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  Partner: UNT Libraries
 Department: Department of Chemistry
 Collection: UNT Theses and Dissertations
Magnetic Exchange in Oxovanadium(IV) Complexes with N-Salicylideneamino Acids

Magnetic Exchange in Oxovanadium(IV) Complexes with N-Salicylideneamino Acids

Date: January 1968
Creator: Hu, James Hung-Jen
Description: Copper(II) and oxovanadium(IV) ions resemble one another magnetically in having one unpaired electron in their complexes irrespective of their geometrical structures and bond types involved. Copper(II) complexes with antiferromagnetic exchange are well known. On the contrary, antiferromagnetic exchange in oxovanadium(IV) complexes is rather new and not well established. Very few oxovanadium(IV) complexes have been reported to have this anomalous magnetic property. In the investigation of the magnetic properties of oxovanadium(IV) complexes, we have successfully prepared two series of new oxovanadium(IV) complexes with N-salicylideneamino acids.
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Magnetic Properties of Copper (II) Complexes of N-(Hydroxyalkyl) Pyrrole-2-Aldimines

Magnetic Properties of Copper (II) Complexes of N-(Hydroxyalkyl) Pyrrole-2-Aldimines

Date: December 1973
Creator: Pauley, Charles Richard
Description: In this work magnetic properties of copper(II) complexes on N-(hydroxyalkyl) pyrrole-2-aldimines were investigated by various techniques, one of which was magnetic susceptibility. Magnetic moments are not directly determined experimentally, but magnetic susceptibilities are.
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Magnetic Properties of Copper (II) Complexes of Schiff Bases

Magnetic Properties of Copper (II) Complexes of Schiff Bases

Date: August 1975
Creator: Jones, William James
Description: The synthesis and characterization of two new Schiff base copper(II) complexes are reported. These are Cu(acac: 2-amino-l-phenylethanol) and Cu(acac:2-amino-l-butanol). The ligands, derived from acetylacetone and the appropriate aminoalcohol, are dibasic tridentates with 0,N,O donor atoms. The magnetic properties of the complexes were studied at several temperatures between 78 OK and 296 OK. The magnetic moment of Cu(acac:2-amino-l-phenylethanol) varied little with temperature, and that of Cu(acac:2-amino-lbutanol) increased as the temperature was lowered. This is in contrast to the magnetic moment of Cu(acac:ethanolamine), which decreases as the temperature decreases. Molecular weight data, infrared spectra, magnetic data, electronic spectra, and electron spin resonance spectra of both complexes are reported and discussed.
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Magnetic Properties of Metal(II) Schiff Base Complexes

Magnetic Properties of Metal(II) Schiff Base Complexes

Date: May 1976
Creator: Hines, Mary Katherine
Description: Ligands prepared from various combinations of aldehydes and ketones with the appropriate aminealcohol were complexed with cupric acetate monohydrate. The complexes with O,NO or N,N,O donor atoms were synthesized to study the influences of the ligand on molecular structure, spin-spin interaction, and on the value of the exchange integral. The magnetic data indicated that of the eight Cu(II) complexes discussed, two behaved differently from known analogous compounds. Cu (benzoylacetone :ethanolamine) was compared to Cu(acac:ethanolamine), and Cu(pyrr:oaminophenol) was compared to Cu(acac:o-aminophenol). Each pair of complexes was postulated to have the same molecular structure. The synthesis and characterization of Mn(pyrr:oaminophenol) 2H2 is also discussed. The following physical data were collected and discussed: elemental analysis, melting point, molecular weight, infrared spectra, electronic spectra, and magnetic susceptibility.
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Magnetic Properties of Oxovanadium(IV) Complexes of Substituted N-(Hydroxylalkyl) Salicylideneimines

Magnetic Properties of Oxovanadium(IV) Complexes of Substituted N-(Hydroxylalkyl) Salicylideneimines

