Colloquium - Spring Semester 2021

Colloquium - Spring 2021 Flyer

Brochure, 5th Annual James O. Stoffer Lecture in Chemistry (digital version, Bulletin Stoffer Lecture 2021 ); Stoffer Lecture - Program

Chemistry, Structure and Applications of 2D Carbides and Nitrides (MXenes) 

Dr. Yury Gogotsi, Charles T. and Ruth M. Bach Distinguished Professor of Materials Science & Engineering, Director, A.J. Drexel Nanomaterials Institute, Drexel University, Philadelphia, PA

Abstract: 2D carbides and nitrides, known as MXenes, are among the most recent, but quickly expanding material families. The field is experiencing very fast growth with the number of papers on MXenes doubling every year. Major  breakthroughs have been achieved in the past 2-3 years, including the discovery of 2D M₅C₄ carbides with the twinned layers and CVD synthesis of MoSi₂N₄, representing a new family of 2D nitrides. Synthesis of dozens of predicted MXenes, demonstration of superconductivity in MXenes with specific surface terminations, stronger interactions with electromagnetic waves compared to metals, metallic conductivity combined with hydrophilicity and redox activity, led to numerous applications. Reversible redox activity of transition metal atoms in the outer layers of MXene flakes combined with high electronic conductivity led to applications in a variety of batteries and electrochemical capacitors. MXenes are promising candidates for energy storage and related electrochemical applications, but applications in optoelectronics, plasmonics, electromagnetic interference shielding, electrocatalysis, medicine, sensors, or water purification are equally exciting.

For more information, visit the webpage here. 

Fluorescent nanodiamonds: fabrication, characterization and applications in biology

Dr. Philipp Reineck I, ARC DECRA Fellow, ARC Centre of Excellence for Nanoscale BioPhotonics, RMIT University, Melbourne, Australia

Abstract: Fluorescent nanodiamonds have unique physical, chemical and optical properties that make them highly attractive for applications from nanocomposites to quantum sensing in biology. Many different types of fluorescent nanodiamonds exist: from high-pressure high-temperature (HPHT) nanodiamonds containing engineered fluorescent defects to detonation nanodiamonds that exhibit various forms of fluorescence depending on their processing. This presentation will focus on our recent progress in areas including the creation and characterization of nitrogen, silicon and nickel-based fluorescent defects in macroscopic and nanoscale HPHT diamond, the effect of surface chemistry on nanodiamond fluorescence and the use of fluorescent nanodiamonds in composite materials and biological imaging and sensing applications. Current challenges and opportunities regarding the application of nanodiamonds in several technologies will be critically discussed.

For more information, visit the webpage here.  

Electrochemical desalination: synergy of energy storage, water remediation, and elemental recovery

Dr. Volker Presser, Professor and Chair of Energy Materials, Saarland University & INM – Leibniz Institute for New Materials, Saarbrücken, Germany

Abstract: The growing population, our increased impact on the environment, and mounting environmental impact call for a different way of storing energy and using/interacting with water resources. Reversible electrochemical processes are a promising technology for energy-efficient water treatment. Electrochemical desalination is based on the compensation of electric charge by ionic species, through which the ions are immobilized. Thereby, ions are being removed from a feed-water stream flowing through a desalination cell. For decades, electrochemical desalination has focused on using carbon electrodes, but their salt-removal ability is limited by ion electrosorption mechanism at low molar concentrations and low charge-storage capacity. Recently, charge-transfer materials, often found in batteries, have demonstrated much larger charge-storage capacities and energy-efficient desalination at low and high molar strengths. Such desalination batteries also allow for ion-specific separation, for example, to recover lithium from hydrothermal or mine water sources.

For more information, visit the webpage http://www.presser-group.com.

