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Archives for 2022

Vogiatzis Publishes in Inorganic Chemistry Frontiers

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The Vogiatzis group recently published a paper in Inorganic Chemistry Frontiers entitled “Data-driven ligand field exploration of Fe(iv)–oxo sites for C–H activation.”

Methane is the main component in natural gas and is expected to become more and more important to the development of fuels and chemicals for applications such as clean energy, light and heat production, and the development of organic chemicals. However, methane’s instability and flammability make storage and transportation difficult. It is possible to improve methane’s stability by converting it into methanol or light hydrocarbons.

One approach to this is the development of new catalysts that mimic naturally existing enzymes. The Vogiatzis group, led by Associate Professor Konstantinos Vogiatzis, focused their research on non-heme Fe(IV)-oxo model complexes.

“Computational studies provide a fundamental understanding of the electronic effects that control the reactivity of the Fe(IV)-oxo species, but also provide directions for the synthesis of the next generation of catalytic complexes and materials,” said Vogiatzis.

Vogiatzis and his team employed machine learning to more quickly and thoroughly investigate possible complexes that may be most effective. They developed machine learning models that use a novel molecular representation based on persistence homology, called persistence images.

“Our methodology uses a novel molecular fingerprinting method based on persistent homology, an applied branch of topology, that can encode the geometric and electronic structure together with molecular topology,” said Vogiatzis. “The new model is trained on accurate data from a few hundred Fe(IV)-oxo complexes and is capable of providing reliable information for thousands of complexes.”

Vogiatzis believes the insights uncovered in this research will aid in the construction of a theoretical framework for the design of novel catalysts for less energetically demanding industrial processes, including the conversion of methane and natural gas. This publication was co-authored by graduate students Grier Jones, Brett Smith, and Justin Kirkland, members of the Vogiatzis research group.

Undergraduate Student Co-Authors Publication

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Earlier this year Macy Hudson, undergraduate student in the Department of Chemistry, co-authored a publication with a team of University of Tennessee, Knoxville faculty, researchers, and students. The paper “Reactive Oxygen Species (ROS) Activated Liposomal Cell Delivery Using a Boronate-Caged Guanidine Lipid” was published in Chemistry: A European Journal in late May.

Hudson, a senior, began her time at the university with a plan; she wanted to study organic chemistry, get some experience in a lab, then continue to graduate school. Despite challenges presented by the onset of COVID-19 in early 2020, which sent students home for virtual learning and paused work in labs across campus, she continued to pursue these goals.

“During my sophomore year I really started looking at how to get involved in undergraduate research,” said Hudson. “I asked around the department and was advised to look at what our individual faculty members are researching, reach out to them directly and see if they had any projects that suited my area of study.”

This active pursuit of her research interests eventually led Hudson to the research group of Michael Best, professor of chemistry. Best’s group works with the design and creation of organic molecules for uses relevant to biological systems. The publication Hudson co-authored describes the results of one such project with applications in the pharmaceutical industry.

“The goal of this project was to create a lipid and then use a disease-associated trigger to cleave off the head group of the lipid. When that happens, it creates a positive charge, and if we can create enough positive charge, nanocarriers called liposomes composed of this lipid can be absorbed into cells. This method can be used for drug delivery by putting drug molecules inside the liposome which the cell then absorbs,” said Hudson. Her work on the project was very hands-on, synthesizing and testing the lipid repeatedly, the results of which were included in the publication. 

Hudson plans to continue working in organic chemistry, and specifically in drug design and delivery, by pursuing a PhD after graduation. She hopes to eventually work in development in the pharmaceutical industry. Hudson credits her time in the Department of Chemistry with preparing her to pursue these goals. 

“I’ve had a really great experience. Getting involved beyond research and classes has really helped. I joined our undergraduate chemistry club and worked as an undergraduate teaching assistant, which allowed me to build relationships with faculty members and teach the material that I love,” said Hudson.

Limbach Wins Student Poster Award

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Miranda Limbach, third year PhD student, recently earned an Outstanding Student Poster award at the fall meeting of the American Chemical Society (ACS). Limbach’s poster, entitled “Atomic View of Aqueous Cyclosporine A: Unpacking a Decades-Old Mystery,” was one of eight student posters in the division of physical chemistry to be honored at the meeting. 

“This was my first time at the ACS Conference,” said Limbach. “Presenting the poster was lots of fun. Everyone who stopped seemed really interested and the judges were anonymous so you didn’t know who was or wasn’t a judge.”

Limbach’s presentation and poster were based on a collaborative effort between the department, the neutron scattering division at Oak Ridge National Laboratory (ORNL), and the University of Vanderbilt. 

Limbach’s work investigates cyclosporine A, a macrocyclic immunosuppressant. Macrocycles are a class of molecules with the ability to permeate the cell membrane and bind to a number of target proteins. Macrocycles have important applications in the pharmaceutical industry and can contribute to both the development of new drugs, including antibiotics, and the successful delivery of those drugs in the human body.

