UNT Theses and Dissertations - 16 Matching Results

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Studies of spin alignment in ferrocenylsilane compounds and in regiospecific oxidation reactions of 1,9-dimethylpentacyclo [5.4.0.02,6.03,10.05,9]undecane-8,11-dione.

Description: Part I. The syntheses of a series of stable ferrocenylsilane compounds and their corresponding polyradical cations are reported. Electron spin properties of these molecules were investigated by cyclic voltammetry, ESR, and magnetic susceptibility measurements. All the compounds presented, showed significant electronic communication (>100 mV) between the redox centers by CV. Part II. Baeyer-Villiger oxidation of (1,9-dimethyl-PCU-8,11-dione) was performed using m-chloroperoxybenzoic acid i… more
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Date: August 2006
Creator: Atim, Silvia
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Synthesis and Photochemical Studies of Wide-Band Capturing Sensitizers Capable of Light Energy Harvesting

Description: Artificial photosynthesis, for the purpose of converting solar energy into fuel, is one of the most viable and promising alternative approaches to solve the current global energy and environmental issues. Among the challenges faced in artificial photosynthesis is in building photosystems that can effectively and efficiently perform light absorption and charge separation in broad-band capturing donor-acceptor systems. While having a broad-band capturing antenna system that can harness incoming … more
Date: August 2016
Creator: Bandi, Venu Gopal
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Acceptor-sensitizers for Nanostructured Oxide Semiconductor in Excitonic Solar Cells

Description: Organic dyes are examined in photoelectrochemical systems wherein they engage in thermal (rather than photoexcited) electron donation into metal oxide semiconductors. These studies are intended to elucidate fundamental parameters of electron transfer in photoelectrochemical cells. Development of novel methods for the structure/property tuning of electroactive dyes and the preparation of nanostructured semiconductors have also been discovered in the course of the presented work. Acceptor sensiti… more
Date: August 2014
Creator: Berhe, Seare Ahferom
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Molecules and Materials for Excitonic Solar Cells Using P-type Metal Oxide Semiconductors

Description: This dissertation has two intersecting foci; firstly, the discovery of a new methodology for the growth of high surface area cuprous oxide (Cu2O) substrates. Secondly, the synthesis and characterization of electron-accepting molecules, and their incorporation into excitonic solar cells (XSCs) using the Cu2O substrates as electrodes. Increasing the surface area of the semiconductor creates more locations for charge transfer to occur thus increasing the overall efficiency of the device. Zinc oxid… more
Date: August 2015
Creator: Haynes, Keith M.
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Synthetic, Mechanistic, and Structural Studies of Polynuclear Metal Clusters and Hydrazido-Substituted Tantalum(V) Compounds

Description: A combined experimental and computational study on the reversible ortho-metalation exhibited by the triosmium cluster Os3(CO)10(dppm) (dppm = 1,1-bis(diphenylphosphino)methane is reported. The conversion of nonacarbonyl cluster HOs3(CO)9[-PhP(C6H4)CH2PPh2] to Os3(CO)10(dppm) is independent of added CO and exhibits a significant inverse equilibrium isotope effect (EIE). Reductive coupling of the C-H bond in HOs3(CO)9[-PhP(C6H4)CH2PPh2] leads to the formation of agostic C-H and tw… more
Date: December 2010
Creator: Huang, Shih-Huang
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Synthesis and Complexation Studies of Novel Functionalized Crown Ethers and Azacrown Ethers

Description: Novel cage-functionalized azacrown ethers, i.e. 51, 52, 53, 55, 57, 61 and 62, which have various crown cavity and different number of nitrogen atoms incorporated, have been prepared. X-ray structures of 53, 55 and 57 have been obtained for the study of the crown topological structure. The complexation properties of crown 51, 52, 57, 61 and 62 have been evaluated via alkali metal picrate extraction, silver picrate extraction and ESI-MS study. The novel cage-fuctionalized azacrown ethers general… more
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Date: May 2006
Creator: Huang, Zilin
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Design, Synthesis and Study of Supramolecular Donor – Acceptor Systems Mimicking Natural Photosynthesis Processes

Description: This dissertation investigates the chemical ingenuity into the development of various photoactive supramolecular donor – acceptor systems to produce clean and carbon free energy for the next generation. The process is inspired by the principles learned from nature’s approach where the solar energy is converted into the chemical energy through the natural photosynthesis process. Owing to the importance and complexity of natural photosynthesis process, we have designed ideal donor-acceptor system… more
Date: December 2015
Creator: KC, Chandra Bikram
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Synthesis and Characterization of Two and Three Coordinate Gold (I) Conjugated and Rigid Metallodendrimers

Description: This dissertation is a study of two major topics that involve synthetic strategies for new classes of phosphorescent gold(I)-based metallodendrimers. The phosphorescence of organic and inorganic luminophores originates from spin-orbit coupling owing to internal or external heavy atom effects as well as metal-centered emissions. Previous work in the Omary group entailed systematically designed small molecules, metallopolymers, and unconjugated metallodendrimers that contain d10 and d8 metals, w… more
Date: August 2012
Creator: Kaipa, Ushasree
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Synthesis and characterization of diphosphine ligand substituted osmium and ruthenium clusters.

