303 Schrenk Hall
Rolla, MO 6540
*changes noted below
Spring 2023 Speakers & Dates:
*Time changed to 3:00 pm
The S&T Department of Chemistry presents Colloquium and Chemistry Seminar as co-equals mindful of their different purposes. Chemistry seminars will generally address a specialized audience and their content will be of a modest scope. Chemistry Seminars will come in various formats and may address several purposes. There will be talks that last for the entirety of the time, which will be given by 3rd or 4th year graduate students as part of their Ph.D. program and covering the scope of their research. Additionally, there will be seminars presented by invited guest speakers from other departments or other universities with the primary aim of fostering and supporting research collaboration. The final category will allow 1st or 2nd year graduate students, and potentially undergraduate students, to refine their presentation skills and obtain audience feedback by giving 25 minute research presentations. Constructive discussion is always encouraged in all Chemistry Seminars and speakers are asked to leave some fifteen percent of their time for a lively Q&A session. Each seminar is announced on the S&T University Calendar.
If you are a student who needs to sign up to present seminar, please email the Chemistry Seminar Coordinator, Dr. Amitava Choudhury.
Intellectual Property and Entrepreneurship
John E. Woodson, Interim Director of Technology Transfer & Economic Development, Office of Technology Transfer & Economic Development
Abstract: Whether you work for someone else or work for yourself, you should have a basic understanding of the different types of intellectual property and what it takes to insure they retain their value. Corporations and entrepreneurs both need and use intellectual property to create value for the enterprise. This talk will cover the patent process, patents, trademarks, and trade secrets, and it will also cover main considerations for seriously considering entrepreneurship. In order to have any chance to make it as an entrepreneur, you need more than a product, most importantly, you need a customer and a plan.
Quantum computing, quantum teleportation and time crystals
Cheng Hsiao Wu, Professor of Electrical Engineering, Electrical & Computer Engineering, Missouri S&T
Abstract: Quantum computing are parallel computing and are nonlocal in nature. Geometry, physics and computing are triangularly interrelated. There exist four new fundamental nonlocal operator-state relations for an entangled atomic chain. Computation states are then cyclic. There exists a minimum entanglement distance between any two atoms of the chain. Any addition of four times of that distance provides the foundation for quantum teleportation in a piece-wise Euclidean chain. Time crystals are the direct computation results that an entangled chain is capable of computing. There are four interacting planar time crystals with the same Poincare cycle, but only half of the results are observable as we predict and thus quantum computing is “irreversible”. However, when geometry changes, there exist “spherical time crystals” from the rotational symmetry breaking. Thus, we predict “time” can be “curved” in the Fourier space, the space we observe all the parallel computation results. In long entangled chain, a small section of time crystal can be duplicated elsewhere of the chain with “birth-and-death’ capability in addition to the “perpetual motion” claimed by the Google group last July. Sierpinski triangle with self-similar features provides the foundation for the true artificial intelligence where larger scales of operator-state space-time relations emerge.
Click to view Dr. Cheng Hsiao Wu's seminar flyer
A Sinuous Search for the Solid Structure of Fe3(CO)12
Fernande Grandjean and Gary J. Long, Emeritus Professor of Physics, University of Liège, Belgium and Adjunct professor of Missouri S&T
Abstract: The search for the solid structure of Fe3(CO)12 beautifully illustrates the mechanism of scientific research, specifically the modification, adjustment, and correction of knowledge through more advanced measurements. This search will use x-ray diffraction, infrared, NMR, and Mössbauer spectral measurements to determine the now well accepted solid structure of Fe3(CO)12 and to better understand the dynamics present in the cluster.
