Structure and Dynamics in Supercritical Fluids

Supercritical fluids (SCFs) are currently receiving much industrial and scientific interest as a result of their unique physical properties. The most characteristic features of SCFs are liquid-like densities, gas-like viscosities, and diffusivities that are intermediate between typical gas and liquid values. The resulting combination of high dissolving power and enhanced mass-transfer rates makes SCFs attractive alternatives to liquid solvents for a variety of industrial applications, such as extraction, separation and reaction processes. In addition, the high compressibility of SCFs in the near-critical region allows one to tune their properties to desired values by applying small changes in pressure, which in turn makes it possible to tailor the rates and selectivities of chemical processes. Since the aforementioned applications of SCFs generally involve dilute solutions, it is essential to develop a microscopic understanding of the structure and dynamics of a supercritical solvent in the vicinity of a solute.

We use the methods of classical statistical mechanics, such as integral equation theory and mode coupling theory, to study structural and dynamical properties of supercritical solutions. Some of the problems we address are as follows. How does the solvent-solute and solute-solute clustering affect the rates and equilibrium constants of chemical reactions in SCFs? How does the proximity to the critical point affect the transport properties and what are the ramifications for diffusion controlled chemical reactions? How is preferential solvation manifested in local composition effects in dilute supercritical solutions? The answers to these questions should help us shed further light on fundamental properties of SCFs and their practical applications.

Quantum and Semiclassical Many-Body Dynamics

Numerous problems in chemical physics involve calculations of quantum time correlation functions (TCFs) in many-body systems. Particular examples include: medium-induced electron transfer, dissipative tunneling, radiationless processes, and electronic spectroscopy of chromophores in crystals and in liquids. While certain systems require a fully quantum mechanical treatment, there exists a large class of systems of chemical interest for which classical mechanics provides a reasonably good approximation. An appealing approach to the calculation of TCFs for such systems involves using semiclassical methods, which are generally based on the assumption that quantum effects can be taken into account by introducing relatively small corrections to the classical results. However, the shorter the time scale on which the behavior is analyzed, the more important quantum corrections may become, even for systems which are classical as far as their static and low-frequency dynamical properties are concerned. One of the research projects in our group involves developing a systematic procedure for including quantum effects into the results for TCFs obtained from classical simulations.

An alternative approach to study quantum dynamics in condensed phases involves calculating imaginary-time correlation functions using path integral Monte Carlo (PIMC) method and performing analytic continuation to the real-time axis. Unfortunately, analytic continuation is numerically unstable, and therefore leads to uncontrollable amplification of statistical noise unavoidable in PIMC simulations. In our group we employ the information theory and the methodology from the field of inverse problems in order to develop various techniques, such as Maximum Entropy and Singular Value Decomposition, for stabilizing the procedure of analytic continuation of quantum imaginary-time TCFs.

Recent Publications

S. N. Merz, Z. J. Farrell, J. Pearring, E. Hoover, M. Kester, S. A. Egorov, D. L. Green, and K. H. DuBay, "Computational and Experimental Investigation of Janus-like Monolayers on Ultrasmall Noble Metal Nanoparticles", ACS Nano, 12, p. 11031-11040, (2018).

 A. Milchev, S. A. Egorov, A. Nikoubashman, and K. Binder, "Nematic order in solutions of semiflexible polymers: Hairpins, elastic constants, and the nematic-smectic transition", J. Chem. Phys., 149, p. 174909, (2018).

K. E. Klop, R. P. A. Dullens, M. P. Lettinga, S. A. Egorov, and D. G. A. L. Aarts, "Capillary nematisation of colloidal rods in connement", Mol. Phys., 116, p. 2864-2871, (2018).

R. J. Chen, R. Poling-Skutvik, M. P. Howard, A. Nikoubashman, S. A. Egorov, J. C. Conrad, and J. C. Palmer, "Influence of polymer flexibility on nanoparticle dynamics in semidilute solutions", Soft Matter, 15, p. 1260-1268, (2019).

