Analysis of Soil Samples to Determine Viability as Calcium Carbonate Mining Locations

Type: Undergraduate
Author(s): Katherine Smith Chemistry & Biochemistry Grace Bobo Chemistry & Biochemistry Tatum Harvey Chemistry & Biochemistry Kaylee Hoang Chemistry & Biochemistry Wyatt Mast Chemistry & Biochemistry Jacques Muhire Chemistry & Biochemistry Samantha Shah Chemistry & Biochemistry Isabella Sullivan Chemistry & Biochemistry Katie Zabel Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry

Texas is home to significant mining activity, both for oil and gas but also for other industrially useful materials. One such material is calcium carbonate. The chemical instrumentation course was contacted by a local mining company interested in analysis of soil samples from potential drilling locations, specifically determining calcium content and the presence of hydrocarbons. Over the course of the semester, the students in chemical instrumentation have analyzed four separate soil samples for both calcium content and various hydrocarbons using multiple instruments in the chemistry department including atomic absorption spectroscopy, infrared sprectroscopy, GCMS, thermogravimetric analysis, and NMR. We determined that calcium is present in the soil samples in concentrations up to 5% by mass, and that some hydrocarbons are present.

Preparation of BiVO4 Films in Multilayer Electrodes for TEMPO Oxidation

Type: Undergraduate
Author(s): Ines Soto Chemistry & Biochemistry Qamar Hayat Khan Chemistry & Biochemistry Favor Igwilo Chemistry & Biochemistry Daisy Li Chemistry & Biochemistry
Advisor(s): Benjamin Sherman Chemistry & Biochemistry

Photoelectrochemical (PEC) systems can be used to harness solar energy to drive sustainable oxidations reactions, such as those mediated by TEMPO ( 2,2,6,6-tetrameth-ylpiperidinyl-N-oxyl), a stable radical with applications in organic synthesis. This work focuses on preparing bismuth vanadate (BiVO4) films for multilayer electrodes (FTO|WO3-BiVO4-NiO) to enable PEC TEMPO oxidation studies. Double-layered BiVO4 films were fabricated on fluorine-doped tin oxide (FTO) substrates through dip-coating and a subsequent thermal treatment at 450°C. Various means of optimizing film performance and quality were explored, including precursor stoichiometry, dipping frequency, and drying conditions.

Our experiments demonstrate that the uniformity and quality of BiVO4 firms are greatly dependent on preparation parameters. Adjustments to the drying procedure, designed to slow solvent evaporation, resulted in improved uniformity as observed through UV-Vis spectroscopy and profilometry. Photoelectrochemical testing of select replicates under illumination confirmed photoactivity, with distinct differences between dark and light conditions. Further experimentation with cyclic voltammetry and chronoamperometry will explore the efficiency of these films in greater detail. This work establishes an effective approach for BiVO4 film preparation for future use in WO3-BiVO4-NiO multilayer electrodes for TEMPO oxidations studies and advancing solar-driven oxidation processes.

Unraveling asphaltene aggregation: Computational insights into sticky situations

Type: Graduate
Author(s): Gretel Stokes Chemistry & Biochemistry
Advisor(s): Benjamin Janesko Chemistry & Biochemistry

Asphaltenes are the heaviest component of crude oil and strongly aggregate during the oil refinement process, fouling equipment and increasing oil runoff. Understanding their propensity for aggregation at the molecular level is crucial for developing strategies to mitigate their role in equipment fouling. Using computational chemistry, we analyzed the dimerization energies of 67 previously published asphaltene structures by running CREST calculations on all possible molecular pairs. Our results reveal that diradical:diradical interactions drive strong aggregation, whereas radical-closed shell interactions are comparable in strength to closed-shell:closed-shell interactions. Additionally, we find that archipelago-type structures weaken dimerization as compared to island-type asphaltenes, likely due to self-association of archipelago structures. These findings provide key insights into asphaltene behavior and suggest potential strategies for disrupting aggregation. Future work will explore whether near-infrared light can be used to disaggregate asphaltenes, offering a novel approach to alleviate asphaltene-related challenges in industry.

Exploring molecular design: A triazine library reveals a surprisingly hydrophobic molecule

Type: Graduate
Author(s): Gretel Stokes Chemistry & Biochemistry Casey Patterson-Gardner Biology
Advisor(s): Eric Simanek Chemistry & Biochemistry

Macrocycles are promising drug candidates due to their ability to selectively interact with biological targets. However, predicting their solubility and membrane permeability remains challenging. To probe this, a library of 35 triazine macrocycles was synthesized and the hydrophobicity of each macrocycle was measured using octanol:water partition coefficients (logP).

