Chemistry Commons^™

Photoluminescence Mechanism And Applications Of Zn-Doped Carbon Dots, Quan Xu, Wei Cai, Miaoran Zhang, Yingchun Ye, Yeqing Li, Lipeng Zhang, Yongjian Guo, Zhiqiang Yu, Siyu Li, Xun Lin, Yusheng Chen, Yan Lou, Jason Street, Meng Xu

Faculty & Staff Scholarship

Heteroatom-doped carbon dots (CDs) with excellent optical characteristics and negligible toxicity have emerged in many applications including bioimaging, biosensing, photocatalysis, and photothermal therapy. The metal-doping of CDs using various heteroatoms results in an enhancement of the photophysics but also imparts them with multifunctionality. However, unlike nonmetal doping, typical metal doping results in low fluorescence quantum yields (QYs), and an unclear photoluminescence mechanism. In this contribution, we detail results concerning zinc doped CDs (Zn-CDs) with QYs of up to 35%. The zinc ion charges serve as a surface passivating agent and prevent the aggregation of graphene p–p stacking, leading to an …

Spontaneous Dna Damage To The Nuclear Genome Promotes Senescence, T Redox Imbalance And Aging, Andria R. Robinson, Matthew J. Yousefzadeh, Tania A. Rozgaja, Jin Wang, Xuesen Li, Jeremy S. Tilstra, Chelsea H. Feldman, Siobhan Q. Gregg, Caroline H. Johnson, Erin M. Skoda, Marie-Celine Frantz, Harris Bell-Temin, Hannah Pope-Varsalona, Aditi U. Gurkar, Luigi A. Nasto, Rena A.S. Robinson, Heike Fuhrmann-Stroissnigg, Jolanta Czerwinska, Sara J. Mcgowan, Nadiezhda Cantu-Madellin, Jamie B. Harris, Salony Maniar, Mark A. Ross, Christy E. Trussoni, Nicholas F. Larusso, Eugenia Cifuentes-Pagano, Patrick J. Pagano, Barbara Tudek, Nam V. Vo, Lora H. Rigatti, Patricia L. Opresko, Donna B. Stolz, Simon C. Watkins, Christin E. Burd, Claudette M. St, Croix, Gary Siuzdak, Nathan A. Yates, Paul D. Robbins, Yinsheng Wang, Peter Wipf, Eric E. Kelley, Laura J. Neidernhofer

Faculty & Staff Scholarship

Accumulation of senescent cells over time contributes to aging and age-related diseases. However, what drives senescence in vivo is not clear. Here we used a genetic approach to determine if spontaneous nuclear DNA damage is sufficient to initiate senescence in mammals. Ercc1-/Δ mice with reduced expression of ERCC1-XPF endonuclease have impaired capacity to repair the nuclear genome. Ercc1-/Δ mice accumulated spontaneous, oxidative DNA damage more rapidly than wild-type (WT) mice. As a consequence, senescent cells accumulated more rapidly in Ercc1-/Δ mice compared to repair-competent animals. However, the levels of DNA damage and senescent cells in Ercc1-/Δ mice never exceeded that …

Brønsted Acid Catalyzed Carbon-Carbon Bond Forming Reactions, Jiangyue Miao

Electronic Theses and Dissertations

The focus of this research project lies in the development of new methodology in the field of Brønsted acid catalysis enabling rapid synthesis of medicinally relevant compounds. It is foreseen that small molecule sulfonic acids evaluated in this research project will unveil new asymmetric carbon carbon bond forming reactions between substrates hitherto unexplored with Brønsted acid catalysis. It has been established that strong Brønsted acids, such as phosphoric acids, are capable of mediating highly selective transformations operating through unique mechanistic manifolds.