S. J. Wang, D. Venkateshvaran, M. R. Mahani, U. Chopra, E. R. Mc-Nellis, R. Di Pietro, S. Schott, A. Wittmann, G. Schweicher, M. Cubukcu, K. Kang, R. Carey, T. J. Wagner, J. N. M. Siebrecht, D. P. G. H. Wong, I. E. Jacobs, R. O. Aboljadayel, A. Ionescus, S. A. Egorov, S. Mueller, O. Zadvorna, P. Skalski, C. Jellett, M. Little, A. Marks, I. McCulloch, J. Wunderlich, J. Sinova, H. Sirringhaus, "Long spin diffusion lengths in doped conjugated polymers due to enhanced exchange coupling", Nature Electronics, 2, p. 98-107, (2019).

J. Midya, Y. Cang, S. A. Egorov, K. Matyjaszewski, M. R. Bockstaller, A. Nikoubashman, and G. Fytas, "Disentangling the Role of Chain Conformation on the Mechanics of Polymer Tethered Particle Materials", Nano Letters, 19, p. 2715-2722, (2019).

S. N. Merz, E. Hoover, S. A. Egorov, K. H. DuBay, and D. L. Green, "Predicting the effect of chain-length mismatch on phase separation in noble metal nanoparticle monolayers with chemically mismatched ligands", Soft Matter, 15, p. 4498-4507 (2019).

J. Midya, S. A. Egorov, K. Binder, and A. Nikoubashman, "Phase behavior of exible and semi exible polymers in solvents of varying quality", J. Chem. Phys., 151, p. 034902 (2019).

U. Chopra, S. A. Egorov, J. Sinova, and E. R. McNellis, "Chemical and structural trends in the spin-admixture parameter of organic semiconductor molecules", J. Phys. Chem. C, 123, p. 19112-19118 (2019).

U. Chopra, S. Shambhawi, S. A. Egorov, J. Sinova, and E. R. McNellis, "Accurate and general formalism for spin-mixing parameter calculations", Phys. Rev. B, 100, p. 134410 (2019).

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Publication list

Photochemistry and Photophysics of Transition Metal Complexes

Professor Demas is not currently accepting graduate students.

Molecules excited by light lose energy by emission of light, transfer of energy or an electron to other molecules, photochemistry, and non-destructive radiationless processes. Solar energy conversion, chemical analysis, and light intensity measurements require information from the study of these processes. The processes can be highly sensitive to environmental factors such as solvent and interactions with organized media such as micelles, cyclodextrins, membranes, proteins, and DNAs. In addition, luminescence properties are very sensitive to the environment in polymer-supported sensors. We are elucidating the nature of these processes, correlating properties with molecular structure and environment, and developing new chemical, instrumental, and mathematical tools for studying these processes.

Our work includes:

• Design, synthesis and characterization of highly luminescent Os, Ir, Re, and Ru complexes.
• Evaluating photochemical properties, excited state ordering, and paths of energy loss.
• Fundamental and applied studies of interactions of photosensitizers with polymers, micelles, membranes and other organized media.
• Developing new luminescence-based sensors (e.g., oxygen, pH, metal ion).
• Design and utilization of metal complexes as probes of the structure and dynamics of organized media such as DNAs and membranes.
• Instrumental and theoretical developments in ultrasensitive, multicomponent fluorometric analyses.

An example of an analytical sensor is shown in the figure.

The photoluminescence of a tris(4,7-diphenyl-1,10-phenanthroline)ruthenium (II) complex in a polymer film is shown while the film is being breathed over. The luminescence is quite sensitive to deactivation by oxygen, and the luminescence intensity is a direct measure of the oxygen in the subject’s breath. Less oxygen yields more luminescence. The region immediately after the subject held his breath is revealing.

Recent Publications

Aromatic difluoroboron β-diketonate complexes: effects of π-conjugation and media on optical properties. Xu S, Evans RE, Liu T, Zhang G, Demas JN, Trindle CO, Fraser CL. Inorg Chem. 52:3597-610 (2013).

Viscosity and temperature effects on the rate of oxygen quenching of tris-(2,2′-bipyridine)ruthenium(II). Reynolds EW, Demas JN, DeGraff BA. J Fluoresc. 23:237-41 (2013).

Environmental sensitivity of Ru(II) complexes: the role of the accessory ligands. Dixon EN, Snow MZ, Bon JL, Whitehurst AM, DeGraff BA, Trindle C, Demas JN. Inorg Chem. 51:3355-65 (2012).

Photophysical and analyte sensing properties of cyclometalated Ir(III) complexes. Leavens BB, Trindle CO, Sabat M, Altun Z, Demas JN, DeGraff BA. J Fluoresc. 22:163-74 (2012).

