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November 2020

Archives for November 2020

Darko Lab Published in Dalton Transactions

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The Darko Lab published their work “Tuning Rh(ii)-catalysed cyclopropanation with tethered thioether ligands” in Dalton Transactions. 

Dirhodium(II) paddlewheel complexes have high utility in diazo-mediated cyclopropanation reactions and ethyl diazoacetate is one of the most commonly used diazo compounds in this reaction. In this study, the lab reports efforts to use tethered thioether ligands to tune the reactivity of RhII-carbene mediated cyclopropanation of olefins with ethyl diazoacetate.

Microwave methods enabled the synthesis of a family of RhII complexes in which tethered thioether moieties were coordinated to axial sites of the complex. Different tether lengths and thioether substituents were screened to optimise cyclopropane yields and minimise side product formation.

Good yields were obtained when equimolar diazo and olefin were used. Structural and spectroscopic investigation revealed that tethered thioethers changed the electronic structure of the rhodium core, which was instrumental in the performance of the catalysts. Computational modelling of the catalysts provided further support that the tethered thioethers were responsible for increased yields.

Vogiatzis Group Published in JCTC

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Electronic structure theory describes the motions of electrons in atoms or molecules, and provides a versatile framework for the calculation of molecular geometries, chemical bonding, electronic and spectroscopic properties, reaction barriers, intermolecular interactions, and more. Wave function theory-based methods such as coupled-cluster methods, provide accurate results in a systematic manner, but they typically carry a significant computational cost.

The Vogiatzis group uses machine learning, the field of study allowing computers to learn without explicit programming, to provide novel approaches on the learning of the underlying electronic structure while subverting a significant portion of the computational expense. In a recent article published in the Journal of Chemical Theory and Computation, Jacob Townsend, under the supervision of Kostas Vogiatzis, presents a new efficient methodology that explores the local nature of the correlated motion of electrons which offers scalability and transferability between different chemical systems.

The novel approach provides coupled-cluster quality electronic energies at the cost of second-order perturbation theory (MP2), a computationally more affordable method. As a result, the authors were able to predict energies of a large molecular database, known as the GDB-9 dataset, at high accuracy at Jacob Townsenda fraction of the cost. Additionally, it was shown that the introduced method could be used to accurately predict energies of large chemical systems based on models trained on smaller ones.

Townsend recently received his PhD in the chemistry doctoral program at UT.

Dai 2020 Highly Cited Researcher

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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 2020, fewer than 6,200, or about 0.1%, of the world’s researchers, in 21 research fields and across multiple fields, have earned this exclusive distinction.
Sheng Dai Sheng Dai is among this elite group recognized for 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™.

2020 BOV Meeting Held Virtually

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The annual BOV meeting will be held virtually on November 6, 2020. 

The BOV is a volunteer advisory body dedicated to helping the Department successfully fulfill its teaching, research and service missions and become one of the preeminent chemistry departments in the nation.

The BOV has a vision of enriching the research and teaching endeavors and the intellectual capital of the Department.

Membership on the Board of Visitors is one of the highest honors that the Department can bestow upon its supporters. The professional experience and perspectives represented collectively in the members of the Board is of great value to the department in helping achieve its missions and guide its future directions.

View Schedule Here

View Research Competition  Program

 

Filed Under: BOV

Musfeldt Group Published in Nature Communications

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The Musfeldt group published their work “Site-specific spectroscopic measurement of spin and charge in (LuFeO3)m/(LuFe2O4)1 multiferroic superlattices” in a collaborative piece in Nature Communications.

Interface materials offer a means to achieve electrical control of ferrimagnetism at room temperature as was recently demonstrated in (LuFeO3)m/(LuFe2O4)1 superlattices. A challenge to understanding the inner workings of these complex magnetoelectric multiferroics is the multitude of distinct Fe centres and their associated environments. This is because macroscopic techniques characterize average responses rather than the role of individual iron centres.

