Chemistry Commons^™

Investigating Evidence In Support Of Validity And Reliability For Data Collected With The Meaningful Learning In The Laboratory Instrument (Mlli), Elizabeth Vaughan, A. Montoya-Cowan, Jack Barbera

Chemistry Faculty Publications and Presentations

The Meaningful Learning in the Laboratory Instrument (MLLI) was designed to measure students’ expectations before and after their laboratory courses and experiences. Although the MLLI has been used in various studies and laboratory environments to investigate students’ cognitive and affective laboratory expectations, the authors of the instrument reported a discrepancy between the intended factor structure of the MLLI and the factor structure suggested by the data collected in preliminary studies. Therefore, the aim of this study was to investigate the validity and reliability evidence related to data collected with the MLLI, especially that related to structural validity. Evidence to support …

Electrochemical Hydrogen Gas Production And Carbon Dioxide Sequestration Via In Situ Formation Of Nickel (Ii) Tris-(Pyridinethiolate) Derivatives, Dayalis Sv. Brown

Dissertations and Theses

In the research presented, we use electrochemical techniques, such as cyclic voltammetry and controlled potential electrolysis, to study in situ formation of hydrogen evolution catalysts which also reduce carbon dioxide. Using pyridinethiol-based ligands and a nickel (II) precursor, both homo- and heteroleptic complexes were investigated as catalysts to produce alternative fuels while mitigating greenhouse gas emissions. Existing synthetic procedures to obtain these Ni(II) catalysts lead to low yields of the complexes and difficulties in crystallizing samples for further analysis, limiting sample size and restricting the number of studies. While current research is heavily focused on photochemically-driven experiments, given that solar …

Developing A Sample-Efficient Analytical Pathway For A Qualitative Chemical Investigation Of Ancestral Chilkat Dyeing And Weaving Practices, Dario Gerlando Durastanti

Dissertations and Theses

The project goal is to identify the dyestuffs used in hand-woven Chilkat blankets from the collection of the Alaska State Museum and the Sheldon Jackson Museum. Chilkat weaving is practiced by Northwest coastal clans, particularly in Southeast Alaska since at least the early 19th century. Through this collaboration, 117 wool fibers from 23 Chilkat textiles, and 193 reference samples consisting of dyed fibers using both natural and synthetic dye sources, raw dye material, and dye bath aliquots were provided to the lab for reference characterization and identification. In these analyses, dyes were classified as being either natural or synthetic, subdivided …

Studies On Bonding, Syntheses, And Applications Of Diarylhalonium Compounds, Shubhendu Karandikar

Dissertations and Theses

Organic compounds containing functionalized benzenoid rings have found tremendous applications in pharmaceuticals, agrochemicals, commodity chemicals, and beyond. As a result, development of methods for the synthesis of functionalized benzenoid rings has gained much attention from the synthetic community. Although many transition-metal mediated methods to functionalize benzenoid rings are known, there has been an upsurge of activity in developing protocols for decoration of benzenoid cores promoted by p-block elements. This excitement stems from the sustainability of earth-abundant elements and unique reactivity patterns observed within the p-block. Among these, transformations promoted by hypervalent halogen compounds, and especially, the diarylhalonium salts are very …

7-Deazaguanines In Dna: Functional And Structural Elucidation Of A Dna Modification System, Samanthi Herath Gedara, Andrew Gustafson, Dirk Iwata-Reuyl, Multiple Additional Authors

Chemistry Faculty Publications and Presentations

The modified nucleosides 2′-deoxy-7-cyano- and 2′-deoxy-7-amido-7-deazaguanosine (dPreQ₀ and dADG, respectively) recently discovered in DNA are the products of the bacterial queuosine tRNA modification pathway and the dpd gene cluster, the latter of which encodes proteins that comprise the elaborate Dpd restriction–modification system present in diverse bacteria. Recent genetic studies implicated the dpdA, dpdB and dpdC genes as encoding proteins necessary for DNA modification, with dpdD–dpdK contributing to the restriction phenotype. Here we report the in vitro reconstitution of the Dpd modification machinery from Salmonella enterica serovar Montevideo, the elucidation of the roles of each protein and the X-ray …