Self-organization and communication processes: colelctive response and emergence in molecular and active matter

Dr. Jerome Delhommelle, Dept. of Chem., University of North Dakota, Grand Folks, ND

Abstract: Self-organization and assembly processes are nonequilibrium phenomena that take place over a wide range of length scales and time scales. For instance, phase transitions often proceed through the nucleation of nano-sized nucleus of a new phase - a key feature for, e.g., atmospheric processes or polymorph selection in pharmaceuticals. Similarly, active, self-propelled, objects can form unexpected structures such as colloidal rotors on the micron scale or bacterial biofilms on the macroscopic scale. While recent advances in experimental, theoretical & computational methods have allowed for unprecedented insights into the behavior of nonequilibrium systems, a complete understanding of how the onset of order, change in symmetry and cooperative behavior has remained elusive. For example, it is still impossible to predict which crystal structure forms when a liquid crystallizes. This complexity arises from the interplay between different types of orders and structures. In this case, accurately sampling the underlying high-dimensional free energy surface is a formidable task. In this talk, I discuss how recent advances in statistical mechanics and algorithmic developments in numerical simulations have shed light on assembly pathways, notably through the use of novel entropy-based reaction coordinates that efficiently sample the free energy surface. I also show how data science and machine learning methods provide a way to accelerate discovery, identify novel collective variables and uncover new physics to elucidate the unexpected behaviors and emergent dynamics in these fascinating systems.

US Editor for Molecular Simulation 

Textbook Author:  A Mole of Chemistry 

Networking with faculty on April 16, 2021 at 2 - 3 pm via Zoom

James Stoffer Lecture Webinar with In-Person Audience in Leach Theatre on April 16, 2021

• Pre-registration required for in-person audience (instructions to be posted here by March 25)
• Doors open at 3:30 pm at Leach Theatre
• Stoffer Lecture begins at 4 pm;  Introductions, Lecture, Q&A
• Link to Webinar: https://umsystem.zoom.us/j/94628802660

The Origins of the Lithium Battery and Future Chemistry and Materials Challenges 

Dr. Stanley Whittingham, SUNY Distinguished Professor & 2019 Nobel Laureate, Binghamton University

Abstract: The success of lithium-ions arose from a fundamental understanding of what controls fast ion transport in solids. Intercalation reactions have been the basis of all rechargeable lithium batteries since their inception 50 years ago, because usually these result in less structural change and the compounds show high solubility for lithium ions, as in Li_xTiS₂ , where 0≤x≤1. However, 40+ years later, commercial cells attain only 25% of their theoretical energy densities. The dominant NMCA cathodes can now attain over 200 Wh/kg commercially at the cell level, and the Battery500 consortium has attained around 350 Wh/kg in full cells, out of a theoretical 1000 Wh/kg. The scientific challenges to improving the energy density will be discussed; these include the need for higher ionic and electronic conductivities, as well as greater stability of the solid materials and the liquid or solid electrolytes.

For more information, visit the webpage here. To view the recording of the event, click here. 

Colloquium - Fall Semester 2020

Science Ethics, Goals and Aspirations in Times of a Pandemic

Dr. Rainer Glaser, Chair, Dept. of Chemistry, Missouri S&T

Abstract: The S&T Department of Chemistry is a dynamic organization with complex interactions between material infrastructure and staff support, a diverse population of undergraduate, graduate and post-doctoral students, and an international faculty. Modern science is a global enterprise adding an exciting and mutually enriching cross-cultural component to the complexity. The department’s success depends on synergy across all of its components, common ethics, shared goals, and shared aspirations. The global pandemic presents an added challenge and reinforces the need for clarity on ethics. Our scientific creed requires curiosity, energy, initiative, and excellence in interdisciplinary science and the development of skills, knowledge and abilities to optimize teamwork, responsible conduct of research, and the interrelations between the teaching, research and service missions. In this presentation, we will address some of the strengths and some of the challenges with regard to departmental infrastructure and personnel, chemistry instrumentation, faculty and scientific staff, and the evolution of the undergraduate and graduate programs. Practical proposals will be presented to facilitate the gradual evolution towards our shared goals.

For more information, visit the webpage here. 

