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April 2021

Archives for April 2021

Musfeldt Group Published in 2D Materials

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The Musfeldt group published their work “Exploring few and single layer CrPS4 with near-field infrared spectroscopy” in 2D Materials. First author is Sabine Neal, UT chemistry alum.

“We combine synchrotron-based near-field infrared spectroscopy and first principles lattice dynamics calculations to explore the vibrational response of CrPS4 in bulk, few-, and single-layer form,” Neal said. “Analysis of the mode pattern reveals a C2 polar + chiral space group, no symmetry crossover as a function of layer number, and a series of non-monotonic frequency shifts in which modes with significant intralayer character harden on approach to the ultra-thin limit whereas those containing interlayer motion or more complicated displacement patterns soften and show inflection points or steps.”

This is different from MnPS3 where phonons shift as 1/size2 and are sensitive to the three-fold rotation about the metal center that drives the symmetry crossover. “We discuss these differences as well as implications for properties such as electric polarization in terms of presence or absence of the P–P dimer and other aspects of local structure, sheet density, and size of the van der Waals gap,” Neal said.

Figure 1. (a) Crystal structure of CrPS4 at 300 K [23]. The sheet thickness and size of the van der Waals gap are indicated. (b) Schematic of the near-field infrared technique in which an atomic force microscope (AFM) cantilever tip directs light to the sample surface. (c) High resolution AFM image of exfoliated CrPS4. (d) Schematic diagram of the symmetry subgroup relationships as they pertain to the presence or absence of a phosphorus dimer.

Remembering Fred M. Schell

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Fred SchellOn Tuesday, April 13, 2021, Fred Martin Schell, loving father and educator passed away at the age of 77.

Schell was born in Cincinnati Ohio to Horace and Rose Schell. He received his BS in pharmaceutical science from the University of Ohio and his PhD in Organic Chemistry from Indiana University.

Schell served on the faculty of the University of Tennessee’s Department of Chemistry for over thirty years as a professor, researcher, and administrator. He joined the chemistry faculty at Tennessee in 1972. He has also been a research and development participant at Oak Ridge National Laboratory.

Fred is survived by his two sons, Chris and Greg, his granddaughter Mckinzie and his two sisters Jane Yost and Joy Yungbluth.

Musfeldt Group Published in npj 2D Materials and Applications

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The Musfeldt Group published their work “Chemical bonding and Born charge in 1T-HfS2” in npj 2D Materials and Applications. This is a collaborative research with the Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN. 

Their research combines infrared absorption and Raman scattering spectroscopies to explore the properties of the heavy transition metal dichalcogenide 1T-HfS2. They employ the LO–TO splitting of the Eu vibrational mode along with a reevaluation of mode mass, unit cell volume, and dielectric constant to reveal the Born effective charge.

 In addition to resolving the controversy over the nature of chemical bonding in this system, we decompose Born charge into polarizability and local charge. Polar displacement-induced charge transfer from sulfur p to hafnium d is responsible for the enhanced Born charge compared to the nominal 4+ in hafnium. 1T-HfS2 is thus an ionic crystal with strong and dynamic covalent effects. 

This work places the vibrational properties of 1T-HfS2 on a firm foundation and opens the door to understanding the properties of tubes and sheets.

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Chemistry of Learning: Machines and Humans

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New courses the Department of Chemistry is offering:

Artificial intelligence (AI) rapidly changes many aspects of chemical sciences, from drug discovery, material design, and the discovery of new reactions and molecules till the acceleration of computer sciences and robotics for chemical applications. In Fall 2021, Dr. Vogiatzis will be teaching Machine Learning for Chemical Applications (CHEM420). This course will cover the key aspects of AI and modern chemoinformatics and how they are applied on chemical sciences.
For more information on this course please email kvogiatz@utk.edu.

In the Spring 2022, students may register for Chemistry of the Brain (CHEM340) with Dr. Sharma. This course will be an overview of basic principles of neuroscience with a focus on the function of key neurochemicals and their receptors. Topics include the chemical bases for neuronal membrane transport, electrical excitability, and ion channels; axonal transport; energy metabolism; synaptic transmission; cellular signaling; Ca2+ homeostasis; neurotransmitters; oxidative stress; apoptosis and necrosis; application of neurochemical principles to the molecular bases of neurodegenerative disorders. Co-Requisite: Organic Chemistry. For more information on this course please email bhavya.sharma@utk.edu.

