Physical Chemistry Commons^™

Approaches Toward Novel 1,2,3-Triazole Sensors For The Detection Of Anions And Heavy Metal Cations, Richard D. Govan

College of Graduate Studies: Theses & Dissertations

Cations and anions play pivotal roles in biological and physiological processes, however an imbalance in concentration of any ion can be detrimental. Therefore, research into the selective recognition of anions and heavy metal cations has acquired much attention. One approach involves the use of chemosensors. Upon interaction with targeted analytes, chemosensors produce a distinct response, in some cases a fluorescent or colorimetric signal. The 1,2,3-triazole unit has much potential as a chemical sensor due to its unique photophysical properties. The specificity, selectivity, and signaling mechanism of triazole sensors can be tuned with conjugation in the motif and choice and placement …

Investigations Into Structure And Properties Of Atomically-Precise Transition Metal-Chalcogenide Clusters Of Crte And Ligated Cr6te8(Pet3)6, Anthony F. Pedicini

Theses and Dissertations

The complete understanding of a clusters electronic structure, the primary mechanisms for its properties and stabilization is necessary in order to functionalize them for use as building blocks within novel materials. First principle theoretical studies have been carried out upon the electronic properties of Cr_xTe_y (x = 1 – 6, y = 0 – 8, x + y ≤ 14), as well as for the larger triethylphosphine (PEt₃) ligated cluster system of Cr₆Te₈(PEt₃)₆. Together, we aim to use the information garnered from the smaller clusters to address …

Preparation And Evaluation Techniques Of Porous Materials And Mixed Matrix Membranes For Targeted Co2 Separation Applications, Tsemre Tessema

Theses and Dissertations

The use of porous sorbents for physisorptive capture of CO₂ from gas mixtures has been deemed attractive due to the low energy penalty associated with recycling of such materials. Porous organic polymers (POPs) have emerged as promising candidates with potential in the treatment of pre- and post- fuel combustion processes to separate CO₂ from gas mixtures. Concurrently, significant advances have been made in establishing calculation methods that evaluate the practicality of porous sorbents for targeted gas separation applications. However, these methods rely on single gas adsorption isotherms without accounting for the dynamic gas mixtures encountered in real-life applications. …

Semiconductor Photocatalysis: Mechanisms, Photocatalytic Performances And Lifetime Of Redox Carriers, Ruixin Zhou

Theses and Dissertations--Chemistry

Photocatalytic reactions mediated by semiconductors such as ZnS, TiO₂, ZnO, etc. can harvest solar energy into chemical bonds, a process with important prebiotic and environmental chemistry applications. The recycling of CO₂ into organic molecules (e.g., formate, methane, and methanol) facilitated by irradiated semiconductors such as colloidal ZnS nanoparticles has been demonstrated. ZnS can also drive prebiotic reactions from the reductive tricarboxylic acid (rTCA) cycle such as the reduction of fumarate to succinate. However, the mechanism of photoreduction by ZnS of the previous reaction has not been understood. Thus, this thesis reports the mechanisms for heterogeneous photocatalytic reductions …

Characterization And Application Of Hybrid Nanostructures For Enhanced Biological Imaging Using Fluorescence Microscopy Techniques, William E. Martin

Theses and Dissertations--Chemistry

Fluorescence microscopy is a powerful tool for interpreting the structure and function of biomolecules, and their interactions with one another. Understanding fundamental biological mechanisms is important to the development of improved treatments for a variety of diseases. Fluorescent tags are used to track the motion and longevity of such events, with the ability to monitor several biomolecules at once. Currently, many of these studies are conducted using bulk measurements, or several biological events at the same time, because the added light from several emitters can more easily overcome the high fluorescence background inherent to biological systems. Although important in their …

