About the Department
Abstracts for Seminars — Spring 2018
Thursday, February 15, 2018
Ali Dhanojwala, University of Akron
Harnessing the Colour and UV Stability of Melanin
Melanin is one of the most important pigments used by birds in producing iridescent colors. It has a high refractive index and a broad absorption in the visible spectral range. The periodic spacing between melanin particles leads to structural colors that have high saturation and contrast. Based on this knowledge we have synthesized melanin particles starting with dopamine monomers and using self assembly to produce structural colors. The control of spacing between particles can be tuned to obtain tunable colors over the whole visible spectral range. The simple one-pot process used for self assembly makes it an economical process for producing structural colors. I will also discuss the UV stability of natural and synthetic melanin and the potential application of melanin-based materials.
Thursday, February 22, 2018
Erich Uffelman, Washington and Lee University
Scientific Adventures with Old Master Paintings and Non-Invasive Instrumentation
The development of easily portable non-invasive spectroscopic and imaging instrumentation is revolutionizing the field often called “technical art history.” This talk will show how portable X-ray fluorescence spectroscopy and multispectral imaging in the visible and infrared can drastically alter how we view, interpret, and conserve a work of art. The discussion will occasionally incorporate microsampling techniques such as scanning electron microscopy energy dispersive spectroscopy and various synchrotron-based X-ray methods.
Thursday, March 1, 2018
Eric J. Amis, University of Akron
Advanced Manufacturing: The 21st Century Opportunity
Even the most exciting new materials must buy their way into real applications, especially in demanding industries. Performance, cost, reliability, sustainability, and time to market must all converge to make a successful transition from the laboratory to successful application. Going from invention and design through scale up and production demands the optimization of multiple factors, and often competing factors. In addition to the scientific discovery that leads to new technologies, there are great opportunities to focus our science and engineering tools on the new challenges of manufacturing. We will consider the application of agile measurement methods, integrated modeling, and virtual design optimization, and their prospects to enable new material applications.
Eric J. Amis serves as Dean of the College of Polymer Science and Polymer Engineering. Dr. Amis came to UA in 2014 from United Technologies Research Center, where he was Director of Physical Sciences with responsibility for external partnerships in advanced manufacturing and for research in materials and chemical sciences, structural integrity, and measurement science.
Prior to UTRC, Amis spent 15 years in leadership in materials science at the National Institute of Standards and Technology, including 10 years in the Polymers Division. Previously, he was on the faculty in chemistry at the University of Southern California for 11 years.
Dr. Amis is a member of the Connecticut Academy of Science and Engineering and a Fellow of American Chemical Society, Materials Research Society, and American Physical Society. His research interests include combinatorial and high-throughput methods for functional polymers or biomaterials, direct write additive manufacturing, nanomaterial characterization, gels and networks, polyelectrolytes, and soft matter physics.
Thursday, March 8, 2018
Geoff Hutchison, University of Pittsburgh
Rapid Rational Design of Molecular Materials: Molecular Springs, Solar Cells & More
The potential of molecular materials is enormous — we can tap the vast (10^60) variety of organic molecules to tailor properties for a wide range of applications. The challenge is how to explore such designs in an efficient manner. We seek to find optimum or nearly-optimum materials properties through a combination of inverse design, genetic algorithms, and machine learning, combined with experimental synthesis and characterization. Key challenges are how to expand computational and experimental searches to be as efficient as possible in accurately finding new targets. We will discuss progress in finding new materials for organic solar cells, combined experimental and computational investigation of charge transport in organic semiconductors. In piezoelectric materials, we have pioneered a new approach, using conformational distortions of individual molecules in an applied electric field to drive a “bottom-up” distortion, with greater piezoresponse than many conventional inorganics.
Dr. Geoffrey Hutchison received a BA degree in chemistry from Williams College in 1999, conducting research with Prof. Lee Park and Prof. Enrique Peacock-Lopez. He received his Ph.D. degree in chemistry from Northwestern University in January 2004 jointly with Prof. Tobin J. Marks and Prof. Mark A. Ratner, studying transparent conducting polymers. Following his graduate work, he was a postdoctoral associate at Cornell University, working with Prof. Héctor D. Abruña and studied multi-metallic single-molecule transistors and lithium-ion batteries. He is an Associate Professor of Chemistry at the University of Pittsburgh and the recipient of the 2012 Research Corporation Cottrell Scholar award and was named a 2017 Scialog Fellow in Energy Storage. His research at Pitt focuses on the combination of experiments and simulations to rapidly design novel organic materials for piezoelectric and photovoltaic applications.
Tuesday, March 29, 2018
Tara Kahan, Syracuse University
“Messy” Atmospheric Photochemistry: Water, Ice, and the Great Indoors
Photochemistry drives the composition of the atmosphere. While the kinetics and mechanisms of many atmospherically-relevant gas-phase photochemical reactions are well understood, this is not always the case for photolysis in condensed phases or at atmospheric interfaces. Atmospheric condensed phases present very complex, heterogeneous reaction environments; predicting reactivity in these “messy” media can be very challenging.
We have measured photolysis kinetics of aromatic pollutants in water and ice; reaction kinetics can differ dramatically in these two “simple” systems. For example, substituted benzenes (toluene, ethylbenzene, and xylenes), which are components of fossil fuels and hydraulic fracturing solvents, do not photolyze in liquid water, but photolyze rapidly at ice surfaces. Solutes such as halide salts suppress photolysis at ice surfaces by melting the ice and creating a more liquid-like environment. We have investigated the distribution of liquid water and solid ice at the surface of frozen saltwater solutions using Raman microscopy. Our results indicate that such surfaces are very heterogeneous, with distinct regions of liquid and solid water under most tropospherically-relevant conditions. This will affect the prediction of photolysis lifetimes of pollutants in salty snow-covered regions (such as coastal regions and cities where road salt is used in the winter).
