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Brantley Lab Publishes in ACS Macro Letters

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The Brantley Lab published their article “Controlled Polymerization of β-Pinadiene: Accessing Unusual Polymer Architectures with Biomass-Derived Monomers” in ACS Macro Letters. Alan Fried, graduate student in the Brantley Lab, is the primary author of this work.

Biomass-derived polymers are emerging as critically needed alternatives to their petrochemical counterparts. Terpenes, which are among the most abundant natural products, represent particularly fertile chemical space for monomer development. 

“Here, we present the living vinyl-addition polymerization of β-pinadiene at room temperature,” Fried said. “Employing [(π-allyl)NiOCOCF3]2 as a catalyst afforded the desired polymers with good control over molecular weight and dispersity.”

The research shows the bicyclic pinane core was retained in the isolated materials and the reported materials exhibited impressive thermal stability and high glass transition temperatures.

“As the polymerization of terpene-derived cumulenes can afford scaffolds that defy current synthetic logic, we anticipate our work will unlock additional avenues for sustainable polymer development,” Fried said.

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Reynolds in Roy Lab Named Goldwater Scholar

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Five students have been named 2020–2021 Goldwater Scholars, ranking the University of Tennessee, Knoxville, first in the country for the prestigious award.

The Goldwater Scholarship Program was established by Congress in 1986 to honor US Senator Barry M. Goldwater. The most prestigious undergraduate STEM scholarships in the United States, Goldwater Scholarships are awarded to college sophomores and juniors who intend to pursue research careers in the natural sciences, mathematics, and engineering. The scholarships provide up to $7,500 annually to cover tuition, fees, books, and room and board. An estimated pool of more than 5,000 sophomores and juniors nationwide applied this year for the Goldwater.

“To lead the country in Goldwater Scholars is a tremendous achievement, a reflection of our nationally competitive undergraduates, and of course a credit to these five outstanding future STEM research leaders,” said Provost and Senior Vice Chancellor David Manderscheid, who is also a professor of mathematics. “These results also underscore our robust undergraduate research infrastructure and the high quality of faculty mentoring our undergraduates receive.”

Several thousand sophomores and juniors nationwide seek their institution’s nomination to the Goldwater national competition. UT can nominate up to five undergraduates. This year 396 Goldwater Scholars were named from the 1,343 students nationwide nominated by 461 colleges and universities.

“The Goldwater competition is rigorous and unfolds over several months, which gives our staff a chance to get to know the students, their goals, and what drives them. Their passion for discovery really rubs off,” said Andrew Seidler, director of UT’s Office of National Scholarships and Fellowships, which facilitates the campus nomination process. “Seeing their potential recognized in this way is so satisfying—personally and professionally. It’s exciting to imagine what lies ahead for them”

Kristopher Reynolds

Kristopher Reynolds, a junior from Coalfield, Tennessee, studying chemistry and biology

Reynolds is a Marine Corps veteran and currently serves as the president of UT’s SALUTE chapter, a national veterans honor society working to serve student veterans. The organization helps connect students with resources about education and career planning. At UT, he is conducting research regarding molecular electronics and integrated circuits and spent the prior two summers conducting research at Harvard.

“I am tremendously honored to have been selected as a Goldwater Scholar and join a community of talented scientists and leaders in shaping the way we conduct research to become more inclusive and tackle the scientific challenges that the world faces and will face in the near future,” Reynolds said.

Reynolds plans to pursue a graduate degree in chemistry, studying the charge and mass transport phenomena between material interfaces. Reynolds ultimately wants to lead a research group at a university or national laboratory.

“We must always remember that science knows no ethnicity or gender; it knows only curiosity and truth, and as long as we confront nature with an open mind, she will humble us every day,” Reynolds said.

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Long Research Group Publishes Study on Mechanochemical Synthesis of Mg/K Allyl Complex

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Members of the Long Research Group, a Department of Chemistry lab headed by Associate Professor Brian Long, published an article titled “An η3‐Bound Allyl Ligand on Magnesium in a Mechanochemically Generated Mg/K Allyl Complex” in the German Chemical Society’s journal Angewandte Chemie.

Members of the research group focus on the use of organic synthesis, polymer chemistry, organometallic design, and polymer science to design and create advanced polymeric materials and to develop and study next-generation polymerization catalysts.

The group’s article concentrates on the mechanochemical synthesis of a magnesium (Mg) and potassium (K) allyl complex.

“Mechanochemistry has emerged as an intriguing synthetic method that utilizes mechanical force or energy to drive reactions in a simplified and solvent free manner,” said Alicia Doerr, a graduate teaching assistant with the Long Research Group.

