Physical Sciences and Mathematics Commons^™

Palladium (Ii)-Catalyzed Selective Reduction Of 4’-(Phenylethynl)Acetophenone In The Presence Of A Formic Acid-Triethylamine Mixture, Suzanne Chayya, Akram Hijazi, Anis Daou, Ali Alaaeddine, Mohamad Sakr, Ghassan Younes, Mohammad El-Dakdouki

BAU Journal - Science and Technology

An efficient and straightforward palladium acetylacetonate-catalyzed hydrogen transfer of 4'- (phenylethynyl)acetophenone was developed in this study. Formic Acid was found to be the best hydrogen source in this catalytic system in the presence of triethylamine. Excellent conversions and selectivity were obtained in reducing the starting internal aromatic alkyne to either (E)-1-(4- styrylphenyl)ethanone or an interesting cyclic product, 1-(phenanthrene-3-yl)ethenone, over the ketone functional group present. Over-reduction was rarely seen. The reaction conditions were optimized in terms of the choice of the palladium catalyst, temperature, solvent, and the H-donor/base combination. Using this catalytic system, a one-step synthetic pathway of the …

Gold (I) Tetrathiomolybdate Clusters: Synthesis, Characterization, Computational Studies, And Reactivity With Thiophenol And Selenophenol, Dhirgam Humaidy

Electronic Theses and Dissertations

This thesis describes the synthesis and reactivity of heterometallic complexes containing medicinally active Au(I) and tetrathiomolybdate, [MoS₄]^2-. The research is motivated by the idea of multifunctional drugs, which are designed to treat diseases through two or more mechanisms of action. Five clusters of the general form, [MoS₄(AuL)₂] were prepared: C-1 (L=IPr), C-2 (L=IBzMe), C-3 (L=IMes), C-4 (L=PPh₃), and C-5 (L=PEt₃). The clusters with NHC ligands, C-1, C-2, and C-3 were prepared for the first time and thoroughly characterized by ¹H NMR,¹³C{¹H} …

Effects Of Surface Ligation On Charge Extraction From Wurtzite Cadmium Selenide Quantum Platelets And Quantum Belts, Hailey Meyer

Arts & Sciences Electronic Theses and Dissertations

This dissertation presents the synthesis of flat, colloidal wurtzite CdSe quantum platelets and quantum belts for ligand exchange to novel and existing organic and inorganic L-, X-, and Z- type ligands. Use of these ligands in conjunction with the semiconductor nanocrystals allows for examination of their ligand exchange abilities, photoluminescence quenching efficiencies, and charge transfer properties.

First, zinc and cadmium dithiocarbamate compounds [M(S2CNR1R2)2] are used as ligands on wurtzite CdSe quantum belts. Complete ligand exchange is achieved when the belts are initially ligated with Cd(oleate)2, a Z-type ligand, prior to the exchange, as opposed to n-octylamine or ammonia, which are …

The Chemistry And Catalytic Activity Of Dehydrogenative Silylation And Hydroboration Of Complexes Bearing Semirigid Ligands With Group 14 Elements, Niroshani S. Abeynayake

Theses and Dissertations

Incorporation of silicon in the ligand backbone would yield electron-rich metal complexes upon coordination to transition metal complexes. The coordination chemistry of semirigid benzyl phosphines bearing a single or multiple phosphorus atoms and varying number of Si−H moieties has gained interest in recent years. This dissertation focuses on synthesizing silyl and germyl transition metal complexes of groups 9 and 10. Chapter II presents the synthesis of a family of four coordinated 14-electron rhodium complexes. The newly synthesized complexes were characterized in solution by multinuclear NMR spectroscopy and in the solid-state by single-crystal X-ray diffraction. These d⁶ complexes possess sawhorse …

Designing And Synthesizing A Warhead-Fragment Inhibitory Ligand For Ivyp1 Through Fragment-Based Drug Discovery, Samuel Moore

