Chemistry

Session I

John Cooley, "Optimizing TICT Performance in Nile Red Dyes using Density Functional Theory"

Twisted Intramolecular Charge Transfer (TICT) occurs in organic fluorophores where a donor group incites electron transfer upon rotation with respect to a planar acceptor moiety. This phenomenon is often suppressed in Single Molecule Spectroscopy (SMS) blinking-based techniques, which examine rapid changes in fluorescence intensity of molecules under constant irradiation, due to its dimming effect on blinking traces. However, valuable diagnostic information has been lost in the suppression of TICT states, which could enhance blinking-based SMS techniques by fully resolving its ability to spatially and temporally map systems at the nanoscale. This project will detail computational efforts using Time-Dependent Density Functional Theory (TDDFT) to determine Nile Red (NR) derivatives that are intermediately favorable to undergoing TICT. It has been found that the pyrrole NR derivative possesses ideal TICT behavior, based on its pre-twisting, degree of charge transfer character, and twisting energy profile.

Student Major(s)/Minor: Chemistry Major, Mathematics Minor

Advisor: Dr. Elizabeth Harbron

Thomas Felton, "Computational Modeling of NMR T₂ Relaxation"

This project addresses the question: Can single-sided nuclear magnetic resonance (NMR) T₂ relaxation times be predicted through molecular simulation? To explore this, we modeled molecular mixtures using simulation tools that replicate how different molecules move and interact over time. These simulations mimic experimental setups in which a magnet generates an NMR signal by aligning molecular spins, which then gradually lose coherence—a process measured as T₂ relaxation.

We analyzed the simulated molecular motion to estimate how this signal decays, using curve fitting to model the relaxation with exponential functions. By comparing our results to experimental data across a range of mixture compositions, we found strong agreement in trends, especially when accounting for molecular diffusion. This work shows that simulations can effectively predict relaxation behavior observed in NMR experiments, offering a valuable tool for studying complex fluids and guiding the design of materials with tunable molecular properties.

Student Major(s)/Minor: Data Science Major, Chemistry Minor

Advisor: Dr. Tyler Meldrum

Kira Fisher, "Nontargeted Analysis of Pepper Spray Using GC×GC"

Comprehensive two-dimensional gas chromatography (GC×GC) is a separation technique used to characterize complex mixtures, finding and identifying compounds that comprise the mixture. This technique uses retention mechanisms such as polarity and volatility to separate analytes so they can be identified. GC×GC is most helpful with complex samples when the number of compounds exceeds the peak capacity of traditional one-dimensional GC systems. This type of nontargeted analysis provides available space for analytes to elute that were not targets. The objective of this research was to optimize a method on pepper spray, a sample of forensic interest known to have a complex profile. Using a previously determined optimization approach, numerous new compounds in pepper spray could be resolved and identified, leading to improvements in forensic characterization for potential use in forensic casework. An updated list of pepper spray components would be immensely helpful in forensic cases where pepper spray is being examined. 

Student Major(s): Chemistry

Advisor: Dr. Katelynn Perrault Uptmor

David Han, "The Effectiveness of Microwave Transmitter Size for Dynamic Nuclear Enhancement"

Nuclear magnetic resonance (NMR) spectroscopy is a common method to non-invasively study molecular structures.  Unfortunately, NMR generates weak signals and can be subject to  a lot of noise.  Currently, the only way to bypass these weaknesses involves expensive cooling systems and the highest quality magnets.  To resolve these limitations, recent research has explored using electron spin resonance (ESR) techniques to enhance NMR to produce signals up to 660 times better than NMR alone.  The process of coupling NMR with ESR is known as dynamic nuclear polarization (DNP).  It involves the excitation of electron spin states with microwaves.  This project aims to further the study of DNP by investigating ways to increase microwave power density in accordance with the DNP enhancement equation.  The results of this project will demonstrate the efficacy of reducing microwave incidence area on a sample to increase microwave power density, and thus DNP enhancement. 

Student Major(s):  Chemistry

Advisor: Dr. Tyler Meldrum

Joshua Kerrigan, "Chiral Induced Selectivity in Molecular Collisions"

Chiral molecules, those that possess the same chemical formula and connectivity yet differ in structure, play a key role in many biological and chemical systems. These chiral molecules, such as 2-butanol, exist as S- and R-enantiomers which can exhibit unique behavior from each other. For example, Chiral Induced Spin Selectivity (CISS) is a phenomenon where the chirality of a molecule can influence the spin of an electron. Nitric Oxide (NO) is a free radical, meaning that it possesses an unpaired electron, which when interacting with a chiral species such as 2-butanol may experience this CISS effect. We investigated bimolecular collision complexes between Nitric Oxide and 2-butanol to determine whether 2-butanol’s chirality would influence the NO product outcomes post dissociation. To do this we made use of IR action spectroscopy along with resonance-enhanced multiphoton ionization (REMPI) and velocity map imaging to probe the dissociation dynamics of the NO-(2-butanol) collision complex. By examining the results of the racemic, (S)-enantiopure, and (R)-enantiopure complexes a preferential spin state selection for the NO product was found. These experimental results can provide a framework for better understanding the influence that chirality has on radical-chiral molecular collisions. 

