Undergraduate Research Day Projects
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Organized by the University of Houston Office of Undergraduate Research and Major Awards, Undergraduate Research Day is an annual event showcasing exceptional scholarship undertaken by the UH undergraduate community.
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Browsing Undergraduate Research Day Projects by Department "Chemistry, Department of"
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Item Acoustic Radiation Force and Noncovalent Bonds(2023-04-13) Nguyen, EmilyInvasive plants disrupt native ecosystems and decrease native plant diversity. Under strong selection pressure, native plants sometimes adapt to better compete with an invasive species. My research investigates two variants of the annual forb Coreopsis that co-occur with the invasive forb Verbena brasiliensis. The objective of my research is to answer three questions: (1) Is an observed phenotypic variant Coreopsis more competitive with the wild type C. tinctoria? (2) IF so, what traits potentially make it more competitive?, (3) Is it an adapted variety of C. tinctoria or a related species? Whether or not it is a separate species, the existence of a more competitive variant may provide an effective replacement for the wild type C. tinctoria in native restoration projects within the range of V. brasiliensis.Item Aldehyde Reduction via Mitochondria Targeting Iridium Complex(2023-04-13) Chew, MatthiasThe human biological environment has built in ways to reduce and dispose of metabolic waste and other toxic buildup that is produced perpetually. For example, the body contains aldehyde oxidases, alcohol dehydrogenases, and enzymes to metabolize aldehydes. However, these pathways are limited or even halted under certain illnesses, such as cancer or Alzheimer's disease, as the body loses its capability to handle waste, resulting in toxic chemical buildup and further damage. In the event of lipid peroxidation, which is associated with Alzheimer's disease, oxidation of lipids causes a surge of aldehydes and free radicals to efflux throughout the body causing cell death. My project serves to find a synthetic pathway to creating an iridium-based metal catalyst, which reduces intracellular aldehydes and is mitochondria targeting. Ramifications of this project are the high cost of iridium, low IC50 of iridium catalysts, as well as lengthy synthetic procedure for the iridium complex.Item Aromatic Guest Incorporation in Naphthalene-Based Cyclotetrabenzil Host(2023-04-13) Lim, Jay J. T.; Robles, AlexandraNaphthalene-based cyclotetrabenzil octaketone is among the derivatives of cyclobenzoins which belong to the class of porous molecular crystals (PMCs), an emerging class of porous solids. These macrocycles show promise as supramolecular hosts which can include guest molecules within their pores and stabilize them by non-covalent interactions. Introduction of electron-rich aromatic compounds to similar macrocycles have provided insight into their applications in gas separation and sequestration, and organic optoelectronic devices. The macrocycle’s affinity towards chlorinated guests has since prompted attempts for co-crystallization of the macrocycle with different chlorinated guests for applications in chemical sensing of toxic contaminants including toxic and persistent aromatic polychlorinated biphenyl (PCBs). Single crystals of complexes of the octaketone with methoxybenzene (1) and 1,3-dichlorobenzene (2) were successfully grown, and their structures were solved. Single crystals of the octaketone with chloroform (3) were also obtained. Study of the single crystal structures show hydrogen bonding between the oxygen atoms of the octaketone and hydrogens of the naphthalene groups and vice-versa. Guest molecules in structures 2 and 3 also hydrogen bond to the host, but with additional chlorine atoms acting as hydrogen bond donors, further stabilizing the guest molecules towards the center of the macrocycle. Additionally, [π ···π] and [Cl···π] interactions are also observed in complexes with 2 and 3, respectively. Collectively, these interactions create a staggered stacking pattern but can hopefully form channels with varying substituents or expansion of the aromatic guest molecules. ***This project was completed with contributions from Thamon Puangsamlee from NANOTEC, Thailand.Item Azide addition in Iridium isocyanide complexes(2023-04-13) Nguyen, NgocDespite being preventable, suicide has consistently been one of the major leading causes of death for