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Metals in Chemistry and Biology: Computational Chemistry Studies

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

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Synthesis of Gold Complexes From Diphosphine Ligands and Screening Reactions of Heterocyclic Acetylacetonato (ACAC) Ligands with Transitional Metal Complexes

Syntheses of diphosphine gold (I) complexes from gold THT and two ligands, 4, 5-bis (diphenylphosphino)-4-cyclopenten-1, 3-dione (BPCD) and 2,3-bis(diphenylphosphino)-N-phenylmaleimide (BPPM), were done separately. The reactions happened under ice conditions followed by room temperature conditions and produced two diphosphine gold (I) complexes in moderated yield. Spectroscopic results including nuclear magnetic resonance (NMR) and X-ray crystallography were used to study and determine the str… more

Date: August 2015

Creator: Nyamwihura, Rogers

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Praseodymium Oxide and Organic Modified Cerium Oxide Nanoparticles for Electrodeposition of Nickel-Ceramic Nanocomposites to Enhance Corrosion Protection and Mechanical Properties

There is a consistent need in many industries, especially oil and gas, to develop coatings which have higher corrosion resistance and better hardness to extend the lifetime of equipment when it is exposed to hostile environments. Electrodeposition has been a favorable method in the synthesis of metal coatings because of its low cost, convenience, ability to work at low temperatures, and ability to control surface morphology and structure. The inclusion of ceramic nanoparticles in metal matrix c… more

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Date: May 2019

Creator: Sanders, Stephen

Item Type: Thesis or Dissertation

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.

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: Thesis or Dissertation

Partner: UNT Libraries

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Computational Studies of Selected Ruthenium Catalysis Reactions.

Computational techniques were employed to investigate pathways that would improve the properties and characteristics of transition metal (i.e., ruthenium) catalysts, and to explore their mechanisms. The studied catalytic pathways are particularly relevant to catalytic hydroarylation of olefins. These processes involved the +2 to +3 oxidation of ruthenium and its effect on ruthenium-carbon bond strengths, carbon-hydrogen bond activation by 1,2-addition/reductive elimination pathways appropriate … more

Date: December 2007

Creator: Barakat, Khaldoon A.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

De novo prediction of the ground state structure of transition metal complexes.

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

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Photochemical and Photophysical Properties of Gold(I) Complexes and Phosphorescence Sensitization of Organic Luminophores

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

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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From Development of Semi-empirical Atomistic Potentials to Applications of Correlation Consistent Basis Sets

The development of the semi-empirical atomistic potential called the embedded atom method (EAM) has allowed for the efficient modeling of solid-state environments, at a lower computational cost than afforded by density functional theory (DFT). This offers the capability of EAM to model the energetics of solid-state phases of varying coordination, including defects, such as vacancies and self-interstitials. This dissertation highlights the development and application of two EAMs: a Ti potential … more

Date: May 2014

Creator: Gibson, Joshua S.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Examination and Development of the Correlation Consistent Composite Approach

The primary focus of this dissertation is the advancement of the correlation consistent composite approach (ccCA) methodology from its original formulation to the current implementation. Although for large main group test sets which contained both first- (Li-Ne) and second-row (Na-Ar) species ccCA produced chemical accuracy (generally estimated as a deviation of ~1 kcal mol-1 from reliable experiment), the second-row species were smaller in molecular size in comparison to their corresponding f… more

Date: December 2010

Creator: Williams, T. Gavin

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Studies of Solvent Displacement from Solvated Metal Carbonyl Complexes of Chromium, Molybdenum, and Tungsten

Flash photolysis techniques were applied to studies of solvent displacement by Lewis bases (L) from solvated metal carbonyl complexes of Cr, Mo, and W. On the basis of extensive studies of the reaction rate laws, activation parameters , and linear-free-energy-relationships, it was concluded that the mechanisms of solvent displacement reactions depend on the electronic and steric properties of the solvents and L, as well as the identities of the metal atoms. The strengths of solvent-metal bondin… more