Click to view Dr. Grandjean and Dr. Long's seminar flyer
Vibronic coupling in N-methylpyrrole
Alexander Davies, Post-doctoral fellow, Chemistry, Missouri S&T
Abstract: The 1A2 ← 1A1 (S1 ← S0) electronic transition of N-methylpyrrole (NMP) is electric dipole forbidden. Therefore, one would not expect to observe any structure arising from this electronic transition; however, this is not the case and there is extensive structure, even at low internal energies (> 1100 cm-1 above the S1 origin). Herzberg-Teller coupling (more generally, vibronic coupling) is a complicated, although well-established phenomenon whereby intensity is ‘stolen’ from a nearby electronic state, to which a transition from the 1A1 electronic state is allowed — this is the key to explaining the observed structure. Assignments of the observed bands are made through a combination of resonance-enhanced multiphoton ionisation (REMPI) and zero-electron-kinetic-energy (ZEKE) spectroscopies, briefly mentioning the two-dimensional laser-induced fluorescence (2D-LIF) technique.
Many of the ZEKE spectra are consistent with the 3s Rydberg nature of the 1A2 electronic state (in the Franck Condon region) and the Herzberg-Teller coupling schemes required to prepare the intermediate; however, there is also some activity which is a little more difficult to explain. Comparisons will be drawn to meta-fluorotoluene (mFT), whose S1 ← S0 electronic transition is electric dipole allowed, as well as a brief discussion on how vibrational couplings within the S1 state, arising from anharmonicity, further add to the complexity of an already intriguing molecule.
Click to view Dr. Alexander Davies's seminar flyer
Addressing diffusion in the solid photo- and photoeletrocatalysts
Pravas Deria, Associate professor, School of Chemical & Biomolecular Science, Southern Illinois University-Carbondale
Abstract: Light-driven reactions hold promise to develop processes that can encompass solar energy conversion, organic transformation, to contamination management. To ease the transformations that are energetically challenged or otherwise not thermally allowed—like, kinetically challenged CO2 reduction, organic transformations involving C-H activation, or thermally inaccessible cycloaddition reactions—one needs to build an efficient deployable photocatalysts platform. Traditional solution-dissolved photosensitizers, exploiting their long-lived triplet state, function by providing a time window for slower diffusion and chemical time scale. However, special care must be taken even for those reactions that do not require a triplet excited state (like cycloaddition) to avoid singlet oxygen-derived side products. The primary criteria for scalable solid photocatalysts are challenging it requires efficient exciton/energy transport to the reaction sites and the ability to split the delivered exciton without the involvement of molecular (i.e., photosensitizer) diffusion. This is simply because of fixed photosensitizers where only a small portion, at the outer surface, is exposed to the light. A porous solid, such as a MOF system that allows substrates to diffuse, can only work if the molecular excitons are spatially dispersed and/or easy to displace -possibly along the direction of the major substrate diffusion channel (i.e., anisotropic exciton transfer). System design with the appropriate ground and excited-state potential will, therefore, be the next step to
driving a redox reaction. A picosecond timescale exciton transport and sub-nanosecond timescale exciton splitting should be the primary target to develop such a platform. With such a design in hand, we will show how MOF-based photo redox chemistry works and what are other benefits of this development.
Click to view: Dr. Pravas Deria's seminar flyer
Spatially resolved spectroscopy: Exploring systems at the nanoscale
Dr. Sabine N. Neal, Research Associate Interface Science and Catalysis group Center for Functional Nanomaterials Brookhaven National Laboratory
Abstract: Vibrational spectroscopy is a sensitive probe of complex physical phenomena in both inorganic and organic systems. The analysis of vibrational mode trends and displacement patterns allows for insight into a material’s properties including lattice distortions, phase transitions, charge ordering, and spin-lattice coupling constants, just to name a few. When coupled with external stimuli, such as temperature, pressure, or magnetic field, infrared spectroscopy can reveal the relationships between charge, structure, and magnetism. However, the ability to obtain real space information has proved to be a challenge due to the inability to focus an infrared beam tightly enough to probe nano-sized samples. This issue, however, has been circumvented with the advent ofspatially resolved infrared spectroscopy, such as O-PTIR and tipbased near-field infrared. These techniques have allowed for the comprehensive studies of nanomaterials, from single layer systems to organic high energy materials.