Unexpectedly, a glycine-derived macrocycle with two primary amine groups displayed high hydrophobicity, contrary to prediction based on conventional computational methods for computing logP (AlogP). Computational analysis revealed that the diamine substitution stabilizes a closed conformation, tethering the macrocycle where its polar groups are shielded from solvent interaction, thus increasing hydrophobicity. Additionally, we found that logP values of heterodimer macrocycles closely approximated the average of their corresponding homodimers, suggesting a predictable trend in partitioning behavior.

We demonstrate how small molecular changes can significantly impact physical properties. By combining synthesis, physical measurements, and computational modeling, our work provides insights into macrocycle behavior that could aid in designing membrane-permeable drug candidates.

Genetic selection of leucyl-tRNA synthetase variants to incorporate N-𝜀-acetyl lysine into proteins

Type: Undergraduate
Author(s): Giang Tran Chemistry & Biochemistry Sophia Tran Chemistry & Biochemistry
Advisor(s): Ryu Youngha Chemistry & Biochemistry

The goal of this project is to select the variants of an archaea leucyl-tRNA synthetase (MLRS) to incorporate N-𝜀-acetyl lysine (AcLys) into specific positions of proteins in bacterial cells. Acetylation of lysine is one of the most important post-translational modifications of proteins that regulate their functions. One application of this study is using site-directed incorporation of AcLys to introduce novel functions to proteins. Previously, we successfully randomized five positions in the MLRS active site to generate millions of different variants. Genetic screening procedures were performed to select MLRS variants specific for AcLys. Positive selection is performed in the presence of AcLys where bacterial cells containing MLRS that attach any natural amino acids or AcLys onto the tRNA can survive in the presence of chloramphenicol antibiotics. In the negative selection performed in the absence of AcLys, bacterial cells containing MLRS that attach natural amino acids will die in the presence of 5-FU as a toxic substance is produced. Only cells containing MLRS variants that attach AcLys can survive in the presence of 5-FU, because no toxic substance is produced. Two clones made it through multiple rounds of selection and are being tested for successful incorporation of AcLys at the 7th position of the Z-domain protein. Mass spectrometry will be used to detect the presence of AcLys.

Impact of Sensor Design on Hydrogel-Porous Silicon Structures Capable of Detecting Ion Concentrations in Human Sweat

Type: Undergraduate
Author(s): Dylan Walters Chemistry & Biochemistry Jeffery Coffer Chemistry & Biochemistry
Advisor(s): Jeffery Coffer Chemistry & Biochemistry

Impact of Sensor Design on Hydrogel-Porous Silicon Structures Capable of Detecting Ion Concentrations in Human Sweat

Dylan Walters1, George Weimer1, Leigh T. Canham,2 and Jeffery L Coffer1

1Department of Chemistry and Biochemistry, Texas Christian University, Fort Worth, TX 76129
2Nanoscale Physics, Chemistry and Engineering Research Laboratory, University of Birmingham, Birmingham, B15 2TT UK

Utilizing the supportive structure of hydrogels, the semiconducting character of porous silicon (pSi) membranes, and the biodegradability of both, a unique biosensor for the chemical analysis of health-relevant analytes can ideally be created.
Hydrogels are water-infused, biodegradable polymer networks. Alginate based hydrogels are particularly useful because of environmental abundance, along with their ability to interface well with human skin. The addition of acrylamide segments to the polymer chains adds stability and useful shelf-life to the material. These characteristics also make them an ideal medium for supporting pSi membranes and simultaneously assimilating them into a wide range of tissues.
Porous silicon (pSi), a highly porous form of the elemental semiconductor, is utilized to measure and conduct electrical signals throughout the hydrogel matrix. In diode form, these membranes exhibit measurable current values as a function of voltage, which can be used to detect bioelectrical stimuli such as the concentration of physiologically relevant ionic species (e.g. Na+, K+, and Ca2+).
Recent experiments center on integrating pSi membranes in Acrylamide/alginate co-polymer hydrogels to test how variations in ion concentration affect the flow of current as a function of applied voltage. pSi membranes ~110 m thick and 79% porosity are fabricated from the anodization of low resistivity (100) Si in methanolic HF at an applied bias of 100 mA/cm2 for 30 min. Membrane pieces ~ 2 mm by 2 mm are heated for one hour at 650°C. They are then fashioned into diodes upon the attachment of Cu wire using Ag epoxy and annealed for 15 minutes at 95°C. The backs of the membranes, the connection to the copper wire, and the copper wire itself are sealed using clear nail polish to prevent current flow from the back of the membranes and bubble formation. In each ion sensing experiment, an electrochemical cell is created by placing two pSi membranes parallel each other ~2 mm apart vertically in a fixed electrolyte composition. Current is measured as a function of applied voltage (typically from 0-5 V) for systems with different NaCl concentrations in the nM to mM range. NaCl solutions are injected directly into the hydrogel in between the two pSi membranes 2 µL at a time. At local concentrations of approximately 0.25M, the magnitude of maximum current response increases with increased volume of ion solution added.
This presentation will focus on the porous silicon hydrogel fabrication protocol, as well as results from experiments with varying NaCl concentrations. Future work is being designed to determine the saturation behavior and the ion concentration limits of the pSi membranes in hydrogels.