Specific focus for the sulfonic acid catalysts was geared towards asymmetric coupling reactions with synthetically useful precursors such as …

Indoleamine 2,3-Dioxygenase And Its Therapeutic Inhibition In Cancer, George C. Prendergast, William Paul Malachowski, Arpita Mondal, Peggy Scherle, Alexander J. Muller

Chemistry Faculty Research and Scholarship

The tryptophan catabolic enzyme indoleamine 2,3-dioxygenase-1 (IDO1) has attracted enormous attention in driving cancer immunosuppression, neovascularization, and metastasis. IDO1 suppresses local CD8 + T effector cells and natural killer cells and induces CD4 + T regulatory cells (iTreg) and myeloid-derived suppressor cells (MDSC). The structurally distinct enzyme tryptophan dioxygenase (TDO) also has been implicated recently in immune escape and metastatic progression. Lastly, emerging evidence suggests that the IDO1-related enzyme IDO2 may support IDO1-mediated iTreg and contribute to B-cell inflammed states in certain cancers. IDO1 and TDO are upregulated widely in neoplastic cells but also variably in stromal, endothelial, and innate …

Selective Carbon-Carbon Bond Formation Promoted By Divalent Samarium Reagents, Christopher David-James Aretz

Electronic Theses and Dissertations

Three efficient methods for synthesis of five membered carbocycles, a highly understudied product motif in samarium(II) chemistry, were explored and optimized. These methods utilized simple starting materials to generate linear substrates with functional groups that are reactive towards samarium(II) iodide. The three methods explored were the Reformatsky-aldol, Reformatsky-alkylation, and pinacol cyclizations. The critical discovery for efficient formation of the Reformatsky-aldol and pinacol carbocycles products was the use of lithium bromide. This addition of lithium bromide facilitates easy in situ formation of samarium(II) bromide. The Reformatsky-alkylation cyclization was a newly realized reaction employing samarium enolates. Two of the three methods, the …

Progress Toward The Synthesis Of Novel Bacterial Topoisomerase Inhibitors Derived From Fluoroquinolones. N-1 Amine Derivatives, Luke Burroughs, Joshua Kuperus, Evamarie Medendorp, Michael Barbachyn

Summer Research

Bacterial resistance to current antibiotics is a growing problem across the globe. The CDC reported that the estimated minimum illnesses caused by antibiotic resistance in the year 2013 was over 2 million, resulting in about 23,000 deaths in the U.S. 1 In 2014, the Obama administration released an executive order mandating that research be conducted to identify solutions to the bacterial resistance problem, especially in Gram-negative bacteria. One antibiotic series that has shown some promise are the fluoroquinolones. Fluoroquinolones have been on the market for years, with a current reference example being moxifloxacin. Fluoroquinolones (FQs) work by targeting DNA gyrase …

Synthesis Of Trisubstituted Indolizines: Optimization And Scope Studies, Matthew D. Rossler, Colin T. Hartgerink, Carolyn E. Anderson

Summer Research

Indolizines are a versatile heterocyclic core, found frequently in pharmaceutical targets, for a wide variety of therapeutic areas, including: anti-bacterial1 and anti-tumor,2 in addition to targets against Alzheimer’s disease,3 asthma,4 erectile dysfunction,5 and inflammation related to respiratory or cardiovascular disease

Synthesis Of Trisubstituted Indolizines: Substitution, On The Pyridine Ring, Jaimie E. Van De Burg, Benjamin L. Boss, Carolyn E. Anderson

Summer Research

Indolizines are a versatile heterocyclic core found frequently in pharmaceutical targets for a wide range of therapeutic areas, including anti-tumor treatments,1 an inhibitor of Lp-PLA2, 2 and antagonists of CRTH2, 3 (Figure 1). As such, efficient synthetic methods, with broad substrate scope, for the preparation of substituted indolizines are of significant importance

Protection Of Triplet Excited State Materials From Oxygen Quenching And Photooxidation In Optical Sensing Applications, Mikhail Filatov

Books/Book chapters

No abstract provided.