Dr. Sabine Neal's seminar flyer
Metal-Free Photoredox Catalysis for the S-Trifluoromethylation of Heteroaromatic Thiols
Raheemat Rafiu, Graduate Student, Chemistry, Missouri S&T
Abstract: The S-Trifluoromethylation of thiols provides access to pharmaceutically interesting compounds. The current synthetic methods for this trifluoromethylation reaction involve the use of either expensive noble metal-based organometallic catalysts and expensive or hazardous reagents. We have demonstrated a convenient visible-light photoredox catalyzed S-trifluoromethylation of various thiols under metal-free conditions, using the cost-effective sodium trifluoromethanesulfinate (Langlois regent) and diacetyl as the photocatalyst. This novel organocatalysis-based synthetic method provides a convenient and cost-effective alternative to the transition-metal catalyzed photoredox reactions.
Chemistry for Environment and Health
Dr. Michael Eze, Postdoctoral Scholar, Bioinstrumentation and BioMEMS Laboratory, University of California Davis.
Abstract: Industrialization and increasing demand for energy have led to an unabating exploitation of natural resources, especially fossil fuels. Even beneficial activities (such as pest control in agriculture) are leaving behind unwanted and toxic effects. This often results in anthropogenic contamination of aquatic and terrestrial ecosystems, which threatens the survival of our planet and species. Similarly, the experience of the recent pandemic brought to bare the havoc that infectious diseases can cause. Even more important, it has shown the need for rapid and non-invasive diagnostic tools for early detection of diseases. Sadly, most traditional diagnostic methods are both invasive and expensive. In view of the environmental and health impacts of toxic contaminants and infectious diseases, it is worth asking: can science provide the urgently needed panacea? This talk will examine the answers to this question. Specifically, it will
amine eco-friendly approaches for environmental pollutant remediation. It will also highlight how advances in (bio)analytical techniques, metabolomics andchemometrics are helping to innovate non-invasive diagnostic tools for early detection of human and plant diseases.
Development of Machine Learning Potentials for Multicomponent Systems
Ridwan Sakidja, Professor, Physics Astronomy and Materials Sci., Missouri State University, Springfield
Abstract: Developing the interatomic potential models for muti-component systems has been “the holy grail” in the field of computational materials science. In this talk, I will discuss the use of Machine Learning as the means to address this issue quite effectively. With the advancement of GPU resources and GPU-based neural network algorithms, we have a great opportunity nowadays to utilize ML potentials to simulate a wide range of materials phenomena and processing in various scales. Typically, the potential development starts from the database generation through electronic structure calculations within the DFT approximation at ground state as well as elevated temperatures. The subsequently extracted critical data (of energy, stress, and forces) is then fed to the neural network with various schemes of invariant/equivariant representations. The key here is the linear scalability associated with these AI-driven models which in turn enable us to develop large scale atomic-based simulations with potential technological implications. Within this context, I would like to also discuss the feasibility in constructing AI-powered Virtual Autonomous Materials Discovery (v-AMD) to help accelerate materials development.
A journey in electrochemistry: From single nanoparticle to in operando electrochemistry and future opportunities
Dr. César A. Ortiz-Ledón, Postdoctoral Scholar, Department of Chemistry, University of Wisconsin-Madison
Abstract: Electrochemistry is an attractive field that offers a wide range of applications. In the last decade, electrochemistry has found applications to study single entity systems, from developing ultrasensitive sensors for single molecule detection to studying electron transfer reactions at individual metal nanoparticles and extract valuable kinetic information. Besides this, several research groups have coupled electrochemistry with other fields such as spectroscopy, this combination becomes a powerful tool to probe electrochemical reactions and obtained chemical information in situ. In this seminar, first section will explain how electrochemistry is used to study electrocatalysis at single nanoparticles and nanoparticle ensembles with ultramicroelectrode dimensions. What are the advantages of these studies and potential applications to obtain kinetic information at the single nanoparticle level. Following by a section that will cover development of in operando electrochemistry to study electrode-electrolyte interfaces in Li-ion batteries. This section aims to demonstrate how combining other techniques such as gravimetry and infrared spectroscopy with electrochemistry helps to understand the origin of electrolyte degradation in Li-ion. Understanding this interface from Li-ion batteries is of high importance, as these devices are widely used for energy storage and found in multiple electronic devices such as cell phones, laptops, and electric vehicles. The third and last part of this talk will explore what are the future opportunities in electrochemistry and why electrochemical interfaces are important. In this section will bring new strategies to study these interfaces by implementing in operando electrochemistry to study nanoconfined spaces and surface reactivity of electrocatalytic materials. Concluding how electrochemistry is of huge importance to study chemical problems found in energy conversion, energy storage, and electrodeposition of metals.