Laser phosphoroscope and applications to room-temperature phosphorescence. Payne SJ, Zhang G, Demas JN, Fraser CL, Degraff BA. Appl Spectrosc. 65:1321-4 (2011).

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Difluoroboron dibenzoylmethane-poly(lactic acid) analogues exhibit both intense fluorescence and long-lived room temperature phosphorescence. When fabricated as nanoparticles, these simple, dual-emissive biomaterials serve as optical oxygen probes for biology and medicine, with impressive combined spatial and temporal resolution. Along with fundamental studies, the materials have been optimized with respect to fluorescence and phosphorescence emission colors, relative intensities, luminescence lifetimes, oxygen sensitivities, and fabrication. With collaborators, we developed a portable, cost-effective, laptop camera imaging system that, in conjunction with boron nanosensors, allows for dynamic, real-time, single or dual mode (ratiometric and/or lifetime) tissue oxygen imaging. We have demonstrated the utility of these materials for in vitro and in vivo optical oxygen imaging in cell, tumor, wound, vascular, brain, immunological, tissue engineering, and other contexts.

Mechanochromic Luminescence and Other Stimuli Responsive and Environment Sensitive Properties

Difluoroboron β-diketonate dyes also show surprising properties as molecular solids. For example, we showed that the difluoroboron complex of avobenzone, a simple sunscreen ingredient, has narrow bandwidth green, cyan, or blue emission depending on the solid form. Furthermore, the emission color changes when crystals are crushed or films are scratched or rubbed. Surprisingly, for thin films, the mechanochromic luminescence is reversible. For the avobenzone complex, regions where force is applied turn yellow but return to the original green-blue background color within minutes at room temperature or seconds with heating. The writing-fading process may be repeated many times. Emission colors, force responsiveness, and self-healing times may be tuned through molecular design, and self-erasing properties may be monitored with video camera imaging. These simple Scratch the Surface InksTM show promise as mechanical sensors and renewable inks for rewritable surfaces. They have even inspired creative works in music, art, and design. Other interesting properties of boron dyes, and in some cases even β-diketones absent difluoroboron, include solvatochromism, viscochromism, halochromism, aggregation induced emission, dye thickness and loading effects, and energy transfer in dye mixtures. Interestingly, some dyes are also thermally responsive and form supercooled liquids. Synthesizing new dyes, exploring their many fascinating properties, and tailoring materials for imaging and sensing in biology, medicine, and other contexts serves as the focus of our research.

Integrative Interdisciplinary Projects

Professor Fraser also has a great passion for envisioning and leading innovative interdisciplinary programs that integrate teaching, research, community engagement and creative pursuits. These projects are often inspired by materials, and environmental health and sustainability themes. They build bridges across STEM and non-STEM disciplines and engage students, faculty, and the community with thought leaders from across UVA and the globe. Examples include the UVA Page Barbour supported Transduction and Plastic/ity projects, the Carnegie Corporation funded Designing Matter Common Course, the NIH Global Health funded Metals in Medicine and the Environment, the Biomaterials Workshop, the Echols seminar Color: Across the Spectrum, and the Science, Careers and Society Forum. Professor Fraser often collaborates with artists and designers on exhibitions and performances (e.g. Chromogenic Materials, Agents of Architecture, UVA Music Technosonics Festival, UVA Art Bestiary Exchange Portfolio, Environmental Art Activism, and Time books). She also engages in design projects to establish new kinds of venues for conducting and displaying interdisciplinary work (e.g. WallSpace, Real World Chemistry Lab). New research is concerned with Anthrochemistry—chemistry of the Anthropocene, investigating the human impacts of chemistry through element, molecule, and material case studies via an interdisciplinary global systems chemistry approach. Of particular interest are ways that materials, their pathways, and processes, are mapped onto and into our bodies and intersect with our everyday lives, affecting health and wellbeing. Laws, policies, social and environmental justice, and ethics and responsibility are also considered. Creative interdisciplinary ways of communicating findings to both university and broader audiences are also of interest.

Selected Publications

Luminescent Difluoroboron β-Diketonate PLA-PEG Nanoparticles.  Kerr, C.; DeRosa, C. A.; Daly, M. L.; Zhang, H.; Palmer, G. M.; Fraser, C. L. Biomacromolecules 2017, 18, 551-561.