Student Major(s)/Minor: Chemistry Major, Mathematics Minor

Advisor: Dr. Nathan Kidwell

Dylan Manning, Yuanheng Zhuang, "Polypyridyl Metal Complexes Containing Amino Acid Functional Groups for Hydrogen Generation and Carbon Dioxide Reduction"

To address global energy needs, renewable and sustainable energy solutions are critical to meet expanding demand. Hydrogen generation from aqueous protons is a promising method to utilize solar energy to produce hydrogen gas, a clean fuel. Hydrogen produces water and energy without emitting carbon dioxide when burned. As atmospheric carbon dioxide levels continue to increase, leading to a warming effect on the globe, the catalytic reduction of carbon dioxide to formate or methane/methanol represents a promising strategy to convert a greenhouse gas into useful chemical materials. This project involves synthesizing first-row transition metal complexes that can photocatalytically generate hydrogen gas from water and/or reduce carbon dioxide. The proposed approach includes designing ligands based on a robust polypyridyl framework that incorporates amino acid residues, mimicking biological systems for these reactions. 

Student Major(s): Dylan: Chemistry; Yuanheng: Chemistry

Advisor: Dr. William McNamara

Grace Saunders, "Courtroom Chromatography: Strengthening the Evidentiary Value of Gunshot Residue Using Comprehensive Two-Dimensional Gas Chromatography"

Gunshot residue (GSR) is dispersed outward from a firearm during a discharge event, settling on surfaces within the weapon’s vicinity. Traditional, courtroom-accepted, GSR analyses involve examination of inorganic components (IGSR) using scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM-EDS) according to a standardized profile. Increasingly widespread use of heavy metal-free, or “green”, ammunition has compromised this profile, diminishing the probative value of GSR in firearm-related criminal investigations. Organic gunshot residue (OGSR) carries additional evidentiary information that may strengthen the value of GSR profiling in courtroom presentation. The goal of this study was to extract additional information from OGSR using comprehensive two-dimensional gas chromatography – time-of-flight mass spectrometry (GC×GC-TOFMS) alongside traditional SEM-EDS methods. A workflow was developed for the examination of green GSR using SEM-EDS, and components of OGSR were conclusively identified using GC×GC-TOFMS. Future work will include optimization of sample analysis protocols and further data collection and processing.

Student Major(s)/Minor: Chemistry Major, English Minor

Advisor: Dr. Katelynn Perrault

Chris Yoo, "Synthesis and Characterization of Silver(I) Complexes With Selenium-Based Ligands for Heavy Metal Detection"

The primary research question for this project was "How do different silver-selenium nanoparticles act as detectors for heavy metals in solution?" By carefully synthesizing nanoparticles with different ligands and concentrations, and testing through qualitative colorimetric and quantitative spectroscopic methods, this project showed different reactions between heavy metals and silver-selenium nanoparticles. The particles were synthesized using chemical bottom-up methods, meaning that the particles were created by assembling atoms into their eventual nanostructures through careful concentration and temperature control of reactants. This research showed certain strong interactions between toxic mercury metal and silver nanoparticles in solution, as well as between other heavy metal combinations. This project has applications in making heavy metal detection for environmental and other uses more accessible, and the hope is that the project will continue to explore other syntheses and methods.

Student Major(s)/Minor: Chemistry, Government

Advisor: Dr. Robert Pike

Emily Yang, "Calmodulin as a Potential Interaction Partner of TRPML1"

TRPML1 is a membrane ion channel implicated in mucolipidosis type IV as well as such neurodegenerative conditions as Alzheimer's, Parkinson's, and ALS. It is not well-understood how TRPML1 interacts with the proteins and molecules in its environment; such an understanding would be vital for potentially developing a cure for many storage diseases. We aim to purify and isolate TRPML1 and the interaction partner of interest, calmodulin, to find their respective binding sites, and to replicate their interactions in the cell. To accomplish this, bacterial cells were transfected with DNA to produce TRPML1 and calmodulin mutants of choice. They were purified, isolated, and collected. Lipid "membranes" were also created. We did not find binding sites but found that lipids and the chosen mutants show promise for further study. 

