UNT Theses and Dissertations - 33 Matching Results

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N-Heterocyclic Carbenes of the Late Transition Metals: A Computational and Structural Database Study

Description: A computational chemistry analysis combined with a crystallographic database study of the bonding in late transition metal N-heterocyclic carbene (NHC) complexes is reported. The results illustrate a metal-carbon bond for these complexes, approximately 4% shorter than that of a M-C single bond found in metal alkyl complexes. As a consequence of this result, two hypotheses are investigated. The first hypothesis explores the possibility of multiple-bond character in the metal-carbon linkage of t… more
Date: May 2005
Creator: Baba, Eduard
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Partner: UNT Libraries
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Modeling the chemical and photophysical properties of gold complexes.

Description: Various gold complexes were computationally investigated, to probe their photophysical, geometric, and bonding properties. The geometry of AuI complexes (ground state singlet) is very sensitive to the electronic nature of the ligands: σ-donors gave a two-coordinate, linear shape; however, σ-acceptors yielded a three-coordinate, trigonal planar geometry. Doublet AuIIL3 complexes distort to T-shape, and are thus ground state models of the corresponding triplet AuIL3. The disproportionation of … more
Date: August 2004
Creator: Barakat, Khaldoon A.
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Photophysical properties of pyrene, 2,7 diazapyrene and 1,3-bis(β-naphthyl)propane.

Description: The luminescence properties of Van Der Waals' dimers and clusters of pyrene and diazapyrene have been investigated. Excimers, dimeric species which are associative in an excited electronic state and dissociative in their ground state, have long been established and play an important role in many areas of photochemistry. My work here focuses on the luminescence and absorption properties of ground state dimers/aggregates, which are less understood, and allows further characterization of the groun… more
Date: August 2007
Creator: Boateng, Stephen
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Layered Double Hydroxides: Synthesis, Characterization, and Interaction of Mg-Al Systems with Intercalated Tetracyanonickelate(II)

Description: The square-planar tetracyanonickelate(II) anion was intercalated into 2:1 and 3:1 Mg-Al layered double hydroxide systems (LDHs). In the 2:1 material, the anion holds itself at an angle of about 30° to the layers, whereas in the 3:1 material it lies more or less parallel to the layers. This is confirmed by orientation effects in the infrared spectra of the intercalated materials and by X-ray diffraction (XRD) data. The measured basal spacings for the intercalated LDH hosts are approximately 1… more
Date: August 2004
Creator: Brister, Fang Wei
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Diimine(dithiolate)platinum(ii) Chromophores: Synthesis, Spectroscopy, and Material Applications

Description: A series of 28 square-planar dithiol(diimine)platinum(II) chromophoric complexes have been synthesized, characterized, and evaluated for potential efficacy in sensitization of solid state photovoltaic devices to the near-infrared regions of the electromagnetic spectrum. The effect of molecular stacking in the solid state and self-association in solution are shown to influence spectral, electronic, and magnetic properties of the chromophores. Such properties are investigated in the pure form and… more
Date: August 2014
Creator: Browning, Charles
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De novo prediction of the ground state structure of transition metal complexes.

Description: One of the main goals of computational methods is to identify reasonable geometries for target materials. Organometallic complexes have been investigated in this dissertation research, entailing a significant challenge based on transition metal diversity and the associated complexity of the ligands. A large variety of theoretical methods have been employed to determine ground state geometries of organometallic species. An impressive number of transition metals entailing diverse isomers (e.g., g… more
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Date: December 2004
Creator: Buda, Corneliu
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Partner: UNT Libraries
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Triimine Complexes of Divalent Group 10 Metals for Use in Molecular Electronic Devices

Description: This research focused on the development of new metal triimine complexes of Pt(II), Pd(II), and Ni(II) for use in three types of molecular electronic devices: dye sensitized solar cells (DSSCs), organic light-emitting diodes (OLEDs), and organic field effect transistors (OFETs). Inorganic complexes combine many advantages of their chemical and photophysical properties and are processable on inexpensive and large area substrates for various optoelectronic applications. For DSSCs, a series of pla… more
Date: August 2010
Creator: Chen, Wei-Hsuan
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Metals in Chemistry and Biology: Computational Chemistry Studies

Description: Numerous enzymatic reactions are controlled by the chemistry of metallic ions. This dissertation investigates the electronic properties of three transition metal (copper, chromium, and nickel) complexes and describes modeling studies performed on glutathione synthetase. (1) Copper nitrene complexes were computationally characterized, as these complexes have yet to be experimentally isolated. (2) Multireference calculations were carried out on a symmetric C2v chromium dimer derived from the crys… more
Date: May 2007
Creator: Dinescu, Adriana
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Modeling wild type and mutant glutathione synthetase.