Oxygen Sensing Difluoroboron β-Diketonate Polylactide Materials with Tunable Dynamic Ranges for Wound Imaging.  DeRosa, C. A.; Seaman, S. A.; Mathew, A. S.; Gorick, C. M.; Fan, Z.; Demas, J. N.; Peirce, S. M.; Fraser, C. L. ACS Sensors 2016, 1, 1366-1373.

Mechanochromic Luminescence and Aggregation Induced Emission of Dinaphthoylmethane β-Diketones and their Boronated Counterparts.  Butler, T.; Morris, W. A.; Samonina-Kosicka, J.; Fraser, C. L. ACS Appl. Mater. Interfaces 2016, 8, 1242-1251.

Polymorphism and Reversible Mechanochromic Luminescence for Solid-State Difluoroboron Avobenzone.  Zhang, G.; Lu, J.; Sabat, M.; Fraser, C. L. J. Am. Chem. Soc. 2010, 132, 2160-2010.

A Dual-Emissive Materials Design Concept Enables Tumour Hypoxia Imaging.  Zhang, G.; Palmer, G. M.; Dewhirst, M. W.; Fraser, C. L. Nat. Mater. 2009, 8, 747-751.

Multi-Emissive Difluoroboron Dibenzoylmethane Polylactide Exhibiting Intense Fluorescence and Oxygen-Sensitive Room-Temperature Phosphorescence.  Zhang, G.; Chen, J.; Payne, S. J.; Kooi, S. E.; Demas, J. N.; Fraser, C. L. J. Am. Chem. Soc. 2007, 129, 8942-8943.

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Astrochemistry concerns the behavior of atoms and molecules in astrophysical environments, which can include star-forming clouds and cores, and circumstellar and interstellar regions, and the solar system. The varied gas-phase chemical compositions of interstellar environments are revealed by radio-telescope observations of molecular spectral-line emission and absorption in the cm, mm and sub-mm bands. Infrared observations also indicate significant solid-phase abundances of simple hydrides, in the form of ices, which coat the sub-micron sized dust grains that permeate interstellar space. The process of star formation – which involves the heating and UV radiative processing of gas and solid-phase material alike – further encourages the production of complex organic molecules that may contribute to the store of pre-biotic material ultimately available on the surfaces of new planetary bodies.

The Garrod group develops and applies new computational techniques to the study of chemical kinetics in interstellar, star-forming, solar-system environments. A particular focus of the group is the formation and processing of simple and complex organic molecules on dust-grain surfaces and within astrophysical molecular ices. Recent new modeling efforts also include the first chemical kinetics models of solid-phase chemistry in comets.

Recent publications:
 

Formation of Complex Organic Molecules in Cold Interstellar Environments through Nondiffusive Grain-surface and Ice-mantle Chemistry

Jin, Mihwa & Garrod, Robin T.

Astrophysical Journal Supplements, 2020, 249, 26
 

Astrochemistry During the Formation of Stars

Jorgensen, Jes K., Belloche, Arnaud  & Garrod, Robin T.

Annual Reviews in Astronomy & Astrophysics (in press), 2020

Exploring molecular complexity with ALMA (EMoCA): complex isocyanides in Sgr B2(N)

Willis, E. R., Garrod, R. T., Belloche, A. et al.

Astrophysical Journal, 2020, 636, 29

Constraining Cosmic-Ray Ionization Rates and Chemical Timescales in Massive Hot Cores

Barger, Christopher J. & Garrod, Robin T.

Astrophysical Journal, 2020, 888, 38

Simulations of Ice Chemistry in Cometary Nuclei

Garrod, Robin T.

Astrophysical Journal, 2019, 884, 69

Re-exploring Molecular Complexity with ALMA (ReMoCA): interstellar detection of urea

Belloche, A., Garrod, R. T., Müller, H. S. P. et al.

Astronomy & Astrophysics, 2019, 628, 10

Organometallic chemistry, inorganic chemistry, homogeneous catalysis, small molecule activation

The development of more efficient synthetic methods represents a major economic and environmental challenge for the chemical industry. With research interests that span the fields of inorganic and organic chemistry, we focus on the preparation and characterization of new transition metal complexes that are capable of activating organic molecules toward novel reactivity. By focusing on fundamental inorganic and organometallic chemistry, our efforts are directed toward the design of single-site catalysts that form the foundation of new synthetic methodologies. We apply our fundamental research toward chemical processes of relevance to the production and use of energy, the synthesis of large-scale chemicals as well as the fine chemical sector.