people ages 10-14 and 25-34 (Centers for Disease Control and Prevention [CDC], 2022). Research has identified depression and perceived stress as risk factors among others for suicide. Additionally, previous studies found that depression mediated the relationship between stress and suicidality in which greater stress was associated with more depressive symptoms, and hence, greater involvement in suicidal behaviors (Hirsch et al., 2019; Smith et al., 2015). The current study examined the interrelationship between depression, stress, and suicidal thoughts. We hypothesize that stress will strengthen associations between depression and stress. Logistic regression was used to analyze data from 958 participants taken from the UC Berkeley Social Networks Study. Results suggest that both depression and stress were positively associated with suicidal thoughts. However, contrary to our hypothesis, as depression increases, people with high stress are less likely to endorse suicidal thoughts in the past year. This finding contradicts prior research on stress and suicide, and proposes the possibility that stress could be a protective factor against suicidal thoughts for people with depression. However, more studies should be conducted to investigate the kind of stress underlying this relationship.Item Bio-Inspired Tishchenko Reaction(2023-04-13) Padron, JavierSynthesized a biocatalyst that acts like a Tishchenko reaction able to react with di-aldehydes to form cyclic esters, lactones. Lactones have many beneficial biological features such as being anti-microbial and anti-tumor agents. Thus, synthesized iridium catalysts with different substituents and electron groups. Ir1 is the model catalyst that was then modified by changing the substituent to a butylamino and variations with different electron groups to form Ir2, Ir3, and Ir4. A kinematics study was performed on each catalyst. Looking at the GC-MS chromatograms, we are able to determine that Ir3 was the fastest reacting catalyst followed by Ir1. A possible intermediate was observed in the GC-MS which would require more testing to characterize and identify its role. Second experiment focused on limiting the sodium formate, which activates the iridium catalyst. By limiting sodium formate, we are able to determine the rate-determining step and gain an idea about the mechanistic approach of the catalyst. As the first step consists of reducing one aldehyde, then either another reduction occurs or an oxidation reaction. H-NMR standards were used to determine the ratios of the compounds present. More testing is required to make a proper conclusion of how limiting sodium formate affects the reaction and the catalyst.Item Carbonate-Terminated Self-Assembled Monolayers for Mimicking Polycarbonate Surfaces(2022-04-14) Hernandez, JenniferPolycarbonates (PCs) are known for their durability, optical transparency, and biocompatibility. Despite the stability of PC, they tend to swell after being exposed to organic solvents, leading to a change in the hydrophobicity of the polymer layers and making it difficult to study the interfacial properties of the polymer layers in contact with organic solvents. Organic thin films in the form of self-assembled monolayers (SAMs) have been utilized in various applications such as catalyst modifiers for hydrogenation reactions, anti-corrosion protectants for metal surfaces, and anti-adhesive films for biosensors. In this project, four targeted adsorbate molecules 3-COC11SH, 3-COC12SH, 2-COC11SH, and 2-COC11SH with different positional isomers of the carbonate groups were synthesized and their SAMs were generated on evaporated gold substrates. These nanoscale organic films will mimic bulk polymer coatings for evaluating the interfacial characteristics without suffering from surface reconstruction or swelling found in bulk polymer coatings. The adsorbate molecules were characterized using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. The corresponding SAMs were characterized by ellipsometry, contact angle goniometry, polarization-modulation infrared reflection-adsorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS). The contact angle data showed that the wettabilities of both SAM series were similar to the PEC-coated surfaces for a wide range of contacting liquids.Item COFACTOR BASED FLUORESCENT PROTEIN FOR NEW OXYGEN-INDEPENDENT METAL SENSORS(2018-10-18) Le, KhoaThe gastrointestinal microbiota is closely related to human health. Many of their metabolisms require the uptake of trace metals from the host. Current metal sensors