Forging Robust Nanoscale Catalytic Interfaces for a Sustainable Future
Dr. Junrui Li, Postdoctoral research associate in the Voiland School of Chemical Engineering and Bioengineering, Washington State University
Abstract: There has been increasing interest in achieving a sustainable future with fuels, chemicals and materials obtained from renewable sources. Sustainable materials and energy production requires efficient catalytic processes. Rational design and development of robust catalysts for such processes remains a key challenge. Despite extensive efforts in this research area, new innovations in effective catalytic design at nanoscale levels are limited. This talk covers examples of how robust catalytic interface can be precisely tailored at nanoscale dimensions to achieve an improved performance in green energy power source-fuel cells and in catalytic valorization of renewable biomass derived molecules. The first section illustrates: (1) intermetallic nanostructures with ordered atomic arrangements can stabilize base metals under the aggressive condition of fuel cells; (2) hard-magnet intermetallic nanostructure interfaced with atomically thin Pt overlayers that exhibit extraordinary fuel cell performance; (3) identification of a structural descriptor to guide high-throughput screening and discovery of high-performance catalysts for fuel cells. The second and third sections detailing oxidative valorization of biomass-derived molecules outlines: (1) the discovery and investigation of a Pt-based ternary nanoscale interface that steers the favorable reaction pathway for efficient electrocatalytic utilization of biomass-derived liquid fuels; (2) interfacing Pt with Au at nanoscale dimensions to suppress the oxidation/dissolution of Pt during thermocatalytic oxidation of glucose to achieve high yields to value-added products and long-term stability.
Investigation of RNA binding by the eIF4B translation initiation factor, and dynamics studies of proteins utilizing NMR and other biophysical techniques
Dr. Somnath Mondal, Postdoctoral Research Scientist, Pennsylvania State University, USA
Abstract: Eukaryotic initiation factor 4B (eIF4B) is a multidomain protein with a range of activities that serve primarily to promote the association of messenger RNA to the 40S ribosomal subunit during the translation initiation process. Deletion and site-directed mutagenesis studies have identified a few functional domains within eIF4B, two of which are involved in RNA binding and are implicated in linking mRNA to the 40S ribosomal subunit during translation initiation. An N-terminal RNA recognition motif (RRM; residues 97-175) has been shown to bind the 18S rRNA of the 40S ribosomal subunit in the earlier report. However, it has not been completely explored except for the RRM domain from eIF4B. A second RNA binding domain is located toward the C-terminus (residues 367-423) and has been termed the basic domain (BD) since it contains two arginine-rich motifs (ARMs). This region, which has not been assigned to a particular structural family, binds RNA nonspecifically but with high affinity and has been proposed to bind mRNA during initiation. In addition, eIF4B has been reported to bind several proteins related to translation, ribosomal RNA, and mRNA, but again only in a few studies. More than three-quarters of the eIF4B protein is intrinsically disordered and tends to display phase separation, attributing the reason why eIF4B has not been explored in depth, except for the RRM domain. We have utilized NMR spectroscopy and other biophysical techniques (smFRET, ITC, CD, Fluorescence, etc.) to address RNA binding properties from different constructs from the C- and N- terminus of eIF4B and addressed the phase separation behavior from the C-terminal domain of eIF4B. In addition, I will briefly discuss studies on various protein dynamics utilizing NMR spectroscopic techniques and other biophysical methods.
