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Abstract: Oxygen reduction reaction (ORR) and conversion of bicarbonate into value-added chemicals are two significant electrochemical processes for energy storage and conversion. ORR is an important electrochemical reaction in fuel cells and metal air batteries that provides power conversion and storage capacity, respectively, for portable electronics and electric vehicles. However, the performance of catalysts (e.g., platinum-based) is critically limited by slow kinetics, inefficient four-electron pathway and surface deactivation. This limited performance of platinum-based catalysts, the scarcity of platinum, and vulnerable supply chains for critical minerals require the development of alternative electrocatalysts now more than ever. 

Carbon-based materials possess several key properties that are beneficial for catalytic applications such as high electric conductivity, large surface area, inert electrode surface and low cost. Catalytic activity of carbon-based electrode can be promoted by tailoring surface and structure through the incorporation of heteroatom dopants. This work focus on synthesis of electrocatalysts and their surface modification to achieve effective ORR performance in alkaline media. The ORR performance of nitrogen (N) and boron (B) co-doped carbon nano onions (CNOs). In this work annealing temperature was found a crucial factor in the synergistic benefit of N and B towards ORR. Furthermore, this research was extended to discuss the impacts of nitrogen heteroatom and copper nanoparticles on ORR performance.

Moreover, electrocatalytic carbon dioxide (CO2) reduction (CO2RR) in a membrane electrode assembly was investigated. Atmospheric CO2 has significantly increased in last two decades. Since CO2 is a primary greenhouse gas emitted on earth, it is imperative to suppress the concentration of emitted CO2. While the regulation of CO2 emissions is critical, CO2 capture and storage (CCS), and biological, chemical, and electrochemical conversions are promising approaches to reduce atmospheric CO2 concentration. In electrochemical conversion, a common method employs the feed of high-purity compressed CO2 gas into an electrolyzer. This method, however, is not economically viable because it requires the release and/or pressurization of CO2 from captured CO2 solution, which are energy-intensive. To resolve this issue, aqueous carbonate/bicarbonate (CO32-/HCO3-) transported from upstream carbon capture process can be directly fed into an electrolyzer. We demonstrate that a cationic exchange membrane coated with a thin copper film can efficiently convert bicarbonate to C1-C2 products such as formic acid and acetic acid. Both liquid and gas products were quantified by using proton nuclear magnetic resonance (H1 NMR) and gas chromatography, respectively. 

The studies herein highlight the importance of structure modification of catalysts, surface chemistry, and membrane-electrode interface to improve the efficiency and selectivity of ORR and CO2RR processes. 

 

Student Profile

Abstract: Smoking and tobacco use (STU) is a major global health problem and worldwide more than six million people die due to tobacco related diseases each year. Although majority of smokers try to quit smoking several times in their life, traditional therapeutic approaches, which focus only on neuronal cells, have a very low success rate.   Understanding the effect of nicotine on glial cells, synaptic communication and blood vasculature in the brain can provide further insights on the neurobiology of substance abuse and can potentially help to design better therapeutic approaches. Glial cells are nonexcitable cells in the brain which do not generate action potentials. Recently many additional functions of glial cells have been discovered which have challenged the traditional neuro-centric view in neuroscience. Astrocytes are major glial cells which regulate synapse, maintain homeostasis, maintain blood brain barrier, and regulate blood flow. Processes from one astrocyte can interact with as many as 10,000 synapses. Astrocyte also couple with blood vasculature and play key role in supply of oxygen and nutrients to the brain. In these studies, we investigated the effect of nicotine on astrocyte morphology and functional activity. By using tissue clearing and time lapse fluorescence imaging approaches, we showed nicotine induces morphological rearrangement of astrocytic processes mediated via nicotinic receptors. We also studied the functional consequences of astrocytic rearrangement in the brain in terms of cytokine release, cell viability and calcium activity. To further characterize the subcellular astrocyte calcium activity in physiological and pathological conditions, we developed a GCaMP based genetic probe by targeting the endoplasmic reticulum (ER) in astrocytes. This probe was shown to measure astrocyte specific calcium activity in the periphery of the ER in cell culture and in vivo. As astrocytic processes form intricated networks with synapses, we also developed a single molecule fluorescence imaging approach to characterize synaptic nicotinic receptors and observed nicotine-induced stoichiometric shift in post synaptic nicotinic receptors in the brain. By using pH sensitive super ecliptic pHluorin (SEP) probe, we showed nicotine also alters the trafficking of nicotinic receptors from the ER to the plasma membrane.  In summary, we developed and applied several fluorescence microscopy-based tools to study the astrocyte activity in various physiological conditions. Nicotine was shown to alter the morphological and functional activity of astrocytes through nicotinic receptor activation. We also developed a genetic probe to image calcium activity in astrocytic processes. Our studies of synaptic nicotinic receptors showed nicotine alters their stoichiometry from low affinity subtype to high affinity subtype. These studies highlight the importance of fluorescence-based approach to study tobacco use disorder and provide further insights on nicotinic receptor pharmacology and astrocyte biology.

