Chemistry

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Author: Kayla Benson

Musfeldt Group’s Recent Achievements

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The Musfeldt Group’s research area focuses on experimental materials chemistry and physics. They employ a variety of spectroscopic methods to reveal and control the properties of quantum materials. External stimuli are used to tune these properties in order to explore new physical phenomena and uncover properties of technological relevance.

The Musfeldt Group provides a very unique opportunity for students with the DMREF team (Designing Materials to Revolutionize and Engineer our Future). This year, the team received “The Creativity Extension which is the highest honor in DMR,” Musfeldt said. “The team received an extra $450,000 for it this year.”

The group has also been busy publishing papers such as “Piezochromism in the magnetic chalcogenide MnPS3” in npj Quantum Materials. Nathan Harms, graduate student in the Musfeldt Group, is the lead author. This research explores combining high-pressure optical spectroscopies and first-principles calculations to reveal piezochromism in MnPS3. Photographs are of piezochromic MnPS3 inside the diamond anvil cell at several characteristic pressures and also after release at room temperature. These images show a gasket hole diameter of 325 μm. The diamond culets are 500 μm.

Musfeldt was also published a cover article in Physics Today titled “Nanotubes from layered transition metal dichalcogenides.”

 

Welcome New Department Members

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Viktor Nemykin, Department Head

Nemykin received his BS and MS in chemistry from the Kyiv State University and a PhD from the National Academy of Sciences in Ukraine working on transition-metal and lanthanide phthalocyanines. He received a highly competitive postdoctoral fellowship, supported by Japan Society for the Promotion of Science, which he completed at Tohoku University working on the preparation of phthalocyanines and their analogs. After completing another postdoctoral program at Duquesne University in bio-inorganic chemistry, Nemykin joined the faculty of the Department of Chemistry and Biochemistry at the University of Minnesota Duluth. In 2016, Nemykin was recruited as a department head to the University of Manitoba. He joined the UT chemistry department in August 2020.

 

Joshua Baccile, Assistant Professor

The focus of Baccile’s doctoral research applied analytical chemistry approaches for a comprehensive annotation of cryptic biosynthetic gene clusters (BGCs) in filamentous fungi. Central to his efforts was the use of 2D-NMR and HPLC-MS-based comparative metabolomics. Correlating changes in fungal metabolomes with genetic modification of BGCs enabled the synchronous discovery of new chemical species and enzymatic activity. His team expanded the recently emerging class of natural products, fungal isoquinolines, to include the imizoquins from the imq cluster in the plant pathogenic fungus Aspergillus flavus. Beyond detailing imq biogenesis, they discovered a functional basis for the imizoquins through characterizing antagonistic cross-talk with the ralstonins of the bacterium Ralstonia solanacearum. While thousands of natural products have been described, their functions within the producing organisms are largely unknown. Baccile’s efforts to bridge this gap, such as his study of the imizoquins, will be important for sustained agriculture, biotechnology, and drug discovery.

 

Ashleigh Thomas, Lecturer

Originally from Beckley, West Virginia and earned a PhD at UT in 2011. Thomas served as an Assistant Professor of Chemistry at Lincoln Memorial University from 2011 until 2020. This fall, Thomas will be teaching CHEM260, CHEM269, and CHEM389. 

 

Douglas Stuart, Lecturer

Originally from State College, Pennsylvania and earned a PhD at Indiana University, Bloomington with Shuming Nie. Stuart performed postdoctoral research with RP Van Duyne at Northwestern University exploring biological applications of the optical properties of noble metal and semiconductor nanoparticles. This fall, Stuart will be teaching CHEM130, CHEM339, and CHEM379.

Dai Group Published in Nature Communications for Entropy-stabilized Single-atom Pd Catalysts Research

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The Dai Lab’s research “Entropy-stabilized single-atom Pd catalysts via high-entropy fluorite oxide supports” was published in Nature Communications. First Author Haidi Xu conducted research in the Dai Lab as a visiting scholar from Sichuan University, China. 

This work explores single-atom catalysts (SACs) as they have demonstrated superior catalytic performance in the catalysis community. Fabricating intrinsically stable SACs on traditional supports remains a formidable challenge, especially under high-temperature conditions.

The Dai Lab propose a new strategy to construct a sintering-resistant Pd single-atom on a novel equimolar high-entropy fluorite oxides (CeZrHfTiLa)Ox (HEFO) as the support by simply mechanical milling with calcination at 900 °C.