Sequestered Alkaloid Defenses In The Dendrobatid Poison Frog Oophaga Pumilio Provide Variable Protection From Microbial Pathogens, K. J. Hovey, E. M. Seiter, Erin E. Johnson, Ralph Saporito

2018 Faculty Bibliography

Most amphibians produce their own defensive chemicals; however, poison frogs sequester their alkaloid-based defenses from dietary arthropods. Alkaloids function as a defense against predators, and certain types appear to inhibit microbial growth. Alkaloid defenses vary considerably among populations of poison frogs, reflecting geographic differences in availability of dietary arthropods. Consequently, environmentally driven differences in frog defenses may have significant implications regarding their protection against pathogens. While natural alkaloid mixtures in dendrobatid poison frogs have recently been shown to inhibit growth of non-pathogenic microbes, no studies have examined the effectiveness of alkaloids against microbes that infect these frogs. Herein, we examined …

Lesson Plan: It’S Not Just The Smoke - The Effects Of Nicotine On The Body, Sheryl Hemkin

5. Nicotine

No abstract provided.

Lesson Plan: Small And Powerful – The Effects Of Ethanol From Consumable Alcohol On The Body, Sheryl Hemkin

4. Ethanol

No abstract provided.

Ethanol Video Questions, Sheryl Hemkin

4. Ethanol

No abstract provided.

Ethanol Product Images, Sheryl Hemkin

4. Ethanol

No abstract provided.

Mechanism Of Water Oxidation By Ferrate(Vi) At Ph 7 – 9., Gui Chen, William W. Y. Lam, Po‐Kam Lo, Wai‐Lun Man, Lingjing Chen, Kai‐Chung Lau, Tai‐Chu Lau

Faculty of Science & Technology (THEi)

The kinetics of water oxidation by K2FeO4 has been reinvestigated by UV/Vis spectrophotometry from pH 7–9 in 0.2 m phosphate buffer. The rate of reaction was found to be second‐order in both [FeO42−] and [H+]. These results are consistent with a proposed mechanism in which the first step involves the initial equilibrium protonation of FeO42− to give FeO3(OH)−, which then undergoes rate‐limiting O−O bond formation. Analysis of the O2 isotopic composition for the reaction in H218O suggests that the predominant pathway for water oxidation by ferrate is intramolecular O−O coupling. DFT calculations have also been performed, which support the proposed …

Reduction Of Ruviºn To Ruiii-Nh3 By Cysteine In Aqueous Solution, Qian Wang, Wai-Lun Man, William W. Y. Lam, Shek-Man Yiu, Man-Kit Tse, Tai‐Chu Lau

Faculty of Science & Technology (THEi)

The reduction of metal nitride to ammonia is a key step in biological and chemical nitrogen fixation. We report herein the facile reduction of a ruthenium(VI) nitrido complex [(L)RuVI(N)(OH2)]+ (1, L = N,N′-bis(salicylidene)-o-cyclohexyldiamine dianion) to [(L)RuIII(NH3)(OH2)]+ by l-cysteine (Cys), an ubiquitous biological reductant, in aqueous solution. At pH 1.0–5.3, the reaction has the following stoichiometry: [(L)RuVI(N)(OH2)]+ + 3HSCH2CH(NH3)CO2 → [(L)RuIII(NH3)(OH2)]+ + 1.5(SCH2CH(NH3)CO2)2. Kinetic studies show that at pH 1 the reaction consists of two phases, while at pH 5 there are three distinct phases. For all phases the rate law is rate = k2[1][Cys]. Studies on the effects of acidity …

Experiential Learning Activity: Biodiesel Inquiry Project, Ji Kim

Open Educational Resources

The activity described herein can be implemented in introductory chemistry and high school chemistry courses. The main goal of the project is to integrate a ubiquitous biodiesel production with experiential learning by providing a community-based project. The students work in groups, research the benefits of using biodiesel over petroleum-based diesel, collect waste cooking oil from home or restaurants, develop simple and cost-effective methods to produce biodiesel.