Networking with faculty and students at 1:45 – 3 pm at the Colloquium ZOOM link

Ozone Reaction Problems in Modern Aquariums

Dr. Michael D. Stafford, DVM, American National Fish and Wildlife Museum

Abstract: There are over 200 aquariums worldwide with the largest being over 14 million gallons. Wonders of Wildlife in Springfield Missouri has 1.5 million gallons and Bass Pro shops has over 230 individual systems comprising 1.7 million gallons. Modern aquariums typically use multiple systems to maintain water quality and clarity. Ozone, a powerful oxidizer, has been added to the arsenal to flocculate and remove organics thereby enhancing water clarity. This has created an issue with the health of the animals. In freshwater systems with ozone, we are seeing epithelial erosion over the bony plates and lateral line. We are trying to determine what this process is. Essentially, are we creating an irritant or are we stripping away an essential nutrient? This lecture will present the problem with the hopes of collaborating with an interested individual(s) in solving the issue.

For more information about the American National Fish and Wildlife Museum, please visit wondersofwildlife. 

Exploring Chemical Physics in Transient Plasma by Broadband Rotational Spectroscopy

Dr. Nick Walker, Senior Lecturer at Newcastle University at Newcastle upon Tyne, UK

Abstract: Rotational spectroscopy provides unrivalled precision for the determination of molecular structure in isolated, gas phase species. Electronics capable of digitising waveforms at gigahertz frequencies now allows chirped-pulse Fourier transform microwave spectroscopy¹ to be performed at high resolution, high bandwidth and with minimal or no cost to sensitivity. Two approaches are possible. Specific molecules or complexes can be targeted and selectively generated for study through a careful choice of appropriate precursors. Alternatively, a survey of chemical products generated under selected environmental conditions can be performed in an approach termed “broadband reaction screening”.² Each of these approaches will be described during this presentation.

One focus will be experiments that have applied broadband rotational spectroscopy to probe interactions between isolated, metal-containing molecules and simple hydrocarbons such as ethene, ethyne and cyclopropane.³ The complexes are generated through laser vaporisation of a metal target in the presence of an expanding gas sample containing the hydrocarbon precursor. Precise changes in the geometry of the hydrocarbons on their attachment to copper, silver and gold atoms will be described. The products of chemical reactions between platinum, palladium and hydrocarbons following laser vaporisation of the metal in the presence of a hydrocarbon precursor have also been characterised. It will be shown that many choices of hydrocarbon allow the efficient generation⁴ of linear PtC₃ or PdC₃ units within the transient plasma. It will also be shown that the method provides a new and powerful approach through which to explore the gas phase chemistry between platinum, palladium and hydrocarbons.   

For more information, visit the webpage here. 

Coherent population transfer in chiral molecules using tailored microwave pulses

Dr. Melanie Schnell, Professor of Physical Chemistry, Christian-Albrechts-Universität zu Kiel;  Leading Scientist at Deutsches Elektronen-Synchrotron of the “Spectroscopy of Molecular Processes” group, Germany

Abstract: Most molecules of biochemical relevance are chiral. Even though the physical properties of two enantiomers are nearly identical, they can exhibit completely different biochemical effects, such as different odor in the case of carvone. In nature and as products of chemical syntheses, chiral molecules often exist in mixtures with other chiral species. The analysis of these complex mixtures to identify the molecular components, to determine which enantiomers are present, and to measure the enantiomeric excesses (ee) remains a challenging task for analytical chemistry.

In collaboration with Dave Patterson (UCSB) and John Doyle (Harvard University), we recently experimentally demonstrated a new method of differentiating enantiomeric pairs of chiral molecules in the gas phase. It is based on broadband rotational spectroscopy and is a three-wave mixing process that involves a closed cycle of three rotational transitions. The phase of the acquired signal bares the signature of the enantiomer, as it depends upon the product of the transition dipole moments, and the signal amplitude is proportional to the ee. A unique advantage of our technique is that it can also be applied to mixtures of chiral molecules, even when the molecules are very similar. It also bears the potential for enantiomer separation, as was recently shown in experiments on enantiomer-selective population transfer. In my lecture, I will introduce the technique and give an update on the recent developments.

For more information, visit the webpage here. 

Networking with faculty at 9 - 10 am via Zoom.