Date: May 1972
Creator: Carey, Elbert Franklin
Description: A series of oxovanadium(IV) complexes of Schiff bases derived from substituted salicylaldehyde and aminoalcohols has been prepared and characterized. The Schiff bases coordinate through 0, N, and 0 as tridentate bivalent ligands. The primary purpose of the investigation is to describe the structure and bonding in these complexes. The subnormal magnetic properties of the complexes provide much information about both the structure and the bonding in the complexes.
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A Materials Approach to Silicon Wafer Level Contamination Issues from the Wet Clean Process

A Materials Approach to Silicon Wafer Level Contamination Issues from the Wet Clean Process

Date: December 1996
Creator: Hall, Lindsey H. (Lindsey Harrison)
Description: Semiconductor devices are built using hyperpure silicon and very controlled levels of doping to create desired electrical properties. Contamination can alter these precisely controlled electrical properties that can render the device non-functional or unreliable. It is desirable to determine what impurities impact the device and control them. This study consists of four parts: a) determination of acceptable SCI (Standard Clean 1) bath contamination levels using VPD-DSE-GFAAS (Vapor Phase Decomposition Droplet Surface Etching Graphite Furnace Atomic Absorption Spectroscopy), b) copper deposition from various aqueous HF solutions, c) anion contamination from fluoropolymers used in chemical handling and d) metallic contamination from fluoropolymers and polyethylene used in chemical handling. A technique was developed for the determination of metals on a silicon wafer source at low levels. These levels were then correlated to contamination levels in a SCI bath. This correlation permits the determination of maximum permissible solution contaminant levels. Copper contamination is a concern for depositing on the wafer surface from hydrofluoric acid solutions. The relationship between copper concentration on the wafer surface and hydrofluoric acid concentration was determined. An inverse relationship exists and was explained by differences in diffusion rates between the differing copper species existing in aqueous hydrofluoric acid solutions. Finally, ...
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The Mechanisms of Human Glutathione Synthetase and Related Non-Enyzmatic Catalysis

The Mechanisms of Human Glutathione Synthetase and Related Non-Enyzmatic Catalysis

Date: May 2015
Creator: Ingle, Brandall L.
Description: Human glutathione synthetase (hGS) is a homodimeric enzymes that catalyzes the second step in the biological synthesis of glutathione, a critical cellular antioxidant. The enzyme exhibits negative cooperativity towards the γ-glutamylcysteine (γ-GC) substrate. In this type of allosteric regulation, the binding of γ-GC at one active site significantly reduces substrate affinity at a second active site over 40 Å away. The presented work explores protein-protein interactions, substrate binding, and allosteric communication through investigation of three regions of hGS: the dimer interface, the S-loop, and the E-loop. Strong electrostatic interactions across the dimer interface of hGS maintain the appropriate tertiary and quaternary enzymatic structure needed for activity. The S-loop and E-loop of hGS form walls of the active site near γ-GC, with some residues serving to bind and position the negatively cooperative substrate. These strong interactions in the active site serve as a trigger for allosteric communication, which then passes through hydrophobic interactions at the interface. A comprehensive computational and experimental approach relates hGS structure with activity and regulation. ATP-grasp enzymes, including hGS, utilize ATP in the nucleophilic attack of a carboxylic acid in a reaction thought to proceed through the formation of an acylphosphate intermediate. Small metal cations are known ...
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The Mechanisms of Methane C–H Activation and Oxy-insertion Via Small Transition Metal Complexes: a DFT Computational Investigation

The Mechanisms of Methane C–H Activation and Oxy-insertion Via Small Transition Metal Complexes: a DFT Computational Investigation

