Chemistry Commons^™

Mobile Protons Limit The Stability Of Salt Bridges In The Gas Phase: Implications For The Structures Of Electrosprayed Protein Ions., Lars Konermann, Elnaz Aliyari, Justin H Lee

Chemistry Publications

Electrosprayed protein ions can retain native-like conformations. The intramolecular contacts that stabilize these compact gas-phase structures remain poorly understood. Recent work has uncovered abundant salt bridges in electrosprayed proteins. Salt bridges are zwitterionic BH⁺/A^- contacts. The low dielectric constant in the vacuum strengthens electrostatic interactions, suggesting that salt bridges could be a key contributor to the retention of compact protein structures. A problem with this assertion is that H⁺ are mobile, such that H⁺ transfer can convert salt bridges into neutral B⁰/HA⁰ contacts. This possible salt bridge annihilation puts into question the …

Surface Functionalization Of Elastomers For Tunable Crystal Growth And Smart Adhesives, John Kapitan

Department of Chemistry: Dissertations, Theses, and Student Research

Silicone rubbers have seen extensive work on modulation of their surface environments for use in microfluidics, cell adhesion, and sensing. Most surface procedures utilize a common initial step of oxidation of the surface to increase the number of active surface functional groups. Following oxidation more permanent functionalities can be imparted on the surface using silanization, grafting polymer brushes, or creating ionic bonds to the surface. Of these three, silanization proves to be the most pervasive due to the range of procedures available and how easy the procedures prove to be. However, the mechanism by which silanization is performed heavily involves …

Sf6+: Stabilizing Transient Ions In Helium Nanodroplets, Simon Albertini, Stefan Bergmeister, Felix Laimer, Paul Martini, Elisabeth Gruber, Fabio Zappa, Milan Ončák, Paul Scheier, Olof E. Echt

Faculty Publications

There are myriads of ions that are deemed too short-lived to be experimentally accessible. One of them is SF₆⁺. It has never been observed, although not for lack of trying. We demonstrate that long-lived SF₆⁺ can be formed by doping charged helium nanodroplets (HNDs) with sulfur hexafluoride; excess helium is then gently stripped from the doped HNDs by collisions with helium gas. The ion is identified by high-resolution mass spectrometry (resolution m/Dm = 15000), the close agreement between the expected and observed yield of ions that contain minor sulfur isotopes, and collision-induced dissociation …

Parallel Computation Of Feynman Path Integrals And Many-Body Polarization With Application To Metal-Organic Materials, Brant H. Tudor

USF Tampa Graduate Theses and Dissertations

The Space Research Group is a computational outfit, and so the work presented herein will reflect that. Much of our simulation code is developed in-house and so what follows is a small exploration of that development—although the physics underpinning our software development is never ignored for long. Following the programming centric work, the code and the physics are put to the test. The final chapter describes a scientific endeavor in which a new, robust force field has been validated. Indeed, the new potential has taken a first step in proving itself by making accurate predictions in what have historically found …

The Interconnectivity Of Parkinson's Disease And Type Two Diabetes Mellitus, Erica Olfson

Honors Scholars Collaborative Projects

This thesis is about the biochemical connection between Parkinson's disease and Type II Diabetes Mellitus.

A Divergent Strategy For The Synthesis Of Redox-Active Verdazyl Radical Polymers, Francois Magnan, Jasveer S. Dhindsa, Michael Anghel, Paul Bazylweski, Giovanni Fanchini, Joe Gilroy

Chemistry Publications

Stable radical polymers have attracted significant attention due to their use as magnetic materials, (co)catalysts in organic synthesis, and as functional components of organic electronics including batteries and memory devices. Despite their importance, a relatively narrow range of synthetic strategies exist for their production. The most common examples involve the transition-metal catalyzed polymerization of radical-containing monomers or the sequential polymerization of monomers containing radical precursors and their post-polymerization conversion to radicals. Post-polymerization installation of stable radicals is not commonly reported. Copper-assisted azide-alkyne cycloaddition (CuAAC) chemistry has seen limited use in this regard, but only for the production of p-conjugated and …

Suppressing Bias Stress Degradation In High Performance Solution Processed Organic Transistors Operating In Air, Hamna F. Iqbal, Qianxiang Ai, Karl J. Thorley, Hu Chen, Iain Mcculloch, Chad Risko, John E. Anthony, Oana D. Jurchescu