Nanoscale Hafnium Metal-Organic Frameworks Enhance Radiotherapeutic Effects By Upregulation Of Type I Interferon And Tlr7 Expression, Eunseo Choi, Madeleine R. Landry, Nathan Pennock, Katherine Weinfurter, Multiple Additional Authors

Chemistry Faculty Publications and Presentations

Recent preclinical and clinical studies have highlighted the improved outcomes of combination radiotherapy and immunotherapy. Concurrently, the development of high-Z metallic nanoparticles as radiation dose enhancers has been explored to widen the therapeutic window of radiotherapy and potentially enhance immune activation. In this study, we evaluate folate-modified hafnium-based metal-organic frameworks (HfMOF-PEG-FA) in combination with imiquimod, a TLR7 agonist, as a well-defined interferon regulatory factor (IRF) stimulator for local antitumor immunotherapy. The enhancement of radiation dose deposition by HfMOF-PEG-FA and subsequent generation of reactive oxygen species (ROS) deregulates cell proliferation and increases apoptosis. HfMOF-PEG-FA loaded with imiquimod (HfMOF-PEG-FA@IMQ) increases DNA double-strand …

Chemical Elements, Flavor Chemicals, And Nicotine In Unused And Used Electronic Cigarettes Aged 5–10 Years And Effects Of Ph, Monique Williams, Wentai Luo, Kevin J. Mcwhirter, Omeka Ikegbu, Prue Talbot

Chemistry Faculty Publications and Presentations

The concentrations of elements/metals, nicotine, flavor chemicals and acids were compared in the e-liquids of unused and used first-generation electronic cigarettes (ECs) that were stored for 5–10 years. Metal analysis was performed using inductively coupled plasma optical emission spectroscopy; nicotine and flavor chemical analyses were performed using gas chromatography/mass spectroscopy. Of the 22 elements analyzed, 10 (aluminum, chromium, copper, iron, lead, nickel, selenium, silicon, tin, zinc) were often found in the e-liquids. Five elements had the highest average concentrations: copper (1161.6 mg/L), zinc (295.8 mg/L), tin (287.6 mg/L), nickel (71.1 mg/L), and lead (50.3 mg/L). Nicotine concentrations were always lower …

A First-Tier Framework For Assessing Toxicological Risk From Vaporized Cannabis Concentrates, Shawna Vreeke, David M. Faulkner, Robert Strongin, Echoleah Rufer

Chemistry Faculty Publications and Presentations

Vaporization is an increasingly prevalent means to consume cannabis, but there is little guidance for manufacturers or regulators to evaluate additive safety. This paper presents a first-tier framework for regulators and cannabis manufacturers without significant toxicological expertise to conduct risk assessments and prioritize additives in cannabis concentrates for acceptance, elimination, or further evaluation. Cannabinoids and contaminants (e.g., solvents, pesticides, etc.) are excluded from this framework because of the complexity involved in their assessment; theirs would not be a first-tier toxicological assessment. Further, several U.S. state regulators have provided guidance for major cannabinoids and contaminants. Toxicological risk assessment of cannabis concentrate …

Enlarging The Stokes Shift By Weakening The Π-Conjugation Of Cyanines For High Signal-To-Noise Ratiometric Imaging, Yongkang Yue, Tingting Zhao, Zhou Xu, Weijie Chi, Xiaojun Chai, Jiahong Ai, Jiawei Zhang, Fangjun Huo, Robert M. Strongin, Caixia Yin

Chemistry Faculty Publications and Presentations

The signal-to-noise ratio (SNR) is one of the key features of a fluorescent probe and one that often defines its potential utility for in vivo labeling and analyte detection applications. Here, it is reported that introducing a pyridine group into traditional cyanine-7 dyes in an asymmetric manner provides a series of tunable NIR fluorescent dyes (Cy-Mu-7) characterized by enhanced Stokes shifts (≈230 nm) compared to the parent cyanine 7 dye (nm). The observed Stokes shift increase is ascribed to symmetry breaking of the Cy-Mu-7 core and a reduction in the extent of conjugation. The fluorescence signals of the Cy-Mu-7 dyes …

Investigating Small-Group Cognitive Engagement In General Chemistry Learning Activities Using Qualitative Content Analysis And The Icap Framework, Safaa Y. El-Mansy, Jack Barbera, Alissa J. Hartig