Graduate Student Profile

Chamikara Karunasena

Graduate Student Profile

Abstract: The immense synthetic design space and material versatility have driven the exploration and development of organic semiconductors (OSC) over several decades. While many OSC designs focus on the chemistries of the molecular or polymer building blocks, a priori, multiscale control over the solid-state morphology is required for effective application of the active layer in a given technology. However, molecular assembly during solid-state formation is a complex function interconnecting the building block chemistry and the processing environment. Insufficient knowledge as to the how these aspects engage, especially at the atomistic and molecular scales, have so far limited the ability to predict OSC solid-state morphology, leaving Edisonian approaches as the stalwart methods. Therefore, through multiscale simulations combining atomistic quantum scale modeling and modern advanced sampling molecular dynamics (MD), we aim to establish first principles understanding required to synthetically regulate solid-state morphology of organic semiconductors (OSC) as a function of molecular chemistry and processing. In turn we try to understand the deceivingly simple yet complex mechanisms behind molecular aggregation and crystallization of OSC. Simultaneously, we develop semi-to-fully automated high-throughput schemes to automate the complex and labor-intensive analyses to generate data based on various crystal structures in different crystallization environments. Ultimately, we aim to bridge molecular-scale information revealed on solid-state physical organization, understood in the context of chromophore chemistry and the molecular environment, with the macro scale properties to uncover useful guidelines for rational design and morphology regulation of OSC systems.

This lecture series commemorates Professor Dawson's leadership in the Department and features speakers noted for the quality, depth and breadth of their research.

Jeffrey Moore received his B.S. in chemistry (1984) and Ph.D. in materials science and engineering with Samuel Stupp (1989), both from the University of Illinois. He then went to Caltech as a National Science Foundation Postdoctoral Fellow working with Robert Grubbs. In 1990, he joined the faculty at the University of Michigan in Ann Arbor and in 1993 returned to the University of Illinois, where he was Professor of ����vlog�ٷ����, as well as a Professor of Materials Science & Engineering until 2022 and was also selected as the Stanley O. Ikenberry Endowed Chair in 2018. Jeff is a member of the National Academy of Sciences and a fellow of the American Academy of Arts & Sciences, the American Association for the Advancement of Science and the American Chemical Society (ACS); he has received the Campus Award for Excellence in Undergraduate Teaching and has been recognized as a “Faculty Ranked Excellent by their Students.”

For 14 years he served as an associate editor for the Journal of American Chemical Society. In 2014, he was selected as a Howard Hughes Medical Institute Professor and in 2016 was chosen as the recipient for the ACS Edward Leete Award in Organic ����vlog�ٷ����. He received the Royal Society of ����vlog�ٷ����’s Materials ����vlog�ٷ���� Division 2018 Stephanie L. Kwolek Award and was part of a team that was honored with the Secretary of Energy Honor Award, Achievement Award the same year. Jeff was also awarded the 2019 National Award in Polymer ����vlog�ٷ���� by the American Chemical Society. He has published over 400 articles covering topics from technology in the classroom to self-healing polymers, mechanoresponsive materials and shape-persistent macrocycles. He served as the Director of the Beckman Institute for Advanced Science and Technology at the University of Illinois from 2017-2022. In this role, he received the 2021 Executive Officer Distinguished Leadership Award from the UIUC Campus.

"Polymeric Materials for Lifecycle Control"

In this talk I will discuss the molecular design of organic structural materials that mimic living systems’ abilities to protect, report, heal and even regenerate themselves in response to damage, with the goal of increasing lifetime, safety and sustainability of many manufactured items. I will emphasize recent developments in frontal ring-opening metathesis polymerization (FROMP)to manufacture composites with minimal energy consumption. The talk will conclude by introducing the idea of morphogenic manufacturing in which we aim to achieve symmetry breaking in neat polymerization reactions through a coupled reaction-diffuse process; the longterm vision is self-patterned form and function in synthetic materials.