Chemistry Faculty Publications

Solution processed organic field effect transistors can become ubiquitous in flexible optoelectronics. While progress in material and device design has been astonishing, low environmental and operational stabilities remain longstanding problems obstructing their immediate deployment in real world applications. Here, we introduce a strategy to identify the most probable and severe degradation pathways in organic transistors and then implement a method to eliminate the main sources of instabilities. Real time monitoring of the energetic distribution and transformation of electronic trap states during device operation, in conjunction with simulations, revealed the nature of traps responsible for performance degradation. With this information, we …

Co-Evolutionary Analysis Suggests A Role For Tlr9 In Papillomavirus Restriction, Kelly King, Brendan B. Larsen, Sophie Gryseeis, Cécile Richet, Simona Kraberger, Robert Jackson, Michael Worobey, Joseph S. Harrison, Arvind Varsani, Koenraad Van Doorslaer

College of the Pacific Faculty Articles

Upon infection, DNA viruses can be sensed by pattern recognition receptors (PRRs) leading to the activation of type I and III interferons, aimed at blocking infection. Therefore, viruses must inhibit these signaling pathways, avoid being detected, or both. Papillomavirus virions are trafficked from early endosomes to the Golgi apparatus and wait for the onset of mitosis to complete nuclear entry. This unique subcellular trafficking strategy avoids detection by cytoplasmic PRRs, a property that may contribute to establishment of infection. However, as the capsid uncoats within acidic endosomal compartments, the viral DNA may be exposed to detection by toll-like receptor (TLR) …

Fluorogenic Probes For Thioredoxin Reductase Activity, Tendai J. Mafireyi, Jorge O. Escobedo, Robert Strongin

Chemistry Faculty Publications and Presentations

The thioredoxin system is vital in maintaining the cellular redox state and is implicated in various cancers and other diseases. It comprises of thioredoxin reductase, thioredoxin and NADPH. Various methods have been developed for the detection and quantification of the thioredoxin reductase enzyme. Most of these methods suffer the shortfall of poor specificity, hence there is need to develop more robust and specific techniques. Recently, there has been an increased interest in fluorescent probes that can target thioredoxin reductase. This review highlights the progress in the synthesis and application of the different fluorescent probes that have been employed for this …

Studies Of The Rectification Behavior Of The Pdt Ligand And The Active Site Of Msrp, Laura J. Ingersol

Chemistry and Chemical Biology ETDs

Molybdenum (Mo) is an essential element that plays an important role in global nitrogen, carbon, and sulfur cycles with a critical role in human metabolism and ecological balance. It becomes catalytically active when complexed with the pyranopterin dithiolene ligand (PDT), forming the nearly ubiquitous molybdenum cofactor (Moco). The complex biosynthetic pathway of Moco, its presence in all three domains of life, and its role as a constituent cofactor in the last universal common ancestor (LUCA) all point toward the importance of the PDT in the development of life on Earth. Molybdoenzymes catalyze the two-electron oxidation or reduction of substrates that …

Direct Detection Of 5-Mev Protons By Flexible Organic Thin-Film Devices, Ilaria Fratelli, Andrea Ciavatti, Enrico Zanazzi, Laura Basiricò, Massimo Chiari, Laura Fabbri, John E. Anthony, Alberto Quaranta, Beatrice Fraboni

Chemistry Faculty Publications

The direct detection of 5-MeV protons by flexible organic detectors based on thin films is here demonstrated. The organic devices act as a solid-state detector, in which the energy released by the protons within the active layer of the sensor is converted into an electrical current. These sensors can quantitatively and reliably measure the dose of protons impinging on the sensor both in real time and in integration mode. This study shows how to detect and exploit the energy absorbed both by the organic semiconducting layer and by the plastic substrate, allowing to extrapolate information on the present and past …

Inhibiting Nitroso Related Methylation Of Guanine Using Dietary Supplements And Flavonoids, Madeline Mccoy, James Davis, Chloe Rippey, Stephen Hobson

Liberty University Research Week

Undergraduate

Basic

Raising Global Awareness And Internationality In The Undergraduate Organic Chemistry Laboratory, Marissa Scilley, Michael R. Korn

