Tag: Chemistry

Structure-Property Relationship of Halogen bonding Supramolecular Receptors

Presenter: Faith Longnight − Chemistry, Sociology

Co-Presenter(s): Scout Trom

Faculty Mentor(s): Hannah Bates, Thaís de

Session: (In-Person) Poster Presentation

Anion receptors hold an important place within the field of supramolecular chemistry due to the vast biological impacts many anions have in biology. Our project focuses on the synthesis of various novel reversible halogen-bonding anion receptors. The investigation varies the withdrawing characteristics of substituents of charged and neutral receptors to enable a thorough structure- property relationship study. Preliminary results show that the neutral receptors have significantly lower binding strength when compared to their corresponding charged receptors. We also see that the more electron-withdrawing the substituent group, the stronger the binding for the charged receptors. We also see that the binding pocket of our receptors best fit to chloride, our target analyte, when compared to the other halide anions. Through this study, we hope to identify the key structural characteristics needed to bind smaller anions, like chloride, so that future work can include creating receptors that can bind chloride in cells. The results of this study will provide fundamental knowledge of the most efficient way to modify receptors for an optimal binding moving forward in the field of halogen-bonding supramolecular sensors.

Development of a Nanohoop Rotaxane for Sensing Reactive Oxygen Species

Presenter: Phyllis Liao – Chemistry

Faculty Mentor(s): Claire Otteson

Session: (In-Person) Poster Presentation

Observing biological processes such as disease progression and gene expression require elaborate probes and sensors. In biomedical research, there is interest in making a multifunctional and modular scaffold that can target specific analytes by having a system that is “triggered” by the analyte which then affords a turn-on fluorescent response. Carbon nanohoops, or [n]-cycloparaphenylenes ([n]-CPPs) are a new nanostructure that allows us to observe biological processes by incorporating it into a larger structure called a rotaxane. Inspired by this model, we developed a novel modular probe system using a benzil trigger to detect reactive oxygen species (ROS). We began by synthesizing the rotaxane via copper-catalyzed azide-alkyne cycloadditions (AT-CuAAC), an active template method familiar to us and has demonstrated efficiency in previous publications. Once the structure was made, we characterized and analyzed it by subjecting it to simple non-biological environments and introduced ROS to see if the turn-on fluorescence is due to dethreading of the rotaxane. Success of the system is indicated by a turn-on fluorescence when reacted with these ROS and this shows that nanohoop-based [2] rotaxanes are tailorable for use in biomedical research.

Spectroscopic Study of Squaraine Molecule Aggregate Formation for use in Solar Cells

Presenter: Laura Leibfried – Chemistry, Physics

Faculty Mentor(s): Cathy Wong

Session: (In-Person) Poster Presentation

Using organic photovoltaic (OPV) devices to harvest solar energy is uniquely enticing as they allow for mass manufacture, greater accessibility, and extraordinary chemical tunability. This study aimed to investigate a class of organic dyes called squaraines (SQs) which are potential donor molecules in OPVs and form molecular aggregates, affecting their electronic structure and energy transfer dynamics. Spatially encoded transient absorption was used to study restructuring SQ films during thermal annealing to reveal how the extent of aggregation affects exciton dynamics. Rapid and verging on total energy transfer from the targeted excitation of monomer molecules to aggregates is observed and dynamics are replicated by a kinetic model that evolves as a function of annealing temperature and the consequent extent of aggregation. Results indicate potential exciton trapping as a consequence of rapid energy transfer to optically darker states, which could imply less effective exciton diffusion in OPVs with only partially aggregated SQ donor domains.