Synthetics Dyes and Their Application as a Ratiometric Molecular Viscometer

Type: Undergraduate
Author(s): Colin Wong Chemistry & Biochemistry
Advisor(s): Sergei Dzyuba Chemistry & Biochemistry

Fluorescent small molecule environment-sensitive probes change their emission properties (including emission wavelength, intensity or lifetime) in response to the changes of the environment around them, such as changes in temperature, viscosity, and polarity. Thus, these probes have found numerous applications in sensing and imaging, especially in biologically relevant systems. Ratiometic probes is a special group of molecules that has two or more emission wavelengths that exhibit a relative change in response to changes in the media, which provides an internal calibration, increases signal-to-noise ration, and improves the integrity of sensing. However, synthesis of such molecules is usually non-modular in nature, and it often requires multiple steps coupled with numerous purifications. In this presentation, we will highlight our synthetic efforts on the developments of several types of fluorescence ratiometric probes that are based on versatile fluorescence scaffolds, such as BODIPY and squaraine dyes.

Macrocycles: the Chemical Chameleons

Type: Undergraduate
Author(s): Amarige Yusufji Chemistry & Biochemistry Eric Simanek Chemistry & Biochemistry
Advisor(s): Eric Simanek Chemistry & Biochemistry

Historically, pharmaceutical companies have created small molecule drugs designed to interfere with chemical reactions. An alternative strategy for therapy relies on inhibiting protein-protein interactions, but larger molecules are required. Nature uses large ring-shaped molecules (macrocycles) to accomplish this task. These molecules present challenges to synthesis: forming rings typically is difficult, expensive, time-consuming and inefficient. In addition, the rules required to make macrocyclic drugs are poorly understood when compared to those for small molecules. Here, a strategy for creating macrocycles is described that addresses the challenges of synthesis: they can be prepared quickly and inexpensively. The basis for this chemistry is stepwise substitution of cyanuric chloride, allowing the target to be prepared in three steps. The advantage of using highly electrophilic molecules like cyanuric chloride is that virtually any primary or secondary amine or amino acid could be used to make a macrocycle. Using a variety of amines has shown to affect properties like hydrophobicity and size, which allows for the creation of a large library of molecules to be tested for biological activity, which mirrors how current drug development programs work. The macrocycle is characterized by NMR spectroscopy and screened for other physical (drug-relevant) properties, such as logP and pKa.

Investigation of Charge Transfer Between Porous Silicon and Metal Halide Perovskites

Type: Graduate
Author(s): William Burnett Chemistry & Biochemistry Bong Lee Physics & Astronomy
Advisor(s): Jeffery Coffer Chemistry & Biochemistry Ignacy Gryczynski Physics & Astronomy Zygmunt Gryczynski Physics & Astronomy
Location: Third Floor, Table 5, Position 1, 1:45-3:45

Silicon-Perovskite tandem solar cells are some of the leading emerging technology solar cells due to their high photoconversion efficiency or the ability to turn light into electricity. These solar cells rely on the ability to harvest a higher percentage of the solar spectrum due to the differences in the two materials. MHPs are an ionic crystal that have the chemical formula ABX3 where A is a monovalent cation (+1) such as cesium, methylammonium or formamidinium; B is a divalent cation (+2) such as lead or tin, and X is a halide such as chloride, bromide, or iodide. Porous silicon is crystalline silicon that has been etched to form pores with properties dependent upon the etching conditions. Porous silicon that has been etched such that the silicon area between the pores is between 1-4nm becomes photoluminescent (PL). It has been shown that the optoelectronic properties of metal halide perovskite (MHPs) grown within porous silicon (pSi) are highly dependent upon the surface area, pore size, and surface chemistry of the pSi. This interaction has led us to investigate the fundamental interactions that occur when nanoscale porous silicon encounters nanoscale MHP, namely the possibility of energy/charge transfer.
We have evaluated two different experimental designs. The first entails adsorbing ligand passivated MHP quantum dots onto a solid piece of luminescent mesoporous Si membrane and allow the solvent to evaporate. The change in luminescence from the pSi can be used to monitor the impact the perovskite has upon the pSi by monitoring the change in intensity and wavelength. The second approach as previously described utilizes MHP quantum dots (QDs) dispersed in toluene which is then titrated with non-luminescent pSi and the PL monitored. The primary impact of the pSi upon the light emission of the perovskite QDs is a significant reduction in the intensity of the emission. Comparisons of different pSi with hydride terminated versus oxide terminated surfaces show a dependence upon the surface chemistry to the change in PL. The PL lifetimes will be measured, and comparisons made to determine the mechanism of energy transfer.

