Inorganic Chemistry Commons^™

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 …

Synthesis Of Molecular Probes For The Detection Of Toxic Analytes, Rashid Mia

Dissertations

Two different types of molecular probes have been synthesized. The first family of probes is the coumarin class of compounds. These chemodosimters are referred to as Low Molecular Weight Fluorescent probes (LMFP). The other type of molecular probe is a macrocycle known as a pillar[5]arene receptor.

The chemodosimters (2.12a-c and 3.12a) were synthesized in four to five steps. The photophysical properties were extensively studied in various solvent systems (DMSO, CH₃CN, DMF, MeOH, EtOH, Me₂CO, MeCO₂Et, CHCl₃, C₆H₅Me, and C₆H₆). Dimethyl sulfoxide (DMSO) …

A Library Of Low Molecular Weight Fluorescent Probes For The Detection Of Cu(Ii) And Fe(Iii) Ions, Ashley Johnson

Dissertations

This dissertation reports the synthesis and photophysical properties of a family of rhodamine dyes (compounds 3.9-3.13 and 4.6). The rhodamine dyes are prepared in two steps, and fully characterized by ESI-MS (Low and High resolution), X-Ray crystallography, NMR spectroscopy, and FT-IR spectroscopy. The coordination environment of the low molecular weight fluorescent probes (LMFPs) was systematically changed to investigate the thermodynamic behavior between the LMFPs and an array of metal ions (Cu²⁺, Fe²⁺, and Hg²⁺ ions) in protic and aprotic solvent systems. Upon coordinating to metal ions, the π-conjugation of the LMFPs changed, resulting in …

Capabilities And Limitations Of The Spin Hamiltonian Formalism In Single Molecule Magnets, Philip Ferko

Dissertations

The rational design of molecular magnetic materials is an ongoing effort involving physics, materials science, and chemistry. A common approach to design of complexes and interpretation of magnetic data is the spin Hamiltonian formalism. In this approach, magnetic data is interpreted through constants extracted from the parameterization of data. In design, certain structural motifs are pursued, rationalized by the minimization or maximization of terms in the spin Hamiltonian. In this work, monometallic complexes were prepared to simplify magnetic behavior and allow the examination of specific factors that influence single molecule magnetism like coordination geometry, ligand identity, symmetry, and spin-orbit coupling. …

Polyhedral Oligomeric Silsesquioxane-Phosphate Glass Matrix Nanocomposites With Additional Chapter On Phosphate Glass-Poly(Ethylene Terephthalate) Matrix Composites, Kyoungtae Kim

Dissertations

Preparation and characterization of tin fluorophosphate glass (Pglass) matrix nanocomposites incorporating polyhedral oligomeric silsesquioxane (POSS) were investigated on the structural, thermal, morphological, mechanical, and rheological properties. Various processes including synthesis, extrusion and sintering processes were applied to prepare the nanocomposite samples. Another application of POSS with hydrophobic functional groups on the well-structured nanoscale silicate cage with three silanol groups was investigated to present the feasibility to use POSS molecule as a coating material on the surface of the hydrophilic inorganic glass. In addition, Poly(ethylene terephthalate) polymer matrix composites incorporating Pglass was studied to present the benefits of the Pglass with …

Photoelectrochemical Studies On Non-Noble Metal Based Catalysts Towards Tandem Solar Water Splitting, Arun Siddarth Sridhar

Dissertations

Photoelectrochemical (PEC) water splitting makes direct use of solar energy incident on semiconductor photoelectrodes, and it is a convenient, economic option to produce high purity hydrogen at low temperatures. The use of multiple light absorbers can increase overall solar energy utilization and provide a solution to the trade-off between overall band gap and band edge positioning of photoelectrodes specific to solar water oxidation and water reduction. The study of non-noble metal based catalysts for hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) are essential for economic practical commercialization of photo-electrolyzers. This dissertation focuses on the use of a variety …

Development Of Rules Of Attraction For Intercalated Guest Molecules Inside Of A Hydrogen Bonded Framework, Matthew Fischer