Earlier in 2022, this work was published in the Journal of the American Chemical Society, with a number of UT Chemistry co-authors, including graduate students Aleksandra Antevska, Damilola Oluwatob, and Amber Gray, Assistant Professor Thanh Do, and Director of Nuclear Magnetic Resonance (NMR) Core Facilities Carlos Steren.

Limbach credits her experience in the Department of Chemistry and time in Thanh Do’s research group with preparing her for a successful presentation.

“The nice thing about Dr. Do’s lab is we use a lot of techniques so we get to learn a little bit of everything,” said Limbach. “I’ve been learning a little bit of mass spectrometry and x-ray diffraction and I learned a lot about 2D NMR. The department has been great. Everyone’s really open to making sure you learn everything you need.”

Limbach plans to continue exploring the significance of cyclosporine analogues during her academic career and, after graduation, is considering a future working with NMR facilities or industry.

Sheng Dai Named 2022 Clarivite Highly Cited Researcher

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Sheng Dai

Each year, Clarivate identifies the world’s most influential researchers ─ the select few who have been most frequently cited by their peers over the last decade. In 2022, fewer than 7,000, or about 0.1%, of the world’s researchers, in 21 research fields and across multiple fields, have earned this exclusive distinction.Dai is among this elite group recognized for your exceptional research influence, demonstrated by the production of multiple highly-cited papers that rank in the top 1% by citations for field and year in the Web of Science. Dai was also included in the prestigious ranking in 2021 and 2020, making this his third consecutive year on Clarivite’s Highly Cited Researchers list.

Sheng Dai Named DOE Distinguished Scientist Fellow

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Sheng Dai

Sheng Dai, professor of chemistry and UT-ORNL joint faculty has been named a 2022 Distinguished Scientist Fellow by the Department of Energy (DOE) Office of Science. This competitive award recognizes exceptional scientists with a history of bridging the gap between academic institutions and national laboratories.

Awardees receive $1 million in funding to be spent over three years with the intention of developing, sustaining, and promoting scientific and academic excellence through collaborations between universities and national laboratories. Only two scientists were awarded this year.

Dai was selected for his pioneering work in the development of functional materials for a variety of uses, including separation science, energy storage, catalysis, and other energy-related applications. It was also noted that Dai has a history of engaging in productive collaborations and serving as a mentor for future generations of researchers.

Dai received his PhD from the University of Tennessee, Knoxville and joined the faculty of the chemistry department in 2009. His current research interests include ionic liquids, porous materials, and their applications for separation sciences and energy storage as well as catalysis by nanomaterials. His research has led to the 2020 Max Bredig Award for Ionic Liquids and Molten Salts, the 2019 ACS Award in Separation Science and Technology, and 2018 IMMA Award given by International Mesostructured Materials Association. He is a Fellow of Material Research Society and Fellow of the American Association for the Advancement of Science.

The DOE Office of Science will host a lecture series featuring the 2022 awarded scientists. Dai will discuss his research accomplishments, career trajectory, and experiences November 9 at 1:30pm. The events are open to the public virtually on Zoom. Attendees can register to receive Zoom information.

Polymer

UT Leads World in Polymer Science

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From your clothing to the fiber-optic cables bringing you high-speed internet, polymers are everywhere, with applications in nearly all fields of science and industry. Polymer science plays a crucial role in providing solutions to global needs including food, clean and abundant water, air, energy, and health.

Researchers at the University of Tennessee, Knoxville, in fields including chemistry, physics, chemical engineering, biosystems engineering, and forestry are investigating polymers through a variety of fundamental scientific problems with real-world impact—from designing and creating new advanced materials to improving industrial processes to creating sustainable biofuels.

As an indication of the significance of their work, UT has been ranked the top global university for polymer science in U.S. News and World Report’s Best Global Universities. The ranking is based on research performance from 2015 through 2019 as well as citations from publications through April 29, 2021.

Polymer science research within UT’s College of Arts and Sciences includes work being conducted by the research group of UT-ORNL Governor’s Chair for Polymer Science Alexei Sokolov. The team is advancing fundamental understanding and design of novel polymeric materials for various current and future technologies—from gas separations and carbon capture to 3D printing.

Sokolov’s group also works on polymer electrolytes for use in new generations of solid-state batteries and other energy storage technologies.

“We are working on polymers with dynamic bonds that are recyclable and have self-healing ability,” said Sokolov. “These polymers might replace current plastics and drastically reduce pollution.”

A segment of a bulky polymer chain, polynorbornene, showing elements of carbon (in black), oxygen (in red), silicon (in green), and hydrogen (in white). This unique polymer is one of several developed by Associate Professor Brian Long’s research group to study advanced gas separation membranes.

An illustration of a unique polymer chain, polynorbornene, that was developed by Associate Professor Brian Long’s research group to study advanced gas separation membranes.