Liberty University Research Week

Undergraduate

Applied

Acid Catalyzed Small Ring Alcohols And Alkenes: An Artistic Approach To Visualizing Relationships Between Features Produced By Uv-Visible Spectra, Madeleine Ware

Campus Research Month

Madeleine Ware

Research Description

Campus Research Day

My physical organic chemistry research was supervised by Dr. Mitch Menzmer who studies the formation of carbocation intermediates in acid-catalyzed reactions of alkylated and non-alkylated small ring alcohols. The goal of my work was to compile data and develop methods to search for relationships between the initial structures of molecules analyzed and the wavelengths of maximum absorbance for features observed within a given spectrum. In addition, my advisor from the School of Visual Art and Design, Associate Professor Marc Boyson, contributed to this process by providing insights about the way information could be …

Polyesters Based On Aspartic Acid And Poly(Ethylene Glycol): Functional Polymers For Hydrogel Preparation, Trent N. Gordon, Anna Kornmuller, Yashveer Soni, Lauren E. Flynn, Elizabeth R. Gillies

Chemistry Publications

Hydrogels are commonly used as scaffolds for the preparation of three-dimensional tissue constructs and for the encapsulation and delivery of cells in regenerative medicine. Polyesters are an attractive class of polymers for hydrogel preparation. However, most polyesters have hydrophobic backbones and lack pendent groups that can be chemically functionalized. We describe here the development of water-soluble polyesters based on aspartic acid and poly(ethylene glycol) (PEG) (600 or 1500 g/mol), having pendent reactive amines. The reactivity of these amines with methacrylic anhydride, maleic anhydride, and itaconic anhydride was explored for the introduction of crosslinkable groups. The resulting methacrylamide-functionalized polymers were successfully …

Pueraria Montana Peroxidase Activity, Kathryn Briley, Gregory Raner

Liberty University Research Week

Undergraduate

Basic

Anion Removal By Partially Positive Adsorbents, Breanna Dragseth, Matt Desmith, Emily Robinson, Abi Bartlett

Undergraduate Research Symposium 2021

Nitrates and phosphates exist naturally but are present in elevated concentrations in many areas primarily due to agriculture; these elevated concentrations are concerning for human and environmental health. The project considered the ability of four different materials used for adsorption (adsorbents) to adsorb nitrate and phosphate. All adsorbents had a silica base with an amine (NH2) group and were further functionalized with different ligands consisting of an aromatic ring functionalized with electron withdrawing groups, creating a partial positive environment to help attract the anions of interest. We also synthesized control materials to determine how effective our engineered materials are. The …

Synthesis Of Transfer Hydrogenation Catalysts Containing Unsymmetrical Bisphosphines, Nora Fritz

Undergraduate Research Symposium 2021

Asymmetric catalysis, where a metal catalyst is used to transform a substrate into a single enantiomer of product, has become a popular synthetic technique in both academic and industrial settings. An enantiomer is a single molecule with a unique three-dimensional shape with a mirror image not superimposable on the original. The chirality, or right or left-handedness, of compounds lead to applications important in the pharmaceutical and agrochemical industries. Commonly, a metal complex’s ability to create a product of a certain enantiomer relies on a chiral group being attached to the metal. However, having the chirality of a metal complex depend …

Co2 Capturing Materials, Isaac Sanchez

Undergraduate Research Symposium 2021

Greenhouse gas emissions are one of, if not the major cause of global warming. With CO₂ emissions rising annually, it is paramount to selectively capture and remove CO₂ from flue gas. One method of capturing CO₂ gas is via porous materials. Covalent organic frameworks (COFs) are porous materials which have been explored throughout this research. Two important features of COFs are the base unit linkage types (BULTs) and the functional groups attached to the organic linkers (OLs). The BULT used in this research was a covalent triazine framework (CTF) and the main functional group used in the …

Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition By Dynamic Kinetic Resolution, En Chih Liu, Joseph J. Topczewski

Chemistry Faculty Research & Creative Works

The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC …

Can CP Be Less Than CV?, Yingbin Ge, Samuel L. Montgomery, Gabriel L. Borrello

All Faculty Scholarship for the College of the Sciences

Can C_P be less than C_V? This is a fundamental question in physics, chemistry, chemical engineering, and mechanical engineering. This question hangs in the minds of many students, instructors, and researchers. The first instinct is to answer “Yes, for water between 0 and 4 °C” if one knows that water expands as temperature decreases in this temperature range. The same question is asked in several Physical Chemistry and Physics textbooks. Students are supposed to answer that water contracts when heated at below 4 °C in an isobaric process. Because work is done to the contracting water, less …