Petroleum distillates make up a considerable fraction of the synthetic building blocks available to the chemical industry and with a steep rise in demand, the efficient use of fossil resources is increasingly important. Carbon and hydrogen are the major elemental constituents of fossil-derived products. One area of focus for our group is the design of transition metal complexes that selectively break C–H bonds to enable reactivity towards useful products. For example, we are exploring the use of late transition metal systems for catalytic C–C bond formation reactions that proceed through transition metal-mediated C–H activation. Systems based on Ru, Pt, Rh and Ir developed in our labs catalyze the addition of aromatic (including arenes and heteroaromatic substrates) C–H bonds across the C=C bonds of olefins. The overall reactions result in arene alkylation or alkenylation. By understanding how the metal identity, metal oxidation state, and ancillary ligand impact the catalytic cycle, we can design improved catalysts.

Another area of interest is the development and study of catalysts for the selective partial oxidation of light alkanes. Natural gas is an abundant resource for chemicals, but current processes for the oxidation of light alkanes (methane, ethane, propane) to form alcohols are indirect and energy intense. As a result, distributed conversion at natural gas wellheads is not generally economical, which often results in natural gas flaring. We are studying new strategies for catalytic conversion of methane, ethane and propane to selectively generate methanol, ethanol and propanol. Our efforts are focused on both thermal and photo-driven processes. 

Recently, we also have initiated projects to elucidate mechanistic details for electrocatalytic water oxidation. This is a half-reaction for overall electrocatalytic splitting of water to form dihydrogen and dioxygen, which is one strategy for the scaled conversion of abundant solar energy to chemical fuels. Electrocatalytic water oxidation is challenging due to the multi-step/multi-electron pathway as well as the common degradation of active sites to metal oxos. In collaboration with other groups, we are studying well-defined molecular catalysts, primarily based on abundant first row transition metals such as Cu and Co, including the integration of molecular active sites into conductive carbon materials.

Representative Publications

"Rhodium-Catalyzed Arene Alkenylation Using Only Dioxygen as Oxidant" Zhu, W., Gunnoe, T. B.* ACS Catal. 2020, 10, 11519-11531. DOI: 10.1021/acscatal.0c03439

"Synthesis of Stilbenes by Rhodium-Catalyzed Aerobic Alkenylation of Arenes via C–H Activation" Jia, X., Frye, L. I., Zhu, W., Gu S., Gunnoe, T. B.* J. Am. Chem. Soc. 2020, 142, 10534-10543. DOI: 10.1021/jacs.0c03935

"Use of Ligand Steric Properties to Control the Thermodynamics and Kinetics of Oxidative Addition and Reductive Elimination with Pincer-ligated Rh Complexes" Gu, S., Nielsen, R. J.*, Taylor, K. H., Fortman, G. C., Chen, J., Dickie, D. A., Goddard III, W. A.*, Gunnoe, T. B.* Organometallics 2020, 39, 1917-1933. DOI: 10.1021/acs.organomet.0c00122 (NOTE: List of "Most Read Articles" for Organometallics)

"Advances in Rhodium Catalyzed Oxidative Arene Alkenylation" Zhu, W., Gunnoe, T. B.* Acc. Chem. Res. 2020, 53, 920-936. DOI: 10.1021/acs.accounts.0c00036

"Styrene Production from Benzene and Ethylene Catalyzed by Palladium(II): Enhancement of Selectivity towards Styrene via Temperature Dependent Vinyl Ester Consumption" Jia, X., Foley, A. M., Liu, C., Vaughan, B. A., McKeown, B. A., Zhang, S., Gunnoe, T. B.*  Organometallics 2019, 38, 3532-3541. DOI: 10.1021/acs.organomet.9b00349 (manuscript was selected for the issue cover)

"Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period" Zhu, W., Luo, Z.,  Chen, J., Liu, C., Yang, L., Dickie, D. A., Liu, N., Zhang, S., Davis, R. J., Gunnoe, T. B.* ACS Catalysis 2019, 9, 7457-7475. DOI: 10.1021/acscatal.9b01480