Symposium of Student Scholars

Fragment-based drug discovery (FBDD) is a powerful tool for developing anticancer and antimicrobial agents. Within this, magnetic resonance spectroscopy (NMR) provides a comprehensive qualitative and quantitative approach to screening and validating weak and robust binders with targeted proteins, making NMR among the most attractive strategies in FBDD. Inhibitor of vertebrate lysozyme (Ivyp1) of P. aeruginosa serves as an excellent target because of its active cellular location and implications in clinical prognosis for cystic fibrosis and immunocompromised patients. This study uses current NMR and biophysical techniques to develop a covalent, fragment-linked warhead inhibitor for Ivyp1 through synthetic methods, warhead linking, and …

Synthesis And Surface Modification Of Azide Decorated Silver Nanoclusters, Alexander H. Stöckli

Electronic Thesis and Dissertation Repository

In nanocluster research, easy modification of the cluster surface while maintaining the cluster core remains a key challenge. Herein we report the synthesis, structure, and properties of four targeted Ag₂₀ nanoclusters (NCs) with surface azide moieties, two of which have 8 azide moieties, [CO₃@Ag₂₀(S^tBu)₁₀(m-N₃-C₆H₄COO)₈(DMF)₄] and [CO₃@Ag₂₀(S^tBu)₁₀(p-N₃-C₆H₄COO)₈(DMF)₄], and two of which have 6 azide moieties, [CO₃@Ag₂₀(S …

Transition Metal Computational Catalysis: Mechanistic Approaches And Development Of Novel Performance Metrics, Brett Anthony Smith

Doctoral Dissertations

Computational catalysis is an ever-growing field, thanks in part to the incredible progression of computational power and the efficiency offered by our current methodologies. Additionally, the accuracy of computation and the emergence of new methods that can decompose energetics and sterics into quantitative descriptors has allowed for researchers to begin to identify important structure-function relationships that predict the properties of unexplored subspaces within the overall chemical space. Catalytic descriptors have been used frequently in data driven high-throughput computational screenings. With the use of machine learning, a large portion of the chemical space an be predicted in matter of minutes or …

Turning Ligands On Their Side: Computational Investigation Into The Binding Of N2o And N2 In Transition Metal Complexes, Cole Donald

Electronic Theses and Dissertations

Common greenhouse gas nitrous oxide (N₂O) is a thermodynamically potent and environmentally benign oxidant, making it a desirable target for metal center activation. Unfortunately, N₂O is a poor ligand for transition metals due to its weak sigma-donating and pi-accepting properties; as a result, few transition metal complexes capable of interacting with N₂O have been found. As the primary source of all nitrogen in organisms, abundant gas dinitrogen (N₂) is a crucially important tiny molecule and an essential part of daily existence. However, due to its inertness, it has limited practical uses in …

Computational And Experimental Investigations Of Alkali Cation Interactions At The Rutile – Water Interface, Isaac Johnston

All Dissertations

Overall, the objective of this dissertation was to investigate the degree of sorption for the alkali cations on rutile to ascertain the impact of different cation properties, such as ion size and charge density, on sorption mechanics as well as probe how the ion may alter the surface – aqueous interface. Initial molecular dynamic simulations and batch experiments showed minimal surface sorption for any alkali cation at relatively low concentrations while simultaneously suggesting the enthalpy of deprotonation shifts slightly in the presence of the alkali cations at different ionic strengths. The cations are likely causing small reorientations of the near-surface …

Synthesis And Characterization Of 2,6-Diisopropylphenoxy Tetrapyrazinoporphyrazines As Potential Molecular Qubits, Benjamin Marx

Masters Theses

This thesis reports the synthesis of metal-free and metal-containing phthalocyanine derivatives using methods typical for that class of functional dyes. A mixture of the target compounds prepared here, one paramagnetic and one diamagnetic tetrapyrazinoporphyrazine, will be tested for their potential use in spintronics – the application of spin-active species in molecular electronics. Phthalocyanines and their derivatives are well-known for their ease of preparation and tunability; they have been utilized as sensitizers for photodynamic therapy of cancer and solar cells, as well as in catalysis and chemical sensing. Tetrapyrazinoporphyrazine complexes are compared with the parent phthalocyanine as their chemistry is similar …