Description: Glutathione syntethase (GS) is an enzyme that belongs to the ATP-grasp superfamily and catalyzes the second step in the biosynthesis of glutathione. GS has been purified and sequenced from a variety of biological sources; still, its exact mechanism is not fully understood. Four highly conserved residues were identified in the binding site of human GS. Additionally, the G-loop residues that close the active site during catalysis were found to be conserved. Since these residues are important for … more
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Date: August 2004
Creator: Dinescu, Adriana
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Partner: UNT Libraries
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Photochemical and Photophysical Properties of Gold(I) Complexes and Phosphorescence Sensitization of Organic Luminophores

Description: Two major topics that involve synthetic strategies to enhance the phosphorescence of organic and inorganic luminophores have been investigated. The first topic involves, the photophysical and photochemical properties of the gold (I) complexes LAuIX (L = CO, RNC where R = alkyl or aryl group; X = halide or pseudohalide), which have been investigated and found to exhibit Au-centered phosphorescence and tunable photochemical reactivity. The investigations have shown a clear relationship between th… more
Date: August 2006
Creator: El-Bjeirami, Oussama
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Solution Studies of ⁶Li Enriched Organolithium Compounds Using New NMR Techniques

Description: With the values of 6Li T1 measured and the literature values of J(13C-6Li) for these compounds, three new 13C NMR techniques are developed for the analysis of organolithium compounds. Modifications to the spectrometer are discussed, as well as calibrations of the 6Li decoupler channel needed to set up these new experiments. The theoretical development of each technique is presented, as well as data from their verification, using organolithium compounds of known structure. Once qualified, the ne… more
Date: May 1990
Creator: Ellington, Donald H. (Donald Howard)
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Modeling Transition Metal Catalysts for Small Molecule Activation and Functionalization

Description: There is a high demand for the development of processes for the conversion of ubiquitous molecules into industrially useful commodities. Transition metal catalysts are often utilized for the activation and functionalization of small organic molecules due to their diverse nature and proven utility with a myriad of chemical transformations. The functionalization of methane (CH4) and dinitrogen (N2) to methanol (CH3OH) and ammonia (NH3) respectively is of particular interest; however, both methane… more
Date: May 2013
Creator: Figg, Travis M.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Group 10 Catalyzed Olefin Hydroarylation

Description: Alkyl-arenes are important industry feedstock chemicals that are used as solvents, pharmaceutical precursors, and polymer monomer units. One alkyl-arene, ethylbenzene, is the main focus of this dissertation, and is produced in the million ton a year scale. As alkyl-arenes are important commodity chemicals, catalytic olefin hydroarylation is a lucrative alternative for their production rather than Friedel-Crafts alkylation or various coupling reactions that have lower atom economy, require stron… more
Date: December 2012
Creator: Gonzalez, Hector Emanuel
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Partner: UNT Libraries
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Photophysical studies of silver(I), platinum(II), palladium(II), and nickel(II) complexes and their use in electronic devices.

Description: This dissertation deals with two major topics that involve spectroscopic studies of (a) divalent group 10 metals and (b) silver(I)-phosphine complexes. The scope of the work involved the delineation of the electronic structure of these complexes in different environments and their use in electronic devices. The first topic is a look at the luminescence of tetrahedral silver(I)-phosphine complexes. Broad unstructured emissions with large Stokes shifts were found for these complexes. Computationa… more
Date: December 2007
Creator: Hudson, Joshua M.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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The Mechanisms of Human Glutathione Synthetase and Related Non-Enyzmatic Catalysis

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… more
Date: May 2015
Creator: Ingle, Brandall L.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Exploring Inorganic Catalysis with Electronic Structure Simulations

Description: Organometallic catalysis has attracted significant interest from both industry and academia due to its wide applications in organic synthetic transformations. Example of such transformations include the reaction of a zinc carbenoid with olefins to form cyclopropanes. The first project is a computational study using both density functional and correlated wavefunction methods of the reaction between ethylene and model zinc carbenoid, nitrenoid and oxenoid complexes (L-Zn-E-X, E = CH2, NH or O, L … more
Date: May 2016
Creator: Khani, Sarah Karbalaei
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Biological Applications of a Strongly Luminescent Platinum (II) Complex in Reactive Oxygen Species Scavenging and Hypoxia Imaging in Caenorhabditis elegans

Description: Phosphorescent transition metal complexes make up an important group of compounds that continues to attract intense research owing to their intrinsic bioimaging applications that arise from bright emissions, relatively long excited state lifetimes, and large stokes shifts. Now for biomaging assay a model organism is required which must meet certain criteria for practical applications. The organism needs to be small, with a high turn-over of progeny (high fecundity), a short lifecycle, and low m… more
Date: December 2015
Creator: Kinyanjui, Sophia Nduta
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Partner: UNT Libraries
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Design and Synthesis of Novel Cage-Functionalized Crown Ethers: A New Class of Ag Complexants.