'Fine-Tuning' Potential Alzheimer's Therapeutics through Pyridinophane Substitution

Type: Undergraduate
Author(s): Will Campa Chemistry & Biochemistry Sarah Dunn Chemistry & Biochemistry Christina Mantsorov Chemistry & Biochemistry Shrikant Nilewar Chemistry & Biochemistry Kristof Pota Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry
Location: Basement, Table 14, Position 1, 11:30-1:30

Pyridinophane molecules have recently been shown to have both antioxidant and pharmacological properties suitable for therapeutic applications targeting neurodegenerative diseases, including Alzheimer’s Disease. We have synthesized derivatives of this parent molecule with added moiety substitutions. These substitutions are designed to enhance the permeability and antioxidant activity beyond that of the parent molecule in the hopes of producing a molecule suitable for pharmacological testing in animal models. To establish a principle between moiety location on the parent molecule and its activity, we have placed 8-hydroxyquinoline, a moiety established in our lab to improve the antioxidant activity of parent molecules, in varying locations. The results presented here will detail our evaluation of the substitution of 8-hydroxyquinoline in varying locations and its impact on the molecule’s permeability and reactivity through a series of statistics, including a DPPH assay, determination of logBB, and the determination of chelating equilibrium quotients at varying pH (“log beta”).

New Approaches to Macrocycle Synthesis

Type: Graduate
Author(s): Liam Claton Chemistry & Biochemistry
Advisor(s): Eric Simanek Chemistry & Biochemistry
Location: Second Floor, Table 1, Position 2, 11:30-1:30

Creating a diverse array of structurally distinct, triazine-containing, macrocycles remain the focus of the Simanek group. Until now, this goal has been accomplished through a straightforward 3 step synthetic route with variation of amino acid incorporation and acetal length. Currently two new approaches to macrocycle synthesis are being pursued. The first approach relies on two like monomers coming together: by changing the relative position of groups in the macrocycle, the persistence of shape can be probed. The second approach relies on two different monomers coming together. Using a similar synthetic route, this strategy, if successful, will allow much finer control over design and engineering these molecules for specific purposes. These libraries of structurally diverse macrocycles are important for the long-term goals of establishing rules that can guide pharmaceutical drug design in these under-explored types of molecules.

An Investigation of Pyclen Metal Chelator Release on the Aggregation of Amyloid Beta

Type: Undergraduate
Author(s): Caroline Crittell Chemistry & Biochemistry
Advisor(s): Jeffrey Coffer Chemistry & Biochemistry
Location: First Floor, Table 2, Position 2, 1:45-3:45

Alzheimer’s Disease (AD) affects over 6.5 million Americans over the age of 65. Previous research links AD with Amyloid-Beta-40 (AB40) aggregation in the brain, which creates neurotoxic plaques, associated with AD. A potential mechanism in the treatment of AD is using therapeutics that will prevent the formation of these plaques, which is possible with Metal Chelation Therapy.
Metal ion chelation ideally stops metal ions from aiding in the aggregation of AB40. However, to deliver metal chelating agents to the brain, a drug-delivery mechanism is required that will be able to deliver this medicine across the Blood-Brain Barrier. Porous silica is a potential drug delivery material due to its small particle size, high loading capacity, surface tunability, and biocompatibility. Along with these characteristics, porous silica can create a “sustained” release of a given drug, allowing for a slow and steady release profile, reducing the risks of medication side effects.
This project seeks to establish the optimal loading capacities of a class of potential metal ion chelate therapeutic molecules known as pyclens into porous silica, each with different pyridyl moieties and chemical functionalities along the rim of the molecule. Encapsulation efficiencies measurements for these pyclen derivatives reveal loading percentages in the 10-19% range, varying by pyclen identity. Additionally, release studies monitored diffusion over time to find which pyclen molecule achieved “sustained” release. All loaded pyclen species were able to show sustained release after 20 minutes, both in the presence and absence of copper (II) ions. Turbidity assays with AB40 present showed that all pyclen species decreased protein aggregation in the presence of copper (relative to non-pyclen controls), showing that all pyclen species were able to successfully prevent the aggregation of AB40 in the presence of copper.
Release studies in a more authentic BBB model remain to be completed.