Student Major(s)/Minor: Neuroscience Major, Marketing Minor

Advisor: Dr. Ute A. Hellmich; Dr. Charlotte Guhl

Noah Zelch, "Reconstructing Pore Structure in Archaeological Pottery Using Single-Sided NMR"

This project develops a non-destructive and reproducible method for mapping the pore structure of archaeological pottery sherds using single-sided nuclear magnetic resonance (NMR). Traditional techniques for characterizing pore networks often damage or destroy the sample, limiting their use in cultural heritage science. Our approach saturates ceramic samples with deionized water and uses atomic spin relaxation measurements to probe the microenvironments of the water molecules within the pores, which reflect pore size. By adjusting NMR parameters to capture exchange dynamics between pores, we can infer additional structural details about the connectivity of the pores. This methodology preserves the physical integrity of artifacts while enabling insight into production techniques, such as firing temperature. Standardizing this approach may significantly advance archaeological analysis by providing a replicable, non-invasive framework for sherd characterization.

Student Major(s)/Minor: Psychology

Advisor: Dr. Tyler Meldrum

Nicolas Zimmermann, "Characterizing PqsE’s enzymatic activity in Pseudomonas aeruginosa by Volatile Organic Compound analysis with GC×GC-TOFMS"

Pseudomonas aeruginosa is an opportunistic pathogen commonly associated with severe respiratory infections in immunocompromised patients. The pathogenic behaviors of P. aeruginosa are controlled by a cell-to-cell communication system called quorum sensing (QS). Many of the genes activated by QS include those responsible for forming biofilms and producing virulence factors. Interestingly, several virulence factors produced by P. aeruginosa are regulated by an interaction between a receptor, RhlR and a hydrolase, PqsE. Thus, the PqsE-RhlR interaction has become a target for antibiotic development and further characterization. By using comprehensive two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC-TOFMS), it is possible to discover volatile substrates and products of PqsE enzyme activity. With GC×GC-TOFMS, the volatile organic compound (VOC), acetophenone, was discovered and utilized to measure dose-dependent inhibition of PqsE enzymatic activity in vivo by the small molecule inhibitor, Vorinostat. Furthermore, additional VOCs were identified that could add additional insight to PqsE’sfunction.

Student Major(s)/Minor: Chemistry, Business Analytics 

Advisor: Dr. Isabelle Taylor

Session II

HongJin Ahn, "Structural Determination and Analyses of Pyridine-Iodobismuthate(III) Complexes"

Bismuth(III) iodide was combined with two types of organic ligands—alkylpyridinium iodide (RPyI, R = Me, Et, Pr) and alkyltriphenylphosphonium iodide (RPPh₃I, R = Me, Et, Pr, Bu, Ph3)—in pyridine solvent. The resulting solution was layered with diethyl ether to promote crystal growth. From this process, eleven crystal structures with novel coordination network arrangements were solved using single-crystal X-ray diffraction. These complexes can be grouped into three anion categories: BiI₄Py₂, BiI₅Py, and Bi₂I₈Py₂, which corresponds to product stoichiometries of 1:1, 2:1, and 2:2, respectively. Bulk syntheses were then performed by precipitating the mother liquor with ether to obtain the powdered products. These powders were used for several analytical tests, including powder X-ray diffraction, thermogravimetric analysis, IR spectroscopy, and UV/Vis spectroscopy. Recrystallization of a select few of these powders yielded three new crystal structures exhibiting polymorphism. 

Student Major(s): Chemistry

Advisor: Dr. Robert Pike

Shalom Akolatse, "Characterization of P. Aeruginosa Biofilms Using Single-Sided NMR"

Contemporary understanding of infection pathology has shown that rather than existing in a planktonic state, P. aeruginosa and other pathogens form specialized colonies called biofilms. These biofilms are characterized by cells encased in a highly structured extracellular matrix (ECM), composed of a plethora of elements providing different functions to the cells. While there have been many advances in knowldge about the ECM’s structure, much of this research has come from the lens of molecular/cellular biological techniques. There remains little understanding, however, of the biofilm as a material.

Single-sided nuclear magnetic resonance (NMR) relaxometry is particularly suited to understanding the composition of various materials. Thus, we assay biofilms grown in liquid culture using T2 relaxometry, with both kinetic and genetic analyses used. 

Student Major(s)/Minor: Mathematics Major, Chemistry Minor

Advisor: Dr. Tyler Meldrum

Rodney Amankwah, "Solvent Free & Sustainable Aldol Reactions with Mechanochemistry​"

Many chemical transformations rely on the use of solvents to drive reactions, to help molecules mix and react with each other while also controlling other reaction parameters such as temperature, rate, and product distribution. Although critical to chemical research and education, solvent use is a significant issue with solvent waste and management, especially in academic lab courses. Our goal is to reduce the amount of solvent waste in chemistry lab courses by developing solvent-free reactions for the classroom. This study will focus on aldol condensation reactions to develop mechanochemical alternatives, thus making chemical education more sustainable. ​

Student Major(s): Chemistry 

Advisor: Dr. Isaiah Speight 

Sara Alter, "Investigating HyCy5 as a Molecular Probe for ROS Production"