Radical Chemistry In A Femtosecond Laser Plasma: Photochemical Reduction Of Ag+ In Liquid Ammonia Solution, Victoria K. Meader, Mallory G. John, Laysa M. Frias Batista, Syeda Ahsan, Katharine M. Tibbetts

Chemistry Publications

Plasmas with dense concentrations of reactive species such as hydrated electrons and hydroxyl radicals are generated from focusing intense femtosecond laser pulses into aqueous media. These radical species can reduce metal ions such as Au3+ to form metal nanoparticles (NPs). However, the formation of H2O2 by the recombination of hydroxyl radicals inhibits the reduction of Ag+ through back-oxidation. This work has explored the control of hydroxyl radical chemistry in a femtosecond laser-generated plasma through the addition of liquid ammonia. The irradiation of liquid ammonia solutions resulted in a reaction between NH3 and OH·, forming peroxynitrite and ONOO−, and significantly reducing …

Nucleation And Growth Of Gold Nanoparticles Initiated By Nanosecond And Femtosecond Laser Irradiation Of Aqueous [Aucl4]-, Collin Rodrigues, Julian A. Bobb, Mallory G. John, Sergey Fisenko, M. S. El-Shall, Katharine M. Tibbetts

Chemistry Publications

Irradiation of aqueous [AuCl4]with 532 nm nanosecond (ns) laser pulses produces monodisperse (PDI = 0.04) 5 nm Au nanoparticles (AuNPs) without any additives or capping agents via a plasmon- enhanced photothermal autocatalytic mechanism. Compared with 800 nm femtosecond (fs) laser pulses, the AuNP growth kinetics under ns laser irradiation follow the same autocatalytic rate law, but with a significantly lower sensitivity to laser pulse energy. The results are explained using a simple model for simulating heat transfer in liquid water and at the interface with AuNPs. While the extent of water superheating with the ns laser is smaller compared to …

Flexible Robotic Actuators, Stephen A. Morin, Robert F. Shepherd, Adam Stokes, Filip Ilievski, Ramses V. Martinez, Jamie L. Branch, Carina R. Fish, Lihua Jin, Rui M. D. Nunes, Zhigang Suo, George M. Whitesides

Department of Chemistry: Faculty Publications

Systems and methods for providing flexible robotic actuators are disclosed. Some embodiments of the disclosed subject matter include a soft robot capable of providing a radial deflection motions; a soft tentacle actuator capable of providing a variety of motions and providing transportation means for various types of materials; and a hybrid robotic system that retains desirable characteristics of both soft robots and hard robots. Some embodiments of the disclosed subject matter also include methods for operating the dis closed robotic systems.

Synthesis Of Trisubstitiuted Indolizines: Mechanistic Studies, Miles M. Mason, Leslie A. Nickerson, Emily E. Zerull, Carolyn E. Anderson

Summer Research

Indolizines are a versatile heterocyclic core, found frequently in pharmaceutical targets, for a wide variety of therapeutic areas, including: anti-bacterial1 and anti-tumor,2 in addition to targets against Alzheimer’s disease,3 asthma,4 erectile dysfunction,5 and inflammation related to respiratory or cardiovascular disease

The Effects Of Ph On The Fluoresnce Of 6-Hydroxy Coumarin, Daniel Harmon, Yukon Tu, Hunter Pham, Mark Muyskens

Summer Research

The Coumarin family are organic chemical compound in the benzopyrone chemical class. They are natural substances that can be found in many plants. Different varieties can have many colors, properties, and uses. Some can be used in the medical field, and perfumes. 6-Hydroxy Coumarin is a synthesized version of coumarin. It has not been found to be present in nature in large quantities. The fluoresnce and other properties of 6- hydroxycouamrin are still being researched. Having the Hydroxy functional in the 6- postion leads to the massive changes in acidity due to a lack of enthalpy−entropy compensation. Of all the …

Chemists Atwitter, Raychelle Burks, Stephani Page, Kiyomi D. Deards, Joan Barnes

University of Nebraska-Lincoln Libraries: Faculty Publications

Twitter can be used to promote chemists, their work, and their events to other scientists and the general public. From checklists to timelines; how to use Twitter successfully as an individual or institution is discussed. This chapter includes: examples of how the authors have used Twitter, how to find and use common subject tags, tags most used when Tweeting about chemistry and science, and a discussion about measuring success. Knowing when and how to Tweet will help chemists communicate successfully with their peers and the general public in 280 characters or less.