Charge Transport In Electronic-Ionic Composites, Long Zhang

Theses and Dissertations--Chemical and Materials Engineering

The goal of this thesis is to generate fundamental understandings of charge transport behaviors of composites consisting of garnet structured Al substituted Li₇La₃Zr₂O₁₂ (LLZO) electrolyte and LiCoO₂ electrode. In order to take full advantage of all-solid-state batteries, bulk type composite electrodes should be introduced to increase energy and power density. However, the charge utilization of bulk type composite electrodes is quite low. Understanding ionic conduction behavior is, therefore, important for improving the performance of all-solid-state batteries, because ion conduction within solids depends on effective pathways. Electronic conductivity can be easily compensated by …

Photoluminescence Mechanism And Applications Of Graphene Quantum Dots, Yiyang Liu

Theses and Dissertations--Chemistry

Graphene quantum dots (GQDs) are small pieces of graphene oxide whose physical dimensions are so confined (a few to a few tens nm) that they have a finite bandgap due to a quantum confinement effect. The finite bandgap of GQDs grants them pronounced absorption bands and a substantial photoluminescence. These optical properties are rarely observed in traditional carbon materials, since most of carbon materials are metallic with a near-zero bandgap and thus have broad absorption spectra with no photoluminescence. The unique optical properties of GQDs, along with GQDs’ inherited advantages from carbon material family (cheap, abundant, non-toxic), make GQDs an …

Synthesis Of New Fullerene Derivatives For Photovoltaic And Biological Applications, Edison Castro

Open Access Theses & Dissertations

Functionalized fullerenes exhibit improved solubility and different chemical and physical properties that allow applications in multiple fields such as photovoltaic and biological applications. Currently, perovskite solar cells (PSCs) are the most rapidly developing type of solar cells with certified efficiencies rising from 3.8% in 2009 to 22.1% in 2016. The good electron transporting and solution processable properties of most fullerene derivatives make them the most popular electron transporting materials (ETMs) in inverted perovskite solar cells (PSCs).

The work is reported in 11 chapters. We start with a fullerene overview followed by cleaver and elegant methodologies that allow the synThesis of …

Manifestations Of Classical Physics In The Quantum Evolution Of Correlated Spin States In Pulsed Nmr Experiments, Martin K. Ligare

Faculty Journal Articles

Multiple-pulse NMR experiments are a powerful tool for the investigation of mole- cules with coupled nuclear spins. The product operator formalism provides a way to understand the quantum evolution of an ensemble of weakly coupled spins in such experiments using some of the more intuitive concepts of classical physics and semi- classical vector representations. In this paper I present a new way in which to inter- pret the quantum evolution of an ensemble of spins. I recast the quantum problem in terms of mixtures of pure states of two spins whose expectation values evolve identi- cally to those of classical …

Improving Cavity Enhanced Spectroscopy Of Molecular Ions In The Mid-Infrared With Up-Conversion Detection And Brewster-Plate Spoilers, Charles R. Markus, Adam J. Perry, James N. Hodges, Benjamin J. Mccall

Chemistry & Biochemistry Faculty Publications

The performance of sensitive spectroscopic methods in the mid-IR is often limited by fringing due to parasitic etalons and the background noise in mid-infrared detectors. In particular, the technique Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy (NICE-OHVMS), which is capable of determining the frequencies of strong rovibrational transitions of molecular ions with sub-MHz uncertainty, needs improved sensitivity in order to probe weaker transitions. In this work, we have implemented up-conversion detection with NICE-OHVMS in the 3.2 - 3.9 μm region to enable the use of faster and more sensitive detectors which cover visible wavelengths. The higher bandwidth enabled …

Criegee Intermediate-Hydrogen Sulfide Chemistry At The Air/Water Interface, Manoj Kumar, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We carry out Born–Oppenheimer molecular dynamic simulations to show that the reaction between the smallest Criegee intermediate, CH₂OO, and hydrogen sulfide (H₂S) at the air/water interface can be observed within few picoseconds. The reaction follows both concerted and stepwise mechanisms with former being the dominant reaction pathway. The concerted reaction proceeds with or without the involvement of one or two nearby water molecules. An important implication of the simulation results is that the Criegee-H₂S reaction can provide a novel non-photochemical pathway for the formation of a C–S linkage in clouds and could be a …