The Synthesis, Lewis Acidity And Catalytic Activity Of Bis(Catecholato)Germanes, Andrew T. Henry

Electronic Thesis and Dissertation Repository

Main group Lewis acids have been shown to be viable alternatives to state-of-theart transition metal catalysts. While extensive research into a variety of p-block Lewis acids have been reported, the field of germanium Lewis acid chemistry has been described as “almost non-existent”. A variety of bis(catecholato)germane derivatives have been synthesized. The Lewis acidity of these compounds was analyzed by the Gutmann-Beckett and fluoride ion affinity methods demonstrating the high Lewis acidity of these complexes. The bis(catecholato)germanes were utilized as Lewis acid catalysts for the hydrosilylation of aldehydes, the hydroboration of alkynes, Friedel-Crafts alkylation of alkenes, and the oligomerization of styrene …

Formation Of Doped Semiconductor Nanocrystals From Doped Molecular Clusters, Jillian E. Denhardt

Doctoral Dissertations

Transition metal doping of semiconductor nanomaterials, particularly magnetic dopant ions, is of great interest for the synthesis of diluted magnetic semiconductors (DMS) with spintronic-based applications. The incorporation of magnetic ions into quantum dots (QDs) would be particularly useful since the quantum confinement of these materials is theorized to enhance magneto-optical related properties. One major challenge in this field is the segregation of dopant ions towards the outer regions of the QD due to the exclusion of dopants during the nucleation process, thereby inhibiting the magneto-optical properties. In this dissertation, we address the dopant segregation challenge by exploring the underlying mechanisms …

The Coordination Chemistry And Reactivity Of Pd Phosphine 1-Azaallyl Complexes, Kyle M. Jackman

Electronic Thesis and Dissertation Repository

Structurally responsive ligands (SRLs) are a class of ligands that change their coordination mode with a metal centre, which permits reactions that are difficult with non-SRLs, allow access to unique mechanisms, and allow isolation of unusual coordination complexes. The 1-azaallyl (1-AzA) family of SRLs are capable of isomerizing between η³-NCC and κ¹-N modes that occupy two and one coordination sites, respectively. This thesis investigates a new class of phosphine 1^AzA (P^AzA) ligands and the reactivity of their coordination complexes with palladium.

The first-generation P^AzA ligand contains a phenyl linkage between the two heteroatoms and affords a …

Bismuth Binding In Human Metallothionein, Emily M. Toswell

Undergraduate Student Research Internships Conference

Bismuth metal is one of the least toxic heavy metals for humans. It is used in a wide variety of applications including organic synthesis, cosmetics and pharmaceutical applications. In biomedicine, bismuth is a therapeutic metal used in metallodrugs such as Pepto Bismol for its antimicrobial and antibacterial properties. Metallothionein (MT) is a cysteine rich protein found in the liver, kidneys, brain and central nervous system. MT can bind a variety of metals including essential metals such as zinc and copper. This research investigates the binding pathway of Bi[EDTA]- with fully metallated Zn₇MT by using mass-spectrometry and UV-vis absorption.

Synthesis And Physicochemical Characterization Of Noncentrosymmetric Quaternary Sulfides With Potential Nonlinear Optical Applications, Andrew J. Craig

Electronic Theses and Dissertations

In this work, several new quaternary sulfides were synthesized and investigated for their potential applications in optics. Chapter 1 provides an overview of nonlinear optical (NLO) materials in general, including their applications, ideal characteristics, current deficiencies, and strategies for the discovery of new candidate NLO materials, particularly those for use in the infrared (IR). Two families of compounds are investigated in this work, including Ln₃LiTS₇ (3-1-1-7) compounds and I₄-II-IV₂-VI₇ (4-1-2-7) diamond-like semiconductors (DLSs). All products were synthesized via traditional high-temperature, solid-state synthesis and their structures were solved and refined through single crystal …