ROS Breakdown By Catalase Macrocycle Ligand Mimics

Type: Graduate
Author(s): Nora Del Bosque Chemistry & Biochemistry Kayla Green Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry
Location: Basement, Table 11, Position 2, 1:45-3:45

EUK-134 is a manganese-salen complex widely used in anti-aging skincare formulations due to its potent antioxidant activity resulting from catalytic decomposition of reactive oxygen species. Despite its popularity, the fundamental kinetic properties that govern its efficacy and recyclability are not well understood, limiting its optimization in skincare products. As a result, the study presented here investigates the efficiency, sustained activity, and selectivity of EUK-134 in comparison to the Green lab ligand library by evaluating its turnover number (TON), turnover frequency (TOF), and reaction rate. Results indicate that while EUK-134 demonstrates high catalase-type activity and selectivity, the activity decreases with continuous exposure to H₂O₂, suggesting a need for re-application in real-world scenarios to achieve long-term protection. Additionally, selectivity studies show that peroxidase activity was observed, which may impact the stability of sensitive ingredients in formulations. These findings provide essential kinetic benchmarks to compare future small molecules and optimize EUK-134’s use in antioxidant skincare products. Without a clear understanding of these fundamental properties, we lack benchmarks to compare future small molecules that compete with EUK-134.

The effect of anionic surfactant on the fluorescence of polyvinyl pyrrolidone in water

Type: Undergraduate
Author(s): Ngan Dinh Chemistry & Biochemistry Shamberia Thomas Chemistry & Biochemistry
Advisor(s): Onofrio Annunziata Chemistry & Biochemistry
Location: Basement, Table 4, Position 1, 11:30-1:30

Polyvinyl pyrrolidone (PVP) is a nonionic synthetic polymer often employed in drug formulations. Due to its hydrophilicity, it is often found in aqueous solutions where it can act as a solubilizing agent for organic molecules with poor water solubility. Interestingly, PVP also exhibits fluorescence in water. Furthermore, PVP fluorescence intensity is known to decrease as the concentration of salt increases. This effect has been attributed to the affinity of inorganic anions to PVP chains. In this poster, we examine the effect of an anionic surfactant, sodium dodecyl sulfate (SDS), on PVP fluorescence. In contrast with inorganic anions, we found that PVP fluorescence intensity increases with SDS concentration. We attribute this effect to the binding of SDS anions to PVP chains. This hypothesis is supported by a crystallization assay showing that PVP suppresses formation of SDS crystals. Our experimental results indicate that PVP fluorescence could be used to determine concentration of other types of anionic surfactants in water. These include perfluoroalkyl substances (PFAS), which are relevant environmental chemistry.

Polyethylene Glycol as an LLPS Temperature Promoter for Protein Crystallization

Type: Undergraduate
Author(s): Joel Dougay Chemistry & Biochemistry Shamberia Thomas Chemistry & Biochemistry
Advisor(s): Onofrio Annunziata Chemistry & Biochemistry
Location: Second Floor, Table 8, Position 2, 1:45-3:45

Protein purification is a critical step in the downstream processing of protein. Although chromatography is the most employed technique for protein purification, novel strategies that reduce operational costs and increase the amount of purified protein are being developed. These strategies have the possibility to reduce the price of protein-based pharmaceutical and biotechnological products through the reduction of purification cost. Preparative protein crystallization is one such economically-sustainable alternative to chromatography, however protein crystallization is very slow and is difficult to implement in current protein purification protocols. In our lab, we explore the use of metastable liquid-liquid phase separation (LLPS) to enhance protein crystallization. LLPS is typically induced by cooling protein aqueous samples below a well-defined temperature, called the LLPS temperature. We have previously shown that cooling aqueous samples of lysozyme in the presence of NaCl (0.15 M) and HEPES (0.10 M, pH 7.4) below LLPS temperature reproducibly produces yields of lysozyme crystallization above 90%. However, this process requires sample cooling to relatively low temperatures
(below –10 °C). In this poster, we examine the use of polyethylene glycol (PEG) as an additive that increases LLPS temperature. Our experimental results show that PEG increases LLPS temperature without appreciably altering formation of lysozyme crystals. The effect of PEG concentration on LLPS temperature is explained by considering the mechanism of macromolecular crowding.

Dual genetic selection of synthetic riboswitches for TMAO as genetic and analytical tools

Type: Undergraduate
Author(s): Isabelle Galvan Chemistry & Biochemistry
Advisor(s): Youngha Ryu Chemistry & Biochemistry
Location: Basement, Table 6, Position 2, 1:45-3:45

The goal of this project is to develop synthetic riboswitches for trimethylamine N-oxide
(TMAO). TMAO has been shown to regulate various physiological processes involved in the
development of atherosclerosis. A riboswitch is a non-coding RNA molecule that specifically
binds to a ligand and thereby controls the expression of genes in the downstream. A synthetic
riboswitch for TMAO could be useful for regulating gene expression in response to TMAO and
detecting TMAO in complex biological samples such as urine and blood. The 17 nucleotides in
the aptamer domain of a naturally occurring glycine riboswitch were randomized to generate a
library containing billions of different variants. The library was placed in the upstream of the
cat-upp fusion gene for a series of dual genetic selections. The positive selection is done in the
presence of TMAO to identify functional riboswitches that make cells resistant to
chloramphenicol. The negative selection is performed in the presence of 5-fluorouracil to kill
the cells containing the riboswitch variants activated by any endogenous molecules. Once
identified by several rounds of dual genetic selections, the synthetic TMAO riboswitches will
be tested by colorimetric and fluorescence assays.