Date: May 2014
Creator: Prince, Bruce M.
Description: Our country continues to demand clean renewable energy to meet the growing energy needs of our time. Thus, natural gas, which is 87% by volume of methane, has become a hot topic of discussion because it is a clean burning fuel. However, the transportation of methane is not easy because it is a gas at standard temperature and pressure. The usage of transition metals for the conversion of small organic species like methane into a liquid has been a longstanding practice in stoichiometric chemistry. Nonetheless, the current two-step process takes place at a high temperature and pressure for the conversion of methane and steam to methanol via CO + H2 (syngas). The direct oxidation of methane (CH4) into methanol (CH3OH) via homogeneous catalysis is of interest if the system can operate at standard pressure and a temperature less than 250 C. Methane is an inert gas due to the high C-H bond dissociation energy (BDE) of 105 kcal/mol. This dissertation discusses a series of computational investigations of oxy-insertion pathways to understand the essential chemistry behind the functionalization of methane via the use of homogeneous transition metal catalysis. The methane to methanol (MTM) catalytic cycle is made up of two key ...
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Mechanisms of Methoxide Ion Substitution and Acid- Catalyzed Z/E Isomerization of N-Methoxyimines

Mechanisms of Methoxide Ion Substitution and Acid- Catalyzed Z/E Isomerization of N-Methoxyimines

Access: Use of this item is restricted to the UNT Community.
Date: December 2001
Creator: Dolliver, Debra D.
Description: The second order rate constants for nucleophilic substitution by methoxide of (Z)- and (E)-O-methylbenzohydroximoyl fluorides [C6H4C(F)=NOCH3] with various substituents on the phenyl ring [p-OCH3 (1h, 2h), p-CH3 (1g, 2g), p-Cl (1f, 2f), p-H (1e, 2e), (3,5)-bis-CF3 (1i, 2i)] in 90:10 DMSO:MeOH have been measured. A Hammett plot of these rate constants vs σ values gave positive ρ values of 2.95 (Z isomer) and 3.29 (E isomer). Comparison of these rates with methoxide substitution rates for Omethylbenzohydroximoyl bromide [C6H4C(Br)=NOCH3] and Omethylbenzohydroximoyl chloride [C6H4C(Cl)=NOCH3] reveal an element effect for the Z isomers of Br:Cl:F(1e) = 2.21:1.00:79.7 and for the E isomers of Cl:F(2e) = 1.00:18.3. With the p-OCH3-imidoyl halides the following element effects are found: Br:Cl:F(1h) = 2.78:1.00:73.1 for the Z isomer and Br:Cl:F(2h) = 1.97:1.00:12.1 for the E isomer. Measurement of activation parameters revealed ∆S≠ = -17 eu for 1e and ∆S≠ = -9.9 eu for 2e. Ab initio calculations (HF/6-31+G*, MP2/6-31+G*//HF/6-31+G*, B3LYP/6- 31+G*//HF/6-31+G*, HF-SCIPCM/6-31+G*//HF/6-31+G*) were performed to define the reaction surface. These calculations demonstrate a relatively large barrier for nucleophilic attack in relation to halogen loss and support the experimental findings that this reaction proceeds by an addition-elimination mechanism (AN# + DN). The imidoyl fluorides have been used to synthesize ...
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The Mercury Photosensitized Reactions of some Hydrocarbons

The Mercury Photosensitized Reactions of some Hydrocarbons

Date: 1946
Creator: Dickinson, Ermintrude
Description: The problem was to study the behavior of several hydrocarbons when they were subjected to ultraviolet light of 2536 Å in the presence of mercury vapor.
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The Mercury-Sensitized Photo-Reactions of 2,3-Dimethyl Butane

The Mercury-Sensitized Photo-Reactions of 2,3-Dimethyl Butane

Date: 1947
Creator: Sutton, Cecil C.
Description: The work encompassed by this thesis is partially a reproduction of the results obtained by John A. Marcia in his work on the photo-chemical reactions of branched hydrocarbons. The previous work done on this particular problem was rendered partially valueless because of the loss of the liquid hydrocarbon product when a fractionation column at the Texas Company Laboratory, Beacon, New York, broke during the fractionation run.
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The Mercury-Sensitized Photo-Reactions of a Mixture of Propane and Isobutane

The Mercury-Sensitized Photo-Reactions of a Mixture of Propane and Isobutane

Date: 1947
Creator: Vaughan, George
Description: It was decided to determine whether or not 2,2,3-trimethylbutane could be formed by the photochemical reaction of isobutane and propane in the presence of mercury vapor energized by ultraviolet radiation from a mercury vapor lamp.
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The Mercury-Sensitized Photo-Reactions of Isobutane