Date: August 1990

Creator: Zhang, Shulin

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Analysis of PAH and PCB Emissions from the Combustion of dRDF and the Nondestructive Analysis of Stamp Adhesives

This work includes two unrelated areas of research. The first portion of this work involved combusting densified refuse derived fuel (dRDF) with coal and studying the effect that Ca(0H)2 binder had on reducing polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) emissions. The second area of work was directed at developing nondestructive infrared techniques in order to aid in the analysis of postage stamp adhesives. With Americans generating 150-200 million tons a year of Mu… more

Date: May 1989

Creator: Poslusny, Matthew

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Synthetic Applications of Ketene Cycloadditions Lactams and Coumarins

The objective of this study was to develop new synthetical routes to natural and industrial products utilizing ketene cycioaddition reactions. The cycioaddition of diphenylketene with α,β-unsaturated imines yields (2+2) cycioaddition products, g-lactams. However, electron donating groups, such as dimethylamine, in the 4-position of the α,β-unsaturated imines result in (4+2) cycloaddition products, ∂-lactams. Dichloroketene reacted with α,β-unsaturated imines to yield (4+2) cycloaddition product… more

Date: August 1984

Creator: Shieh, Chia Hui

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Methods Development for Simultaneous Determination of Anions and Cations by Ion Chromatography

The problem with which this research is concerned is the determination of inorganic anions and cations with single injection ion chromatography. Direct detection of the separated analyte ions occurs after the analyte ions have passed through ion-exchange resins where they are separated according to their affinity for the ion-exchange resin active sites. The techniques involve the use of essentially a non-suppressed ion chromatographic system followed by a suppressed ion chromatographic system. … more

Date: May 1987

Creator: Jones, Vonda K. (Vonda Kaye)

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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

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… more

Date: May 2014

Creator: Prince, Bruce M.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Computational Studies of Catalysis Mediated by Transition Metal Complexes

Computational methods were employed to investigate catalytic processes. First, DFT calculations predicted the important geometry metrics of a copper–nitrene complex. MCSCF calculations supported the open-shell singlet state as the ground state of a monomeric copper nitrene, which was consistent with the diamagnetic character deduced from experimental observations. The calculations predicted an elusive terminal copper nitrene intermediate. Second, DFT methods were carried out to investigate the … more

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Date: May 2019

Creator: Jiang, Quan

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Computational Modeling of Small Molecules

Computational chemistry lies at the intersection of chemistry, physics, mathematics, and computer science, and can be used to explain the behavior of atoms and molecules, as well as to augment experiment. In this work, computational chemistry methods are used to predict structural and energetic properties of small molecules, i.e. molecules with less than 60 atoms. Different aspects of computational chemistry are examined in this work. The importance of examining the converged orbitals obtained … more

Date: December 2015

Creator: Weber, Rebecca J.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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The Impact of Computational Methods on Transition Metal-containing Species

Quantum chemistry methodologies can be used to address a wide variety of chemical problems. Key to the success of quantum chemistry methodologies, however, is the selection of suitable methodologies for specific problems of interest, which often requires significant assessment. To gauge a number of methodologies, the utility of density functionals (BLYP, B97D, TPSS, M06L, PBE0, B3LYP, M06, and TPSSh) in predicting reaction energetics was examined for model studies of C-O bond activation of met… more

Date: December 2015

Creator: Wang, Jiaqi

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Transition Metal Mediated C-o Bond Cleavage: From Co2 Activation to Lignin Degradation

CO2 activation and conversion mediated by transition metal (TM) catalysts were investigated. Homogeneous catalysis of the reverse water gas shift reaction CO2+H2→H2O+CO was studied as a means to reduce CO2. β-diketiminato metal models L'MI ( L' =C3N2H5-; M = first-row TMs) were considered as potential catalysts. The thermodynamics of prototypical reaction pathways were simulated using B3LYP/aug-cc-pVTZ. Results show that middle series metal complexes result in more thermodynamically favorable … more

