Inorganic Chemistry Commons^™

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, …

Exploring The Potential Use Of Porous Silica Nanoparticles In Cest-Mri, Lydia Makotamo

Dissertations and Theses

Magnetic resonance imaging (MRI) is a widely used modality in diagnostics, treatment, and monitoring various conditions due to its ability to generate high-resolution images using non-ionizing radiation. The advent of contrast agents, which generally work by increasing the spin relaxation rate constants of water protons, has led to image enhancement. Despite the usefulness of this class of agents in diagnostic medicine, their inability to provide in-depth functional and anatomical information, coupled with their high detection limits, has led to new agents being explored.

Chemical exchange saturation transfer (CEST) presents an alternative route to generate signals via repetitive saturations transfers between …

Designing Environmentally Responsible And Highly Effective Bioorthogonally Functionalized Chiral Mri Contrast Agents, Karley Breann Maier

Dissertations and Theses

Magnetic resonance imaging (MRI) revolutionized diagnostic imaging and modernized the characterization of numerous diseases. The clinical success of MRI is in large part due to the employment of gadolinium-based contrast agents (GBCAs). Due to sensitivity limitations, GBCAs are indicated at markedly high dosages (~1 g Gd³⁺ per exam). The routine use of such large quantities of gadolinium poses significant health and environmental risks. There are growing concerns over the effects of dechelation of the metal in vivo and the possible effect of resulting gadolinium deposition. Concurrently, there is a rising awareness of gadolinium anomalies borne by GBCAs which undergo …

Tellurorhodamine Photocatalysts In Aerobic Oxidation Reactions: Development Of Synthetic Methods And Reaction Mechanisms, Irving D. Rettig

Dissertations and Theses

Aerobic oxidation photocatalysis involves the use of oxygen as an oxidant species, coupled to a light driven catalyst to achieve useful chemical transformations. Catalytic aerobic oxidation reactions can be defined as either oxidase-like, in which O₂ acts as an electron donor/acceptor but is not incorporated into the reaction products, or oxygenase-like where O₂ acts as an electron donor/acceptor and is incorporated into the reaction products. A multitude of inorganic catalysts have been developed that can achieve a wide scope of oxidase-like or oxygenase-like reactivity, however, it is rare for a catalyst to be capable of both. We report …

Synthesis And Assessment Of Radiotherapy-Enhancing Nanoparticles, Hayden Winter

Dissertations and Theses

Radiation Therapy (RT) is a common treatment for cancerous lesions that acts by ionizing matter in the affected tissue, causing cell death. The disadvantage of RT is that it is most often delivered via an external beam of radiation which must pass through healthy tissues to reach the target site, ionizing matter within healthy tissues as well. To address this drawback, techniques are being developed for increasing RT-induced cell death in a target tissue while minimizing cell death in surrounding tissues. This effect is known as radiation dose enhancement or RT enhancement.

The approach to RT enhancement studied in this …

Scanning Electron Microscopy (Sem) Investigation Of Morphology Changes In The Reduction Of Silica Nanoparticles To Elemental Silicon, Allison M. Cairns

University Honors Theses

The application of silicon nanoparticles varies from energy storage materials, to drug-delivery, and molecular recognition. Various chemical and physical properties of the Si nanoparticles arise from their morphology. This paper aims to reveal the morphology of Si nanoparticles following magnesiothermic reduction of silica (SiO₂) nanoparticles. Two sets of SiO₂ nanoparticles were used, commercially available NanoXact nanoparticles and laboratory-synthesized Stöber nanoparticles. A Zeiss Sigma VP FEG SEM was used to examine the morphology. Following the magnesiothermic reduction, the nanoparticles were etched with HF. Ten sets of images were taken of both Stöber and NanoXact nanoparticles: 1,2: the SiO …

Dft Analysis Into The Intermediates Of Nickel Pyridenthiolate Catalysed Proton Reduction, Carolyn N. Virca, Theresa M. Mccormick

Chemistry Faculty Publications and Presentations

Nickel pyridine 2-thiolate (Ni(PyS)₃ −) has shown good stability and activity as a H₂ generation catalyst for use in solar energy storage. The experimentally proposed catalytic pathway is explored using DFT calculations. Free energy changes along the reaction coordinate, spin states, localization of charge and geometry of the intermediates were explored. Calculations were performed using Gaussian 09 with a B3P86/ 6-31+G(d) basis set and a CPCM water solvation model. Of particular interest were our findings that the first reduction occurs at the nickel rather than through non-innocent ligands and that water coordination is not favourable although protonation of …