Chemistry Faculty Publications and Presentations

The level of students’ engagement during active learning activities conducted in small groups is important to understanding the effectiveness of these activities. The Interactive–Constructive–Active–Passive (ICAP) framework is a way to determine the cognitive engagement of these groups by analyzing the conversations that occur while student groups work on an activity. This study used qualitative content analysis and ICAP to investigate cognitive engagement during group activities in a General Chemistry course at the question level, a finer grain size than previously studied. The analysis determined the expected engagement based on question design and the observed engagement based on group conversations. Comparisons …

Chemical Interactions And Cytotoxicity Of Terpene And Diluent Vaping Ingredients, Yanira Baldovinos, Alexandra Archer, James C. Salamanca, Robert M. Strongin, Christie Sayes

Chemistry Faculty Publications and Presentations

Vaping devices have risen in popularity since their inception in 2007. The practice involves using a variety of commercially available devices. Internal heating systems in devices aerosolize e-liquid formulations of complex mixtures including an active ingredient (e.g., THC, CBD, and nicotine), diluents (or cutting agents), solvents, and flavoring agents (e.g., terpenes and aldehydes). The vaping toxicology literature consists of cytotoxicity studies of individual chemicals and commercial formulas. Because of the variation of e-liquid composition, there is a limited understanding of the toxicity of ingredient combinations. This study analyzed the cytotoxic effects after exposure to individual and binary mixtures of a …

Computational Investigation Into Heteroleptic Photoredox Catalysts Based On Nickel(Ii) Tris-Pyridinethiolate For Water Splitting Reactions, Avik Bhattacharjee, Dayalis S.V. Brown, Trent E. Ethridge, Kristine M. Halvorsen, Alejandra C. Acevedo Montano, Theresa M. Mccormick

Chemistry Faculty Publications and Presentations

This work demonstrates a strategy to fine-tune the efficiency of a photoredox water splitting Ni(II) tris-pyridinethiolate catalyst through heteroleptic ligand design using computational investigation of the catalytic mechanism. Density functional theory (DFT) calculations, supported by topology analyses using quantum theory of atoms in molecules (QTAIM), show that the introduction of electron donating (ED) −CH3 and electron withdrawing (EW) −CF₃ groups on the thiopyridyl (PyS–) ligands of the same complex can tune the pK_a and E0, simultaneously. Computational modeling of two heteroleptic nickel(II) tris-pyridinethiolate complexes with 2:1 and 1:2 ED and EW −CH₃ and −CF_{3 …}

Nmr Analyses Of Flavored E-Cigarette Liquids Before And After Aerosolization, Paul Joseph Kerber

Dissertations and Theses

Electronic cigarettes (e-cigarettes) are the most commonly used tobacco products among adolescents with ~11 and ~3% of high school and middle school students reporting past 30 day use in 2021 according to the Centers for Disease Control and Prevention (CDC), respectively. Furthermore, greater than ~80% of high school and middle school e-cigarette consumers use flavored e-liquids. Consumers can be exposed to variable toxicant levels upon e-liquid aerosolization, depending on the composition of the e-liquid, type of e-cigarette, e-cigarette settings, and other customizations.

E-liquids are typically composed of a carrier solvent (propylene glycol (PG) and glycerol (GL)), flavorants, and nicotine. PG …

Improved Photodecarboxylation Properties In Zinc Photocages Constructed Using M‐Nitrophenylacetic Acid Variants, Austin K. Shigemoto, Avik Bhattacharjee, Erin E. Hickey, Hallee Jade Boyd, Theresa M. Mccormick, Shawn C. Burdette

Chemistry Faculty Publications and Presentations

The methoxy- and fluoro-derivatives of meta-nitrophenylacetic acid (mNPA) chromophores undergo photodecarboxylation with comparable quantum yields to unsubstituted mNPA, but uncage at red-shifted excitation wavelengths. This observation prompted us to investigate DPAdeCageOMe (2-[bis(pyridin-2-ylmethyl)amino]-2-(4-methoxy-3-nitrophenyl)acetic acid) and DPAdeCageF (2-[bis(pyridin-2-ylmethyl)amino]-2-(4-fluoro-3-nitrophenyl)acetic acid) as Zn2+ photocages. DPAdeCageOMe has a high quantum yield and exhibits other photophysical properties comparable to XDPAdeCage ({bis[(2-pyridyl)methyl]amino}(9-oxo-2-xanthenyl) acetic acid), the best perforiming Zn2+ photocage reported to date. Since the synthesis of DPAdeCageOMe is more straightforward than XDPACage, the new photocage will be a highly competitive tool for biological applications.