Crystal Engineering of Programmable Sponges for Energy, Environmental and Health Applications
Dr. Mario Wriedt, Kodak CAMP Distinguished Professor, Department of Chemistry and Biomolecular Science, Clarkson University, NY, USA
Abstract: Metal-organic frameworks (MOFs) are crystalline porous materials composed of metal clusters or ions connected by polytopic organic linkers. Their framework structures, pore environment, and functionality make them uniquely tunable by the choice and connection of metal and organic building blocks, allowing the design of innovative materials with customized properties. Our research programs all address interrelated fundamental aspects of the design, synthesis, and characterization of functional MOF materials. This presentation is a comprehensive overview on how the synergy of crystal engineering and X-ray diffraction will pave the way for the rational design of novel advanced functional MOF materials to address our society’s most pressing energy, environmental, and health needs (e.g., carbon capture, water remediation, viral testing).
Evaluation of N-acetylcysteine Amide as a Potential treatment option for Traumatic Brain Injury using tandem LC-MS
Olajide Adetunji, Graduate Student, Chemistry, Missouri S&T
Abstract: Physical injury from sports and freak accidents are common causes of Traumatic Brain Injury (TBI). Commonly overlooked, is TBI via exposure to explosives with prevalence in military personnel and veterans. Existing diagnostics are costly, time consuming, and sometimes insensitive to milder TBI forms, influencing a need for fast and sensitive techniques for mild TBI detection by investigating potential biomarkers that may be altered due to TBI. A pathophysiological consequence of TBI is oxidative stress from reactive oxygen species proliferation after physical disruption of neurons and glial cells leading to alteration in the levels of endogenous antioxidants and their oxidized products in the brain and peripheral fluids. Antioxidant therapy using N-acetylcysteine Amide can be useful mitigators of this oxidative stress characteristic. Additionally, lipid peroxidation by-products and other important small molecule biomarkers can give invaluable information about TBI progression. In our study, rats were exposed to open-field blasts mimicking of a real-life explosion to induce TBI and evaluate antioxidant therapy. Subsequently, various biomatrices were harvested from test animals for analysis. Coupling rigorous sample clean-up with LC-MS/MS analysis, levels of potential biomarkers for TBI in the groups and sample matrices were determined in this study. The LC-MS/MS methods yielded excellent sensitivity, linearity, recovery, and reproducibility for all the investigated analytes.
Explorations of the Synthesizability and Photoelectrochemical Properties of Metastable Semiconductors
Dr. Paul A. Maggard, Professor of Chemistry, North Carolina State University, USA
Abstract: Metastable semiconductors have been discovered in many chemical systems that have desirable properties for driving fuel-producing redox reactions from sunlight, including broad visible-light absorption, optimal band edge energies, defect tolerance, and functional carrier mobilities. These photoelectrochemical properties have frequently been found to stem from their metastable nature, e.g., specific features in their crystalline structures and/or compositions lead to being thermodynamically unstable with respect to phase segregation. Recent results will be presented on mixed-metal oxides and carbon nitrides that demonstrate new flux-mediated syntheses and kinetic stabilization in this growing class of semiconductor systems.1-3 Their syntheses have been achieved by reactions that leverage the exothermic formation of stable salt side products as well as shortened reaction diffusion pathways and low reaction temperatures. Kinetic stabilization of the products has also been enhanced via the application of a) high cohesive energies of an underlying substructure that is maintained during the reaction, and b) solid solution compositions which help to inhibit phase segregation while also providing for percolation pathways. These approaches have yielded, e.g., the first known Sn(II)-perovskites that are isoelectronic to widely commercialized Pb(II)-containing piezoelectrics. Photocatalytic properties in these systems will primarily be described for light-driven H2O and CO2 reduction as polycrystalline films and as suspended powders when in aqueous solutions under ultraviolet and visible-light irradiation.
New NLO Materials: Design, Synthesis, and Crystal Growth
Prof. P. Shiv Halasyamani, Department of Chemistry, University of Houston
Abstract: Nonlinear optical (NLO) materials are critical in generating coherent light through frequency conversion, e.g., second harmonic generation (SHG). From the ultraviolet (UV) to the infrared (IR), NLO materials have expanded the range of the electromagnetic spectrum accessible by solid-state lasers. Wavelengths where NLO materials are still needed include the UV (~200 - 400nm) and deep UV (< 200nm). Coherent deep-ultraviolet (DUV) light has a variety of technologically important uses including photolithography, atto-second pulse generation, and in advanced instrument development. Design strategies will be discussed, as well as synthetic methodologies. In addition, the crystal growth, characterization, and structure-property relationships in new UV and DUV NLO materials discovered in our laboratory will be presented. Finally, our crystal growth capabilities and recent crystal growth of functional materials will be described.