Dissertations

Supramolecular chemistry has synthesized large and small molecules which host guest molecules for several decades. What started as a way to mimic of enzymes in nature, has exploded into a sea of materials such as porous coordination polymers, low-density metal-organic frameworks, inclusion compounds, and hydrogen bonded frameworks. We previously designed a layered framework consisting of a metal complex with coordinate covalent ligands. These ligands have peripheral carboxylic acid groups which hydrogen bond to organic pillars containing terminal amines. The layered structure is separated by these pillars, which are closed-packed, creating 1-dimensional channels able to co-crystallize molecules. There is interest in …

Steric Effects On The Formation Of Manganese Oxide Clusters And 2-Dimensional Ammonium Formate Architectures, Carl Oberle

Dissertations

It has been demonstrated by the Beatty group that altering the identity of the ortho-substituent of a dianiline counterion affects the assembly and dimensionality of a cadmium-chloride layer from 2-D to 0-D. This work seeks to extend this finding to metal oxide and organic hydrogen-bonded materials. By systematically increasing the ortho­-substituent’s size on the benzoate building block of reported manganese oxide clusters, of formula Mn_xO_y(O₂C-R)_zL_w (where R = Alkyl, L = neutral monodentate ligand), we aim to impact the self-assembly of these materials relative to their parent …

Principles Of Surface Chemistry Central To The Reactivity Of Organic Semiconductor Materials, Gregory J. Deye

Dissertations

Organic thin-films are rapidly becoming implemented as semiconducting materials in electronic devices and as a result, surface reactivity plays an increasingly important role in the improvement of semiconducting properties. My dissertation addresses how organic thin-films react with gaseous molecules. Previous reports of chemical reactions on organic surfaces claim, “phase rebuilding reaction mechanisms,” whereby reactions only proceed if chemisorbed adsorbate molecules are able to traverse through voids in the molecular lattice. The over-assumptions of this model and lack of correlation to reaction temperature make understanding of organic substrate reactivity incomplete. In contrast, I argue applied heat causes deformation of the molecular …

Surface Modification For The Improvement Of Metal/Organic Semiconductor Interfaces, Jonathan Paul Hopwood

Dissertations

Organic electronics have become much of the forefront of scientific research due to their advantages over tradition electronics as well as their applications in consumer devices, medical devices, and harnessing renewable sources of energy. Despite their appeal, two major obstacles are responsible for poor performance and limited applications. These problems occur at the interface between the two main components of the devices, the organic semiconductor and the metal electrodes. The first, high electrical resistance, is a result of the misalignment between the metal’s free electrons and the organic semiconductor’s conduction band. We seek to capitalize on this misalignment using light-responsive …

Cadmium Chloride Dimensionality Changes From Ortho-Substituted Anilines, Stephanie Cernicek

Dissertations

Inorganic-organic hybrid metal halide materials have been of great interest recently due to the useful properties offered by such a combination. The inorganic portions usually consisting of MX₆^2- subunits, (M = Pb, Sn, Cd, Cu; X = Cl, Br, I) most often form 2-D perovskite layers where the metals are bridged by corner sharing halides. The organic portion, usually consisting of primary amines or anilines provides a template for the inorganic framework and in some cases, dictates the dimensionality (2-D, 1-D, 0-D) of the network. These materials have various applications in host-guest chemistry catalysis, and gas storage, or …

Syntheses, Structures And Magnetic Properties Of Cyano-Bridged Transition Metal Compounds, Uma Prasad Mallik

Dissertations

To investigate the hypotheses, that systematically changing the electronic and relative sizes of tricyanido building blocks will tune magnetic properties of their cluster derivatives, we prepared two new tricyanido pyrazolylborate complexes, [NEt₄][(Tp*^Me)­Fe(CN)₃]­·H₂O and [NEt₄]­[(Tp^*Bn)­Fe^III(CN)₃]­·H₂O·MeOH, and investigated their self-assembly. The new building blocks were prepared, structurally characterized, and their coordination chemistry explored to prepare small molecule-based magnetic materials.