Exploring Structure-Function Relationship In Small-Molecular Catalysts Using Computational And Experimental Methodologies, Avik Bhattacharjee

Dissertations and Theses

Molecular modeling is a useful tool in the field of catalyst design for various processes. The use of Density Functional Theory (DFT) is routine in almost every discipline of chemistry. This allows for a deeper understanding of a molecular system even in situations where implementation of an experimental technique is unfeasible. However, without the right choice of theory and insufficient description, the model becomes susceptible to produce ambiguous results. This often leads to poor correlation with experimental findings hence an incomplete understanding of the system under study. Hence, to acquire a thorough knowledge of the intricacies involved in a system, …

A Multi‑Analytical Approach To Identify Red Colorants On Woodblock Prints Attributed To Suzuki Harunobu, Lyndsay Nichole Kissell, Trine K. Quady, Dario Durastanti, Samantha Springer, Jeannie Kenmotsu, Tami Lasseter Clare

Chemistry Faculty Publications and Presentations

Red organic dye identification is an important topic for conservation of Japanese ukiyo-e prints. Of particular interest are the works of Suzuki Harunobu, who was working at the inception of full-color printmaking. These prints were made on thin kōzo paper and woodblock printed with semi-transparent to opaque regions of dye(s) and/ or pigment(s) mixed with binder. This study used imaging analysis, X-ray fluorescence (XRF), Raman, and surfaceenhanced Raman spectroscopies (SERS) to identify the red dyes and pigments on Harunobu prints in the collection of the Portland Art Museum. Through image analysis (visible, UV, and IR illuminations), 23 prints were categorized …

Detection And Quantification Of Arsenic Pollution With A Moss Bio-Indicator And Icp-Ms, Erin R. Bowey

University Honors Theses

Heavy metal pollution is a recognized concern with an established source of anthropogenic activity, which is ever-increasing. While work has been done to make the monitoring of some metals more accessible, resourceful, and efficient with the use of epiphytic moss as a bio-indicator, this method has not been optimized for the detection of arsenic. Previously used analytical instrumentation has not proven sensitive enough to reliably detect arsenic, creating a gap in the monitoring process. However, inductively coupled plasma mass spectrometry (ICP-MS) is proposed as the solution to fill this gap. Its potential for low limits of detection and quantification express …

Investigating Student Engagement In General Chemistry Active Learning Activities Using The Activity Engagement Survey (Aces), Nicole Naibert, Jack Barbera

Chemistry Faculty Publications and Presentations

Investigating student engagement in active learning activities could provide valuable insight into variations of student learning outcomes when active learning is included in a course. This study sought to explore students’ engagement in relation to active learning activities incorporated in a general chemistry lecture course using the Activity Engagement Survey (AcES). The AcES can be used to simultaneously assess students’ overall engagement, as well as dimensions above and beyond overall engagement including their combined behavioral/cognitive engagement, emotional engagement, and social engagement. As students’ engagement may be influenced by aspects related to the learning environment and context, differences in engagement were …

The Hyperporphyrin Concept: A Contemporary Perspective, Carl C. Wamser, Abhik Ghosh

Chemistry Faculty Publications and Presentations

The Gouterman four-orbital model conceptualizes porphyrin UV–visible spectra as dominated by four frontier molecular orbitals─two nearly degenerate HOMOs and two exactly degenerate LUMOS under D4h symmetry. These are well separated from all the other molecular orbitals, and normal spectra involve transitions among these MOs. Unusual spectra occur when additional orbitals appear in this energy range, typically as a consequence of the central coordinated atom. For example, metals with empty d orbitals in a suitable energy range may lead to charge transfer from porphyrin (ligand) to metal, that is, so-called LMCT transitions. Metals with filled p or d orbitals may …

Development Of The Chemistry Mindset Instrument (Chemi) For Use With Introductory Undergraduate Chemistry Students, Deborah L. Santos, Jack Barbera, Suazette R. Mooring