The study was done in conjunction with the Hanusa Research Group at Vanderbilt University.

“Through use of this synthetic technique, the Hanusa Research Group was able to access a unique Mg/K allyl complex that could not be accessed by conventional solution-based synthetic techniques,” Doerr said. “We evaluated the polymerization activity of these catalysts for a variety of monomers and found that they are particularly active for the polymerization of methyl acrylates. This collaboration combines the classic inorganic expertise of the Hanusa Research Group with the polymer chemistry expertise of the Long Research group to obtain and study this unique catalyst system.”

Written by Kelly Alley

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Dai Lab Publishes Study on High-Entropy Perovskite Fluorides

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Members of the Dai Lab, a Department of Chemistry lab headed by Professor Sheng Dai, recently published an article titled “High-Entropy Perovskite Fluorides: A New Platform for Oxygen Evolution Catalysis” in the Journal of The American Chemical Society.

Members of the Dai Lab focus their research projects on the synthesis and characterization of functional materials for energy-related applications, including electrical energy storage.

This study highlights oxygen evolution reactions (OERs) and the beneficial uses of high-entropy perovskite fluorides (HEPFs) in oxygen evolution catalysts.

“The oxygen evolution reaction is a critical process for many energy storage options, such as water splitting and metal-air batteries,” said Tao Wang, a post-doc working with the lab.

HEPFs consisting of cost-effective elements can act as excellent catalysts for OREs in an alkaline medium.

“HEPFs can provide a new platform for oxygen evolution catalysis,” Wang said. “Moreover, the flexible synthesis of HEPFs in a boiled solution combining the hydrothermal method with mechano-chemistry, provides a new concept for the low-temperature synthesis of high entropy materials.”

Written by Kelly Alley

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Dai Lab Publishes Study in Nature Communications

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Members of the Dai Lab, a Department of Chemistry lab headed by Professor Sheng Dai, recently published an article titled “Mechanochemical synthesis of pillar[5]quinone derived multi-microporous organic polymers for radioactive organic iodide capture and storage” in the Nature research journal Nature Communications.

Members of the Dai Lab studied porous organic polymers (POPs), high surface area materials with sponge-like qualities. These POPs can be easily designed and constructed at molecular levels.

The incorporation of supramolecular macrocycles with the reservation of their cavities into porous organic polymers may endow the material with enhanced uptake of specific guests through host−guest interactions,” said Kecheng Jie, a post-doctoral research associate working with the lab. “This work demonstrates not only a new synthetic pathway to porous polymers but also the superiority of the incorporation of a supramolecular host into porous polymers for guest uptake.”

Written by Kelly Alley

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Jenkins Group Published in Angewandte Chemie

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The Jenkins Group published their work “A Benchtop Method for Appending Protic Functional Groups to N‐Heterocyclic Carbene Protected Gold Nanoparticles” in the highly-profiled journal Angewandte Chemie. Joseph DeJesus is the first author and recent PhD alumus from the Department of Chemistry’s program. 

This piece explores the resilience of N‐heterocyclic carbene (NHC) gold bonds. They synthesize NHC‐functionalized gold surfaces from gold(I) NHC complexes and aqueous nanoparticles without the need for additional reagents, enabling otherwise difficult functional groups to be appended to the carbene.

The resilience of the NHC−Au bond allows for multi‐step post‐synthetic modification. “Beginning with the nitro‐NHC, we form an amine‐NHC terminated surface, which further undergoes amide coupling with carboxylic acids,” DeJesus said.  “The simplicity of this approach, its compatibility with aqueous nanoparticle solutions, and its ability to yield protic functionality, greatly expands the potential of NHC‐functionalized noble metal surfaces.”

Musfeldt Group Published in Inorganic Chemistry

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The Musfeldt Group recently published their work “Spin-Lattice Coupling Across the Magnetic Quantum-Phase Transition in Copper-Containing Coordination Polymers” in Inorganic Chemistry.

The group employs a series of copper-containing coordination polymers as a platform for exploring spin−lattice coupling across the magnetic quantum-phase transition. This interaction, which they quantify for the out-of-plane pyrazine bending mode as a function of the magnetic and structural dimensionality, reaches a maximum in ladderlike [Cu(pyz)1.5(4-HOpy)2](ClO4)2 because of the intermediate dimensionality.

They also sought to reveal spin−phonon coupling under compression but instead discovered a pressure-induced transition in the ladder to a state that is likely ferroelectric.