Long Group Published in Chem. Eur. J.

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The Long Group published their research “Mechanochemical Formation, Solution Rearrangements, and Catalytic Behavior of a Polymorphic Ca/K Allyl Complex” in Chemistry—A European Journal. Authors Brian Long and Alicia Doerr, graduate student, collaborated with Vanderbilt University and the University of Rochester. 

Without solvents present, the often far‐from‐equilibrium environment in a mechanochemically driven synthesis can generate high‐energy, non‐stoichiometric products not observed from the same ratio of reagents used in solution. Ball milling 2 equiv. K[A´] (A´ = [1,3‐(SiMe3)2C3 H3]– ) with CaI2  yields a non‐stoichiometric calciate, K[CaA´3], which initially forms a structure (1) likely containing a mixture of pi‐ and sigma‐bound allyl ligands. Dissolved in arenes, the compound rearranges over the course of several days to a structure (2) with only  η3‐bound allyl ligands, and that can be crystallized as a coordination polymer. If dissolved in alkanes, however, the rearrangement of 1 to 2 occurs within minutes. The structures of 1 and 2 have been modeled with DFT calculations, and 2 initiates the anionic polymerization of methyl methacrylate and isoprene; for the latter, under the mildest conditions yet reported for a heavy Group 2 species (one‐atm pressure and room temperature).

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Albert and Suoma Tuinman’s Passing

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It is with deep sorrow we announce the death of Albert Andrew Tuinman and Suoma Annikki Tuinman.  The couple passed away in their home on March 16, 2020.  Albert came to the University Of Tennessee Department of Chemistry from the Cancer Research Institute in Tempe, AZ serving in the position of Director of Mass Spectrometry and Research Associate Professor from March 1987 until his retirement in April 2006.  A Celebration of Life ceremony will be held May 29, 2021 at the Norris United Methodist Church, 62 Ridgeway Road, Norris, TN 37828, at 10:45 AM.  The hybrid event will include friends and family throughout Europe and South Africa.  Friends of the Tuinmans are invited to attend either in person or on Zoom. For those interested in attending the event through Zoom, please send Linda Lewis (lewisla7755@gmail.com) your desire to participate.

Bone Selected to Attend NX School

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Alex Bone, graduate student in the Xue Group, has been selected to attend the Twenty-Third National School on Neutron and X-ray Scattering to be held virtually from Oak Ridge National Laboratory and Argonne National Laboratory.

Due to the COVID-19 pandemic, the National School on Neutron and X-ray Scattering (NX School) will be held virtually from July 12-30, 2021. The first week of the program will consist of half day lecture sessions, the second and third week will be lectures, remote experiments and data analysis tutorials.

The main purpose of the National School on Neutron and X-ray Scattering is to educate graduate students in the use of major neutron and x-ray facilities. Lectures, presented by researchers from academia, industry, and national laboratories, include basic tutorials on the principles of scattering theory and the characteristics of the sources, as well as seminars on the application of scattering methods to a variety of scientific subjects. Students will conduct short remote experiments at Argonne’s Advanced Photon Source and at Oak Ridge National Laboratory’s Spallation Neutron Source and High Flux Isotope Reactor, which provides hands-on experience using neutron and synchrotron sources.

This year’s NX School will be three weeks in length. The first week will consist of half day lecture sessions. The second two weeks will be full-time consisting of lectures and remote experiments.

Jointly Conducted by: Argonne National Laboratory’s, Advanced Photon Source and Materials Science Division, and Oak Ridge National Laboratory’s Neutron Sciences Directorate and Materials Science and Technology Division.

The School is supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, and Materials Sciences and Engineering Division.

Tin Awarded Shull Wollan Center Graduate Research Fellowship

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Pagnareach (Reach) Tin, graduate student in the Xue Group, has been awarded the Shull Wollan Center Graduate Research Fellowship for Spring 2021.