"Catalytic Synthesis of Super Linear Alkenyl Arenes Using a Rh(I) Catalyst Supported by a "Capping Arene" Ligand: Access to Aerobic Catalysis" Chen, J., Nielsen, R. J.*, Goddard III, W. A., McKeown, B. A., Dickie, D. A., Gunnoe, T. B.* J. Am. Chem. Soc. 2018, 140, 17007-17018. DOI: 10.1021/jacs.8b07728

"Catalytic Synthesis of "Super" Linear Alkenyl Arenes Using an Easily Prepared Rh(I) Catalyst" Webster-Gardiner, M. S., Chen, J., Vaughan, B. A., McKeown, B. A., Schinski, W., Gunnoe, T. B.* J. Am. Chem. Soc. 2017, 139, 5474-5480. DOI: 10.1021/jacs.7b01165. This manuscript was highlighted in Chemical and Engineering News 2017, 95(17), 8.

"Organometallic Complexes Anchored to Conductive Carbon for Electrocatalytic Oxidation of Methane at Low Temperature" Joglekar, M., Nguyen, V., Pylypenko, S., Ngo, C., Li, Q., O’Reilly, M.E., Gray, T.S., Hubbard, W.A., Gunnoe, T. B.*, Herring, A. M.*, Trewyn, B.G.*. J. Am. Chem. Soc. 2016, 138, 116-125. This manuscript was highlighted in Chemical and Engineering 2015, 93 (43), 6; featured on cover of J. Am. Chem. Soc., selected for JACS Spotlights). DOI: 10.1021/jacs.5b06392

"A Rhodium Catalyst for Single-Step Styrene Production" Vaughan, B. A., Webster-Gardiner, M. S., Cundari, T. R.*, Gunnoe, T. B.* Science 2015, 348, 421-424. This manuscript was highlighted in Chemical and Engineering News 2015, 93 (17), 26. DOI: 10.1126/science.aaa2260

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The science of organic synthesis is central to both the discovery and manufacturing of pharmaceuticals and other fine chemicals and the emergence of subdisciplines of biology that are becoming increasingly focused on phenomena at the molecular level (e.g., synthetic biology and chemical biology). Over the last half-century revolutionary advances in synthetic organic chemistry have made it possible to synthesize virtually any molecule given enough time, money, and manpower. However, this is frequently not enough since a lack of practical and cost-effective synthetic access can and does prevent promising drug leads from ever helping patients. The grand challenge for synthetic organic chemistry is therefore to advance the field of synthesis to the point where any molecule can be not only synthesized, but also synthesized in a way that minimizes the cost, time, and manpower required as well as environmental impact. Our group’s research is focused on eliminating synthetic considerations as a barrier to the discovery of new therapeutics.

Recent Publications

Organocatalytic, Dioxirane-Mediated C-H Hydroxylation under Mild Conditions Using Oxone. W. G. Shuler, S. L. Johnson, M. K. Hilinski, Org. Lett. 2017, 19, 4790–4793.

An Iminium Salt Organocatalyst for Selective Aliphatic C–H Hydroxylation. D. Wang, W. G. Shuler, C. J. Pierce, M. K. Hilinski, Org. Lett. 2016, 18, 3826–3829.

Intermolecular Electrophilic Addition of Epoxides to Alenes: [3+2] Cycloadditions Catalyzed by Lewis Acids. W. G. Shuler, L. A. Combee, I. D. Falk, M. K. Hilinski, Eur. J. Org. Chem. 2016, 3335–3338.

Chemoselective Hydroxylation of Aliphatic sp3 C–H Bonds Using a Ketone Catalyst and Aqueous H2O2. C. J. Pierce, M. K. Hilinski, Org. Lett. 2014, 16, 6504–6507.

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Polyethylene Terephthalate Microdevices

Our research group has developed a technique for fabricating microfluidic devices with complex multilayer architectures using a laser printer, a CO2 laser cutter, an office laminator, and common overhead transparencies as a printable substrate via a laser print/cut and laminate (PCL) methodology.  The printer toner serves three functions; (1) it defines the microfluidic architecture, (2) acts as the bonding agent, and (3) provides printable, hydrophobic "valves" for fluidic flow control. Using common graphics software, the protocol produces microfluidic devices with a design-to-device time of ~40 min.  Devices of any shape can be generated for an array of multistep assays with colorimetric detection of molecular species ranging from small molecules to proteins.  The simplicity of the protocol, availability of the equipment and substrate and cost-effective nature of the process make microfluidic devices available to those who might benefit most from expedited, microscale chemistry.