Design And Surface Modification Of Noble Metal-Based Nanocatalysts, Xuchun Wang

Electronic Thesis and Dissertation Repository

This thesis investigates approaches to modifying the surface structure of noble metal-based nanocatalysts. Noble metal-based nanocatalysts, such as Pt and Pd, play a significant role in heterogeneous catalysis due to their capabilities in activating the cleavage or formation of chemical bonds, but still suffer from the high-cost issue and unsatisfied catalytic performance due to too strong or too weak adsorption of intermediates. Considering the surface specificity of heterogeneous catalysis, Bi, a cheap metal, was used to modify the surface of Pt- and Pd-based nanocatalysts. This thesis aims to unveil the role of Bi in improving their catalytic performance from both …

Synthesis, Characterization, And Reactivity Studies Of Highly Reduced Early-Metal Complexes Supported By Imidazolin-2-Iminato Ligands, Maria Alejandra Gomez Torres

Open Access Theses & Dissertations

Our group has shown that reduction of titanium complexes supported by the sterically encumbering N-donor ligands 1,3â??bis(Dipp)imidazolinâ??2â??iminato (ImDippNâ??) and ketimine guanidinate (ketGuan = [(tBuC=N)C(NDipp)2]-) gives access to electron rich platforms featuring a metal coordinated, reduced, dearomatized arene substituent, which act as an electronic reservoir capable of facilitating multi-electron transfer chemistry driven by the rearomatization driving force. For instance, the arene-masked Ti(II) synthon (DippketGuan)(η6-ImDippN)Ti (Dipp = 2,6-iPr2C6H3) (TiDipp) is a versatile and potent one- and two-electron reductant capable of distinctive late-metal type reactivity such as transfer hydrogenation and catalytic olefin hydrogenation. Interestingly, TiDipp can mediate the reversible cleavage of thiophene and, …

Synthesis And Evaluation Of Water-Dispersed Aryl-Gold Nanoparticles And Applications In Catalysis, Ahmad Al Ahmad

Electronic Theses and Dissertations

Gold nanoparticles have been used in environmental remediation as catalysts through biological and chemical redox reactions of many types of industrial waste including nitroarenes, organic dyes, carbon monoxide, and others. These reactions occur in harsh environmental conditions (e.g. changing temperature, presence of salts, extreme pH solutions) which require robust nanoparticles that can keep their activity and resist aggregation. This thesis describes the synthesis, characterization, and investigation of the catalytic activity of gold-aryl nanoparticles. Gold–aryl nanoparticles (AuNPs-COOH) fabricated using a mild reduction process of a molecular aryldiazonium gold(III) salt [HOOC-4-C6H4N≡N]AuCl4 showed high stability in the presence of high ionic strength salt, …

Catalytic Activity Of Tungsten-Dioxo And Tungsten-Diimido Complexes, Kayla Denike

Graduate Theses and Dissertations

Due to the significant decline in the availability of petrochemical resources and the increasing demand for the useful olefin mixtures extracted from oil, a sustainable and efficient alternative to these materials has become vital. Fortunately, renewable biomass derived materials may serve as a sustainable solution to the limited resources problem. Molecules derived from the degradation of biomasses are highly oxygenated and highly functionalized. Developing processes to efficiently defunctionalize these oxygen-rich materials will lead to potential up-conversion to carbon chemicals. Homogeneous catalytic deoxygenation processes present an opportunity to access valuable carbon commodity chemicals from biomass derived polyols. This dissertation details the …

Hierarchically Structured Photoelectrodes Via Atomic Layer Deposition, Justin Rowan Reed Demoulpied

Graduate Theses and Dissertations

In the search for a sustainable method to meet increasing energy needs, solar energy emerges as an underutilized, plentiful resource. Solar intermittency and requirements for transportation necessitate storing solar energy in the form of chemical bonds via artificial photosynthesis. Photoelectrochemical (PEC) water splitting generates hydrogen fuel from solar energy and water. A semiconducting material that successfully meets the complex requirements for building an industrially scalable PEC device has yet to emerge. This is leading to a reevaluation of materials previously overlooked within PEC research, mainly materials with limitations such as minimal charge carrier mobility and propensity to corrosion under illumination …