Carboline:  Global Supplier of Industrial Coatings, Linings and Passive Fire Protection

Mary Roley, Technical Director, Innovation; Jeff Anderson, Vice President, Research, Development and Innovation; Steve Bockhold, Carboline Company, Saint Louis

Abstract: The presentation will discuss our career paths from undergrad to our current position. A discussion of industrial chemistry as well as types of jobs. Overview of Carboline, products we produce, and chemistry we apply. Internship opportunities at Carboline.

For more information, visit the webpage here. 

Colloquium - Spring Semester 2020

Using Direct Analyte Probe Nanoextraction (DAPNe) and Nanoparticle Deposition-coupled to MALDI to exact chemical information from one cell and one organelle 

Dr. Guido Verbeck, IV, Prof. of Chemistry and Biochemistry, Univ. of North Texas

Abstract: Typical cellular chemical analysis employs the application of lysing groups of cells to observe biomolecules of interest in their roles of metabolic processes. This approach destroys the cells analyzed and does not allow for true one-cell chemistry to be determined. Individual cells have unique physiologies and produce different metabolites even within cells of the same tissue. As such, a method for investigating a single cell without destroying it or surrounding cells is desired to further understand these unique cellular processes. Recently, the application of directing femtosecond laser pulses at cell membranes to create sub-micron dissections has been accomplished. This novel method leaves cellular chemistry unaltered, and in combination with nanomanipulation and Raman microscopy, a novel bioworkstation was developed, capable of providing accurate and localized one-cell chemical analysis. Our group has demonstrated the capabilities of this workstation via nanoextraction of adipocytes from tumorous and healthy breast tissue with the nanomanipulator and utilizing nanoparticle deposition for MALDI small molecule analysis. Preliminary data suggests that the triglyceride make-up appears to be influenced by the cellular location within a tissue, evident by the ratios of three triglyceride peaks identified in each cell. The lipid heterogeneity identified here supports the notion that specific fatty acids may play a role in tumor cell proliferation, however the mechanism is currently unknown thus further investigation is warranted.

•Create a clinical/pathology tool for more accurate precancer screening

•True one-cell biomarker discovery

•Explore biochemical pathways and one-cell life cycles

•Understanding accurate one-cell nature in a heterogeneous tissue sample

•Ability to extract the metabolome with the RNA for upregulation in true one-cell

•Ability to extract both lipophilic and hydrophilic metabolites in drugs in one extraction

For more information, visit the webpage here. Find the itinerary of the visit here. 

Green chemistry to the rescue of materials synthesis 

Dr. Jerome Claverie, Dept. of Chemistry, University of Sherbrooke

Abstract:  Green chemistry has recently revolutionized the way we think about synthesis. However, most common organic materials have been conceived at times when environmental concerns and green chemistry concepts were often overlooked. In this lecture, we will present our efforts to design novel materials with usage properties that equal or surpass those existing, by strictly adhering to the principles of green chemistry. We will first present our efforts to prepare functional polymers by catalytic means, and using biosourced raw materials. We will then present an aqueous encapsulation process that is very versatile for the preparation of nanocomposites. The resulting nanocomposites are excellent catalysts for artificial photosynthesis and the oxygen reduction reaction (ORR).

For more information, visit the webpage here.  Find the itinerary of the visit here. 

Sensitization of Oxide Single Crystals with Quantum Confined Semiconductors 

Bruce Parkinson, Professor of Chemistry & Energy Resources, Univ. of Wyoming

Abstract:  We study the fundamentals of electron injection by molecules, quantum dots, quantum confined nanoplatelets and semiconducting nanotubes into large bandgap metal oxide semiconductors and gallium phosphide. We have been testing a theoretical model that predicts that the photocurrent yields and photocurrent-voltage behavior are controlled by the doping density that then determines the field gradient of the Schottky barrier at the electrode/electrolyte interface. The model was shown to be applicable to sensitization by both thiacyanine and ruthenium based sensitizing dyes with the difference of the behavior between the two classes of dyes being attributed to the different distance of the photogenerated hole on the dye from the injected electron that influences the rate of the back reaction. We have extended these studies to monolayers of adsorbed CdSe quantum dots (QDs) of various sizes on well- characterized TiO 2 single crystals with varying doping densities. We are also building on our previous work where we were able to observe sensitized photocurrent quantum yields >1 from multiple exciton generation and collection from PbS quantum dots adsorbed on single crystal anatase electrodes and are working on preparation of InSb QDs that may be capable of producing 3 excitons per high energy photon.