Reply To ‘On The Bonding In Ligand-Protected Gold Clusters’, Wen Wu Xu, Xiao Cheng Zeng, Yi Gao

Xiao Cheng Zeng Publications

In the recent Correspondence, Professor Henrik Grönbeck made several comments on the recently developed grand unified model (GUM), in particular using the ligand-protected gold cluster [Au₂₅(SR)₁₈]¹⁻ as an example. We noted that the latter cluster can be viewed as belonging to a special group of ligand-protected gold clusters that contain one or several icosahedral Au₁₃ motifs. For this group of clusters, a secondary block Au₁₃(8e) has been identified as a more convenient way to describe their structure anatomy and evolution. Another extension of the GUM is the identification of the new elementary …

Photodynamic Cancer Therapy A Study Of The Photochemical Properties Of Meso-Tetra (2,3,4-Trifluorophenyl) Porphyrin And Meso-Tetra (2,3,5,6-Tetrafluorophenyl) Porphyrin, Delanie L. Newberry

Honors College Theses

Photodynamic therapy(PDT) is a type of cancer treatment that utilizes photosensitive molecules that absorb photons and use that energy to create cytotoxic molecules. Porphyrins are photosensitive compounds that can be used selectively at the site of cancerous tumors. Their selectivity is due to the fact the porphyrins are generally not toxic in absence of light; in the presence of light, the drug will be activated to produce the cytotoxic molecule, singlet oxygen(1O2 ). 9,10 diphenyl anthracene(DPA) was used to simulate the cancer cells and monitor how effective the porphyrin was in creating 1O2, because DPA reacts with 1O2 form diphenyl …

Size And Shape Control In Metal Nanoparticles And Nanocomposites, Tomendro Subedi

Theses and Dissertations (Comprehensive)

This thesis describes major findings on the shape transformation of the precursor silver decahedral nanoparticles (AgDeNPs) with pentagonal symmetry and twin defects into silver pentagonal prism nanoparticles (AgPPNPs) using Br¯ as a shape selective reagent. Silica-encapsulation of the gold-plated AgDeNPs was also carried out forming ordered arrays of silica encapsulated gold-plated AgDeNPs (SiO₂@Au@AgDeNPs) of different sizes. At first, synthetic procedures for AgDeNPs (pentagonal bipyramids), silver pentagonal rod nanoparticles (AgPRNPs) and gold-plating of AgDeNPs (Au@AgDeNPs) were optimized. Gold plating enhances the chemical stability of AgDeNPs and preserves the superior plasmonic properties of silver. This thesis deals with the transformation …

A Density Functional Theory Study Of Intrinsically Chiral Semiconductor Nanocrystals, Richard Edwards

Theses and Dissertations (Comprehensive)

A plethora of work has been done in the area of nanoparticles of late due to the fact that chemists (and physicists) have discovered that the properties of nanoparticles differ from both those of the bulk material and the atoms themselves. Nanoparticles have become of high interest for the use as catalysts while materials like graphene, being only one atom thick, have been shown to be great electrical conductors in comparison with the 3D structure of diamond. Among these peculiar nanoscale properties is the phenomenon of nanochirality, where a nanoparticle can exhibit chirality that does not extend to the macroscale …

Choline Chloride Eutectics: Low Temperature Applications, Kaila M. Kuehn, Camille M. Massmann, Natalie R. Sovell

The Journal of Undergraduate Research

Deep eutectic solvents (DESs) have a lower melting point than each of their individual components due to ion dipole interactions or hydrogen bonding. Traditionally, DES are used for processing metals through plating and have many synthesis applications. DES are able to be substituted for hazardous solvents that are traditionally used for metal plating and synthesis. This, along with many other advantageous properties, appear promising for the use of DESs as solvents or for use in electrochemical systems, particularly at low temperatures. Choline chloride:propylene glycol was a novel DES synthesized and analyzed for its properties, including melting point, viscosity, conductivity, heat …