Description: The kinetics for the bridge-to-chelate isomerization of the dppe ligand in H4Ru4(CO)10(dppe) have been investigated by UV-vis and NMR spectroscopies over the temperature range of 308-328 K. The isomerization of the ligand-bridged cluster 1,2-H4Ru4(CO)10(dppe) was found to be reversible by 31P NMR spectroscopy, affording a Keq = 15.7 at 323 K in favor of the chelating dppe isomer. The forward (k1) and reverse (k-1) first-order rate constants for the reaction have been measured in different sol… more
Date: August 2007
Creator: Kandala, Srikanth
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Self-assembly Polymeric Nanoparticles Composed of Polymers Crosslinked with Transition Metals for Use in Drug Delivery

Description: A major drawback of chemotherapy is the lack of selectively leading to damage in healthy tissue, which results in severe acute side effects to cancer patients. The use of nanoparticles as a drug delivery system has emerged as novel strategy to overcome the barriers of immunogenic response, controlled release of therapeutic, and targeting the toxicity only to cancerous cells. In this study, polymeric nanoparticles composed of transition metals and particles derived from natural biopolymers hav… more
Date: December 2015
Creator: Nguyen, Duong Thuy
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Synthesis of Novel Organic Chromophores and Their Characterization

Description: Nonlinear organic liquids that exhibit two-photon absorption (TPA) function as good optical limiters for sensor protection from laser pulses. L34 (4-butyl-4'-propyl-diphenylethyne) is a liquid organic compound exhibiting nonlinear optical absorption. A thiol- derivatized analog of L34 (“thiol-L34”) was prepared to bind the molecules to the surface of gold nanoparticles. Surface binding is necessary to investigate synergy between nonlinear optical absorption of gold nanoparticles and thiol-L34. … more
Date: December 2014
Creator: Pokharel, Sundari D.
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Synthesis and characterization of quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers and reaction chemistry of the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) at triosmium carbonyl clusters.

Description: Quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers have been synthesized as possible specific metal host systems. The synthesis and characterization of quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers have been described. The characterization of these host systems have been fully achieved in solution by using various techniques such as IR, 1H NMR, and 13C NMR spectroscopic methods, high-resolution mass spectrometry (HRMS), elemental microanalysis, and X-ray… more
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Date: December 2006
Creator: Poola, Bhaskar
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Synthesis of Peropyrene and Tetracene Derivatives for Photochemical Applications

Description: A novel route for the synthesis of the polycyclic aromatic hydrocarbon peropyrene (Pp) is reported along with the efforts to synthesize derivatives of Pp, 2,2′- and 5,5′-linked tetracene dimers as candidates for study as singlet fission materials in photovoltaic devices. Peropyrene was synthesized by the McMurry coupling conditions from phenalenone and low-valent titanium species. The crystal structure of Pp is formed by π-stacked molecular pairs in a herringbone arrangement. The direct functio… more
Date: May 2015
Creator: Rodríguez López, Marco Tulio
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Design of New Monodentate Ligands for Regioselectivity and Enantioselectivity Tuning in Late Transition Metal Catalysis

Description: The ability of gold(I) to activate many types of unsaturated bonds toward nucleophilic attack was not widely recognized until the early 2000s. One major challenge in gold catalysis is the control over regioselectivity when there are two or more possible products as a result of complicated mechanistic pathways. It is well know that the choice of ligand can have dramatic effects on which pathway is being followed but very rarely are the reasons for this selectivity understood. The synthesis of n… more
Date: May 2016
Creator: Ruch, Aaron A.
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Examination and Development of the Correlation Consistent Composite Approach

Description: 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
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Kinetic Studies on C‐h Bond Activation in the Reaction of Triosmium Clusters with Diphosphine and Amidine Ligands

Description: The reaction of 1-(diphenylphosphino)-2-(diphenylphosphito)benzene (PP*) and Os3(CO)10(ACN) has been investigated. A combined experimental and computational study on the isomerization of 1,2-Os3(CO)10[μ-1,2-Ph2P(C6H4)P(OPh)2] (A) and 1,1-Os3(CO)10[μ-1,2-Ph2P(C6H4)P(OPh)2] (B) and reversible ortho-metalation exhibited by the triosmium cluster B are reported. The subsequent conversion of cluster B to the hydrido cluster HOs3(CO)9[μ-1,2-PhP(C6H4-η1)C6H4P(OPh)2] (E) and the benzyne-substituted clus… more
Date: December 2014
Creator: Yang, Li
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