are derived from green fluorescent proteins (GFP), which require oxygen to develop their fluorescence, therefore, they cannot be applied to study the anaerobic environment. The Zastrow lab is developing a new oxygen-independent zinc sensor by combining the CreiLOV domain from Chlamydomonas reinhardtii and the GAF3 domain from cyanobacteriochrome (CBCR) using a zinc binding domain. Site-directed mutanogenesis was conducted on CreiLOV to help abrogate the photocycle which results in the loss of its fluorescence. Next, plasmid cloning by PCR was used to transfer the gene from mammalian to bacterial vectors for expressing in E. coli. DNA sequencing results confirmed the plasmid has been made. The level of expression was then estimated by the solubility screening diagnostic to determine the best condition for the gene to be purified. The condition at 16°C, 0.5 IPTG, OD600 ~ 0.5 seems promising, however, more tests will be considered to achieve the highest result. The protein will be ready to be purified and characterized by UV-Vis and fluorescent spectroscopy in the future works.Item Data Compression and Machine Learning in the Analysis of the Entropy of Photodissociation in Organic Donor-Acceptor Interfaces(2018-10-18) Mroczek, DeboraOrganic photovoltaics have become increasingly relevant in recent years, resulting in a growing demand for theoretical models that can accurately approximate the behavior of electrons in organic donor-acceptor inter- faces. As an attempt to simplify the analysis of electron-hole dynamics, we make a case for the use of the Shannon Entropy as measure of the degree of entanglement of e-h pairs using Schmidt decomposition. The Schmidt form also allows us to determine the number of effective dimen- sions occupied by an arbitrary eigenstate Ψk in Hilbert space. In the case of a 50 × 50 diabatic density matrix for a 1-D system, we were able to reduce the number of bytes required to store this information by ∼65% using the Schmidt form. We then reconstructed the original matrix from the reduced model and calculated values for charge transfer character and inverse participation ratio and found that the average percent error was less than 0.05% in both cases. Lastly, we demonstrate that machine learn- ing algorithms can be used to accurately differentiate between excitonic, charge-transfer, and charge-separated states. By combining data compres- sion and machine learning, we developed a simplified and computationally efficient way to quickly sift through thousands of eigenstates and single out relevant information regarding the Shannon Entropy and charge sep- aration. We present the results of this analysis for a 1-D interface with 50 sites and energetic offsets varying between 0.0 - 0.5 eV.Item Development of a High-Throughput Flow Biofilm Reactor System for the Study of Bacteria Interference against Uropathogenic Colonization on Silicone Urinary Catheters(2018-10-18) Nguyen, Nhien; Thang, ChristopherThe prevention of pathogenic colonization on medical devices remains a significant challenge, especially in high-nutrient environments that influence biofouling. Catheter-associated urinary tract infections (CAUTIs) represent common infections that patients contract from indwelling catheters. In this project, an experimental system was designed to use bacterial interference with benign E. coli to prevent CAUTIs under conditions paralleling those in vivo. The system contains three main parts: an ultraviolet (UV) disinfection subsystem; a 100L artificial urine preparation, storage, and flow guiding subsystem; and a 34-channel catheter array. The key part is the array of 34 Foley silicone catheters, modified with a propynylphenyl mannoside derivative that promotes the formation of fim+ E. coli 83972 biofilms inside catheter surfaces. Catheters will be challenged by at least three multidrug-resistant, uropathogenic isolates under a flow of artificial urine at a constant rate up to four weeks. Samples will be collected from each catheter, and bacterial plate counting will determine the potency of benign E. coli biofilms in reducing uropathogenic colonization. We expect this biofilm flow reactor system to be applicable to studying other types of biofilms found in water treatment systems and the environment. The construction and testing of the model system will be presented.Item Development Of A High-Throughput Flow Biofilm Reactor System For The Study of Bacterial Interference Against Uropathogenic Colonization On Silicone Urinary Catheters(2019) Thang, Christopher; Wang, Mengfan; Cashin, ThomasIn