Development of Catalytic Membranes and Composites for Energy Storage Devices and Nonenzymatic Biosensors
Harish Singh, Graduate Student, Chemistry, Missouri S&T
Abstract: The continuous excessive usage of fossil fuels has resulted in its fast depletion, leading to an escalating energy crisis as well as several environmental issues leading to increased research towards sustainable energy conversion. Electrocatalysts play crucial role in the development of numerous novel energy conversion devices, including fuel cells and solar fuel generators. In particular, high-efficiency and cost-effective catalysts are required for large-scale implementation of these new devices. Over the last few years, transition metal chalcogenides have emerged as highly efficient electrocatalysts for several electrochemical energy conversion processes such as water splitting, oxygen reduction reaction and solar energy conversion. These transition metal chalcogenides exhibit high electrochemical tunability, abundant active sites, and superior electrical conductivity. Hence, they have been actively explored for various electrocatalytic activities. Herein, we have explored of transition-metal chalcogenide electrocatalysts for oxygen evolution, oxygen reduction, and illustrated structure–property correlation with the help of density functional theory (DFT). Lastly, we will discuss the electrocatalytic activity of the transition metal chalcogenides towards biomolecule conversion, enhancing their applicability as biosensors for detecting potentially life-threatening disorders. Detailed studies of the chemical reactivity, electrochemical activity, interfacial chemistry, and functional stability of the transition metal chalcogenides that make all these applications feasible will be discussed in depth.
Molecular Spectroscopy and Dynamics on Multiple Potential Energy Surfaces
Dr. Jinjun Liu, Department of Chemistry, University of Louisville
Abstract: Research in the University of Louisville Laser labs (UL3) (https://sites.google.com/site/uofllaserlabs/) consists of spectroscopic studies of gas-phase molecules and condensed-phase materials using state-of-the-art high-resolution and ultrafast laser systems and cutting-edge spectroscopy techniques. Our high-resolution spectroscopy studies center on the detection and characterization of open-shell molecules on multiple potential energy surfaces (PESs). Our target molecules include molecular free radicals as reactive chemical intermediates in combustion and atmospheric chemistry. The spectroscopic methods employed include laser-induced fluorescence/dispersed fluorescence (LIF/DF) spectroscopy for alkoxy (RO⸱) radicals and cavity ring-down (CRD) spectroscopy for peroxy (ROO⸱) radicals. These two techniques are also used to study metal-containing molecules, e.g., alkaline-earth monoalkoxide radicals (MORs), which have been proposed as candidates for direct laser cooling and will have important applications in quantum computing, quantum information, and fundamental physics. Recently, our group has built a mid-infrared high-resolution laser spectroscopy apparatus to support the observations of the James-Webb Space Telescope (JWST) and started developing a novel cavity-enhanced double-resonance spectroscopy technique to investigate molecular “dark states” and to decipher the complex energy level structure and intramolecular interactions. On the theoretical side, we are particularly interested in molecular species with the Jahn-Teller (JT) and pseudo-Jahn-Teller (pJT) effects, symmetry-specific vibronic (vibrational-electronic) interactions that cause spontaneous distortion of the geometry and PESs of polyatomic molecules in degenerate or nearly degenerate electronic states. Spectroscopic models and software have been developed to predict, analyze, simulate, and fit vibronic, rotational, and fine structures in high-resolution spectra of open-shell molecules. High-level quantum chemistry calculations are used to help understand the geometry, energy level structure, and dynamics of molecules on multiple PESs.
The nature and strengths of inter-state coupling can also be directly detected in time-resolved spectroscopy, a powerful tool for investigating energy and charge transfer processes. I will use the femtosecond pump-probe transient absorption study of excited-state dynamics of molecule-like ligand-passivated (CdSe)34 nanoclusters (d=1.6 nm) to demonstrate the capabilities and limitations of ultrafast spectroscopy in understanding charge carrier dynamics in nanostructures and on their interfaces, which can aid in the design of high-efficiency photovoltaic and light-emitting devices.