Chemistry Faculty Publications and Presentations

Chemistry education research has increasingly considered the role of affect when investigating chemistry learning environments over the past decade. Despite its popularity in educational spheres, mindset has been understudied from a chemistry-specific perspective. Mindset encompasses one's beliefs about the ability to change intelligence with effort and has been shown to be a domain-specific construct. For this reason, students’ mindset would be most relevant in chemistry if it were measured as a chemistry-specific construct. To date, no instrument has been developed for use in chemistry learning contexts. Here we present evidence supporting the development process and final product of a mindset …

Synthesis Of Diaryl And Alkyl-Aryl Ethers Via Diaryl Iodonium Reagents, Rory Tennessee Gallagher

Dissertations and Theses

Substituted benzenoid rings are a prevalent motif in many industries including high tech, agrochemicals, and pharmaceuticals. As a result, the arylation of chemical compounds is a highly sought-after chemical transformation. There are many literature methods to achieve this chemical transformation, nucleophilic aromatic substitution and transition metal catalysis are both widely used and studied. Diaryliodonium salt mediated chemistry is an attractive alternative to these methods as it does not require the expensive toxic metals and designer ligands of transition metal catalysis and is not restricted to electron deficient aryl rings with specific substitution patterns like nucleophilic aromatic substitution.

Many diaryliodonium salt …

Orbital Analysis Of Bonding In Diarylhalonium Salts And Relevance To Periodic Trends In Structure And Reactivity, Shubhendu S. Karandikar, Avik Bhattacharjee, Bryan Metze, Nicole Javaly, Edward J. Valente, Theresa M. Mccormick, David R. Stuart

Chemistry Faculty Publications and Presentations

Diarylhalonium compounds provide new opportunities as reagents and catalysts in the field of organic synthesis. The three center, four electron (3c–4e) bond is a center piece of their reactivity, but structural variation among the diarylhaloniums, and in comparison with other λ3-iodanes, indicates that the model needs refinement for broader applicability. We use a combination of Density Functional Theory (DFT), Natural Bond Orbital (NBO) Theory, and X-ray structure data to correlate bonding and structure for a λ3-iodane and a series of diarylchloronium, bromonium, and iodonium salts, and their isoelectronic diarylchalcogen counterparts. This analysis reveals that the s-orbital on the central halogen …

Simple Arenes As Aryne Synthetic Equivalents Via Sulfonium Salt Intermediates, Riley A. Roberts

Student Research Symposium

Arynes are ephemeral molecules that are yet to be fully exploited in synthetic strategy because they are often challenging to access. These reactive intermediates participate in a myriad of reactions that conventional chemistry is incapable of, making them extremely useful for the synthesis of important molecules like pharmaceuticals and agrochemicals. While classical approaches for synthesizing arynes employ cheap starting material, extremely harsh reagents are necessary to generate the aryne. In contrast, methods that do not require harsh reaction conditions do require starting material that is exceedingly difficult to synthesize. To access arynes quickly and efficiently, the work described herein aims …

Comparison Of Heavy Metals In Spinach Grown On The Roof Ground Location At Portland State University, Tyler A. Robin

Student Research Symposium

As a result of urbanization, fresh, healthy food can be expensive and easily contaminated but space for local farming is limited. Roofs can be underutilized in densely populated cities and can offer a space for local fresh farming. The purpose of this study is to continue a previous study done in 2021, to find if growing leafy vegetables on the roof can limit heavy metal exposure from air pollutants. This study compares spinach grown on the roof in 2021, 2019 and spinach bought from stores around the Portland State University campus and the heavy metals found in these greens. The …

Computational Investigation Of The Mechanism Of An Octahedral Ni(Ii) Proton Reduction Catalyst And Importance Of Intramolecular Hydrogen Bonding, Avik Bhattacharjee, Dayalis S.V. Brown, Carolyn N. Virca, Trent E. Ethridge, Oreana Mendez Galue, Uyen T. Pham, Theresa M. Mccormick

Student Research Symposium

Water-splitting to make hydrogen gas is of extreme importance in the field of alternative energy research. Transition-metal complexes are capable of catalyzing the conversion of water to hydrogen at higher pH, with low overpotential. Our research focuses on the importance of intramolecular hydrogen bonding (H-bonding) on the pKa and thermodynamic stability of the catalytic intermediates of a well-known proton-reduction catalyst, nickel (II) tris-pyridinethiolate. Density Functional Theory (DFT) calculations on the parent catalyst and eleven derivatives demonstrate geometric isomer formation after the protonation step of catalysis. These isomers differ in the relative thermodynamic stabilities and pKa values, which can be attributed …