Competition Between Halogen And Chalcogen Bonding And Their Role In Probing Organic Transformations, Andrew Peloquin

All Dissertations

Halogen bonding, the attractive interaction of an electrophilic region on a halogen atom with a nucleophilic region on another atom or molecule, provides a highly directional tool in forming solid-state motifs. This interaction, along with the related chalcogen bonding interactions, forms powerful synthons, which, when combined with other typical intermolecular attractions such as hydrogen bonding, allow for the design of supramolecular structures and inputs to crystal engineering. This dissertation research serves two primary purposes: (1) to catalog halogen and chalcogen bonding interactions with various donor molecules and (2) to utilize these interactions to probe interesting organic transformations.

In order to …

Alkylthiocarbamate Metal Complexes With Antiproliferation Activity., Kritika Bajaj

Electronic Theses and Dissertations

Bis(thiosemicarbazones) (BTSCs) and their metal complexes have been extensively studied for various applications including catalysis for hydrogen evolution reactions, treatment of neurodegenerative diseases, hypoxia imaging, and a wide range of pharmacological purposes including antitumor, antiviral, antibacterial, and antifungal agents. The paramount property that makes BTSC metal complexes interesting for their use in these applications is the reduction potential of the coordinated metal, which can be selectively tuned by varying the substituents present on the ligand framework. Although the BTSCs have shown a great deal of success as potential cancer therapeutic agents, they lack selectivity towards cancer cells. For this matter, …

Dissolution And Electrochemical Recovery Of Uo2, Uo3, And U3o8 In Ionic Liquids, Katherine Iolani Thornock Luebke

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explores a novel method of increasing the solubility of uranium oxides and other actinide oxides in room temperature ionic liquids (IL) using direct dissolution. The goal is to further expand our knowledge of actinide dissolution and possible nuclear fuel cycle material applications using ionic liquids. The novelty of the methods is focused on the use of oxidizing gas generated using air passed through an ozone generator. While examples of dissolution exist in IL using acidic functionalized ionic liquids, the solubility of all possible oxide species was not demonstrated. Also, the addition of aqueous acid to IL containing actinide …

Extracting Lithium Using The Steric Bulk Of An Aminimide Functional Group, Jacob Parker, Martin Chin Ph.D.

Summer Undergraduate Research Program (SURP) Symposium

An aminimide is a zwitterionic group containing a cationic nitrogen bonded to an anionic nitrogen. The goal of this project was to use the steric bulk and electronic properties of the aminimide to block other species in a brine solution such as potassium, and selectively pick up lithium. To test this, polymethacrylate beads which contain carboxyl groups were modified to the desired aminimide. Three different aminimide groups were tested, a trimethylaminimide, aminopyridiniumaminimide, and a triethylaminimide. The modified beads would be introduced to a solution containing lithium and the lithium concentration was measured before and after exposure to the beads using …

Using An Aminimide Polymer To Extract Lithium From A Brine Solution, Austin Heidbreder, Martin Chin Ph.D.

Summer Undergraduate Research Program (SURP) Symposium

Fast lithium isolation from water partly containing lithium ions would be an improvement over the current method of obtaining lithium in lithium mining water operations. The aminimide functional group can be used to selectively bind to lithium cations to extract lithium from brine. To characterize this uptake, the concentration of water containing lithium was measured with atomic absorption spectroscopy before and after the solution has been exposed to a polymer with the aminimide functional group. Three different polymers were used: trimethyl EGDM polymer, trimethyl TMPTA polymer, and the triethyl TMPTA polymer. Of the three, the trimethyl TMPTA polymer seemed to …

Investigating The Influence Of Synthetic Environments On The Electronic Structure And Luminescence Of Cr-Doped Zinc Gallate, Xincheng Li