Reactivity of Coinage Metal Complexes Supported by Tetramethylguanidinyl Triphenyl Stibine and Bismuthine Ligands towards Nitrene Transfer Chemistry
Meenakshi Sharma, PhD Candidate, Department of Chemistry, Missouri S&T
Abstract: Carbon Nitrogen (C-N) bonds are ubiquitous in pharmaceuticals, agrochemicals, natural products, and ligands for transition metal catalysts. Transition-metal catalysts introduce new C-N bond into the desired molecules by C-H bond activation or by addition of nitrene across a C=C bond to form aziridines, which can easily be converted into an amine by various chemical transformations.
Transition-metal catalyst frameworks supported by tripodal [TMG3trphen] ligands mediate nitrene transfer from nitrogen sources such as PhI=NR (PhI=NTs or PhINTces) to a diverse group of aliphatic and aromatic hydrocarbons and olefins. These reactions are categorized as amination and aziridination reactions. Novel tripodal ligands and their complexes with coinage transition metals (Cu, Ag, Au) with different axial atoms such as CH, Sb and Bi and benzene platform have been designed to impart weaker axial ligand field, which, in turn, enhances the electrophilicity of nitrene, potentially affording more reactive and site-selective aminated products. The trinuclear copper catalysts [TMG3trphenSbCu3(μ2-Cl)3] and [TMG3trphenBiCu3(μ2-Cl)3] have shown promising results towards aziridination of styrenes with excellent yields though the reactivity of the silver catalyst [TMG3trphenSbAg3(μ2-Cl)3] needs to be explored more for comparative studies. The copper complexes are also reactive for the selective amination of various hydrocarbons at benzylic and tertiary C–H sites.
Meenakshi Sharma's seminar flyer
Accessing anionic and cationic redox in metal chalcogenides through building block approach
Santhoshkumar Sundaramoorthy, Graduate Student, Chemistry, Missouri S&T
Abstract: Boosting the energy density of Li-ion batteries is of prime importance in the current era to meet the energy demands for electric vehicles (EV’s). In this regard cathodes play an important role as the specific capacity is directly related to the number of Li-ions to be extracted from or inserted into the cathode as a function of redox. Towards achieving this goal, researchers are looking into combining both cation and anion redox in the new generation cathode materials. In this regard, we have developed building block approach of synthesis targeting specific compositions that can potentially act as candidate for cathodes and solid
electrolytes. Through this technique we discovered two new polyanion sulfidebased cathodes with Cu+and Fe2+ cations exhibiting high reversible specific capacities. Further their charge storage mechanism and structural stability were evaluated by spectroscopic (XAS and XPS) and diffraction studies (Synchrotron XRD). Following these works we also synthesized two new ternaryselenidebased building blocks (Li5MSe4, M = Al & Ga) and measured their ionic conductivity. Aliovalent doping in these building block showed improvement in Li-ion conduction showing promises in search of potential solid electrolytes for Li-solid state batteries. At the end, an overall overview on chalcogen based materials and its optimization for energy storage devices will be summarized.
Harnessing the chemistry of cementitious materials towards the next-generation eco-efficient concretes
Monday Okoronkwo, Assistant professor, Chemical and Biochemical Engineering, Missouri S&T
Abstract: The production of conventional cement is an energy and CO2-intensive process contributing to over 8 % of the global anthropogenic CO2 emissions. To reduce the carbon footprint of cement and concrete, efforts are increasingly directed toward developing sustainable low-carbon alternative cementitious materials. Chemistry is at the heart of such efforts, helping us to understand what forms when cements react with water (hydration), and how they may impact the properties and performance of the resulting cement-based products. Through such understanding, the design and optimization of new alternative cements are enabled. This talk will present some of our work in understanding the hydration reactions and the development of phase assemblages and properties of some candidate low-carbon alternative cements, including blended cements, alkali-activated cements, sulfoaluminate cement, and carbonated cements.