Continuum Dynamics And Statistical Correction Of Compositional Heterogeneity In Multivalent Idp Oligomers Resolved By Single-Particle Em, Barmak Mostofian, Russell Mcfarland, Aiden Estelle, Jesse Howe, Elisar J. Barbar, Steve L. Reichow, Daniel M. Zuckerman

Chemistry Faculty Publications and Presentations

Multivalent intrinsically disordered protein (IDP) complexes are prevalent in biology and act in regulation of diverse processes, including transcription, signaling events, and the assembly and disassembly of complex macromolecular architectures. These systems pose significant challenges to structural investigation, due to continuum dynamics imparted by the IDP and compositional heterogeneity resulting from characteristic low-affinity interactions. Here, we developed a modular pipeline for automated single-particle electron microscopy (EM) distribution analysis of common but relatively understudied semi-ordered systems: 'beads-on-a-string' assemblies, composed of IDPs bound at multivalent sites to the ubiquitous ∼20kDacross-linking hub protein LC8. This approach quantifies conformational geometries and compositional heterogeneity on …

Efficient Capture Of Co2 And Its Selective Reduction To Formic Acid Using Tin-Based Nanomaterials, Emmanuel Oluwaseun Abdul

Dissertations and Theses

CO₂ emissions from the combustion of fossil fuels and other anthropogenic sources have become the main contributing factors to global warming. Chemical methods of absorbing/capturing CO₂ from combustion flue gases have made it a sought-after approach in engineering emission solutions because of its simplistic and convenient operation and high absorption efficiency. The conversion of CO₂ into renewable fuels and high energy density chemicals by clean and economic processes has drawn scientists' attention over the decades. The electrocatalytic conversion of CO₂ using Sn-based materials has been demonstrated to be a promising method for producing formate, an important …

Speciation Of Diaryliodonium Salts In Solution And Their Reactivity Towards N-Nucleophiles (Phthalimide And Amines) And O-Nucleophiles (Phenols And Phenoxide), Souradeep Basu

Dissertations and Theses

Benzenoid rings are prevalent in pharmaceutical drug molecules, agrochemical molecules and even in some polymers used in electronic device. Aryl rings are often installed using metal catalysis, however, metal free arylations are known but limited. Diaryliodonium salts are novel electrophilic arylating agents. Herein, metal free N-arylation of phthalimide and diarylether formation using aryl(TMP)iodonium salts is described.

The structure of diaryliodonium salts has been primarily studied in either the solid state or in-silico. The structure and speciation of diaryliodonium salts in solution is not well explored. In this work evidence of dimer formation of aryl(Mes)iodonium salts in chloroform using …

Development And Evaluation Of A Survey To Measure Student Engagement At The Activity Level In General Chemistry, Nicole Naibert, Jack Barbera

Chemistry Faculty Publications and Presentations

Student engagement is an important consideration when incorporating active learning activities into a classroom. To facilitate the large-scale assessment of students’ engagement in activities, a survey measure must first be developed and evaluated. Therefore, the goal of this study was to create a self-report measure of student engagement for use with active learning activities in general chemistry classes. The Activity Engagement Survey (AcES) was modified from an existing survey of engagement of middle and high school science students that contained behavioral, cognitive, emotional, and social engagement items. Multiple rounds of response process interviews and factor analyses were used to modify …

Exploring Student Perceptions Of Behavioral, Cognitive, And Emotional Engagement At The Activity Level In General Chemistry, Nicole Naibert, Elizabeth Vaughan, Kylee M. Brevick, Jack Barbera

Chemistry Faculty Publications and Presentations

Although active learning strategies are being incorporated into many higher-education STEM courses, not all students benefit from these activities to the same extent. As these types of activities are designed to engage students in their learning, differences in student engagement may explain some of the differences in learning outcomes. However, before student engagement in active learning activities can be meaningfully measured using a self-report survey, it is important to evaluate if students perceive engagement similarly to the literature definitions on which these measures are based. Therefore, this study sought to explore students’ perceptions of the behavioral, cognitive, and emotional dimensions …