The Mercury-Sensitized Photo-Reactions of Isobutane

Date: 1943
Creator: Stallings, James Cameron
Description: A study of the mercury-sensitized photo-reactions of isobutane.
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Mercury-Sensitized Photochemical Action on a Mixture of Isobutane and Isobutene

Mercury-Sensitized Photochemical Action on a Mixture of Isobutane and Isobutene

Date: June 1939
Creator: Gary, Felice
Description: This study investigated mercury-sensitized photochemical action on a mixture of isobutane and isobutene. Flow runs of isobutane-isobutene 3.2.1 mercury-saturated gases illuminated with unfiltered radiation of mercury vapor lamp gave no detectable change to hydrocarbons heavier than C4 at reaction tempratures of 27C. and 99C.
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The Mercury-Sensitized Photochemical Reactions of Cyclohexane

The Mercury-Sensitized Photochemical Reactions of Cyclohexane

Date: 1950
Creator: Layne, Douglas Kenneth
Description: This study is about the mercury sensitized photochemical reactions of cyclohexane.
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Mercury-Sensitized Photochemical Reactions of Isopropyl Alcohol

Mercury-Sensitized Photochemical Reactions of Isopropyl Alcohol

Date: August 1955
Creator: Brown, Robert Wade
Description: This thesis discusses the mercury-sensitized photochemical reactions of isopropyl alcohol.
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Mercury-sensitized Photochemical Reactions of Isopropyl Alcohol

Mercury-sensitized Photochemical Reactions of Isopropyl Alcohol

Date: 1956
Creator: Brady, William Thomas
Description: The nature and scope of this problem is to determine from the irradiation of isopropyl alcohol with 2537 A, the behavior and mechanism of the reaction, since it is known that a reaction does occur.
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Mercury-Sensitized Photochemical Reactions of Isopropyl Alcohol

Mercury-Sensitized Photochemical Reactions of Isopropyl Alcohol

Date: May 1959
Creator: Armstrong, Andrew Thurman
Description: This thesis describes the reactions of mercury-sensitized isopropyl alcohol when bombarded with 2537 Angstrom radiation.
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The Mercury-Sensitized Photochemical Reactions of Isopropyl Benzene and Methylcyclohexane

The Mercury-Sensitized Photochemical Reactions of Isopropyl Benzene and Methylcyclohexane

Date: 1951
Creator: Holland, Walter
Description: This thesis describes the theoretical results of mercury-sensitized photochemical reactions of isopropyl benzene and methylcyclohexane. The reactions are carried out and the results are analyzed.
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Metal-Aluminum Oxide Interactions: Effects of Surface Hydroxylation and High Electric Field

Metal-Aluminum Oxide Interactions: Effects of Surface Hydroxylation and High Electric Field

Date: December 2001
Creator: Niu, Chengyu
Description: Metal and oxide interactions are of broad scientific and technological interest in areas such as heterogeneous catalysis, microelectronics, composite materials, and corrosion. In the real world, such interactions are often complicated by the presence of interfacial impurities and/or high electric fields that may change the thermodynamic and kinetic behaviors of the metal/oxide interfaces. This research includes: (1) the surface hydroxylation effects on the aluminum oxide interactions with copper adlayers, and (2) effects of high electric fields on the interface of thin aluminum oxide films and Ni3Al substrate. X-ray photoelectron spectroscopy (XPS) studies and first principles calculations have been carried out to compare copper adsorption on heavily hydroxylated a- Al2O3(0001) with dehydroxylated surfaces produced by Argon ion sputtering followed by annealing in oxygen. For a heavily hydroxylated surface with OH coverage of 0.47 monolayer (ML), sputter deposition of copper at 300 K results in a maximum Cu(I) coverage of ~0.35 ML, in agreement with theoretical predictions. Maximum Cu(I) coverage at 300 K decreases with decreasing surface hydroxylation. Exposure of a partially dehydroxylated a-Al2O3(0001) surface to either air or 2 Torr water vapor results in recovery of surface hydroxylation, which in turn increases the maximum Cu(I) coverage. The ability of surface hydroxyl ...
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Metal Complexes of 2,3-Quinoxalinedithiol