The Shull Wollan Center Graduate Research Fellowship Program has been designed to recognize and support outstanding graduate students in neutron science disciplines who are pursuing research-based doctoral degrees at the University of Tennessee, Knoxville. 

The Shull Wollan Center Graduate Research Fellowship will be awarded to two UTK doctoral students with majors in physics, chemistry, materials science and engineering, biology, or a related area who are engaged in active research as part of their PhD thesis.  Successful applicants will be awarded a monthly stipend for January through June 2021.

Sharma Announced Winner of 2021 Emerging Leader in Molecular Spectroscopy

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Bhavya Sharma, assistant professor, has been named the winner of the 2021 Emerging Leader in Molecular Spectroscopy Award. The award will be presented to Sharma at the SciX 2021 conference this fall, where she will give a plenary lecture and be honored in an award symposium.

“We would like to extend congratulations to Professor Sharma for winning the 2021 Emerging Leader in Molecular Spectroscopy Award,” said Mike Hennessy Jr., president and CEO of MJH Life Sciences™, the parent company of Spectroscopy®. “Sharma is well deserving of this recognition for all of her excellent work as a molecular spectroscopist. We are proud to honor her with this award at the SciX conference this fall.”

Sharma received her Ph.D. from the University of Pittsburgh in 2011. She has become a leader in the area of neurochemical detection with various forms of Raman spectroscopy, including surface-enhanced Raman spectroscopy (SERS) and spatially offset Raman spectroscopy. Sharma has developed novel Raman spectroscopy methods for neurological detection, including surface-enhanced spatially offset Raman spectroscopy. Additionally, she is developing methods to demonstrate direct detection of molecules for the first time by combining SERS and multivariate analysis.

Sharma has published 26 papers and has given more than 40 oral and poster presentations at scientific conferences. She is a reviewer for multiple journals and received an Outstanding Reviewer award for the journal Analyst in 2018. As an active member of the Coblentz Society, Sharma has served on multiple award committees and was also a member of the program committee for the OSA Optical Sensors Conference for 2018 and 2019. Sharma has also been active in organizing sessions at various scientific conferences, including Pittcon, the SPIE Defense + Commercial Sensing Symposium, and SciX. 

Selected by an independent scientific committee, the Emerging Leader in Molecular Spectroscopy Award recognizes the achievements and aspirations of a talented young molecular spectroscopist who has made strides early in his or her career toward the advancement of molecular spectroscopy techniques and applications. The winner must be within 10 years of receiving his or her PhD. 

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Doerr Selected for Prestigious Symposium

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Alicia Doerr, graduate student in the Long Group, has been selected to take part in the ACS national meeting’s symposium entitled “Excellence in Graduate Polymer Research.” This annual symposium is organized by the POLY division and held at Spring national meetings of the ACS to recognize outstanding graduate students in polymer science and engineering, foster networking and exposure, and help develop the careers of future leaders in the field of polymers. This symposium was started in 2004 and includes both oral and poster sessions with presentations exclusively from graduate students.

Due to this meeting’s hybrid nature, the ACS POLY division created an independent web page to highlight the accomplishments of these graduate scientists. 

Doerr’s research explores the field of redox-switchable catalysis which has gained considerable interest in recent years, enabling catalytic reactivity/selectivity to be oscillated based on the redox-state of the ligand or active metal center. Unfortunately, though a myriad of redox-switchable catalysts have been developed for the ring opening polymerization of cyclic esters, very few fundamental structure-catalytic performance studies have been conducted that ascertain how systematic changes in ligand structure affect the catalytic performance.

This work describes studies used to determine how changes in the placement and number of redox-active moieties, ligand denticity, and active metal center identity impacts the catalytic performance.

The results of these studies reveal that the proximity of the redox-active moiety to the active metal center may influence both catalyst activity and redoxswitchability. Conversely, the number of redox-active moieties present within the ligand scaffold may not play a crucial role in the catalysts’ switchability. Lastly, when Ti-/ Zr-centered analogues of these catalysts were compared it was revealed that the choice of metal center may dramatically influence both catalyst activity and redox-switchable.