Increasing the Antiaromaticity of s-Indacene by Fusion of Naphthofuran

Presenter: Garret Laurie – Chemistry

Faculty Mentor(s): Gabrielle Warren

Session: (In-Person) Poster Presentation

Scientific literature has seen a dramatic increase in interesting antiaromatic structures which function as a key component within organic electronics. These molecules are novel for their inherently smaller HOMO-LUMO gap but often require protection with bulky groups or aromatic ring fusion, thereby reducing the antiaromaticity. Through heterocycle fusion at the [2,3] position of s-indacene, the antiaromaticity of the structure is increased, thereby shortening the HOMO-LUMO gap further. Our group reports the naphthofuran-fused-s-indacene which shows computational promise to not only exceed the antiaromaticity of s-indacene itself, but also the previously synthesized Haley Lab indeno[1,2b]fluorene isomers. This result is examined computationally through nucleus-independent chemical shift XY calculations and experimentally via nuclear magnetic resonance spectroscopy. Synthesis of stable antiaromatic molecules are desirable targets for providing insight on the structure, bonding, and reactivity of other highly conjugated structures.

Selective Advantage of avr-14, avr-15 and glc-1 knockout in C. elegans in High Ivermectin Conditions

Presenter:  Ellie Laufer – Chemistry

Faculty Mentor(s): Zach Stevenson, Patrick Phillips

Session: (In-Person) Poster Presentation

Lineage tracking experimentally enables highly precise measurements of fitness effects among different mutant backgrounds. The Phillips lab has pioneered the development of high-throughput lineage marking utilizing barcodes in animal systems. This has been implemented through “Transgenic Arrays Resulting in Diversity of Integrated Sequences” or T.A.D.R.I.S. The T.A.R.D.I.S. method utilizes a unique genetic feature in Caenorhabditis elegans, which is the formation of artificial chromosomes from experimentally injected dsDNA fragments. These fragments form into large megabase circular chromosomes which can be used as a ‘library’ in which to draw sequences from. The T.A.R.D.I.S. process allows us to experimentally input random nucleotides that are passed down through generations into precise, pre-defined, chromosome locations, allowing for the identification of lineages within a population. My research question focuses on measuring the individual contributions to fitness from three separate alleles associated with ivermectin resistance. Ivermectin is an anti-parasitic drug that is toxic to C. elegans and nematode parasites. Ivermectin enters through the cuticle and inhibits neuronal transmission, resulting in death in wildtype worms. Resistance to ivermectin has been associated with several genes, however, I will be focusing on three specific genes: avr-14, avr-15 and glc-1.

Nanoemulsions at the oil water interface

Presenter: Riley Cowen — Chemistry

Faculty Mentor(s): Konnor Jones

Session: (In-Person) Poster Presentation

Oil-water interfaces are present in many household products that you use daily, from cosmetics to detergents to drugs, these products change according to their interfacial properties, which can be manipulated be the choice of surfactants at the oil-water interface. A change of the interfacial properties is done in this experiment though mixing a cationic and an anionic surfactant, making the charge at the interface change depending on how much of each is added. The effective stability of these ratios will be measured using the zeta potential and the PDI taken over several weeks. This experiment is based off results found at the planar interface, where there is no charge, and the results are compared to better understand the difference between these interfaces. The solutions made for this experiment have a very small net charge, on the scale of milli molar. I will be using SDS and DTAB mixtures and varying the amount of DTAB to show the change on the charge at the interface, seeing that these surfactants are oppositely charged.

Non-Platinum Group Metal Anodic Catalysts in Anion-Exchange-Membrane Electrolysis

Presenter: Sarah Beaudoin − Chemistry

Faculty Mentor(s): Shannon Boettcher, Grace Lindquist

(In-Person) Poster Presentation 

Electrolysis, also known as water splitting, consists of two half-reactions occurring within an electrolytic cell that make possible the extraction of storable and non-pollutive hydrogen gas. Anionexchange-membrane water electrolyzers (AEMWEs) in principle operate without soluble electrolyte using earth-abundant catalysts and cell materials and thus lower the cost of green H2. However, the degradation methods of specific catalysts when used in the electrolyzer are still unclear. This study outlines the durability and activity of five commercially available non-PGM catalysts in an AEMWE system. In-situ and ex-situ characterization of each catalyst explores its electrochemical performance, conductivity, and interaction with the polymer membrane. Initial results indicate that electrical conductivity of the catalyst is a significant factor in its performance as a water oxidation catalyst in pure water. More specifically, Co3O4 catalyst nanoparticles show the greatest potential to compete with the current industry standard, IrOx, in both stability and activity. Further development of cobalt oxide catalysts, through synthesis and characterization, is required to achieve competitive durability in industrially relevant operating conditions for a pure water membrane-electrode assembly (MEA).