The objective of this project is to quantify the production of reactive oxygen species (ROS) through use of a unique dye known as HyCy5. Specific ROS, like singlet oxygen and superoxide, react with the dye in different ways. When the superoxide reacts with the HyCy5, the dye is oxidized into a fluorescent dye known as Cy5. More HyCy5 is reacting than there is Cy5 being formed. It is unknown whether the superoxide is also breaking down the dye into degradation products, or if the other ROS are also reacting with the dye. Two methods were carried out. First, superoxide was selectively produced in the presence of the dye. Second, scavengers were used to selectively remove either superoxide or singlet oxygen. While additional scavenger experiments are necessary to make conclusions about the reactivity of the dye, this method did lead to the conclusion that the superoxide is the primary ROS responsible for the oxidation of HyCy5 into Cy5. 

Student Major(s)/Minor: Chemistry Major, Mathematics Minor

Advisor: Dr. Elizabeth Harbron

Kate Bellamy, "How Solvent Environment Affects Fluorescent Dye Blinking Patterns: Developing a Method"

This project focused on developing a method for immobilizing fluorescent dyes on glass slides and immersing them in solvents to examine how solvent to dye interactions affect the fluorescent blinking patterns. Fluorescent molecules exhibit unique “blinking” patterns of bright, dim, and dark states of emission after being excited. These blinking patterns are informed by changes in the solvent, which  can be used to provide information about the environment which the molecule is in. Both the APD and EMCCD microscopes were used in development of the method, along with a 532 nm laser. Methods for immobilizing fluorescent dye in solvent were tested using both Nile Blue and Rhodamine 6G with various procedures for applying solvent to determine what was best for examining the effects on blinking patterns. A basis of method was established for immobilization in solvent, which should be expanded upon in further research on decreasing solvent leakage.

Student Major(s): Chemistry; Russian, Eurasian, and Eastern European Studies (REES)

Advisor: Dr. Kristin Wustholz

Emiko Buntin, "Controlling Photochemical Reactivity With a Nanoparticle 'Valve'"

This project will explore to what extent one can have control over a photochemical reaction using nanoparticles. The reaction uses a fluorescent dye that is covalently bonded to a quencher, which is a molecule that eliminates the fluorescence. When the dye reacts, the bond to the quencher is broken and fluorescence is restored. This means that the reaction can be tracked by monitoring the appearance of fluorescence. Dye-doped conjugated polymer nanoparticles (CPNs), which are light-harvesting fluorophores with dye doped onto them, gives its energy to the dye on its surface, which is called Fluorescence Resonance Energy Transfer (FRET).

However, photo responsiveness to light presents an issue of balancing efficiency and control in a reaction. Many photochemical reactions can be too fast and uncontrollable, so having nanoparticles as a valve to tune the reaction rate is important. The nanoparticles could act as a closing valve by making FRET less efficient with the choice of polymer, therefore making the reaction go slower and vice versa. 

Student Major(s)/Minor: Chemistry Major; Japanese Studies Minor

Advisor: Dr. Elizabeth Harbron

Alexander Conomos, "Viscosity Sensitivity in Benzothiazole Rotor-based Fluorophores"

Rotor-based fluorophores (RBFs) are a group of fluorescent molecules that are highly sensitive to viscosity. This sensitivity predominantly arises from two decay mechanisms: radiative decay (photon emission) and twisted intramolecular charge transfer (TICT). Viscosity inhibits TICT, resulting in a strong correlation between viscosity and emission intensity. This sensitivity to viscosity has been utilized to track the progression of various biological diseases such as diabetes and Alzheimer's disease. This project explored how steric and electronic properties affect an RBF’s viscosity sensitivity. After synthesizing four RBFs and measuring their emission intensity in varying viscous solutions, it was found that RBFs with stronger electron donors and higher pre-twisted angles exhibited a higher viscosity sensitivity. These results can be used to inform future RBF design and expedite research. Further research will be continued by synthesizing additional RBFs and conducting a multi-parameter linear free energy analysis to quantitatively predict the viscosity sensitivity of an RBF. 

Student Major(s): Chemistry

Advisor: Dr. Elizabeth Harbron

Claire Cook, "Identification of Artist Dye Alizarin by Blinking Characteristics"

Current techniques to identify colorants in art conservation require large samples whereas Single Molecule Spectroscopy (SMS) presents a minimally invasive alternative, classifying molecules based on their blinking. Blinking emerges from fluorescent molecules alternating between forms where a photon is released and where it is not. Each molecule has a unique blinking trace, with dye classes sharing characteristic patterns. It was investigated if Alizarin, an artist’s dye susceptible to fading, could be distinguished by its blinking from molecules which are structurally different and structurally similar, using Rhodamine-B and Purpurin respectively. Data sets for each molecule were collected on an APD microscope and compared to one another via a logistic regression program. The blinking character of the molecules were distinct as to be differentiated from one another. However, the program cannot yet classify an unknown blinking trace as belonging to a specific molecule type with satisfactory accuracy. Future research will involve the collection/use of larger data sets to improve the program’s classification accuracy.