Description: Three different types of cage crown ethers have been prepared and their complexation properties with Ag(I) have been studied. Atomic absorption, fluorescence quenching, and UV absorption have been used to study the interaction between the hosts (cage crown ethers) and guests (Ag+). For the cage-annulated crown ethers that contain aromatic rings, cation-π and π-π interactions may contribute significantly to the overall complexation ability of the host system. Piperazine groups may cooperate, and… more
Date: August 2003
Creator: Lai, Huiguo
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Photochemical and Photophysical Properties of Mononuclear and Multinuclear Closed Shell D10 Coinage Metal Complexes and Their Metallo-organometallic Adducts

Description: This dissertation covers the studies of two major topics: the photochemistry of mononuclear and multinuclear gold(I) complexes and synthetic approaches to tailor photophysical properties of cyclic trinuclear d10 complexes. First a detailed photochemical examination into the photoreactivity of neutral mononuclear and multinuclear gold(I) complexes is discussed, with the aim of gold nanoparticle size and shape control for biomedical and catalysis applications. Next is a comprehensive systematic s… more
Date: December 2013
Creator: McDougald, Roy N., Jr.
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An NMR Study of Trimethylsilylmethyllithium Aggregates and Mixed Trimethylsilylmethyllithium/Lithium trimethylsilylmethoxide Aggregates

Description: An NMR spectroscopy study of trimethylsilylmethyllilthium, TMSM-Li, indicates that TMSM-Li exists as two different aggregates in cyclopentane solution. Using previously reported colligative properties of TMSM-Li in different solutions in connection with new 13C and 6Li NMR data collected in this study, aggregation states were assigned as octamer and hexamer. Low temperature 13C and 6Li NMR peak intensities indicated an equilibrium exists between the two aggregates that shifts toward the octam… more
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Date: December 2004
Creator: Medley, Marilyn S.
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Modeling Transition Metal Chemistry for Catalytic Functionalization of Molecules

Description: The diversity of transition metal complexes allows for a wide range of chemical processes to be mediated by the metal, from catalysis to surface chemistry. Investigations into the structure and electronic configuration of transition metal complexes allow for tuning of desired species by modifications to the ligands and/or metals to achieve more efficient thermodynamics and kinetics for the process of interest. Transition metals, often used in catalysts for a number of important processes, requi… more
Date: August 2011
Creator: Morello, Glenn
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Computational Studies of Inorganic Systems with a Multiscale Modeling Approach: From Atomistic to Continuum Scale

Description: Multiscale modeling is an effective tool for integrating different computational methods, creating a way of modeling diverse chemical and physical phenomena. Presented are studies on a variety of chemical problems at different computational scales and also the combination of different computational methods to study a single phenomenon. The methods used encompass density functional theory (DFT), molecular dynamics (MD) simulations and finite element analysis (FEA). The DFT studies were conducted… more
Date: August 2013
Creator: Olatunji-Ojo, Olayinka A.
Item Type: Refine your search to only Thesis or Dissertation
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Design, Synthesis and Screening of Homoleptic and Heteroleptic Platinum(ii) Pyridylazolate Complexes for N-type Semiconducting and Light-emitting Devices

Description: A series of heteroleptic and homoleptic platinum(II) complexes has been synthesized and characterized towards their use in thin film devices such as organic light-emitting diodes (OLEDs) and organic thin film transistors (OTFTs). Pyridylpyrazolate- and pyridyltetrazolate-containing ligands were selected due to their structural rigidity and ease of functionalization. Single-crystal x-ray diffraction studies of two selected heteroleptic complexes show strong aggregation with preferential stacking… more
Date: August 2012
Creator: Oswald, Iain William Herbert
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Pathways for C—H Activation and Functionalization by Group 9 Metals

Description: As fossil fuel resources become more and more scarce, attention has been turned to alternative sources of fuels and energy. One promising prospect is the conversion of methane (natural gas) to methanol, which requires an initial activation of a C-H bond and subsequent formation of a C-O bond. The most well studied methodologies for both C-H activation and C-O bond formation involve oxidation of the metal center. Metal complexes with facile access to oxidation states separated by four charge uni… more
Date: May 2015
Creator: Pahls, Dale R.
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Partner: UNT Libraries
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