Three bent trinuclear ferromagnetic cluster derivatives of {[(Tp^*Me)­Fe^III(CN)₃]_2­[Ni^II(L)₂]}·n(solvent) [L = …

The Synthesis Of Chemosensors For Toxic Analytes, Johnathan Hugh Broome

Dissertations

A number of chemosensors have been designed and synthesized to target cations (Zn²⁺ions), neutral molecules (cathinones), charged molecules (aminoindanes), and anions. The Zn²⁺ ion sensor featured bistriazole designed binding unit and ferrocene signaling units. Characterization of Zn²⁺ ion binding was carried out with electrochemical techniques (CV and DPV), ¹H-NMR, mass spectrometry, and molecular modelling. It exhibited a 1:1 binding stoichiometry with Zn²⁺ and had an affinity for ZnCl₂ (Log K_1:1 = 4.1 ± 0.02) over other Zn²⁺ salts.

The cathinone probe was designed to selectively bind mephedrone over common street drugs …

A Library Of Coumarin-Enaminone Chemodosimeters For The Detection Of Analytes, Aaron Berrell Davis

Dissertations

Many anions and metal ions are of biological and environmental importance. This work describes our attempts to synthesize molecular probes to specifically target cyanide, zinc, cadmium and mercury as these species can often result in negative effects to the environment and the human body.

The work in this dissertation, describes the synthesis of a family of coumarin-enamine chemodosimeters, in a straightforward synthetic procedure, the reaction between 7-(diethylamino)-4-hydroxycoumarin and a primary amine. The work presented in this dissertation demonstrates that these molecules can play dual roles and therefore the work is split into two distinct parts: Part 1 describes one role …

Exploring Conditions For The Enhancement Of Acene Semiconductors Through The Use Of The Diels-Alder Reaction, Brittni Qualizza Qualizza

Dissertations

This dissertation demonstrates the application of SAMs to the surface of acene crystals, specifically of tetracene and rubrene, using the Diels-Alder reaction. The second chapter details preliminary reaction results and two analytical methods which were employed to confirm adsorption of the dienophile on the surface of single crystals, tetracene and rubrene. These were mass spectrometry and X-ray photoelectron spectroscopy (XPS). Mass spectrometry experiments distinguish the chemical identity of adduct on the crystals and also it discerned chemi- and physisorbed molecules from one another. XPS was used to prove face selectivity of the reaction by the detection of dichloromaleic anhydride. From …

Molecular Probes For The Detection Of Zn2+ And Fe3+ Ions, Erendra Manandhar

Dissertations

A number of molecular probes have been designed and synthesized for the detection of Zn²⁺ and Fe³⁺ ions. Two types of functional groups have been incorporated into the molecular scaffolds to utilize different fluorescent mechanisms. The first class of receptors contains a pyrene moiety. These molecular probes use the excimer mechanism for the detection of Zn²⁺ ion. The probes work well in an organic solvent with a detection limit of 20 nM (one ppb). Alternatives are made to make them water soluble, but this proved to be difficult. An interesting ion-induced self-assembly system will also be discussed. …

Optical And Electrochemical Sensors For The Detection Of Metal Ions And Nerve Gas Mimics Via Fluorescein And Coumarin Derivatives, Fasil Adefris Abebe

Dissertations

Trace element detection of metals, for example, iron, Copper and zinc, are important in biological systems and in the environment. Many of us are aware that our cells contain metal ions that are “tied” up in proteins. However, chelatable or “free” trace elements can also be found in small quantities, and can have a negative impact on our bodies. Despite the increasing surge in developing sensors for metals and nerve gas agents, efficient detection still remains a challenge. Among the various sensors developed so far, fluorescence sensors play an important role due to their simplicity. I design fluorescein-based chemosensors for …

Optical And Electrochemical Properties Of Monolayer Protected Gold Clusters Modified With Fluorophores, Mary Sajini Devadas

Dissertations

My research focused on the synthesis, characterization and the investigation of the optical and electrochemical properties of monolayer-protected quantum-sized gold clusters. Significant research attention was focused on the solution phase optical and electrochemical properties of these clusters. Highly monodisperse Au clusters with different types of ligands were successfully synthesized with sizes varying from 1 nm to 13 nm. These preformed gold clusters were modified with fluorophores and pseudo-rotaxanes for developing better nonlinear optical materials for sensing and biological imaging purposes. We have tried to focus on the interaction of the outer ligand shell, made up of –S-Au-S-Au-S- bonds, with the …