In this article, researchers combine optical absorption, magnetic circular dichroism and first-principles calculations to uncover the origin of high-temperature magnetism in these superlattices and the charge-ordering pattern in the m = 3 member. In a significant conceptual advance, interface spectra establish how Lu-layer distortion selectively enhances the Fe2+ →  Fe3+ charge-transfer contribution in the spin-up channel, strengthens the exchange interactions and increases the Curie temperature.

Comparison of predicted and measured spectra also identifies a non-polar charge ordering arrangement in the LuFe2O4 layer. This site-specific spectroscopic approach opens the door to understanding engineered materials with multiple metal centres and strong entanglement.

Dai Group Published in Advanced Energy & Sustainability Research

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The Dai Group published their work “Organic Cathode Materials for Lithium‐Ion Batteries: Past, Present, and Future” in Advanced Energy & Sustainability Research.

With the rapid development of energy storage systems in power supplies and electrical vehicles, the search for sustainable cathode materials to enhance the energy density of lithium‐ion batteries (LIBs) has become the focus in both academic and industrial studies. Currently, the widely utilized inorganic cathode materials have suffered from drawbacks such as limited capacity, high energy consumption in production, potential safety hazards, and high‐cost raw materials. It is necessary to develop green and sustainable cathode materials with higher specific capacity, better safety property, and more abundant natural resources.

As alternatives, organic cathode materials possess the advantages of high theoretical capacity, environmental friendliness, flexible structure design, systemic safety, and natural abundance, making them a promising class of energy storage materials.

This research reviews the development history of the organic cathode materials and recent research developments, introducing several categories of typical organic compounds as cathode materials for LIBs, including conductive polymers, organosulfur compounds, organic radical compounds, organic carbonyl compounds, and organic imine compounds. The electrochemical performance, electrode reaction mechanism, and pros and cons of different organic cathode materials have been comparatively analyzed to identify their challenges to be addressed.

The future research and improvement directions of the organic cathode materials have also been proposed in this review.

Dai Group Published in I&EC

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The Dai Group published their work “Mechanochemical Synthesis of High-Purity Anhydrous Binary Alkali and Alkaline Earth Chloride Mixtures” in the Journal of Industrial and Engineering Chemistry (I&EC).

A direct synthesis route for high-purity, anhydrous binary salt mixtures has been developed. This atom efficient, solvent-free process is easily scalable, with the potential to produce salt mixtures that meet the purity standards required for industrial heat transfer and nuclear applications. The essence of the methodology lies in mechanochemical synthesis of carnallite precursors that can mitigate the hydrolysis of MgCl2·6H2O under direct heating. Each dehydrated salt carnallite was then analyzed for purity and oxide content through subsequent powder X-ray diffraction, and strong acid titration. This process presents a more effective alternative route compared to previous methods for obtaining low-oxide, high-purity chloride salt mixtures.

Phillip Halstenberg, graduate student, oversaw all experimentation and writing of this manuscript. Dmitry Maltsev was responsible for pXRD
measurements and data evaluation. Ellie Kim and Dianna
Nguyen performed titrations and calculations to quantify oxide
content as part of their undergraduate research. Sheng
Dai advised and oversaw all experimentation.

Campagna Lab Published in JNP

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The Campagna Lab published their work “Isoflurane anesthesia disrupts the cortical metabolome” in a collaborative piece in the Journal of Neurophysiology (JNP). 

Identifying similarities and differences in the brain metabolome during different states of consciousness has broad relevance for neuroscience and state-dependent autonomic function. This study focused on prefrontal cortex (PFC) as a brain region known to modulate states of consciousness.

Anesthesia was used as a tool to eliminate wakefulness. Untargeted metabolomic analyses were performed on microdialysis samples obtained from mouse PFC during wakefulness and during isoflurane anesthesia.