Solid State And Solution Dynamics Of Pyridine Based Tetraaza- Macrocyclic Lanthanide Chelates Possessing Phosphonate Ligating Functionality (Ln-Pctmb): Effect On Relaxometry And Optical Properties, Garry Kiefer, Mark Woods

Chemistry Faculty Publications and Presentations

The macrocyclic ligand 3,6,9-tris(methylenebutyl phosphonic acid)-3,6,9−15-tetraazabicyclo [9.3.1]pentadeca-1(15),11,13-triene (PCTMB) was synthesized and complexes of Eu³⁺, Tb³⁺, and Gd³⁺ studied by X-ray crystallography, luminescence, and relaxometry. In the crystal these complexes are dimeric and possess 8-coordinate Ln³⁺ centers that are linked by bridging phosphonates. The rigidity introduced by the pyridyl nucleus forces the EuPCTMB and TbPCTMB to adopt a twisted snub disphenoid (TSD) coordination geometry. Examination of the ⁵D₀ → ⁷F₀ luminescent transition of EuPCTMB in the solid state confirmed the existence of a single distinct Eu³⁺ coordination environment, whereas two …

Synthesis And Evaluation Of Lanthanide Ion Dota-Tetraamide Complexes Bearing Peripheral Hydroxyl Groups, Azhar Pasha, Mai Lin, Gyula Tircso, Cynthia L. Rostollan, Mark Woods, Garry Kiefer, A. Dean Sherry, Xiankai Sun

Chemistry Faculty Publications and Presentations

The use of lanthanide-based contrast agents for magnetic resonance imaging has become an integral component of this important diagnostic modality. These inert chelates typically possess high thermodynamic stability constants that serve as a predictor for in vivo stability and low toxicity. Recently, a new class of contrast agents was reported having a significantly lower degree of thermodynamic stability while exhibiting biodistribution profiles indicative of high stability under biological conditions. These observations are suggestive that the nature of contrast agent stability is also dependent upon the kinetics of complex dissociation, a feature of potential importance when contemplating the design of new …

Potentiometric And Relaxometric Properties Of A Gadolinium-Based Mri Contrast Agent For Sensing Tissue Ph, Ferenc K. Kálmán, Mark Woods, Peter Caravan, Paul Jurek, Marga Spiller, Gyula Tircso, Róbert Király, Ernő Brücher, A. Dean Sherry

Chemistry Faculty Publications and Presentations

The pH-sensitive contrast agent, GdDOTA-4AmP (Gd1) has been successfully used to map tissue pH by MRI. Further studies now demonstrate that two distinct chemical forms of the complex can be prepared depending upon the pH at which Gd³⁺ is mixed with ligand 1. The desired pH-sensitive form of this complex, referred to here as a Type II complex, is obtained as the exclusive product only when the complexation reaction is performed above pH 8. At lower pH values, a second complex is formed that, by analogy with an intermediate formed during the preparation of GdDOTA, we tentatively assign …

Structural And Chiroptical Properties Of The Two Coordination Isomers Of Ybdota-Type Complexes, Lorenzo Di Bari, Gennaro Pescitelli, A. Dean Sherry, Mark Woods

Chemistry Faculty Publications and Presentations

Studies of the structural, physical, and chemical properties of the lanthanide(III) complexes of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and related ligands are often complicated by the presence of two coordination isomers in solution. Since these coordination isomers are in exchange and cannot be separated, many techniques offer information only on the weighted average of the two isomers. Lanthanide ion complexes formed with the ligands S(RRRR)NO₂BnDOTMA and S(SSSS)NO₂BnDOTMA preferentially adopt only one of the two common coordination isomers in solution, so the ytterbium complexes of these ligands offer a unique opportunity to study …

Synthesis And Characterization Of Some Sf₅- Containing Sulfonic Acids, Robert J. Willenbring

Dissertations and Theses

Pentafluorosulfur (VI) bromide (SF₅Br) adds to olefins of the form CX₂=CX₂, where X= H or F, with the pentafluorosulfur group usually adding to the carbon with more hydrogens attached to it. This series of compounds was used in an attempt to prepare the corresponding sulfonic acid hydrates of the general formula SF₅CX₂CX₂SO₃H·nH₂O, in order to have these compounds tested as possible fuel cell electrolytes. The reaction scheme involved reflux of the SF₅Br adduct with an equimolar amount of sodium sulfite in 50% …