Student Major(s)/Minor: Chemistry Major; Anthropology Minor

Advisor: Dr. Kirstin Wustholz

Sarah Foster, "Implementing Multivariate Statistics for Analyzing Multidimensional Kombucha Data"

Kombucha is a fermented beverage produced through the addition of a symbiotic community of bacteria and yeast (SCOBY) to a sugary tea. Despite the odors associated with kombucha, studies lack in understanding its chemical aroma profile. This study aimed to identify the aroma profile of Virginia kombucha products using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry with flame ionization detection (GC×GC-TOFMS/FID). Samples were extracted via headspace solid phase microextraction (SPME) arrow and analyzed using GC×GC-TOFMS/FID. Data analysis resulted in a comprehensive view of the VOCs present in kombucha products. It was possible to distinguish products from one another as well as differentiate the tea matrix from the microbial matrix. Preliminary analysis suggests detected compounds can be attributed to one or more SCOBY microorganisms described in literature. This work builds on the overall aim of linking bacterial genetics, metabolism, and flavor profile in fermented foods as examined by advanced analytical techniques.

Student Major(s): Chemistry

Advisor: Dr. Katelynn Perrault Uptmor

John Golding, "Detection Of Fluorinated Microplastics in Environmental Media"

There is growing interest in detecting “forever chemicals," also known as per- and polyfluoroalkyl substances (PFAS), due to their adverse health effects. These substances are commonly found in microwaveable popcorn bags (as inner coatings), non-stick cookware, and stain-resistant fabrics. As a result, PFAS have become widespread in the environment and human body. Determining their presence and extent is essential for protecting environmental and public health. The current method for quantifying PFAS primarily uses liquid chromatography paired with mass spectrometry. However, this approach is resource-intensive and limited to traditional lab settings, making it less suitable for field-based screening. Single-sided NMR enables mobile detection with minimal sample preparation and non-destructive sampling. It also offers the ability to determine particle size based on transverse relaxation time (T ). We used single-sided NMR to measure fluorine concentrations in both aqueous and soil samples. For water, a calibration curve was established using potassium hexafluorophosphate solutions and compared to a fluorine-free control. Additionally, soil from the Williamsburg area was doped with PFAS, and a similar methodology was applied. Finally, theory suggests that PFAS particle size can be inferred from the decay rate of the single-sided NMR signal.

Student Major(s): Chemistry

Advisor: Dr. Tyler Meldrum

Sophia Guinea, "Further Mechanochemical Implications of 3D Printed Vessels"

The cost of mechanochemical equipment can be prohibitive to new researchers seeking to explore the field. To mitigate this barrier, we aim to utilize traditional synthetic chemistry laboratory equipment, such as rotary evaporators, to serve as a common entry point into mechanochemistry. We hypothesize that 3D printing can serve as a low-cost method to provide mechanochemical reactors that fit to a rotary evaporator, thus enabling researchers to explore mechanochemistry without the cost encumbrance. This presentation will discuss early studies and developments in print styles and print materials.​

Student Major(s): Neuroscience

Advisor: Dr. Isaiah Speight

Luke Iacobucci, "Elucidating the Antimicrobial and Biofilm Inhibiting Properties of Polyyne Amine Compounds"

This project will explore the antibiotic properties of several newly synthesized compounds. Earlier research explored the antibiotic and biofilm inhibiting processes of polyyne alcohols (compounds that have an OH group as well as two consecutive triple bonds). The research question I will be addressing is: Do polyyne amines (compounds that have an NH2 or NHR group as well as two consecutive triple bonds) show antibacterial and biofilm inhibiting processes? Polyyne amines are an exciting subject for further study, as they can be more easily substituted than alcohols and can be synthesized using a very similar method. The method can yield more compounds that could potentially have the desired properties. In order to create these compounds, the Glaser-Hay reaction is used to join two alkynes at a triple bond.

Student Major(s): Biology Major; Chemistry Minor

Advisor: Dr. Douglas Young

Amalia Johnson, "Synthesis and Structural Determination of Copper(I) Complexes with Thioxane Ligand"

The observed luminescence of organic light-emitting diodes (OLEDs) comes from the emissive layer, often a thin sheet of organic materials situated between electrodes. OLEDs have the potential to be more cost-effective and efficient then semiconductor-based LEDs. As such, there is a high demand for effective luminescent materials to incorporate into these emissive layers. This present study explores the luminescence of complexes formed from copper(I) iodide and sulfurous ligands. Commercial 1,4-thioxane was tested for its reactivity with copper(I) iodide under various experimental conditions. Reactions were repeated with varying solvents and stoichiometric ratios to fully explore reaction spaces. Details on structure were gathered via X-ray crystallography. The result was a collection of monomers and one dimensional chains. Each complex was evaluated for its luminescence when irradiated with UV light, with one complex shining through as a strong contender for future study.