For more information, visit the webpage here. Find the itinerary of the visit here. 

Two-dimensional Transition Metal Carbides and Carbonitrides for Electrochemical Energy Storage and Conversion 

Michael Naguib, Asst. Prof. of Physics and Engineering, Tulane University

Abstract: MXenes are large family of two-dimensional (2D) transition metal carbides and nitrides of M _n+1X _nT _z composition; where M is an early transition metal (e.g. Ti, V, Mo, Nb) and X is either carbon or nitrogen, “T _z ” stands for a mixture of surface terminations (e.g. O, OH, F, Cl), and n can be 1, 2, or 3. So far, about two dozens of MXenes have been produced experimentally (e.g. Ti₃C₂ , V₂C, Nb₂C, Mo₂C, (V_0.5 ,Cr_0.5 )₃C₂ , Ti₃CN, Ta₄C₃ , and Nb₄C₃ ). In addition, ab initio calculations predicted many others to be stable. Combining the metallic conductivity of transition metal carbide/nitrides with the hydrophilic nature of their terminated surfaces place MXenes in a unique position among all other 2D materials. MXenes can be intercalated by a wide range of intercalants from mono- and multi-valent ions to organic and inorganic molecules. Since their discovery, intercalation has been of a critical importance for MXenes processing and applications including electrochemical energy storage, water purification and sensing. However, very little has been known for the nature of intercalant and the bonding between MXenes surface and the intercalant. Using various neutron scattering techniques, we studied MXenes intercalation for two systems: Ti₃C₂ /ion/water and Ti₃C₂/urea/water. In this presentation, the recent fundamental findings and understanding for the complexity of intercalations in MXenes, will be discussed. In addition, the performance of MXenes as electrode materials hosting ions for batteries and supercapacitors and their performance as electrocatalyst will be presented.

For more information, visit the webpage here.

Organic Chemistry in Harsh Reaction Environments 

Robert McMahon, Prof. of Chemistry, Univ. of Wisconsin-Madison

Abstract:  Our research efforts focus on elucidating the chemistry and spectroscopy of organic species that are postulated to play a role in harsh environments (e.g. combustion, planetary atmospheres, interstellar space). These environments contain a remarkable diversity of organic functionality, including reactive intermediates such as anions, radicals, and carbenes. We have drawn on our knowledge of mechanistic and structural organic chemistry to identify chemically-significant targets for detection and characterization. Many of these investigations are made possible through our ability to prepare specific chemical precursor molecules via synthetic organic chemistry. I will present case studies that exemplify how modern physical-organic chemistry spans the disciplines of organic chemistry, chemical physics, and astronomy.

For more information, visit the webpage here. 

Development and Fundamental Understanding of the World’s Most Versatile Polymers, Polybenzoxazine: From Smart to Extreme Property  

Hatsuo Ishida, Distinguished Research Professor of Macromolecular Science and Engineering, Case Western Univ.

Abstract: We are now in the dark age of commercialization of new polymers. In the past 40 years, only a few new polymers have been commercialized. The subject of the lecture, polybenzoxazine, is one of them. It is an extremely versatile material that can be readily synthetized from off-the-shelf commercially available raw materials, and the material can be easily tailored to the desired properties. They can also be synthesized from many natural renewable raw materials, such as cashew nut shell oil, vanillin, chitosan, and furfural amine. Polybenzoxazines exhibit several unusual properties other polymers do not show, including surface free energy lower than Teflon without fluorine atoms, extremely high char yield, near-zero shrinkage upon polymerization, and property increase at low conversions. Polybenzoxazines defy the common wisdom of “the higher the properties, the more expensive and difficult to process,” It can be easily processed like an epoxy resin, and show an unusual “polymerization temerature << Tg” relationship. Utilizing these advantageous and very versatile properties, we have been developing a number of materials that can be applied to many potential fields, such as aerospace, electronic, automotive, coating, catalysis and many others. The lecture introduces fundamental unique chemistry of benzoxazine polymerization, and development of smart, high-performance and extreme-performance materials.