References:

1. Patrick, J.F.; Robb, M.J.; Sottos, N.R.; Moore, J.S.; White, S.R. Polymers with Autonomous Life-cycle Control, Nature, 2016, 540, 363-370.

2. Robertson, I.D.; Yourdkhani, M.; Centellas, P.J.; Aw, J.; Ivanoff, D.G.; Goli, E.; Lloyd. E.M.; Dean, L.M.; Sottos, N.R.; Geubelle, P.H.; Moore, J.S.; White, S.R. Rapid Energy-efficient

Abstract: The biosynthesis of both fatty acids and polyketides involves a common reaction, the iterative carbon-carbon bond formation between acyl-thioesters and malonyl-thioesters. While fatty acids and polyketides are essential to society for a plethorea of reasons, how the underlying carbon-carbon bond forming reactions occur remains an open question. Malonyl-thioesters are akin to biochemical hot-potatoes, because they are prone to hydrolysis and decarboxylation. While these two high-energy reactions are exploited by nature for biosynthetic purpose, they plague the structural biologist. We developed molecules that look like malonyl-thioesters but are much more stable, thus we have chilled the hot-potato. These stable malonyl-thioester analogs have provided us with insight into the catalysis of three enzymes. Our preliminary studies with these malonyl-thioester analogs demonstrate that we will be able to generate insight into fatty acid and polyketide biosynthesis, paving the way for new routes to drugs, agrochemicals and biofuels.

The Yoshimoto research laboratory at UTSA harnesses the power of synthetic chemistry to solve challenging problems relevant to human health.

Artemisinin, one of the topics of the 2015 Nobel Prizes in Medicine, is an endoperoxide-containing sesquiterpenoid plant natural product used to treat malaria. The biosynthesis of the endoperoxide functional group, which gives the natural product its antimalarial activities, has been controversial. Using isotope-labeling strategies, we have elucidated the mechanism of the nonenzymatic endoperoxide forming cascade reaction that converts the precursor, dihydroartemisinic acid, to artemisinin in four steps: (i) first oxygen incorporation, (ii) C-C bond cleavage, (iii) second oxygen incorporation, (iv) and polycyclization to form artemisinin (1,2). Analogs of DHAA have been synthesized to probe endoperoxide formation, which led to the elucidation of the mechanism of the formation of the aromatic ring in serrulatene, an antibiotic plant natural product (3).

Secondly, human cytochrome P450 8B1, the oxysterol-12a-hydroxylase enzyme implicated in bile acid biosynthesis, is a therapeutic target to treat obesity. Preliminary studies involving the synthesis of a rationally designed inhibitor of P450 8B1 through the incorporation of a C12-pyridine in the steroid backbone, will be discussed (4).

1.         Varela, K., Arman, H. D., and Yoshimoto, F. K. (2020) Synthesis of [3,3-²H₂]-Dihydroartemisinic Acid to Measure the Rate of Nonenzymatic Conversion of Dihydroartemisinic Acid to Artemisinin. J. Nat. Prod. 83, 66-78

2.         Varela, K., Arman, H. D., and Yoshimoto, F. K. (2021) Synthesis of [15,15,15-²H₃]-Dihydroartemisinic Acid and Isotope Studies Support a Mixed Mechanism in the Endoperoxide Formation to Artemisinin J. Nat. Prod. 84, 1967-1984

3.         Varela, K., Al Mahmud, H., Arman, H. D., Martinez, L. R., Wakeman, C. A., and Yoshimoto, F. K. (2022) Autoxidation of a C2-Olefinated Dihydroartemisinic Acid Analogue to Form an Aromatic Ring: Application to Serrulatene Biosynthesis. J. Nat. Prod. 85, 951-962

4.         Chung, E., Offei, S. D., Jia, U. A., Estevez, J., Perez, Y., Arman, H. D., and Yoshimoto, F. K. (2022) A synthesis of a rationally designed inhibitor of cytochrome P450 8B1, a therapeutic target to treat obesity. Steroids 178, 108952

Abstract:

The human genome is composed of 46 DNA molecules — the chromosomes — with a combined length of about two meters. Chromosomes are stored in the cell nucleus in a very organized fashion that is specific to the cell type and phase of life; this three-dimensional architecture is a key element of transcriptional regulation and its disruption often leads to disease.  What is the physical mechanism leading to genome architecture? If the DNA contained in every human cell is identical, where is the blueprint of such architecture stored? 