Impact of Selected Ionic Liquids on the Properties of Metal Halide Perovskites

Type: Graduate
Author(s): Maegyn Grubbs Chemistry & Biochemistry Sergei Dzyuba Chemistry & Biochemistry
Advisor(s): Jeff Coffer Chemistry & Biochemistry
Location: Basement, Table 8, Position 1, 11:30-1:30

Metal-halide perovskites are crystalline materials that work as a semiconductor in both Light Emitting Diodes (LEDs) and solar cells. In general, perovskites possess the formula ABX3. For this project, the A site is an organic molecule such as Methylammonium (MA), the B site is Lead, and the X site is Bromide. While perovskites are easily fabricated, their crystal size and number of defects present are challenging to control. Defects cause LEDs to be less stable and/or less photoluminescent (bright) and cause solar cells to be less efficient at converting light to energy. One approach to reduce the number of defects is to use ionic liquids during perovskite formation. Ionic liquids are compounds made of ions in the liquid state due to a low melting temperature. They can be added to the perovskite precursor solution to slow down the crystallization process so that fewer defects are created. The goal of this project is to create new metal halide perovskites in the presence of selected ionic liquids, evaluate their structure and photophysical properties, with the long-term goal of creating new LEDs that are both stable and efficient.

In this project, cetyl-ionic liquids (cetyl meaning 16 carbon chains) were investigated for their effects on perovskite structure and light emission. The three ionic liquids were investigated: [C16-mim]Br (referred to as "IL1"), [C16-py]Br ("IL2"), [C16-C1pyrr]Br ("IL3"), and CTAB (“IL4”). Variations in the deposition method of the perovskite films were studied as well. It was hypothesized that the inclusion of cetyl-ionic liquids will protect the perovskite films from the environment (increasing stability) by providing a hydrophobic layer on the surface and will improve the electronic properties by filling in pinholes that cause defects. It is found that perovskite films with IL1 produced through a two-step spin coat deposition method are more photoluminescent than the perovskite films formed with IL2, IL3, IL4 or no IL (control). These results, along with detailed structural characterization of a given perovskite film, will be discussed in this presentation.

Isolating Chiral Nanoparticles from Paper: Templates for Chiral Semiconductor Nanoparticles

Type: Undergraduate
Author(s): Sarafina Gutterres Chemistry & Biochemistry
Advisor(s): Jeff Coffer Chemistry & Biochemistry
Location: Second Floor, Table 6, Position 2, 11:30-1:30

Chirality is a property of two molecules of the same composition to not be structurally superimposable on each other. Chiral structures are both common and essential throughout nature. Porous material can be used as templates for creating chirality. The use of cellulose as a template provides environmentally friendly alternatives for templating chirality onto materials such as silica. New research in this field includes using chiral silica templates for the synthesis of chiral perovskite films, a semiconductor material with bright light emission found in light sources like light emitting diodes (LEDs).

This project began by testing cellulose obtained from several different vendors to determine which product has the ideal properties for use in chiral films. An important aspect of cellulose product is its relative acidity/basicity (quantified in terms of pH), which can be regulated to control the degradation of cellulose into nanocrystals as well as the formation of chiral structures. Initially, the cellulose was acidified using sulfuric acid which causes aggregation and kinetic arrest within particles. A technique known as ion exchange chromatography is now being used in these experiments as the method of choice for acidifying cellulose samples.

The time allotted for cellulose nanocrystals to obtain chiral conformation is also an important aspect of creating chiral films. Initially, samples were not left to stand motionless and were immediately converted into silica films. Currently however, our procedure has been modified to allow the chiral cellulose nanocrystals at least seven days of sitting undisturbed before the addition of a silica precursor molecule, thereby facilitating the chiral product from the rest of the product mixture. Upon successful isolation of chiral cellulose-silica films, experiments will be initiated to template the formation of chiral light-emitting perovskite structures by infiltration.