For more information, visit the webpage here.

Colloquium - Fall Semester 2019

Science Ethics, Goals and Aspirations

Dr. Rainer Glaser, Chair, Dept. of Chemistry, MS&T

Abstract: The S&T Department of Chemistry is a dynamic organization with complex interactions between material infrastructure and staff support, a diverse population of undergraduate, graduate and post-doctoral students, and an international faculty. Modern science is a global enterprise adding an exciting and mutually enriching cross-cultural component to the complexity. The department’s success depends on synergy across all of its components, common ethics, shared goals, and shared aspirations. Our scientific creed requires curiosity, energy, initiative, and excellence in interdisciplinary science and the development of skills, knowledge and abilities to optimize teamwork, responsible conduct of research, and the interrelations between the teaching, research and service missions. In this presentation, we will address some of the strengths and some of the challenges with regard to departmental infrastructure and personnel, chemistry instrumentation, faculty and scientific staff, and the evolution of the undergraduate and graduate programs. Practical proposals will be presented to facilitate the gradual evolution towards our shared goals.

For more information, visit the webpage here. 

Quantitative NMR to Measure Drug Release from Pharmaceutical Formulations

Dr. Nathan Oyler, Assoc. Prof. of Chemistry, UMKC

Abstract: Accurately assaying the amount of drug released (as a function of time) in human bodily fluids is a crucial requirement of the drug formulation development process (i.e. developing the matrix to enclose the drug).  Classically, a method combining dialysis (to separate the released drug from the bodily fluid) and HPLC (to quantify the amount of drug) is commonly used due, in part, to its high sensitivity, but here we demonstrate a more direct, while still accurate method to determine the real-time release using quantitative NMR.  The fundamental NMR concepts that makes the method possible will be discussed, and directly detected real-time drug release profiles of drug formulations dissolved in simulated bodily fluids will be presented. Additionally, the extensibility of the methods to other drugs/formulations will be discussed.

For more information, visit the webpage here. Find the itinerary of the visit here. 

The Challenge of Organic Radical Design for Materials, Biomedicine, and Biophysics

Dr. Andrzej Rajca, Charles Bessey Professor of Chemistry, University

Abstract: Open-shell organic molecules and polymers, with well-defined spin-spin interactions, are becoming more prominent building blocks for materials, as well as for applications in biomedicine and biophysics. Stability of organic radicals at room temperature and above is essential for their applications, and for biomedical applications and for emerging biophysical applications, the radicals should be highly resistant to the reduction in vivo. Design of organic paramagnetic compounds that require optimization of multiple properties has proven to be a challenge. This lecture will describe the design of organic radicals with well-defined structures that are tailored to specific target properties for organic magnets, contrast agents for magnetic resonance imaging, dynamic nuclear polarization (DNP) NMR enhancement agents, and spin labels for distance measurements in proteins.

For more information, visit the webpage here. Find the itinerary of the visit here. 

Repairing the Body with Glass

Dr. Delbert Day, Curator’s Professor Emeritus Of Ceramic Engineering, S&T

Abstract: As I thought about a topic for this lecture, I immediately thought of the material we call glass and how mankind has benefited from this remarkable and fascinating material for thousands of years.  We all benefit from the glass windows and insulation in our homes, sky scrapers, vehicles and airplanes.  We use a wide range of glass containers (bottles) of all sizes and shapes.  Glass is an important component of electronic devices such as cell phones, radios, and flat screen TV’s.

Fortunately, new and surprising uses for glass also are constantly being found.  Thus, the title of my lecture today is “Repairing the Body with Glass.”  I would like to share with you two examples of how glasses of special composition are being used to repair medical conditions in the human body.  The first example describes how bioinert glass microspheres are now being used world-wide to treat patients with inoperable liver cancer.  The second example shows how bioactive glass fibers are being used to treat patients with chronic, non-healing wounds.

For more information, visit the webpage here. 