In this talk, I will demonstrate how the architecture of interphase chromosomes is encoded in the one-dimensional sequence of epigenetic markings much as three-dimensional protein structures are determined by their one-dimensional sequence of amino acids. In contrast to the situation for proteins, however, the sequence code provided by the epigenetic marks that decorate the chromatin fiber is not fixed but is dynamically rewritten during cell differentiation, modulating both the three-dimensional structure and gene expression in different cell types.

This idea led to the development of a physical theory for the folding of genomes, which enables predicting the spatial conformation of chromosomes with unprecedented accuracy and specificity. Finally, I will demonstrate how the different energy terms present in our model impact the topology of chromosomes across evolution. Our results open the way for studying functional aspects of genome architecture along the three of life.

Bio:

Michele Di Pierro is Assistant Professor of Physics at Northeastern University and senior investigator of the Center for Theoretical Biological Physics — an NSF Frontier of Physics Center. He studied Condensed Matter Physics at the University of Rome “La Sapienza” and received a PhD in Applied Mathematics from The University of Texas at Austin. Prior to joining Northeastern University, he was the Robert A. Welch Postdoctoral Fellow at Rice University.

His research focuses on the physical processes involved in the translation of genetic information, a branch of biophysics which he refers to as Physical Genetics. His group develops novel theoretical approaches to characterize the structure and function of the genome using the tools of statistical physics, information theory, and computational modeling.

Graduate Student Profile

Abstract: 1,2-diamine substructures are prevalent functional motifs found in natural products, pharmaceutical compounds, and ligands. The interesting utilities of 1,2-diamines have inspired many synthetic chemists to design various methodologies for the preparation of these structures from simple precursors such as alkenes. Despite the well-established analogous dihydroxylation or aminohydroxylation of alkenes, the introduction of two amino groups across the double bond has been more challenging to accomplish. In this work, we described two different, but related methods using simple and easily accessible reagents for 1,2-diamination of alkenes. In the first method, an alkene undergoes 1,3-dipolar cycloaddition with an organic azide to form a 1,2,3-triazoline. Subsequent N-alkylation of the generated 1,2,3-triazoline gives the 1,2,3-triazolinium ion, which was then hydrogenated over Raney Ni with a balloon of H2 to produce 1,2-dimine. Traditionally, it has been believed that a 1,2,3-triazoline is an unstable species in the presence of heat or light and will readily extrude N2 to form an imine or an aziridine.  However, most of the 1,2,3-triazolines prepared in this work were stable to the extrusion of N2 at the temperature required for their formation. In the second method, the alkene undergoes 1,3-dipolar cycloaddition with a 1,3-diaza-2-azoniaallene (azidium ion) to afford a 1,2,3-triazolinium ion directly. The 1,2,3-triazolinium ions are reduced to the corresponding 1,2-diamines using the same conditions described above. X-ray crystallographic analysis and 1D/2D NMR spectra confirmed the stereochemistry of the synthesized 1,2,3-triazolinium ions and 1,2-diamines.

Biosketch: Christopher H. Hendon is an Assistant Professor of Computational ����vlog�ٷ���� at the University of Oregon, with interests in energy materials and coffee extraction. He obtained his BSc. Adv. HONS from Monash University (2011) and PhD from the University of Bath (2015). After a two year postdoc at Massachusetts Institute of Technology he joined the University of where his research group focuses the chemistry of transition metal clusters.

Prof. Hendon’s interest in coffee began during his PhD, and since  then has published several peer-reviewed articles and a book, Water For Coffee. He enjoys washed African coffees, dry rieslings, and east coast oysters.

Abstract: Although generally thought of as highly ordered crystals, all metal-organic frameworks contain defects. Some defects may reveal catalytic active sites or hint at competing material phases, while othersmay result in electronic doping. Modern computational approaches are well-suited to studying theemergent chemistry of these imperfections, and can be used to directly inform experiment and characterization of materials with properties that diverge from those gleaned from crystallography. This talk discusses the chemistry afforded by defects in metal-organic frameworks, with a focus on structural dynamics and adatoms, both promoted by Lewis basic sites within the scaffolds. The utility of these defects will be presented from the perspective of heterogeneous catalyst development.

This lecture series commemorates the life and legacy of Professor Susan Odom, an energetic, productive, and driven faculty member in the Department of ����vlog�ٷ���� from 2011 to 2021. It features speakers noted for outstanding research in Professor Odom’s fields of synthetic and materials chemistry.

Visit this page for more information on the Susan A. Odom lecture series.