First Year engagement - Chemistry Club

Type: Undergraduate
Author(s): Tatum Harvey Chemistry & Biochemistry Saba Anjum Biology Grace Bobo Chemistry & Biochemistry Jack Bonnell Chemistry & Biochemistry Braden Chadwick Biology Kathryn Collins Biology Caroline Crittell Chemistry & Biochemistry Delaney Davis Biology Audrey Dolt Biology Annie Downum Chemistry & Biochemistry Izzie Galvan Chemistry & Biochemistry Mark Sayegh Chemistry & Biochemistry Sam Shah Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry Heidi Conrad Chemistry & Biochemistry Julia Fry Chemistry & Biochemistry
Location: First Floor, Table 5, Position 2, 11:30-1:30

Texas Christian University’s Chemistry Club has always made a conscious effort to interest and include first year students through events and volunteering. This year’s project was focused on boosting numbers and cultivating a stronger community within the Chemistry and Biochemistry Department by specifically holding events to engage first year students. Events included the citrus social, periodic table of cupcakes, murder mystery play, tie dye event, and jeopardy night. This gave students a chance to get to know their peers better, to interact with a wide range of professors, and to gain knowledge about chemistry from outside the classroom. The success of these events has lead to record high attendance not only for the events but also for the Chemistry Club meetings held bi-weekly. The success of this initiative will ensure these and other events will be hosted for years to come, hopefully growing to the size where other schools can join and collaborate, further building a community within the field of chemistry and biochemistry.

Predicting pKas of flexible polybasic pyclen derivatives: A pKa challenge

Type: Undergraduate
Author(s): Tatum Harvey Chemistry & Biochemistry
Advisor(s): Benjamin Janesko Chemistry & Biochemistry Kayla Green Chemistry & Biochemistry
Location: Third Floor, Table 2, Position 1, 1:45-3:45

Predicting pKas is an outstanding challenge in computational chemistry. The Green group
at TCU is working to develop a library of pyclen derivatives that can successfully reduce oxidative
stress within the brain of people afflicted with neurodegenerative diseases1. Predicting the various
pKas of these flexible molecules, which are charged at neutral pH, challenges conventional
approaches to predicting pKas. For each pyclen derivative, we combine an extensive survey of
protonation site isomers, with conformational sampling using the CREST package2, DFT
calculations with continuum solvent models, followed by a linear fit to correct the solvent models
limitations for calculating energy of highly charged species. We can predict three to five measured
pKa values for each pyclen derivative with a RMSD of 0.9 pKa units, which is competitive with
the best-physics based method in the SAMPL6 blind challenge for the first pKa3. We are pushing
the boundaries of computational chemistry and its abilities to predict multiple pKas of flexible
molecules.

Models for the Next Generation of Drugs: Design, Synthesis, and Conformational Analysis of a 26-Atom Macrocycle

Type: Undergraduate
Author(s):
Advisor(s):
Location: First Floor, Table 4, Position 1, 1:45-3:45

To fight disease, pharmaceutical companies have historically prepared small molecules
designed to interfere with specific sites on proteins (enzymes) to prevent chemical reactions
from taking place. However, a second paradigm for interfering with proteins has gone largely
unexplored--blocking protein-protein interactions. To accomplish the latter, large molecules are
needed to bind to large areas on the protein target. However, large molecules present additional challenges. Typically, they are hard to synthesize, not orally available, and typically cannot cross cell membranes. Nature has designed large molecules like cyclosporin that should not work as drugs based on our current understanding. Despite its size, cyclosporin is orally available and can cross cell membranes. This research explores the design, synthesis, and conformational analysis of similar large ring-shaped molecules, so-called macrocycles. In this work, we are increasing the size of the ring-shaped molecule. By increasing the size of the ring-shaped molecule and varying the amino acid (in this case, valine), we are expanding the possible ways in which our macrocycle may interfere with protein-protein interactions. Here, a 26-atom macrocycle is reported. 1H NMR spectroscopy reveals a protonated molecule that is highly dynamic which has access to a beta-sheet conformation.

Implication of Steric Congestion on Sheet Formation: 26-Atom Macrocycles

Type: Undergraduate
Author(s): Lola Kouretas Chemistry & Biochemistry Luke Homfeldt Chemistry & Biochemistry Alex Menke Chemistry & Biochemistry
Advisor(s): Eric Simanek Chemistry & Biochemistry
Location: Second Floor, Table 1, Position 1, 1:45-3:45

Molecular engineering of larger macrocyclic compounds offers new avenues to disrupt protein-protein interfaces and potentially halt pathways that lead to neurodegenerative diseases, such as Alzheimer’s. The hallmark of Alzheimer’s disease involves the aggregation of so-called amyloid peptides that exhibit characteristic β-sheet structures. Thus, designing macrocycles that structurally/topologically mimic β-sheets should enhance the affinity of these macrocycles towards the amyloid aggregates and lead to rational design of more advanced scaffolds with superior structures. This will potentially present opportunities to interrogate protein-protein interactions, thus preventing amyloid plaque formation.

This work will describe the synthesis of structurally and functionally-diverse macrocyclic scaffolds containing leucine and isoleucine to understand the factors that contribute to β-sheet formation. Here, 26-atom macrocycles prepared in three steps will be described. Using a triazine core, a protected hydrazine group, and an amino acid constitute the base acid. In the second step the addition of an acetal of variable length forms the monomer. Acetals ranging from 2-4 carbons can be used to yield rings of 22-28 atoms. Previous work proves acetal length dictates morphology; three-carbon acetals demonstrate folded conformations and five-carbon acetals yield crinkled b-sheets. Four-carbon acetals yield the flattened b-sheets described here. Treatment with acid leads to dimerization in very high yields. Varying the amino acid choice can give way to synthesis of different homodimers and heterodimers.