Nicotine Video Questions, Sheryl Hemkin

5. Nicotine

No abstract provided.

Lesson Plan: Am I More Awake? Or Just Not So Sleepy? The Effects Of Caffeine (And Adenosine) On The Body, Sheryl Hemkin

2. Caffeine

No abstract provided.

Identification Of 4-Isopropyl–Thiotropolone As A Novel Anti-Microbial: Regioselective Synthesis, Nmr Characterization, And Biological Evaluation, Mohamed Elagawany, Mohamed Elagawany, Lamees Hegazy, Feng Cao, Maureen Donlin, Nigam Rath, John Tavis, Bahaa Elgendy, Bahaa Elgendy

Chemistry & Biochemistry Faculty Works

We have synthesized and separated tosylated thujaplicin isomers for the first time, and elucidated their structures using 1D, 2D-NMR techniques and X-ray crystallography. The tosylated isomers were used to synthesize 4-isopropyl–thiotropolone and 6-isopropyl–thiotropolone in a regioselective manner. 1H and 13C Chemical shifts of synthesized isomers were fully assigned using several NMR experiments, and their isotropic magnetic shielding was calculated using the GIAO (Gauge Including Atomic Orbitals) method and the B3LYP def2-TZVPP level of theory. The calculated chemical shift values were in a good agreement with the experimental results. The biological activity of all synthesized compounds was evaluated against the fungal …

The Scientific Contributions Of Donald J. Cram, Leiah Carney

Natural Sciences Student Research Presentations

This poster for the Natural Sciences Poster Session summarizes the work of Donald J. Cram in the field of organic chemistry. A Nobel prizewinner in 1987, he is known for his work with hemicarcerands and carcerands, molecular containers which aided in the study of unstable molecules.

Improvement Of Emissions Of Internal Combustion Engines Using Reduction In Weight, Javier Alanis

Natural Sciences Student Research Presentations

This slide presentation for the Natural Sciences Poster Session at Parkland College identifies the health hazards associated with combustion engine emissions and summarizes a study conducted to determine if an engine with reduced weight would also reduce emissions.

Synthesis Of Volatile And Thermally Stable Aluminum Hydride Complexes And Their Use In Atomic Layer Deposition Of Metal Thin Films, Kyle Blakeney

Wayne State University Dissertations

The research discussed in this dissertation spans both synthetic inorganic and nanomaterials chemistry. Aluminum hydride complexes have been synthesized and characterized which are highly volatile and thermally stable and their potential as reducing agents for ALD of electropositive metal and metal-containing films was evaluated. A major discovery has been the deposition of aluminum metal films by thermal ALD using an aluminum dihydride complex supported by a simple amido-amine ligand (Chapters 2). Aluminum is the most electropositive element deposited by purely thermal ALD to date and represents a significant breakthrough for this field. This process may have important industrial applications and …

Photochemistry Of Polycyclic Aromatic Hydrocarbons With Environmentally Relevant Metals, John P. Haynes

Electronic Theses and Dissertations

The details of the work presented in this dissertation focus on simulated reactions in the atmosphere and water systems between persistent aromatic compounds and varying species of metals with an emphasis on iron. Bulk water suspensions of a standard soil and polycyclic aromatic hydrocarbons (PAH) were analyzed for soluble iron by inductively-coupled plasma mass spectroscopy (ICP-MS) following a 16 hour reaction period using simulated sunlight. Significant increases in soluble iron were only seen with 2-3 ring linear PAH and carboxylic acids.

A two-stage study was conducted to investigate the potential for and possible mechanisms involving the photo-oxidation of PAH into …