Theoretical Study of the Molecular Dynamics of Diubiquitin

Presenter: Kimberly Davidson, Chemistry

Poster: A-5

Mentor: Marina Guenza, Chemistry

In eukaryotic cells, polyubiquitin chains attach themselves to proteins that are ready for proteolysis. When the proteolysis pathway is disturbed, diseases such as cancer can result. This study focuses on the molecular dynamics of diubiquitin on a small time scale. Diubiquitin contains two ubiquitin chains connected by an isopeptide bond between Gly76 and Lys48. We used GROMACS to simulate the protein chain for ~10 ns with an average RMSD of ~0.2 nm. A change in RMSD was observed at ~4 ns indicating a conformational change in diubiquitin. Calculation of T1 and T2 values revealed the theoretical spin-relaxation time for each residue. Further study of diubiquitin will be useful in understanding the proteolysis pathway and how disruption can occur.

An Improved Route for the Synthesis of Phosphine Oxides Via the Alkylation of Phosphonates Through the Use of Grignard Reagents and Halide Scavengers

Presenter: Chase Salazar

Mentor: David Tyler

Oral Presentation

Major: Chemistry

An added improvement to the low-yielding reaction of phosphonates to phosphine oxides is shown. The use of a halide scavenger will increase the yield of the phosphonates to phosphine oxides alkylation from 20% to up to 95% yields by preventing a side reaction that is suggested to be caused by halides from the Grignard reagents. The large scope of substrates and excellent yields of the reaction makes it a pragmatic method for phosphine oxide synthesis as compared to the current method that requires harsh chlorination conditions with low yields. This high yielding adaptation to the alkylation of phosphonates to phosphine oxides offers a new synthetic route to the synthesis of asymmetric tertiary phosphines. Phosphines are highly used for coupling reactions in the manufacturing of pharmaceuticals and other specialty chemicals. This new proposed route is performed with bench top chemistry that has equal or higher yields to the current phosphine ligand synthesis that requires strict air-free chemistry techniques and hazardous work with pyrophoric materials. The new method allows for a simpler and safer synthetic route for phosphine ligand synthesis.

New Pt(II) Complexes for the Investigation of Copper-Mediated Degradation in Pt-Bound RNA Click Reactions

Presenter: Lindsay Guzman

Mentor: Victoria DeRose

Oral Presentation

Major: Chemistry

RNAs contribute to a wide range of essential biological processes such as protein function, catalysis, transcriptional and translational regulation. Small-molecule binders, such as the platinum(II) anticancer drug cisplatin, can be used to probe cellular RNA structures and functions. We are focusing on the functionalization of Pt complexes with azide and alkyne moieties that may allow for the subsequent purification and high-throughput sequencing of Pt-RNA adducts in the copper-catalyzed Huisgen cycloaddition (click) reaction. The click reaction involves the formation of a thermodynamically stable five-membered ring between an azide and alkyne in the presence of a Cu catalyst. Because of the reactive nature of the necessary Cu catalyst, it is speculated that Cu is facilitating observed RNA degradation in model reactions, thus lowering the efficiency and usefulness of the post-treatment click modifications. Three new Pt(II) complexes that vary in linker length from the platinum center to the copper-catalyzed click reaction site will be synthesized to probe the possible influence of click-mediated Cu recruitment on cleavage of the oligonucleotide, which will be determined by gel chromatography. This will allow for further investigation of additional and undesired copper-mediated reactivity as well as improved yield of Pt-bound RNA click reactions, which will help elucidate the biological processes of RNA.