Preparation Of Perylene Bisimide Acceptors With Ethylcarboxyl And Pyrenylcyclohexyl Imide Groups, Michael Cashen Stark

Honors Theses

Multiple attempts were made to deprotect TBDMS-protected (tert-butyldimethylsilyl protected) serinol and swallowtailed PBI (Compound 2), synthesized by past researcher Tarrah Frederick, to generate Compound 1. The theoretical Compound 1 product is intended for use in molecular rectification of electricity because the perylene core acts as a good acceptor with high electron affinity, and it does not require an electron donor group. Many rectification molecules are amphiphilic Donor-σ-Acceptor compounds, which allow for electron transfer through localized molecular orbitals when placed between electrodes (Langmuir-Blodgett Method). However, PBIs can transfer electrons from one electrode, through the LUMO of perylene, and to the other …

Engineering Donor-Acceptor Conjugated Polymers For High-Performance And Fast-Response Organic Electrochemical Transistors, Hanyu Jia, Zhen Huang, Peiyun Li, Song Zhang, Yunfei Wang, Jie Yu Wang, Xiaodan Gu, Ting Lei

Faculty Publications

To date, high-performance organic electrochemical transistors (OECTs) have mostly been based on polythiophene systems. Donor–acceptor (D–A) conjugated polymers are expected to be promising materials for OECTs owing to their high mobility and comparatively low crystallinity (good for ion diffusion). However, the OECT performance of D–A polymers lags far behind that of the polythiophenes. Here we synergistically engineered the backbone and side chain of a series of diketopyrrolopyrrole (DPP)-based D–A polymers and found that redox potential, molecular weight, solution processability, and film microstructures all have a severe impact on their performance. After systematic engineering, P(bgDPP-MeOT2) exhibited the best figure-of-merit (μC …

Comparison Of Methods For Measuring Cation Exchange Capacity In Clays, Sarah Glaesemann

Undergraduate Research Conference

No abstract provided.

Study Of Potential Drug For Alzheimer’S Disease: Small Organic Molecules, 1,5-Dhn And Tmpyp Inhibit Amyloid-Β Peptide Aggregation And Quench Hydroxyl Radicals, Matthew Murphy

Undergraduate Research Conference

Alzheimer disease (AD) is recognized as the six leading cause of the death in the United States. As of now, there is no cure for this fatal disease. The current treatment methods can only temporarily slow the worsening of symptoms. Research data suggested that an excess generation of hydroxyl radical in the brain causing the aggregation of Amyloid-β (Aβ) peptide which is considered to be responsible for Alzheimer's disease. Thus, there is a pressing need to find a suitable drug which can quench hydroxyl radicals effectively and stop or slow down the formation of aggregation of Aβ peptide. The primary …

A Novel Molecular And Cellular Study On Curcumin, Khang Nguyen

Undergraduate Research Conference

Since the discovery of G-quartet (G4)by M. Gellertin 1962, much attention has been given on G4and C4(also called i-motif) as important drug design targets for the treatment of various human disorders. G4 forming sequences are prevalent in human genome, which includes many important regions of the eukaryotic genome, such as telomere ends, regulatory regions of many oncogenes c-kit, proto-oncogene c-myc, Kirsten rat sarcoma viral oncogene homolog (KRas). Curcumin(diferuloylmethane), an antiinflammatory and antioxidant compound, is found in the rhizomes of the plant Curcuma longa. The phytopolyphenolic chemical curcumin has been in the prominence due to its diverse pharmacological activities. Here, we …

Biotransformation Of Hbe And Other Benzofuran Derivatives, Hannah Trauger

Undergraduate Research Conference

No abstract provided.

Synthesis Of Phosphindolizine, Tyler Bell

Campus Research Month

Synthesis of Phosphindolizine which hasn't been done before.

Deletion Of Ph Response Genes In Cryptococcus Neoformans, Hannah Finson, Michael S. Price

Liberty University Research Week

Undergraduate

Basic

Greening Of Ferrocene Column Chromatography, Marissa Scilley, Anderson Hill, Michael R. Korn

Liberty University Research Week

Undergraduate

Basic