Date: August 2013

Creator: Liu, Cong

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Reducing the Computational Cost of Ab Initio Methods

In recent years, advances in computer technology combined with new ab initio computational methods have allowed for dramatic improvement in the prediction of energetic properties. Unfortunately, even with these advances, the extensive computational cost, in terms of computer time, memory, and disk space of the sophisticated methods required to achieve chemical accuracy - defined as 1 kcal/mol from reliable experimental data effectively - limits the size of molecules [i.e. less than 10-15 non-h… more

Date: August 2008

Creator: Mintz, Benjamin

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Phosphorescent Emissions of Coinage Metal-Phosphine Complexes: Theory and Photophysics

The major topics discussed are all relevant to the bright phosphorescent emissions of coinage metal complexes (Cu(I), Ag(I) and Au(I)) with an explanation of the theoretical background, computational results and ongoing work on the application in materials and optoelectronic devices. Density functional computations have been performed on the majority of the discussed complexes and determined that the most significant distortion that occurs in Au(I)-phosphine complexes is a near and beyond a T-s… more

Date: December 2009

Creator: Sinha, Pankaj

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Kinetic studies and computational modeling of atomic chlorine reactions in the gas phase.

The gas phase reactions of atomic chlorine with hydrogen sulfide, ammonia, benzene, and ethylene are investigated using the laser flash photolysis / resonance fluorescence experimental technique. In addition, the kinetics of the reverse processes for the latter two elementary reactions are also studied experimentally. The absolute rate constants for these processes are measured over a wide range of conditions, and the results offer new accurate information about the reactivity and thermochemi… more

Date: August 2009

Creator: Alecu, Ionut M.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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The Multi-reference Correlation Consistent Composite Approach: A New Vista In Quantitative Prediction Of Thermochemical And Spectroscopic Properties

The multi-reference correlation consistent composite approach (MR-ccCA) was designed to reproduce the accuracy of more computationally intensive ab initio quantum mechanical methods like MR-ACPF-DK/aug-cc-pCV?Z-DK, albeit at a significantly reduced cost. In this dissertation, the development and applications of the MR-ccCA method and a variant of its single reference equivalent (the relativistic pseudopotential ccCA method) are reported. MR-ccCA is shown to predict the energetic properties of r… more

Date: December 2011

Creator: Oyedepo, Gbenga A.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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The performance of density functional theory with the correlation consistent basis sets.

Density functional theory has been used in combination with the correlation consistent and polarization consistent basis sets to investigate the structures and energetics for a series of first-row closed shell and several second-row molecules of potential importance in atmospheric chemistry. The impact of basis set choice upon molecular description has been examined, and irregular convergence of molecular properties with respect to increasing basis set size for several functionals and molecules… more

Date: August 2005

Creator: Wang, Xuelin

Item Type: Thesis or Dissertation

Partner: UNT Libraries

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Experimental and Theoretical Studies of Polycarbocyclic Compounds

Part I. Diels-Alder cycloadditions of 1,2,3,4,9,9-hexachloro-1α,4α,4aα,8aβ-tetrahydro-l,4-methanonaphthalene (32) and 1,2,3,4,9,9-hexachloro-lα,4α,6,7- tetrahydro-l,4-methanonaphthalene (33) to 4-methyl- and 4-phenyl-l,2,4-triazoline-3,5-dione [MTAD and PTAD, respectively] and to N-methylmaleimide (NMM) have been studied. The structures of several of the resulting cycloadducts were determined by X-ray crystallographic methods. The observed stereoselectivity of each of these Diels-Alder reaction… more

Date: May 1998

Creator: Shukla, Rajesh, 1964-

Item Type: Thesis or Dissertation

Partner: UNT Libraries