Finally, we report measurements important to photochemistry in the “messy” system that is indoor environments. We have measured wavelength-resolved photon fluxes from indoor light sources, including sunlight filtered through windows and commonly used light bulbs, and have used these photon fluxes to calculate radical production rates indoors. Our results suggest that photochemistry could be an important indoor radical source, even in the absence of sunlight. We have also measured oxidant concentrations in a detached home over the period of a few weeks. This work shows that humans greatly affect the composition of indoor air through activities such as cooking. Our results will improve predictions of indoor air composition and indoor air quality.
Dr. Kahan obtained a bachelor of science degree from the University of Regina and a PhD in Environmental Chemistry from the University of Toronto where she worked with Jamie Donaldson. During her PhD she investigated physical and chemical processes of atmospheric species at ice surfaces. Tara completed two postdoctoral fellowships. The first was at University of California Irvine with John Hemminger, where she used molecular dynamics simulations to investigate physical processes at ice surfaces, and the second was at University of Colorado Boulder, where she worked with Veronica Vaida using spectroscopic techniques to investigate the atmospheric fate of trace gases such as ozone and hydrogen peroxide. Tara joined Syracuse University in August 2012. Her research program at SU focuses on the fate of pollutants in water and ice, chemistry at urban surfaces, and indoor chemistry.
Thursday, April 5, 2017
Xavier Roy, Columbia University
Molecular Clusters: Building Blocks for Nanoelectronics and Material Design
The programmed assembly of nanoscale building blocks offers exciting new avenues to creating electronic devices and materials in which structure and functions can be chemically designed and tuned. In this context, the synthesis of inorganic molecular clusters with atomically-defined structures, compositions and surface chemistry provides a rich family of functional building elements. This presentation will describe our efforts to assemble such “designer atoms” into a variety of hierarchical structures and devices, and study the resulting collective properties. In one design, single clusters are wired into electrical junctions that can be operated as molecular-scale transistors. The single cluster devices exhibit room-temperature current blockade below a threshold voltage, and they can be “turned on” by applying an electrochemical potential across the junction, enabling the temporary occupation of the cluster core states by sequential transiting carriers. A second area of exploration is in creating solid state materials in which preformed clusters emulate the role of atoms in traditional “atomic” solids. These materials offer a unique opportunity to combine programmable building blocks and atomic precision. As such, they bridge traditional crystalline semiconductors, molecular solids, and nanocrystal arrays by synergizing some of their most attractive features. Recent synthetic advances to develop this concept into a “modular” platform for materials design will be presented. It will be shown that novel, tunable, collective properties (magnetic, optical, electrical and thermal transport) emerge from specific interactions between the building blocks within these assemblies.
Xavier Roy received a B.Eng. (2002) and a Master of Applied Science (2005) in Chemical Engineering from École Polytechnique of Montreal, performing research under the guidance of Prof. Basil Favis. He earned his Ph.D. in Chemistry with Prof. Mark MacLachlan at the University of British Columbia in 2011, working as an NSERC Alexander Graham Bell Scholar. He went on to do postdoctoral research as a Canada NSERC Postdoctoral Fellow with Prof. Colin Nuckolls at Columbia University from 2011 to 2013. He joined the Columbia University Faculty in 2013 as an Assistant Professor of Chemistry.
Thursday, April 19, 2017
Ivan Korendovych, Syracuse University
De Novo Design of Catalysts
Design of a novel catalytic function in proteins and peptides, apart from its inherent practical value, is important for fundamental understanding of origins of enzymatic activity. Two applications of a computationally inexpensive, minimalistic approach to design of artificial catalysts will be presented.
- Strategic introduction of single mutations is sufficient to confer catalytic activities (Kemp elimination, ester hydrolysis, retroaldol reaction) onto calmodulin, a non-enzymatic protein. The catalytic efficiencies of the resulting allosterically regulated catalysts are on par with those of the best computational approaches. Directed evolution allowed for further improvement of catalysts’ efficiency.
- We designed a series of 7-residue peptides that self-assemble into amyloid-like fibrils to act as metal-dependent esterases and oxidases. Metal ions, such as Zn2+ or Cu2+ help stabilize the fibril formation, while also acting as cofactors to catalyze chemical reactions. The resulting catalytic amyloids show efficiency that rivals that of some enzymes by weight. These results indicate that amyloid fibrils are able to not only catalyze their own formation — they also can catalyze chemical reactions. Thus, amyloids might have served as intermediates in the evolution of modern-day enzymes.
Nature Chem. 2014, 6, 303-309; ACIE 2013, 52, 6246-6249; JACS 2015, 137, 14905, J. Biol. Inorg. Chem. 2013, 18, 411-418; PNAS 2011, 108, 6823-6827; Protein Sci. 2015, 24, 561-570;PNAS 2017, 114, 6191-6196.
Prof. Korendovych received both B.S. (1999) and M.S. (2000) degrees with distinction from National Taras Shevchenko University of Kiev, Ukraine. He received his PhD from Tufts University in 2006 for his studies of mechanistic aspects of dioxygen activation using complexes of iron with macrocyclic ligands in Prof. Rybak-Akimova’s lab. Prof. Korendovych then joined the group of Prof. William F. DeGrado at the University of Pennsylvania School of Medicine as a postdoctoral fellow working on de novo design of proteins. In 2011, he joined the faculty at Syracuse University and was promoted to Associate Professor in 2017.