this project, a 34-channel catheter array system was designed to investigate our bacterial interference strategy under in vivo flow conditions. The catheter model system consists of three main parts: an ultraviolet (UV) disinfection subsystem; a 100L artificial urine preparation, storage, and flow guiding subsystem; and a 34-channel catheter array. This catheter-model project opens vast possibilities toward studying the interactions among nonpathogenic and pathogenic bacteria involved in CAUTI and its prevention based on the bacterial interference strategy.Item Evaluating the Hardness of Yttrium Ruthenium Borides(2022-04-14) Loloee, AryaHigh hardness materials are used for a multitude of applications, ranging from drill bits and saw blades to artificial joint replacement. Most of these materials are constructed out of simple binary phases, namely transition metal borides and carbides. Their simplicity makes them easy to produce but limits the ability to tune the mechanical properties through chemical substitution. As a result, we are investigating ternary borides that may have high hardness. The project started by preparing three yttrium ruthenium borides (YRu3B2, YRu4B4, YRuB4). The powders were mixed and pressed into pellets that were then melted into homogeneous ingots using an arc-melter under an argon atmosphere. After optimising the reaction conditions, the samples are ground, and the sample purity is checked using powder X-ray diffraction. The samples’ resistances to plastic deformation are measured with the Vickers hardness test under different loads. Density functional theory calculations were then used to understand how changes in electron density as a function of chemical composition could be used to maximise the mechanical properties. We are now using this information to develop new ternary high hardness materials with even better mechanical properties.Item Glimpse into the Dimerization, Distribution and Interaction Dynamics of ATP7A using Super Resolution Imaging(2018-10-18) Calindi, AparnaCopper is a very important component in the body for various cellular functions but an imbalance in its levels can be very toxic to the body. ATP7A and ATP7B are important to provide instructions in making proteins that regulate copper levels in the body. Despite ATP7A and ATP7B showing high homology they perform different functions that are not fully understood yet. Recently, ATP7B has been reported as a dimer in the cells, suggesting dimerization as a potential regulatory mechanism. Therefore, this research focuses on testing if the ATP7A can dimerize similar to the ATP7B and also aim to understand the sub-cellular distribution as well as the interaction dynamics of the dimer complex. To achieve that, we want to use signal molecule super-resolution imaging technique to visualize the dimerization and spatial temporal behaviors of ATP7A under different Cu conditions. For this purpose, I generated fluorescent protein (FP) tagged ATP7A constructs for mammalian cell expression. After transfecting the construct into COS7 cells, the expression and Cu responsibility of FP tagged ATP7A was characterized by Western blotting and fluorescent microscopy imaging respectively in fixed cells. With successful FP-tagging on ATP7A, we are ready for further single molecule imaging in live cells.Item Heterobimetallic Complex for Homo- and Copolymerization(2019) Williams, ChristopherOlefin polymerization is an important process for making many plastics that we use in our daily lives. One of the problems with current polymer manufacturing practices is that it is difficult to synthesize certain types of polyolefins. For example, more efficient catalysts are needed for the polymerization of polar olefins to make functional plastics. These materials can be used in a wide range of applications, such as water-resistant paints, adhesives, and drug delivery devices. The primary goal of my proposed summer research project is to develop new Nickel based catalysts that are active for olefin homo- and copolymerization. We are particularly interested in the polymerization of monomers such as acrylates, vinyl acetates, and vinyl halides since they endow polymers with unique material properties. Furthermore, we would also like to have the capability to fine-tune polymer characteristics such as molecular weight and branching. Another goal of my project will be to prepare heterobimetallic complexes comprising of nickel and either alkali or zinc ions. The steric and electronic properties of the heterobimetallic complexes could be