Nuclear Magnetic Resonance (NMR) Strategies for Understanding Nanoparticle Surface Interactions 

Dr. Leah Casabianca, Assoc. Prof. of Chemistry, Clemson University

Abstract: Nanotechnology is becoming increasingly prevalent in our everyday lives. Nanoparticles that are used as lubricants, in drug delivery, and as antibacterial agents are finding their way into the body and into the environment, where they interact with biological macromolecules such as proteins. Understanding the nature of the interactions between nanoparticles and absorbed
molecules is therefore increasingly relevant in fields such as drug delivery, nanoparticle catalysis, and nanoparticle toxicity. In this talk, I will discuss several recent studies in my lab that are aimed at developing solution-state Nuclear Magnetic Resonance (NMR) techniques for studying noncovalent nanoparticle surface interactions.

NMR is an incredibly powerful characterization technique, capable of providing atomic-level structural as well as dynamic information. However, NMR is not ideally suited for surface studies due to the inherent low sensitivity of this technique. One way of improving the sensitivity of NMR is Dynamic Nuclear Polarization (DNP). DNP relies on the transfer of polarization from a nearby unpaired electron to nuclei of interest in NMR. My group has recently 1 developed Highly-effective Polymer/Radical Beads (HYPR-Beads), which are organic nanoparticles that have been doped with radicals for use as DNP polarization agents. Using HYPR-beads, we were able to hyperpolarize nuclei in small molecules that are located near the beads in an aqueous environment.

We are also using Saturation Transfer Difference (STD)-NMR Spectroscopy to identify small molecules that interact noncovalently with the surface of functionalized organic nanoparticles in solution. 2 STD-NMR was originally developed to identify small-molecule ligands that bind to a protein receptor. Since this technique does not require the receptor to be seen by solution-state NMR, there is no upper limit to the size of the receptor that can be studied. This makes the STD-NMR technique an ideal one to study small molecules adsorbed on the surface of nanoparticles. We have used STD-NMR to examine the binding between small molecules and
solvent water on the surface of nanoparticles, 2 to screen individual amino acids for binding to the nanoparticle surface, 3 and to determine the binding epitopes of a fluorescent dye associating with the nanoparticle surface. 4 This work has future applications in determining the structure of proteins adsorbed on the surface of nanoparticles, and in the development of dual-use (for example fluorescence and magnetic resonance) imaging contrast agents.

For more information, visit the webpage here.  Find the itinerary of the visit here. 

Charge Carrier Dynamics in Nanostructures Studied by Femtosecond Laser Spectroscopy 

Dr. Jinjun Liu, Assoc. Prof. of Chemistry, University of Louisville

Abstract: Ultrafast laser spectroscopy is a powerful tool for the investigation of charge and energy trasnfer processes in molecules and condesned-phase materials. Our research group uses femtosecond transient absorption (TA) technique to study charge carrier dynamics in nanomaterials. In this talk, I will first introduce the principles of the ultrafast TA spectroscopy. Results from two recent projects will be presented to illustrate the effectiveness and limits of the spectroscopic technique. In the first, femtosecond TA spectroscopy was employed to investigate photoinduced exciton dynamics in three novel CH 3 NH 3 PbBr 3 perovskite nanostructures: nanocrystals (0D), nanowires (1D), and nanoplatelets (2D). Time scales of different charge carrier processes were determined in the experiment. It has been found in our work that the excition recombination process obeys the rate law of a second-order reaction, but the rate constant depends strongly on the initial charge carrier desnitry and the morphology of the nanostructures. In the second experiment, excited-stat dynamics of molecule-like ligand-passivated (CdSe) 34 nanoclusters (d=1.6 nm) was monitored by femtosecond TA spectroscopy. In addition, sub-picosecond hole transfer from a nanocluster to its strongly bound ligand shell was observed. A second sub-picosecond process in the TA spectra was attributed to "hot" electron transfer to interfacial states created by charge separation. THe critical role of energy level alignment between the semiconductor nanocluster and its passivating ligands has been confirmed in a series of control experiments. Understanding charge carrier dynamics in nanostructures and on their interfaces can aid in the design of high-efficiency photovoltaic and light-emitting devices.

For more information, visit the webpage here. Find the itinerary of the visit here.