9:00 - 9:20 am
Jason Stone
Institution: Bloomsburg University
Faculty Mentor: Matthew Polinski
The trivalent lanthanides and actinides are considered hard Lewis acids under the Pearson definition with the latter being a bit softer due to their slightly larger ionic radii. The differences in hardness between these trivalent series have been exploited for chemical separations and nuclear waste remediation purposes. However, less attention has been focused on the differences in chemical behavior of the harder trivalent lanthanides and the softer, yet less chemically stable, divalent lanthanides (Eu2+ and Yb2+). This is most likely attributed to the difficulties in preparing divalent lanthanide complexes as they are often oxidized in aerobic conditions. In order to prepare and stabilize both the divalent and trivalent lanthanides under identical aerobic conditions, it is necessary to complex the metals using a ligand that is flexible in terms of hard-soft character. The anionic squarate ligand fits this mold and is a bit softer than typical oxoanionic ligands due to its extensive delocalization, making it ideal to complex and stabilize both divalent and trivalent lanthanides. In this study, we prepared two new families of trivalent lanthanide squarates and an aerobically stable divalent Europium squarate. The divalent Europium squarate was prepared by in situ reduction of a trivalent Europium salt using a Zinc amalgam and mild solvothermal heating. These new compounds have been structurally and spectroscopically characterized. In all structures, the squarate ligands bind to the metal centers with varying, and sometimes uncommon, coordination modes and denticities. Herein, the syntheses and structures will be discussed.
9:20 - 9:40 am
Youssef Tewala
Institution: Towson University
Faculty Mentor: Mary Devadas
Nanostars have been increasingly researched due to their numerous characteristics that make branched gold nanostars invaluable assets in an array of applications ranging from sensing like surface-enhanced Raman scattering sensing to use in cancer treatments like photothermal treatment. In addition to being a great asset, nanostars are highly reproducible and require very short reaction times. Despite these benefits, gold nanostars have a short history in the field of nanotechnology; hence, scientists have not fully reaped or understood gold nanostars' benefits. More notably, few researchers have reported green syntheses of gold nanostars that are highly branched. In this project, we are presenting a green synthesis that is cheap, reproducible, and easily adaptive to different demands. Using our strong expertise in plant extracts, we can develop a green synthesis using the reducing power of polyphenols. As of now, we have successfully devised efficient polyphenol extraction methods; assayed the concentration of polyphenols, flavonoids, and anthocyanin in the extracts; created high branched nanostars; and stabilized the stars with cheap ligands in place of the very expensive ligands that is currently used in the field like mPEG thiol. Our current nanostars' synthesis is very fast, usually taking 30 seconds for the whole reaction based on a literature synthesis, and it could be easily adjusted to allow for different results in spike length, molecule diameter, and wavelength of the peak absorption. We are currently experimenting with different concentrations of polyphenols as well as using the stars for Surface Enhanced Raman Spectroscopy.
9:40 - 10:00 am
Kadie Goodin
Institution: Messiah University
Faculty Mentor: Jesse Kleingardner
Heme is an important protein cofactor that performs the transport, storage, and catalytic reduction of molecular oxygen. To create heme c, ferrochelatase inserts a central iron atom into a porphyrin ring which holocytochrome c synthase (HCCS) covalently ligates to cytochrome c. This research explores the ability of ferrochelatase and HCCS to generate cobalt-substituted heme c in vivo, creating an artificial metalloenzyme with expanded catalytic functions compared to iron-heme proteins. Cobalt concentration was increased gradually until it reached 400 μM in E. coli cells containing expressing horse cytochrome c, overexpressed K. pneumonia ferrochelatase, and variants of HCCS previously shown to enhance the production of cytochrome c with unusual sequences. Although UV-Vis spectra were consistent with cobalt-substituted heme, cation exchange purifications and inclusion body purifications were performed on the soluble lysate of several samples, but neither yielded cytochrome c. Future research will be based on the results of an in vitro testing of these same HCCS variants.
10:00 - 10:20 am
Lynn Krushinski
Institution: Towson University
Faculty Mentor: Mary Devadas
Synthesis of magnetic nanoparticles (MNPs) in a colloidal form is of pertinent interest due to their unique size dependent chemical and physical properties. This makes them suitable for a host of applications, with a primary focus being put on their use in biomedicine in this work. One specific application being magnetic hyperthermia, which involves targeted cancer cell necrosis by heat generation of MNPs placed in a localized alternating magnetic field. For magnetic hyperthermia use, there is a requirement that these MNPs have a narrow particle size distribution while maintaining high magnetization, complete biocompatibility, and ease of surface modification. Synthesis of gold-doped iron cobalt nanoparticle based ferrofluid has the potential to provide MNPs with these properties while potentially offering higher magnetization values than that demonstrated by iron oxide nanoparticles. These nanoparticles also provide the capability to be functionalized through surface modification for other chemotherapy applications, such as photodynamic therapy (PDT) and magnetic drug targeting. Details of the synthesis and charaterization will be presented.