readily tuned by replacing one secondary metal ion for another. The success of this project will further our knowledge of olefin polymerization catalysts and may lead to the development of new techniques for manufacturing.Item How Phenolic Based Compounds can be increase productivity in the Pharmaceutical Industry(2020-09-29) Nguyen, NicholasDrug development is a strenuous, expensive, and time-consuming process in the US. In recent years, pharmaceutical productivity has decreased, resulting in a lower number of new drugs being synthesized every year. It is important that pharmaceutical companies continue to innovate and create new drugs and not stagnate on old methods and processes, although this has proven difficult as the cost and time for developing a drug has increased. A potential solution to increase the diversity and productivity of the pharmaceutical industry could be the shifting of resources and research in developing more drugs based on phenolic compounds. These compounds are composed of phenols with at least one hydroxyl group. Comparisons were drawn between drugs developed from traditional reactions and sources to drugs of similar purpose that were based on phenolic compounds. Furthermore, a litany of sources about the drug development process was explored, in order to examine how this potential shift of course could be immensely beneficial. Overall, drugs created from phenolic compounds have been shown to have the same efficacy and effectiveness as traditionally produced drugs, with a myriad of benefits, namely in the areas of cost, toxicity, and ease of creation. Drugs from phenolic compounds can be a viable source of innovation and a way for the pharmaceutical industry to develop cheaper and more easily tested drugs.Item Influence of Metals' Redox States on Lunar Evolution(2020-09-29) Shipman, Angela M.Objectives: The purpose of this research is to determine the activity of NiO and FeO in liquid at various temperatures, and by doing so, generate a phase diagram. This diagram will be used to elucidate information about the formation and evolution of the moon. Motivations: This study takes an experimental approach to determining the activities of FeO and NiO in silicate liquids.Item Intramolecular Oxidative Phenol Coupling and Hydrazone-Initiated C-H Bond Insertion in Stemodane Synthesis: A Reproduction of Work by Samir Chatterjee(2017-10-12) Olumba, MorrisThe replication of the report entitled "Regio- and Stereo-controlled Total Synthesis of the Stemodane Nucleus; an Unusual Diterprene Skeleton, a suspect publication by Dr. Samir Chatterjee", has been initiated. The Goal of this project is to evaluate the reproducibility of the synthetic pathway reported to produce the stemodane diterprene structre in figure 1, proposed by Dr. Chatterjee in 1979. In addition to other reports from this author having been refuted in published work, key elements of this stemodane report are believed to be inaccurate and improbable.Item Investigating Glutathione Tolerance of a Macrocyclic Dinuclear Organoiridium Catalyst in Transfer Hydrogenation(2022-04-14) Campbell, DylanToxic aldehyde overload is a pathological condition that can lead to oxidative stress-related diseases in humans. A small-molecule intracellular metal catalyst (SIMCat) was synthesized to selectively convert these toxic aldehydes into less toxic alcohols. To assess the biocompatibility of the catalyst, transfer hydrogenation reactions were performed in the presence of biological nucleophiles, such as, glutathione (GSH). The aldehyde substrate scope was evaluated to confirm the specificity and selectivity of the catalyst. The SIMCat of interest, the caged organoiridium catalyst (Ir3) was prepared using a 7-step procedure. The products for each step were purified via silica gel column chromatography and characterized using 1H/13C-NMR spectroscopy and mass spectroscopy. Subsequently, the GSH tolerance of Ir3 was evaluated and compared to a control organoiridium catalyst, Ir1, using benzaldehyde as the substrate, sodium formate as the hydride source, and DMSO:H2O (1:9) as the solvent. The reaction was performed inside a vial at physiological temperature (37-38 degrees C) for 24 h on a 0.5 mol% scale for Ir3 and 1 mol% scale for Ir1. The substrates we studied included long-aliphatic and alpha,beta-unsaturated aldehydes, ketones, imines, oximes, and Beta-ketoesters. The yields of the products for each reaction, with and without GSH, were determined using gas chromatography. The significance of this project is the facilitation of scientific