Analyses detected 2153 molecules, 91 of which could be identified. Analytes were grouped as detected during both wakefulness and anesthesia (n=61), and as unique to wakefulness (n=23) or anesthesia (n=7). Data were analyzed using univariate and multivariate approaches. Relative to wakefulness, during anesthesia there was a significant (q < 0.0001) four-fold change in 21 metabolites. During anesthesia 11 of these 21 molecules decreased and 10 increased.

The Kyoto Encyclopedia of Genes and Genomes database was used to relate behavioral state specific changes in the metabolome to metabolic pathways. Relative to wakefulness, most of the amino acids and analogs measured were significantly decreased during isoflurane anesthesia. Nucleosides and analogs were significantly increased during anesthesia. Molecules associated with carbohydrate metabolism, maintenance of lipid membranes, and normal cell functions were significantly decreased during anesthesia.

Significant state-specific changes also were discovered among molecules comprising lipids and fatty acids, monosaccharides, and organic acids. Considered together, these molecules regulate point to point transmission, volume conduction, and cellular metabolism. The results identify a novel ensemble of candidate molecules in PFC as putative modulators of wakefulness and the loss of wakefulness.

Barnes Wins FYCA Faculty Lead Award

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The First Year Course Academy (FYCA) provides resources, tools, and information to help UT-Knoxville instructors make a difference for students enrolled in their first-year courses. FYCA is a new initiative to equip instructors of these courses with best practices for teaching and engaging with first-year students in online, hybrid, and hyflex courses. The Office of the Provost, Teaching & Learning Innovation, the Division of Student Success, and the Office of Information Technology have partnered to make these resources and information available to instructors of the 15 highest-enrolled courses with first-year students.

These courses are:

  • Biology 101 & 150
  • Chemistry 120
  • Engineering Fundamentals 151
  • English 101 & 102
  • Geography 131
  • Geology 101
  • Psychology 110
  • Math 119, 123, 125, 141, & 130
  • Sociology 120

All of these courses are also significant for our campus because of the high drop, fail, and withdrawal rate for our students. The FYCA program is also intended to help improve these concerns and equip our instructors with the tools they need to be advocates of student success.

Department of Chemistry’s, Christiane Barnes, has received a Faculty Lead Award for the work she did with Noodle partners for the development of FYCA.

“I enjoyed working with the Noodle people this past summer.  Building the Chem 120 course shell made me look at the course material and the way we set up the course on Canvas from a different perspective,” Barnes said. “It was truly an educational experience and it gave me a better grasp on the delivery of course content when you are teaching online. We are currently working on a new Chem 130 course shell and I believe it will even be better than the one we did this past summer.”

Brantley Group Published in ACS Macro Letters

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The Brantley Group published their work “General Access to Allene-Containing Polymers Using the Skattebøl Rearrangement” in ACS Macro Letters. Primary author is Nick Galan, graduate student in the Brantley Group.

Postsynthetic modification is a powerful strategy for tuning soft materials. While methods for side-chain functionalization abound, modifications of backbone structural elements can be difficult to achieve. This challenge arises, in part, from a lack of intrinsically reactive motifs that can be installed in the main chain of a polymer. Incorporating established synthetic handles into polymer architectures is paramount for overcoming this limitation.

Allenes are salient examples of moieties that could be leveraged in a wide range of postsynthetic modifications; however, the synthesis of a polyallene has proven elusive. Using the metathesis polymer of norbornene as a model architecture, the Brantley Group have established the Skattebøl rearrangement as a facile route to polyallenes. Polymers with varying allene content (20–95%) were readily prepared in excellent yields (89–94%). These materials possess unique optical properties and can be engaged through further postsynthetic modifications. As such, polyallenes could serve as valuable platforms for developing functional soft materials.

Nicholas Galan
Nick Galan

“Our results suggest that installing allenes within soft materials could open underexplored chemical space for polymer design and modification,” Galan said. “As such, we expect that our work will serve as a general platform for developing new types of tunable or stimulus-responsive materials.”