Another area of focus, led by the research group of Associate Professor of Chemistry Brian Long, is creating new synthetic materials to separate greenhouse gases such as carbon dioxide from nonharmful gases in a more energy-efficient and cost-effective manner. This research has shown tremendous promise, with implications for reducing industrial greenhouse gas emissions.

“Think about what your body is touching right now—your clothing, your chair, your phone or computer. What are you touching that’s not a polymer or that doesn’t contain polymers? Polymers have provided solutions to almost every societal need in modern human history—even the DNA, RNA, and proteins in our body are polymers,” said Long.

Researchers at UT are even tackling one of the most pressing global needs today—how to minimize or eliminate waste plastics in the environment. For example, research efforts led by Professor Mark Dadmun and Assistant Professor Johnathan Brantley seek to develop new chemical methods to aid recycling of waste plastics, improve the properties of new products and materials made from mixed plastic waste streams, and create a circular plastics economy.

Commenting on the announcement of the ranking, Vice Chancellor for Research Deborah Crawford said, “Our researchers deserve this recognition for their work advancing our understanding of polymers and how they can contribute to making life and lives better. At UT, our commitment is to contribute to the creation of a more just, prosperous, and sustainable future through world-class research and scholarship. Our polymer scientists and engineers are doing just that!”

About the ranking

The polymer science ranking is determined by 10 indicators, including the impact of citations and research publications. Impact is calculated based on data from the Clarivate Web of Science, a web-based research platform. The Web of Science is a web-based research platform that covers more than 21,100 of the most influential and authoritative scholarly journals worldwide in the sciences, social sciences, and arts and humanities.

water jug

UT Professors Investigate Solutions for “Forever Chemicals”

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University of Tennessee, Knoxville faculty members Shawn Campagna, professor and associate department head in chemistry, and Frank Loeffler, Governor’s Chair professor in microbiology, have made a discovery that could lead to new capabilities for managing environmental contamination.

Commercially used per- and polyfluoroalkyl substances (PFAS) were developed in the 1940’s and made their way into a variety of common household products. Today, PFAS are used for plastic and rubber manufacturing and in food wrappers, umbrellas, firefighting foam and more.

PFAS have also been called “forever chemicals” due to their resistance to breaking down in both the environment and the human body. PFAS have been discovered lingering in rivers, Arctic sea ice, human breast milk and in the blood of 97% of Americans. Most troublesome is their potential impact on human health and PFAS have been linked to metabolic disruption, obesity, diabetes, immune suppression, and cancer.

Loeffler and Campagna’s work, recently published in Environmental Science and Technology, explores a potential avenue for decreasing broad contamination with these chemicals. Their team found that a naturally occurring soil bacterium, Pseudomonas sp. strain 273, was capable of degrading and detoxifying 1,10-difluorodecane, a fluorinated compound that could be a model for dealing with PFAS. Surprisingly, this bacterium was also able to use the fluorine containing byproducts to build lipid bilayers, or cellular membranes, which indicates that we don’t yet know all that we should about the fate of this type of compounds in biological systems.

“This research is important since fluorinated organic chemicals are emerging contaminants, and we do not yet know how and if they enter the food web,” said Campagna. “The fact that bacteria can incorporate breakdown products of these molecules into their biomass indicates that we don’t fully understand the environmental impact of these contaminants.”

This discovery developed from a long-standing series of collaborations between Campagna and Loeffler and leverages the capabilities of both the Center for Environmental Biotechnology and the Biological and Small Molecule Mass Spectrometry Core.

“There is a pressing need to demonstrate that natural degradation processes for PFAS exist – that they are not forever chemicals,” said Loeffler. “The new findings emerged through collaborative efforts at the interface of disciplines, specifically environmental microbiology and analytical chemistry. My group obtained and characterized the unique microorganism, and Dr. Campagna’s group had the instrumentation and expertise to perform the analytical procedures. The results are a product of teamwork and neither group individually would have succeeded.”

Campagna and Loeffler hope their work can lead to further discoveries of bacteria capable of degrading the entire range of fluorinated pollutants, which could lead to removing PFAS from contaminated areas like drinking water.

As part of the bipartisan infrastructure law funding initiative, the U.S. Environmental Protection Agency is making available $1 billion in grant funding, the first of $5 billion through the law. This initiative aims at reducing PFAS in drinking water specifically in communities facing disproportionate impacts.

Both Loeffler and Campagna have been contacted by the Tennessee Department of Environment and Conservation (TDEC) regarding state mandated PFAS monitoring in drinking water. Their capabilities are facilitating statewide efforts to improve the quality of life for all residents of the state of Tennessee.

Brantley Group Published in JACS

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The Brantley group recently published a paper in JACS entitled “Electroediting of Soft Polymer Backbones” Alan Fried, Breana Wilson, and Nick Galan contributed to the research, under the supervision of Johnathan Brantley.

The paper discusses new methodology for degradation and functionalization of olefin-containing polymers through electrochemistry. This method can be carried out in both homogeneous and heterogeneous systems, in addition to using mild conditions and being experimentally simple.

The work was completed in memory of Alan Fried.