progress for the chemical reactivity and biocompatibility of intracellular catalysts. Future work includes the development of techniques for studying SIMCats and the synthesis of new transfer hydrogenation catalysts.Item Investigating Gold Intermetallics Featuring Disordered Networks(2023-04-13) Doan, Darren; Arrieta, RoyIntermetallic compounds consist of two or more metallic elements that form an ordered structure in a defined stoichiometric ratio. They may possess desirable properties, such as catalysis, superconductivity, and super hardness, with various industrial applications in fields like energy and aerospace. Accordingly, this drives the increased demand to discover new intermetallic compounds. Gold-based intermetallics, in particular, form diverse and complex crystal structures owing to gold's relativistic effects. In this work, systematic exploration was performed in the RE-Au-Si (RE=Y, La) and Na-Au-Cd systems, revealing four new gold-based intermetallic phases with nominal compositions Y(Au0.28Si0.72)2, La(Au0.24Si0.76)2, Na(Au0.51Cd0.49)2, and Na(Au0.9Cd0.1)2. RE-Au-Si phases were arc melted, while Na-Au-Cd phases were reacted in sealed Ta containers at 600°C, followed by annealing at 400°C. The resulting crystal structures were determined via single crystal x-ray diffraction. Y(Au0.28Si0.72)2 and La(Au0.24Si0.76)2 are isotypic and crystallize in the AlB2-type structure, while Na(Au0.51Cd0.49)2 crystallizes in the MgZn2-type structure and Na(Au0.9Cd0.1)2 in the MgCu2-type structure. All four phases feature disordered networks with Au/Si or Au/Cd sites respectively. Le Bail refinement of powder x-ray diffractograms indicates the presence of the product phases, with minor impurities. Density of states calculations reveal metallic behavior in all four phases. These results support that complex intermetallic compounds are significantly influenced by diverse constituents and gold's relativistic effects.Item Ir(III)-Catalyzed Reductive Amination of Carbonyl Compounds with High Selectivity(2019) Sladek, Noah; Nguyen, DatAmines are a nitrogenous class of organic compounds and functional groups found present in pharmaceuticals, agrochemicals, and many biologically relevant molecules. Traditional synthetic routes to produce amines pose various toxicity issues, poor chemoselectivity, and unstable precursor molecules. In this work, we display the reductive amination of carbonyl compounds at 37 ˚C in methanol catalyzed by a Cp*Ir(III) complex ligated by N-phenyl-2-pyridinecarboxamidate using ammonium formate as a nitrogen and hydride source. Various aromatic ketone and aldehyde substrates were run for 15 h with a catalytic loading of 1 mol % to give excellent chemoselectivity of primary amines. We plan to expand our substrate scope to α-ketoacids to demonstrate the synthetic preparation of α-amino acids.Item Iridium-Coumarin Ratiometric Oxygen Sensors(2021-04-01) Halamicek, Michael; Wu, YanyuRatiometric sensing is the simplest and most accurate method for measuring O2. Our sensors use an oxygen insensitive fluorescence signal and an oxygen attenuated phosphorescence signal. A ratio made from these two signals allows for the definitive measurement of oxygen concentrations. Oxygen measurements taken with ratiometric oxygen sensors remove the calibration inaccuracies resulting from oxygen sensor measurements in heterogeneous environments. We produced a new ratiometric oxygen sensor for hypoxic environments (pO2 ≤ 160 mmHg) with a blue-fluorescent part attached to the phosphorescent iridium. The color of phosphorescence observed is dependent on the ligands appended to the iridium. Adjustment of the spacer between the two modulates energy transfer to ensure both components' simultaneous luminescence. The most recent candidate shows improved signal resolution between the oxygen-insensitive blue fluorescence and the oxygen-sensitive red phosphorescence over a physiologically relevant range of concentrations. This candidate has the desired dual luminescence due to the increased intramolecular spacing between the coumarin and iridium, which inhibits Dexter energy transfer. The effect of this spacer alteration highlights one of the challenges in developing molecules composed of parts both capable of spin-forbidden and spin-allowed luminescence. A few applications for ratiometric oxygen sensors include investigating tumor growth rates and informing ground control of oxygen deprivation. We have reasonably minimized the overlapping of fluorescence and phosphorescence in sensor 2 and continue to improve our designs.