High Valent Chromium (V) And Chromium (Vi) Complexes, Harry Bennett Davis

Dissertations and Theses

A new preparative route to the only neutral chromium (V) oxide fluoride, chromium oxide trifluoride, has been accomplished by the reaction of xenon difluoride with chromyl fluoride at high temperature. The chromium oxide trifluoride is produced as crystals which are suitable for single crystal studies. In reactions of chromium oxide trifluoride with alkali and alkaline metal fluorides in anhydrous hydrogen fluoride, new chromium(V) oxide fluoride salts were obtained; these salts were not of high purity due to unknown problems. An attempt to prepare chromium oxide tetrafluoride by the reaction of xenon difluoride with chromyl fluoride in anhydrous hydrogen fluoride failed …

An Investigation Of Cadmium And Sulfur Reactions In Dimethylsulfoxide, Howard W. Hogle

Dissertations and Theses

The study of the reaction of cadmium and sulfur in dimethylsulfoxide (DMSO) is presented. Specifically, the reaction of dissolved molecular sulfur in DMSO at temperatures greater than 90°C with freshly precipitated metallic cadmium is followed by UV-visible spectrometry, atomic absorption spectrometry, and Raman spectrometry. Evidence for the formation of a new cadmium-sulfur species and S₃- is discussed. In a second reaction, an equilibrium sodium polysulfide solution in DMSO is titrated with a solution of cadmium ion at room temperature and the reaction progress is followed by means of UV-visible spectrometry. A calculation of the average number of polysulfide …

Chemistry Of Chromium Oxyfluorides And Group Vib Perfluoroglutarates, Bruce Michael Johnson

Dissertations and Theses

Pure chromium oxide trifluoride was prepared for the first time by reaction of CrO₃ and ClF with subsequent multiple fluorine treatments at 120°C. On the basis of its infrared spectrum, the purple CrOF₃ was assigned as a fluorine-bridged polymer with terminal oxygen groups. Chromium oxide trifluoride was found to be stable to 300°C, where it decomposes with the loss of oxygen to CrF₃.

On The Mechanism Of The Diels-Alder Reaction--Dimerization Of Trans-Phenylbutadiene, Michael Ward Mcnicholas

Dissertations and Theses

The Diels-Alder dimerization of trans-1-substituted butadienes is expected to yield a cyclohexene adduct with the substituents in the 3 and 4 positions cis to one another. This prediction is based on past observations of other Diels-Alder additions. The cis-isomer is the only one consistent with a two-stage mechanism proposed by Woodward and Katz.

In the case of trans-phenylbutadiene, the expected adduct is cis-3-phenyl 1-4-(trans-styry1) cyclohexene. Alder, Haydn and Vogt, however, reported that the corresponding trans-isomer is the dimerization product. There is reason to believe that the observation of the trans-isomer may have been the result of product isomerization during purification. …

Reaction Of Aqueous Catechol Solutions With Minerals, Boonthong Poocharoen

Dissertations and Theses

The effectiveness of catechol, an aromatic vic-diol, in dissolving silicate minerals was studied. A synthetic amorphous magnesium trisilicate, Mg₂Si₃O₈∙5H₂O, as well as the minerals olivine, sepiolite, diopside, augite, and enstatite were used to react with catechol in slightly acidic, basic, and neutral solutions. It was found, depending on the solvent used, that 33-52, 8-17, 14-30, 5-11, 3-6, and 0.5-1 % of the minerals dissolved, respectively.

The reaction with Mg₂Si₃0₈·5H₂0 resulted in the formation of crystals of magnesium tris (catecholato) siliconate nonahydrate Mg[Si(Cat)₃]∙9H₂0. Dehydration of the crystals at room temperature resulted in the loss of 6 moles of water to form …

Kinetics Of The Cope Rearrangement Of 3,4-Diphenylhexa-1,5-Diene, Harlan Albert Jerome Berg

Dissertations and Theses

Kinetics investigations of the thermal Cope rearrangement of meso-and d1-3,4-diphenylhexa-1,5-dienes were undertaken in order to gain information about the transition states for these reactions by determining the appropriate enthalpies and entropies of activation. Of particular interest were the activation parameters for the meso compounds' rearrangement as it represents the only known example in which both four-and six-centered transition states are of comparable energy.

Kinetics of the dl isomers' rearrangement in the temperature range 90-110⁰were determined using 5 X 10¯⁵M solutions of the olefin in heptane contained within sealed Pyrex ampules. Extents of reaction were determined from UV absorbance measurements at …