Student Major(s): Interdisciplinary Studies: Medicinal Biochemistry

Advisor: Dr. Robert Pike

Dylan Jones, "Illuminating Chemistry: The Synthesis and Fluorescent Wonders of Nile Red and its Derivatives"

Fluorescence microscopy is an important tool in biotechnology and medicine today, facilitating research advances and diagnoses by illuminating biological structures. Most microscopy studies use fluorescent molecules that are maximally bright. The Harbron lab hypothesizes that organic fluorescent molecules, which provide brightness moderated by a process called twisted intramolecular charge transfer (TICT), can provide richer information on dye location, identity, and local environment. We tested this hypothesis with a well-known fluorescent molecule: Nile Red.

Previous research suggests that Nile Red can capture a snapshot of its local environment due to its fluorescence and rotor-like motion. Combining both elements in one dye has the potential to condense experiments relating to the lipid membrane and its environment. The Harbron lab created and studied derivatives of Nile Red, designed to be more environmentally sensitive than the commercially available product. Overall, this project created new fluorescent derivatives of Nile Red that can potentially report more information about complex environments.

Student Major(s)/Minor: Chemistry Major; Hispanic Studies Minor

Advisor: Dr. Elizabeth Harbron

Manya Kaladi, "Inhibition of the PqsE-RhlR Interaction in Pseudomonas Aeruginosa Downregulates Expression of the phz2 Operon"

Pseudomonas aeruginosa is a multi-drug resistant, gram-negative pathogen that is often spread in hospital settings via ventilators. Consequently, P. aeruginosa infections can be fatal for individuals with chronic respiratory diseases such as cystic fibrosis (CF). Quorum sensing (QS) is responsible for virulent phenotypes when bacteria are present in a high population density. QS is largely facilitated by the protein-protein interaction of RhlR and PqsE which activates the transcription of associated genes. The phz2 operon, which is one such genetic sequence, produces a precursor to the virulence factor pyocyanin. In this study, reporters with phz2 promoter regions combined with mutant forms of PqsE were developed in Escherichia coli and P. aeruginosa models. Expression of the phz2 operon was observed over a 13 h period. Lower expression levels of the phz2 operon were observed in reporter strains containing PqsE with lowered/no binding affinity for RhlR when compared to those with the wild-type PqsE. Thus, the use of phz2 reporter strains is a promising approach for screening drugs that inhibit QS in P. aeruginosa.

Student Major(s): Chemistry

Advisor: Dr. Isabelle Taylor

Grace LaFrancois, "Developing Water-Soluble Fluorescent Probes for the Detection of Heavy Metals in Drinking Water"

A fluorescent probe with the capability to sense Fe3+, Pd2+, Al3+, and Mo5+ in aqueous environments was synthesized. This fluorescent probe utilizes a turn-off fluorescence quenching mechanism to sensitively detect the metals for which it is selective via chelation. For the first generation sensor, the limit of detection of 8.75 μg/L for Fe3+, 21.0 μg/L for Pd2+, 14.9 μg/L for Al3+, and 36.6 μg/L for Mo5+, which are all within WHO and EPA standards for water quality. Other ligands have been developed based on the first generation sensor, such as a sulfonic acid functionalized probe. To examine the chelation to this second generation fluorescent probe, a ligand was synthesized with the same functionalization, but without the fluorophore. These fluorescent probes show potential to be utilized for analysis of water samples to assess the safety and quality of drinking water. 

Student Major(s): Chemistry

Advisor: Dr. William McNamara

Elizabeth MacQueen, "N-Heterocyclic Carbene Ligand Synthesis for Carbon Dioxide Reduction"

Carbon Dioxide Reduction is a promising strategy to repurpose a greenhouse gas to provide a renewable feedstock of hydrocarbon fuels. One technique to tackle CO2 reduction involves designing transition metal catalysts capable of turning CO2 into CO, formate, or methane. A ligand is a molecule that has the ability to accept or donate electrons to or from a metal center, resulting in a metal complex with unique properties. N-Heterocyclic Carbene (NHC) ligands, in particular, are known for being strongly binding, characteristically stable, and easily modified. Once complexed with transition metals, some NHC-metal complexes have even proven capable of reducing carbon dioxide as a metal catalyst in electrochemical settings. We have designed a ligand that is tetradentate, binding to the metal center through two pyridine groups, an amine, and an N-heterocyclic carbene. This ligand scaffold originally contained an imidazole group that functionally mimics the naturally occurring amino acid, histidine. Once synthesized, the histidine ligand was then treated with iodomethane for N-methylation of the imidazole groups, leading to an N-heterocyclic carbene salt. However, this methylation reaction yielded mixed results, and further testing is needed before complexation with transition metals will be possible.