Electronic Thesis and Dissertation Repository

Cr doped ZnGa₂O₄ (Cr-ZGO) has shown potential in the field of bioimaging. To achieve the nano-size suiting for bioimaging, Cr-ZGO is normally synthesized using a hydrothermal method. There are few studies on how the hydrothermal conditions influence the structure and optical properties of the Cr-ZGO. The first two parts of this thesis study how different hydrothermal temperatures and pH environments will affect the optical properties of Cr-ZGO by photoluminescence spectroscopy. By combining the electronic structure information extracted from X-ray absorption near-edge structures (XANES) and extended X-ray absorption fine structure (EXAFS), a relationship among hydrothermal conditions, optical properties …

Sol-Gel Synthesis And Spectroscopic Characterization Of Titanium Dioxide Doped With Copper And Iron, Erin L. Jacoski

Chemistry Senior Theses

A source of bioavailable iron in open oceans stems from aerosols, increasing phytoplankton growth and the sequestration of atmospheric carbon dioxide. These aerosols contain semiconductors, like titanium dioxide, which is known to increase the bioavailability and can trigger photoreduction of Fe3+. Recently, it is suspected that other metals in the aerosols also influence the release of iron. In this work, the effects of doping with iron and copper on the physical characteristics of titanium dioxide nanoparticles, since the photocatalytic potential of titanium dioxide depends on its structure and metal content (anatase vs. rutile), were explored. Titanium dioxide nanoparticles were prepared …

Mechanism Of Sila- And Germafluorenes For Biological Applications, Shelby Jarrett

Dissertations

2,7-disubstituted silafluorenes and germafluorenes, originally designed for OLED applications, are a class of fluorescent dyes that have gained recent interest as probes for bioimaging and as biosensors to monitor cellular dynamics and interactions. Desirable biological probes absorb in the visible region, have high extinction coefficients, high quantum yield and excellent photostability. Here, their spectral properties are investigated under aqueous conditions for relevant biological applications. These molecules display intense blue fluorescence in the solid state and in solution, have high extinction coefficients, and exhibit appreciable solubility in aqueous solution. To better understand potential applications, the mechanism of fluorescence was investigated. It …

Exploring Structure-Function Relationship In Small-Molecular Catalysts Using Computational And Experimental Methodologies, Avik Bhattacharjee

Dissertations and Theses

Molecular modeling is a useful tool in the field of catalyst design for various processes. The use of Density Functional Theory (DFT) is routine in almost every discipline of chemistry. This allows for a deeper understanding of a molecular system even in situations where implementation of an experimental technique is unfeasible. However, without the right choice of theory and insufficient description, the model becomes susceptible to produce ambiguous results. This often leads to poor correlation with experimental findings hence an incomplete understanding of the system under study. Hence, to acquire a thorough knowledge of the intricacies involved in a system, …

Calcium Bistriflimide-Mediated Sulfur(Vi)–Fluoride Exchange (Sufex): Mechanistic Insights Toward Instigating Catalysis, Brian Han, Samuel R. Khasnavis, Matthew Nwerem, Michael Bertagna, Nicholas D. Ball, O. Maduka Ogba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We report a mechanistic investigation of calcium bistriflimide-mediated sulfur(VI)–fluoride exchange (SuFEx) between sulfonyl fluorides and amines. We determine the likely pre-activation resting state─a calcium bistriflimide complex with ligated amines─thus allowing for corroborated calculation of the SuFEx activation barrier at ∼21 kcal/mol, compared to 21.5 ± 0.14 kcal/mol derived via kinetics experiments. Transition state analysis revealed: (1) a two-point calcium-substrate contact that activates the sulfur(VI) center and stabilizes the leaving fluoride and (2) a 1,4-diazabicyclo[2.2.2]octane additive that provides Brønsted-base activation of the nucleophilic amine. Stable Ca–F complexes upon sulfonamide formation are likely contributors to inhibited catalytic turnover, and a proof-of-principle redesign …