Metal Complexes of 2,3-Quinoxalinedithiol

Date: May 1969
Creator: Ganguli, Kalyan Kumar, 1912-
Description: A series of new planar complexes with the dianion of 2,3-quinoxalinedithiol ligand has been prepared. The complexes have been characterized from the study of their analyses, magnetic moment, conductance, polarograms, electron spin resonance spectra, and electronic spectra, and compared with the available data on the corresponding maleonitriledithiolene and toluene-3,4-dithiolene complexes.
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Metal (II) Complexes with N-Salicylideneamino Acids

Metal (II) Complexes with N-Salicylideneamino Acids

Date: August 1969
Creator: Carlisle, Gene Ozelle
Description: Transition metal complexes derived from Schiff bases have rendered an important contribution to the development of modern coordination chemistry. Various stable compounds have been prepared having synthetic, biological, and physicochemical interest. In particular, complexes of salicylaldimines, B-ketoamines, and closely related ligand systems have been investigated.
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Metal Oxide Reactions in Complex Environments: High Electric Fields and Pressures above Ultrahigh Vacuum

Metal Oxide Reactions in Complex Environments: High Electric Fields and Pressures above Ultrahigh Vacuum

Date: August 2005
Creator: Qin, Feili
Description: Metal oxide reactions at metal oxide surfaces or at metal-metal oxide interfaces are of exceptional significance in areas such as catalysis, micro- and nanoelectronics, chemical sensors, and catalysis. Such reactions are frequently complicated by the presence of high electric fields and/or H2O-containing environments. The focus of this research was to understand (1) the iron oxide growth mechanism on Fe(111) at 300 K and 500 K together with the effect of high electric fields on these iron oxide films, and (2) the growth of alumina films on two faces of Ni3Al single crystal and the interaction of the resulting films with water vapor under non-UHV conditions. These studies were conducted with AES, LEED, and STM. XPS was also employed in the second study. Oxidation of Fe(111) at 300 K resulted in the formation of Fe2O3 and Fe3O4. The substrate is uniformly covered with an oxide film with relatively small oxide islands, i.e. 5-15 nm in width. At 500 K, Fe3O4 is the predominant oxide phase formed, and the growth of oxide is not uniform, but occurs as large islands (100 - 300 nm in width) interspersed with patches of uncovered substrate. Under the stress of STM induced high electric fields, dielectric ...
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Metallization and Modification of Low-k Dielectric Materials

Metallization and Modification of Low-k Dielectric Materials

Date: December 2008
Creator: Martini, David M.
Description: Aluminum was deposited onto both Teflon AF and Parylene AF surfaces by chemical vapor deposition of trimethylaluminum. This work shows that similar thin film (100 Angstroms) aluminum oxide adlayers form on both polymers at the low temperature dosing conditions used in the studies. Upon anneal to room temperature and above, defluorination of the polymer surfaces increased and resulted in fluorinated aluminum oxide adlayers; the adlayers were thermally stable to the highest temperatures tested (600 K). Angle-resolved spectra showed higher levels of fluorination toward the polymer/adlayer interface region. Copper films were also deposited at low temperature onto Teflon AF using a copper hexafluoroacetylacetonate-cyclooctadiene precursor. Annealing up to 600 K resulted in the loss of precursor ligands and a shift to metallic copper. As with aluminum adlayers, some polymer defluorination and resulting metal (copper) fluoride was detected. Parylene AF and polystyrene films surfaces were modified by directly dosing with water vapor passed across a hot tungsten filament. Oxygen incorporation into polystyrene occurred exclusively at aromatic carbon sites, whereas oxygen incorporation into parylene occurred in both aromatic and aliphatic sites. Oxygen x-ray photoelectron spectra of the modified polymers were comparable, indicating that similar reactions occurred. The surface oxygenation of parylene allowed enhanced reactivity ...
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