Dadmun Group Published in ACS Applied Nano Materials

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The research in Dadmun Group utilizes a variety of techniques to examine methods by which the properties of polymer mixtures can be optimized by control of dispersion size or by the selective migration of a polymeric additive to the surface.

The group was recently published in ACS Applied Nano Materials for their work “Impact of Substrate Rigidity on the Structure of Multilayer Nanoscale ITO Films: Implications for Flexible Electronic Devices.” 

This research looks into polymeric substrates, which have become increasingly important in the recent drive in technology to produce flexible displays and mechanically adaptable devices. Multi-nanoscale layer coatings are often necessary for specific device applications, and these complex coatings are often fabricated by sputtering onto the substrate.

The work presented here investigates the impact of depositing increasingly thick bilayer films of indium tin oxide (ITO) and tungsten (W) on flexible (poly(ethylene terephthalate) (PET)) and rigid (silicon) substrates by utilizing complementary characterization methods of X-ray and neutron reflectivity to study the nanoscale structures (depth profile and interfacial breadth) between layers. 

This fundamental study defines the influence of substrate properties on coating composition, density, and interfacial structure at the nanoscale—all of which play important roles in the application specific properties and function of the targeted bilayers. The findings from this study have implications on the nanoscale structure in flexible functional thin films used in a wide range of applications such as flexible television and smartphone displays.

Sharma Lab Published in Analytical Chemistry and Analyst

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The Sharma Raman Lab published their work “Direct Surface Enhanced Raman Spectroscopic Detection of Cortisol at Physiological Concentrations” in Analytical Chemistry.

Josh Moore is the first author on this piece and recently earned his PhD in the Chemistry program.

Cortisol is an important steroid hormone in vertebrate physiology and plays a role in acute and chronic stress response. Current methods for determination of cortisol concentrations in biofluids require extensive sample preparation and long run times. Raman spectroscopy is an attractive alternative because analysis is rapid and non-destructive to the sample.

The Sharma Lab has developed a surface-enhanced Raman spectroscopy (SERS)-based method for detection of cortisol in ethanol that shows a sigmoidal concentration response and a limit of detection of 177 nanomolar, which is in the physiologically relevant range. The method can be applied to more complex solvent environments through the use of multivariate analysis techniques, where principal components analysis (PCA) demonstrates a linear separation according to cortisol concentration in a serum mimic. “We are, to our knowledge, the first group to report on the detection of cortisol using label-free SERS, which does not require a Raman reporter molecule to obtain signal,” Moore said.

The Sharma Lab published their work “Surface-enhanced spatially-offset Raman spectroscopy (SESORS) for detection of neurochemicals through the skull at physiologically relevant concentrations” in Analyst. 

Detection techniques for neurotransmitters that are rapid, label-free, and non-invasive are needed to move towards earlier diagnosis of neurological disease. Surface-enhanced Raman spectroscopy (SERS) allows for sensitive and selective detection of target analytes. The combination of SERS with spatially offset Raman spectroscopy (SORS) in a technique termed surface enhanced spatially offset Raman spectroscopy (SESORS) permits a sensitive and selective detection of neurotransmitters through the skull.

In this piece, the group presents the SESORS detection of individual neurotransmitters and mixtures of neurotransmitters at physiologically relevant concentrations, while also establishing limits of detection.

Brantley Group Publishes in Polymer Chemistry

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The Brantley Group published their work “Ion Specific Fluorescence Modulation of Polyvinyl Alcohol-Boronate Matrices” in Polymer Chemistry. Brian Jacobs, graduate student in the Brantley Lab, is the primary author. 

Borylated polymers are emerging as valuable chemosensors that can report analyte binding through an array of responses. Fluorescent materials are particularly valuable in this regard, as modulation of their photophysical properties can facilitate rapid substrate detection and quantitation.

“In this manuscript, we report the condensation of aryl boronic acids onto polyvinyl alcohol (PVA) to afford fluorescent polymers, a phenomenon that has been widely overlooked,” Jacobs said. “ Importantly, selective modulation of the photophysical properties was observed in the presence of borophilic anions (e.g. fluoride, hydroxide, and cyanide).”

Density functional theory (DFT) calculations, performed by collaborator Jacob Townsend in the Vogiatzis Research Group, suggested that a combination of covalent and non-covalent interactions were crucial for anion binding. Time-dependent DFT computations were also performed to explain the appearance of a distinct peak in the polymer’s absorbace profile.

“Lastly, films of these PVA-aryl boronates were employed in ion extraction studies, highlighting a useful secondary function these materials possess,” Jacobs said. “Given the ease with which these polymers can be accessed, they could serve as general platforms for developing ion selective membranes or detectors.”

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