Characterization results reveal that single Pd atoms are incorporated into HEFO (Pd1@HEFO) sublattice by forming stable Pd–O–M bonds (M=Ce/Zr/La) compared to Pd-O-Pd (PdOx clusters) bonds of Pd@CeO2 synthesized by the same method with the traditional support, thus exhibiting not only higher low-temperature CO oxidation activity but also outstanding resistance to thermal and hydrothermal degradation. T

“This work exemplifies the superiority of high-entropy materials for the preparation of SACs,” Xu said.

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Jenkins Group Published in ACS Nano

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Kristina VailonisResearch from the Jenkins Group was recently published in ACS Nano for their work “In Situ Monitoring of the Seeding and Growth of Silver MetalOrganic Nanotubes by Liquid-Cell Transmission Electron Microscopy“. Kristina Vailonis was one of the primary authors of this piece. Vailonis recently graduated with her PhD from the University of Tennessee’s Department of Chemistry.

Metal–organic nanotubes (MONTs)  are highly ordered one-dimensional crystalline porous frameworks. Despite being nanomaterials, virtually all studies of MONTs rely on characterization of the bulk crystalline material (micron-sized) by single-crystal X-ray diffraction.

This research analyzes their formations under a variety of reaction conditions in solution, and employ liquid-cell transmission electron microscopy (LCTEM), which allows the early stages of MONT assembly to be monitored in real time.

Changing the metal-to-ligand ratio alters the local concentrations of reactant monomers, resulting in multiple nucleation and growth pathways and diverse morphologies at the nanoscale.

“As we develop MONTs, it is critical to characterize them on the nanoscale before they have grown into bulk 3D materials that are microns in size,” said Jenkins “By collaborating with experts on liquid cell-TEM, we can observe the chemical reactions and watch these 1D materials grow in real time.”

Free Virtual Physical Symposium

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Despite its introduction almost three decades ago, the ability to couple the measurement of nonlinear phenomena with the spatial resolution of a microscope objective has continued to rapidly evolve through both the application of more sophisticated techniques and the study of more complex systems. Progress in the field of nonlinear microscopy has afforded deep penetration in biological tissues, additional modalities for chemical contrast, and dynamics on ultrafast timescales. Challenges remain, however, in extracting new information from increasingly congested samples with minimal perturbation. Innovations in instrumentation, the development of new image analysis methodologies, and novel applications of existing techniques promise new insight into intrinsically heterogeneous samples. 

Tessa Calhoun, Associate Professor with the Department of Chemistry, has been co-organizing a symposium for the virtual ACS conference August 17-20, 2020. There will be live Zoom presentations that are free for anyone to participate in. Registration information can be found here. 

This symposium will gather scientists from the fields of chemistry, physics, engineering and biology into a collaborative environment where ideas of technology innovations and sample applications can be shared and discussed. Progress, existing challenges, impact will be emphasized.

While this symposium originated as part of the ACS Fall 2020 Virtual Conference, participation in these Zoom sessions is not limited to those registered for the conference. 

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Scientists Catch a Glimpse of Elusive Cell Membrane Nanodomains

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A collaborative team including University of Tennessee researchers has captured the first direct images of tiny cell membrane domains known as lipid rafts. The images were published in a research article in this week’s edition of Proceedings of the National Academy of Sciences of the USA.

First hypothesized over thirty years ago, rafts are specialized microenvironments found within cell membranes, the sheets of lipid and protein that both surround a cell and delineate its internal compartments. They are thought to play a crucial role in the way cells transport materials and communicate with each other. Some viruses, including influenza and HIV, have even co-opted rafts in their life cycle.

At nearly a thousand times smaller than the width of a human hair, rafts are impossible to detect with conventional microscopy. “Although their existence is well supported by biochemical evidence, the lack of direct visual observations of rafts has led to some healthy skepticism” said Fred Heberle, an assistant professor in the Chemistry Department at UT and lead author of the study.

The researchers used a powerful technique called cryogenic electron microscopy (cryoEM) to take the first pictures of the tiny structures. “An ordinary light microscope can’t resolve objects smaller than a few tenths of a micrometer, but cryoEM can visualize structures as small as a tenth of a nanometer” said Heberle. “It’s revolutionizing the field of structural biology, but to date has mostly been used to look at protein structure. We decided to zoom in on membranes and see if we could visualize rafts.”