These studies also address the optimization of the macrocyclization step. Early results indicate that a >300x reduction in the time of reaction (from 7 days to 30 min) might be realized. NMR spectroscopy provides confirmation of synthesis and 2D-NMR techniques offer opportunities to probe solution structure more efficiently.

Fabrication Process And Efficiency Analysis Of Organic Light-Emitting Diodes (OLEDs)

Type: Undergraduate
Author(s): Nhu Le Engineering
Advisor(s): Jeffery Coffer Chemistry & Biochemistry
Location: Second Floor, Table 1, Position 3, 1:45-3:45

Display technology is one of the industries of great significance, providing benefits for consumers with applications such as smartphones, televisions, and computer monitors. One of the current research topics in this industry of extensive interest is the development of new organic light-emitting diodes or OLEDs.

While such devices are common, fundamental challenges remain. Three pressing needs are: (1) longer device lifetimes, (2) lower fabrication costs, and (3) better control over emission color for ultrahigh definition displays and white-light lighting. Today, high-quality displays are built using high-vacuum deposition of molecular precursors, an expensive method unsuitable for ultra-large displays. Methods that rely on spin coating or printing of solutions of such precursors are far more economical, but present fabrication challenges of their own.

Our goal here is to improve device function and stability in OLEDs through simple solution-based routes with innovative fluorescent structures known as perovskites as building blocks. Ideally these new OLEDs will perform well at low voltage ranges and maintain good light emission intensity, as evaluated using techniques known as photoluminescence and electroluminescence spectroscopies.

In this research project, single-layer OLED and three-layer OLED devices are analyzed. Single-layer OLED devices consist of the substrate, anode, emissive layer, and cathode. Fluorine-doped Tin Oxide (FTO)/glass and Indium Tin Oxide (ITO)/plastic are the main substrates used, acting as anode. Ga-In eutectic, Silver Nanowire (AgNW), and Silver Epoxy are used as the interconnect / cathode layer to the emissive layer. To fabricate a three-layer OLED, the electron transport layer (ETL) is added between the cathode and emissive layer and a hole transport layer (HTL) added between emissive layer and anode, both to ideally improve energetics of electron/hole injection to the emissive layer. In our experiments, a species known as PEDOT:PSS is typically the hole transport layer and for the electron transport layer, we use ZnO or a mixture of ZnO and polyethylenimine.

The most success to date has been achieved with [Ru(bpy)3]2+ as the active emitting species in a thin polymer matrix referred to poly-vinylalcohol (PVA). Our current results show that the photoluminescence spectroscopy intensities were relatively high while the electroluminescence needs to be improved. The best result was recorded with the single-layer red OLED, which is made of FTO, [Ru(bpy)3]2+, and Ga-In eutectic. Visible light emission at low voltages from 3.5V-7V could be observed with the unaided eye under these conditions.

From Macroscopic to Molecular: Investigating the Behavior of Self-Assembling Hinges

Type: Graduate
Author(s): Alexander Menke Chemistry & Biochemistry
Advisor(s): Eric simanek Chemistry & Biochemistry
Location: First Floor, Table 2, Position 1, 11:30-1:30

Hinges are pervasive in the world today. Most common is a simple mortise door hinge  - defined by the flush stacking of leaves and fully revolute motion. Chemists have long sought to reproduce such structures on the molecular scale. Here, the hinge behavior of large, cyclic molecules is described.  Moreover, hinge motion can be controlled by "gumming up" the parts responsible for motion. While dirt and debris work in the macroscopic world, additional atoms are used in these molecular mimics. Specifically, by increasing the size of groups in the hinge domain, the rate of hinging decreases. Hinge motion is visualized by variable temperature NMR spectroscopy where in, at low temperatures the hinging both faces of the leaves (inside and outside) can be observed. At high temperatures, the hinging speeds up and the inside and outside exchange too quickly to be observed. Unlike hinges of everyday use that require human assembly, the molecular hinges described here assemble themselves. As a result, hinges with identical leaves as well as hinges with mismatched leaves can be prepared. Surprisingly, the results of this assembly process are biased: a statistical distribution of hinges is not observed.  Further studies to understanding this steric (gumming) sorting are ongoing.

Bridging Theory and Practice Enhancing Drug Design Through Molecular Simulations and Solvent Stability Analysis

Type: Undergraduate
Author(s): Alejandro Munoz Chemistry & Biochemistry
Advisor(s): Benjamin Janesko Chemistry & Biochemistry
Location: Second Floor, Table 2, Position 3, 1:45-3:45