Student Major(s)/Minor: Chemistry Major; Creative Writing Minor

Advisor: Dr. William R. McNamara

Olivia Molz, "Determination of the Antimicrobial Activity of Diynes Containing a Homopropargylic Ester"

Antibiotic resistance is a growing issue as microbes continue to adapt to existing treatments. Therefore, the search for new antimicrobial agents, particularly those based on natural products with established activity, is essential. Diynes, naturally occurring organic molecules with two consecutive carbon-carbon triple bonds, have been demonstrated to act as antimicrobial and antifungal agents, making them prime candidates to inspire future drugs. Previous studies have identified several structurally unique diynes with a common homopropargyl alcohol (an alcohol group two carbons away from the triple bond) that successfully impeded the viability of E. coli and disrupted a biofilm of P. fluorescens. Since many diynes isolated from natural sources contain ester functional groups, this project looks to expand these findings by evaluating the ability of diynes with an ester at the homopropargylic position to inhibit bacterial activity. The overarching goal is to deepen the understanding of diynes to identify structural features critical for optimal antimicrobial activity. 

Student Major(s): Chemistry

Advisor: Dr. Robert Hinkle

Madison O'Brien, "Redefining Extraction for Cleaner Forensic Chemistry"

Forensic laboratories continuously adapt to federal regulatory changes. Historically, dichloromethane (DCM) was used as a solvent for fire debris analysis. However, new government regulations on DCM require laboratories to identify alternative solvents aligning with green chemistry principles.

This study evaluates five alternative solvents for extracting ignitable liquid residues (ILRs) in forensic fire debris investigations. Solvents included diethyl ether, pentane, hexane, methanol, and isopropanol. Chromatographic performance was examined to identify greener options complying with safety and regulatory demands. Solvent performance was assessed by one dimensional gas chromatography – mass spectrometry (GC-MS) and comprehensive two-dimensional gas chromatography – time-of-flight mass spectrometry (GC×GC-TOFMS). GC×GC-TOFMS enhanced separation, enabling better visualization of complex mixtures compared to GC-MS. Pentane was the best solvent to prevent chromatographic artifacts and provided sufficient resolution to differentiate ILRs. Results demonstrated how optimization of solvent choice, informed by chromatographic metrics, provides laboratories with safer and sustainable alternatives without compromising quality.

Student Major(s)/Minor: Chemistry Major; Kinesiology Minor

Advisor: Dr. Katelynn A. Perrault Uptmor

Sophia Rothman, "Exploring Non-canonical Amino Acids as a Method to Facilitate Protein Dimerization"

Proteins are essential to life as they are integral to a variety of biological processes. Expanding the range of protein building blocks through the synthesis of non-canonical amino acids (ncAAs) enables the introduction of new functions into these crucial biomolecules. For instance, the incorporation of a ncAA can introduce site-specific reactivity into the protein of interest. Importantly, this addition of a unique handle allows the preparation of bioconjugates in which a biological molecule is covalently linked to another small molecule or protein. This project aims to utilize ncAAs as a tool to access protein dimers that might possess unique biological relevance. To do so, the non-canonical amino acid p-propyloxyphenylalanine (pPrF) is incorporated into the model protein ubiquitin during translation. This introduces a terminal alkyne that can react with a linker molecule via a Glaser-Hay reaction which couples two terminal alkynes. This linker, which has two terminal alkynes, in theory, then allows for attachment to another protein containing the alkynyl pPrF moiety. Successful dimerization would serve as yet another example of the usefulness of ncAAs.

Student Major(s)/Minor: Biology Major; Chemistry Minor

Advisor: Dr. Douglas Young

Grace Sliwinski, "Production of H2O2 with Singlet Oxygen"

Abstract coming soon!

Student Major(s)/Minor: Chemistry Major, Biochemistry Minor

Advisor: Dr. Lisa Landino

Amanda Stebner, "4-Azafluorenones: Synthesis and Spectrophotometric Analysis"

Azafluorenones are a class of molecules with unique fluorescent and medicinal properties. Related natural products have been isolated from plants in the soursop family and have shown antimicrobial, antifungal, and cytotoxic qualities. Given this, azafluorenones have been synthesized for their biological activity and less for the exploration of their photophysical properties. This study focuses on a synthesis of 4-azafluorenones and subsequent analysis of their fluorescence. The synthetic approach was two steps and afforded a 4-azafluorenone that was substituted at the third position. The third position of the 4-azafluorenone was then functionalized in various ways resulting in the synthesis of seven new derivatives. We then analyzed the fluorescent properties of these 4-azafluorenone derivatives in order to gain insight into how changes in functional groups modifies fluorescent behavior. This informs our ability to tune the fluorescence of 4-azafluorenones to our needs which can have a variety of potential applications in fluorescent probes, imaging, and fingerprinting. 