The study grew out of a collaboration between Heberle and two research groups at the University of Texas Health Science Center at Houston led by cell biologist Ilya Levental and neurobiologist M. Neal Waxham. “We have a common interest in membrane structure but different ways of approaching it,” said Heberle. “My lab studies synthetic membranes, while Ilya and Neal specialize in more complicated biological membranes. We also have combined expertise in small-angle scattering, molecular simulations, and electron microscopy. Ultimately, we needed all of those tools to convince ourselves that we were really seeing rafts.”

The researchers first imaged model biomimetic membranes to show that cryoEM can resolve sub-nanometer differences in their thickness, a feature known to distinguish rafts from the surrounding membrane. They then used simulations to predict how rafts would appear in a cryoEM image and to fine-tune their analysis, before finally capturing images of raft domains in both biomimetic and biological membrane preparations. A team at the University of Washington led by Sarah Keller and graduate student Caitlin Cornell independently made a similar discovery using a variation of cryoEM called cryo-electron tomography, and the two articles were published together.

While the new images should settle some long-standing questions, many aspects of raft formation and structure remain poorly understood. At a basic level, rafts are a consequence of the immiscibility of different lipids found in cell membranes, much like a mixture of olive oil and vinegar will separate in a bottle of salad dressing. “Cell membranes are fluid mixtures of lipids and proteins, and some of the different types of lipids don’t mix well and can separate to form a raft,” Heberle said.

One problem that has confounded researchers is why rafts remain small rather than coalescing into larger structures, but Heberle says that the ability to finally visualize the domains may eventually provide answers. “A better understanding of rafts will not only give insights into the normal functioning of our own cells, but may also lead to improved therapies for viral infections.”

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Hazari Online

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Dr. Al Hazari Magic ShowAl Hazari, retired UT professor, has been conducting experiments on Zoom to teach and inspire chemistry enthusiasts.

“I have always enjoyed teaching and sharing something of myself and my knowledge with anyone ages 2 to 102,” Hazari said. “What we’re really after are science-literate citizens. Everyone should know about science, be comfortable with science, and never stop being curious and inquisitive about the wonders of science.”

This summer, Hazari has utilized the Zoom platform to teach Forensic Chemistry Camp for middle school students, ORAU workshops, the Harriman Public Library Chemistry Magic Show, and local WBIR presentations. 

Hazari WBIR 1

Hazari WBIR 2

Hazari WBIR 3

Larese Named ACS Fellow

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John Larese, professor in the Department of Chemistry, has been named an 2020 ACS Fellow.

The primary purpose of the ACS Fellows Program is to recognize and honor members of the American Chemical Society for their outstanding achievements in and contributions to the science and the profession and for their equally exemplary service to the Society.

“I have truly benefited by my service to ACS and LSAC and by all of the great individuals who have contributed to my scientific endeavors and career,” Larese said. “I’m especially proud of my effort in leading the science/design/funding case for the VISION Spectrometer at the SNS and the training of future scientists in the use of neutrons and novel materials. Clearly without the support and patience of my wife Maryann and children such pursuits are impossible.”

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Mourning the Passing of Ffrancon Williams

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Thomas Ffrancon Williams was born on January 30, 1928, and passed away on July 18, 2020.

Williams received his BSc degree from University College London in 1949, and an external Ph.D. degree from the University of London in 1960. He was employed at the Atomic Energy Research Establishment, Harwell, United Kingdom from 1949 to 1961 except for a leave of absence as a research and teaching associate at Northwestern University from 1957 to 1959. In 1961 he joined the chemistry faculty at the University of Tennessee, Knoxville.

“Francon was a dedicated teacher and outstanding experimental physical chemist,” said Jeffery Kovac, chemistry emeritus professor. “He was an ESR spectroscopist who studied radicals produced by gamma radiation.  Ffrancon did some groundbreaking work on cationic polymerization,” 

Williams was a National Science Foundation Visiting Scientist to Kyoto University, Japan from 1965 to 1966 and was the recipient of a Guggenheim Fellowship in 1972. He has been chairman of the Gordon Research Conferences on Radiation Chemistry (1971) and Radical Ions (1984), and served as an associate and consultant editor of Radiation Research, the official journal of the Radiation Research Society, from 1994 to 1999.

“He was always so kind and nice to me. Our respect went both ways. I will surely miss him, his kind words and phone calls,” said Pam Roach, chemistry staff.

“Ffrancon was a devoted member of our chemistry faculty for many years, and had a wonderful, calm and knowledgeable manner about him,” said Don Esidenberg, development director. “He will surely be missed. Gratefully, he will be remembered by future generations through the Ffrancon Williams Faculty Award in Chemistry Endowment.”