10:20 - 10:40 am
Noah Garrett
Institution: Indiana University of Pennsylvania
Faculty Mentor: Avijita Jain
Ruthenium polypyridyl complexes have been shown to photocleave and photo bind with DNA, a unique property of photodynamic therapy agents (PDT). Incorporation of a sterically strained Ru-based chromophore to a cis-PtCl2 moiety yields complexes capable of covalently binding to DNA upon photoirradiation through Ru(II) chromophore unit along with covalent binding through cisplatin moiety. Herein we will present the design, synthesis, spectroscopic, electrochemical, and photochemical properties of a series of bimetallic complexes, including [Ru(6-Mebpy)2dppPtCl2]2+, [Ru(4,4-Me2bpy)2dppPtCl2]2+, and [Ru(6-Mebpy)2dpqPtCl2]2+(where dpp= 2,3-bis(2-pyridyl)pyrazine, dpq = 2,3-bis(2-pyridyl)quinoxaline, 4,4-Me2bpy = 4,4’-dimethyl-2,2’-bipyradine, and 6Mebpy = 6-methyl-2,2’-dipyridyl. The impact of substituent position on terminal ligand and size and structure of bridging ligands on electrochemical and photochemical properties will be discussed.
11:00 - 11:20 am
Mika Maenaga
Institution: Swarthmore College
Faculty Mentor: Chris Graves
The development of sustainable catalytic systems is a major effort in green chemistry. Expanding main group chemistry into new catalytic applications offers relatively non-toxic, sustainable, and environmentally conscious alternatives to their heavy metal counterparts. We have focused on the group 13 elements. Aluminum and gallium, though stable at the 3+ oxidation state, lack the ability to readily access multiple redox states. One way to overcome this challenge is through the addition of non-innocent or redox-active ligands. Non-innocent ligands can enable reactivity in many ways including actively participating in the forming or breaking of substrate covalent bonds. We report the O-H bond activation of various alcohols via element-ligand cooperative chemistry with aluminum and gallium tripodal tris(nitroxide) [{(2‐tBuNO)C6H4CH2}3N]3− (TriNOx3−) complexes. Experimental characterization and computational mechanistic studies will be presented on the element-ligand cooperative pathway.
11:20 - 11:40 am
Nicole Hondrogiannis
Institution: Towson University
Faculty Mentor: Mary Devadas
Gold nanoclusters are minimally toxic to the human body at ultrasmall dimensions. Their surface-area-to-volume ratio increases exponentially and this allows for gold nanoclusters to be administered in low concentrations, with an increased payload per kilogram. Monolayer protected Au25 nanoclusters (MPCs) are particularly of interest. They show extreme versatility and unique optical and electrochemical properties that differ from the bulk gold material. They are magic numbered clusters and thus show increased stability due to their closed-shell electron configuration. A limitation of Au25 MPCs is low optical absorption in the near-infrared region (NIR). Capitalizing on their NIR fluorescence allows for modification of each gold nanocluster to display enhanced fluorescence and thus an increase in quantum yield in the NIR region. NIR radiation reduces toxicity when used in biological applications. This project focuses on the modification of Au25 MPCs using chromophore ligands for applications such as enhanced biological imaging.
11:40 - 12:00 pm
Marjanii Walton
Institution: Lincoln University of PA
Faculty Mentor: Thomas Gluodenis
Cannabidiol (CBD) is a phytocannabinoid found in hemp which is commonly extracted and used in dietary supplements. CBD tincture oil is designed to be taken orally and contains the extracted CBD typically diluted in medium chain triglycerides (MCT), hemp seed or olive oil. In addition to being a source of CBD, hemp is known for its bioaccumulation properties that allow for the extraction of metals from the soil in which the plants grow. Due to this property, hemp plants have been used to decontaminate soils. This ability to accumulate metals raises questions about the concentration of potentially toxic metals in CBD based products. In this study, several CBD oils purchased from local smoke shops were screened for all metals in the periodic table using microwave digestion followed by ICP-MS analysis. Elements present at concentrations above the limit for oral permitted daily exposure were reported.
12:00 - 12:20 pm
Joseph Pantel
Institution: Ursinus College
Faculty Mentor: Amanda Reig
Many proteins that are found in nature contain metals that help perform catalytic functions. Metallohydrolases are enzymes that cleave chemical bonds using water and are responsible for important biological functions such as oxygen reduction and photosynthesis. Due Ferri single chain proteins (DFsc), a family of synthetic model proteins first used to study diiron enzymes has an active site similar to the metallohydrolases found in nature. To see if DFsc can function as a metallohydrolase, the colorimetric probe bis-(4-nitrophenyl) phosphate (BNPP) was used to monitor hydrolytic catalysis in the presence of manganese (II) and zinc (II) ions. The effect of active site mutants was also explored by comparing rates of G4DFsc to DFsc, with G4DFsc showing faster hydrolytic cleavage rates. Understanding how DFsc proteins perform hydrolysis reactions can help explain the reactivity in natural metallohydrolases, and produce new metallohydrolases that can be used in pharmaceutical and biotechnological areas.