoic membranes (CAM) as a dose dependent manner. Eggs treated with 2-11 μmol 100 μl- 1 per egg of the safrole oxide for 48 h exhibited a significant reduction in blood vessel area of the CAM, a process likely mediated by apoptosis as demonstrated by DNA fragmentation. Our results suggest that safrole oxide has antiangiogenic activity and this effect might occur by induction of cellular apoptosis.

No description available.

New preparative routes to chromyl fluoride were sought. It was found that chlorine monofluoride reacts with chromium trioxide and chromyl chloride to produce chromyl fluoride. Attempts were made to define a mechanism for the reaction of ClF and Cr03 in light of by-products observed and previous investigations. Carbonyl fluoride and chromium trioxide react to form chromyl fluoride and carbon dioxide. A mechanism was also proposed for this reaction. Chromium trioxide with MoF6 or WF6 to produce chromyl fluoride and the respective oxide tetrafluoride.

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).