Student Major(s): Chemistry

Advisor: Dr. Jonathan Scheerer

Gunnar Ternstrom, "Cascade Alkyne-Aza-Prins Reactions to Access Ergot Bioisosteres"

Previously, the Hinkle lab discovered that by adding local aromatic rings to the Prins reaction, we could induce a cascade intramolecular Friedel-Crafts. This cascade enabled the facile formation of novel tetracylic heteroatom-containing molecules.

Using these coupled reactions, it was predicted that our lab could access ergot alkaloid scaffolds at higher efficiency than previously documented. The original target was 7-aza ergoline, a nitrogen-shifted version of a naturally occurring medicinal scaffold. During the project, we discovered new selectivity of the Friedel-Crafts reaction in our cascade. While this reactivity towards the indole did not allow for the synthesis of 7-aza ergoline as initially planned, it opened the pathway to various C2 indole cyclization products. With this new understanding of cyclization selectivity towards indole-containing molecules, we propose the synthesis of an aza-shifted scaffold of a candidate L-DOPA replacement for Parkinson's disease treatment. 

Student Major(s): Chemistry

Advisor: Dr. Robert Hinkle

Patrick Tingley, "Transition Metal MOFs for Ammonia Storage"

Ammonia is an immensely useful chemical useful as a major component of fertilizer, as a precursor to many chemicals, and as a potential clean-burning fuel. However, its gaseous nature, toxicity, and reactivity make it cumbersome to store in large quantities. Metal-organic frameworks (MOFs) can effectively store gases like ammonia in a solid state while being able to release and reabsorb ammonia gas in a controllable way. This research developed an easy and inexpensive synthesis method for a MOF with nickel (II) acetate and the orange organic dye, quinizarin. The structure of the nickel-based and other transition metal-based MOFs were roughly characterized utilizing Thermo-Gravimetric Analysis (TGA), Powder X-ray Diffraction (PXRD), IR Spectroscopy, and Elemental Analysis (CHN). The network became saturated when exposed to an atmosphere of ammonia for less than a day and was selective for ammonia over water. Lastly, this research developed several simple and accessible methods to estimate the ammonia content of saturated network samples. 

Student Major(s): Chemistry

Advisor: Dr. Robert D. Pike

Justin Titus, "Synthesis of Pro-Fluorophores to Fluorescently Track Proteins Containing Non-Canonical Amino Acids (ncAAs)"

Observing protein activity within cells is an important tool in understanding cell metabolism and is often tied to cellular location. The use of site-specific functionalities, such as proflourophores, offers a promising method in accomplishing this task. Profluorophores can be introduced into proteins via exploiting non-canonical amino acids (ncAAs). The ncAA can be genetically engineered into a desired protein at a specific residue and provide a handle for a biologically uniqe reaction with a profluorophore. The profluorophore is not fluorescent until the reaction occurs, but then becomes fluorescent upon reaction. This conditional fluorescence is a more promising approach than other fluorescent tracking methods utilizing molecules that may be constantly fluorescent, offering only background interference. This project involves two stages. The first involves the synthesis of the pro-fluorophore, EBTZ. This three-step synthesis was optimized to both maximize the product yield while not compromising its purity associated with side-reactions. The second stage involves successful cellular expression of the protein ubiquitin containing an alkynyl ncAA (pPrF). Future work on this project requires covalently linking these two components together via their terminal alkyne chemical functionalities. Upon success of this reaction, we next will assay the conditional fluorescence of the EBTZ-ubiquitin complex and assess its applications to protein tracking.

Student Major(s)/Minor: Chemistry Major; Mathematics Minor

Advisor: Dr. Doug Young

Virginia Weina, "Analysis of Volatile Organic Compounds from Submerged Animal Tissue Decomposing at Varied Temperatures"

Decomposing bodies emit volatile organic compounds (VOCs), resulting in decomposition odor of forensic interest. These complex samples from decomposition can be more accurately characterized using a technique called comprehensive two-dimensional gas chromatography (GC×GC).  In a previous experiment,  decomposing pork belly submerged in tap water was sampled in triplicate at varying temperatures over the course of twelve days. This study aimed to evaluate how these data could be analyzed in a way that benefited forensic casework involving submerged remains. Using various software approaches, it was determined that batch alignment software was most promising for forensic research for longitudinal data to show trends in VOCs emerging over time. Another software, a tile-based approach for class differentiation, was determined to be best suited to compare samples from submerged remains to control samples only containing water. This type of comparison has potential to assist forensic scientists with an additional method to locate submerged remains.  

Student Major(s): Chemistry

Advisor: Dr. Katelynn Perrault Uptmor