Figure 1.  A microfluidic chip designed to dispense sample and mix reagents by rotating at varying speeds.  This specific device is used to measure albumin concentration, white blood cell count, and hematocrit in whole blood.

Biological, Bioanalytical and Clinical Chemistry

Almost every aspect of the biochemical, biomedical and clinical sciences involves separation of species in complex matrices. Electrophoresis has been a benchmark technique for separation and characterization of biologically-active species. Instead of using conventional slab gel electrophoretic approaches, electrophoresis in micron-scale capillaries using applied fields as high as 30,000 volts, results in unprecedented resolution with unique selectivities and short analysis times. As a result of the microscalar nature of the capillary, only microliters of reagent are consumed by analysis with only a few nanoliters of samples injected for analysis. These characteristics, as well as the ability for on-line detection with laser-induced fluorescence sensitivities in the attomole (10-18 moles) range, made capillary electrophoresis (CE) appealing as a replacement for electrophoretic gels in the biomedical and clinical arenas. We have demonstrated the potential impact of CE on clinical diagnostics through the development of new CE-based assays for measuring kidney function, detecting multiple sclerosis and viral infections, screening for lymphoma, as well as for diagnosing drug abuse and alcoholism.

Figure 1. A – Schematic of capillary electrophoresis instrumentation. B – CE separation of human serum for the diagnosis of alcoholism.

While the diagnostic impact of standard CE technology is clear, an alternative platform for electrophoresis in microscalar structures has evolved in the form of microchip electrophoresis. The use of microfabricated glass devices containing etched capillary-like channels provides an electrophoretic platform akin to CE but with more flexibility. “Microchip electrophoresis” allows for analysis times to be decreased by an order of magnitude over times achievable by CE (as fast as 10-200 seconds) and two orders of magnitude faster than gel electrophoresis. This provides obvious value to clinical diagnostic laboratories in terms of more rapid turn around time and capability for high throughput screening. We have demonstrated this with the detection T-cell and B-cell lymphoma in a separation remarkably faster than with conventional means.

Figure 2. Demonstration of microchip electrophoresis as a technique for rapid diagnosis of T-Cell lymphoma. Sample T1 shows a negative sample, which is represented by the smear after 100 seconds of separation. T4 is a positive sample with a sharp peak.

With a program focused on the application of miniaturized electrophoretic technology to the clinical and forensic sciences, our current efforts involve broadening the scope of applications for microchip technology. This involves addressing issues associated with integrating functions other than "separation" onto microchips. For example, we are focused on defining approaches for integrating DNA sample preparation into microchips. PCR amplification of DNA carried out using infrared-mediated thermocycling for rapid on-chip amplification and rapid DNA extraction using microchamber-bound solid phases are two examples of our integration efforts.

Figure 3. A – Demonstration of IR-mediated PCR in a polyimide microchip. Total time necessary for thermocycling was 220 seconds. B – Elution profile of DNA in mSPE chip.

The successful integration of DNA extraction and amplification will lead to the development of an “Integrated Diagnostic” or ID-chip, which we ultimately hope will improve laboratory medicine. Efforts are also underway to 1) define better detection systems using acoustic-optic technology, 2) develop multichannel devices for high-throughput analysis using this optical technology, 3) explore proteomic aspects of disease using multi-dimensional microchips for protein separations, and 4) apply the relevant methods to forensic applications.

Recent Publications

Simultaneous metering and dispensing of multiple reagents on passivelycontrolled microdevice solely by finger pressing.  Xu K, Begley M, Landers JP. Lab on a Chip. 15: 867-876 (2015).

Integrated sample-in-answer-out microfluidic chip for Rapid HumanIdentification by STR analysis.  Le Roux D, Root B, Reedy C, Hickey J, Scott O, Bienvenue J, Landers JP, Chassagne L, Mazancourt P.  Lab on a Chip. 14:4415-4425 (2014).

DNA Analysis Using an Integrated Microchip for Multiplex PCRAmplification and Electrophoresis for Reference Samples.  Le Roux D, Root B, Reedy C, Hickey J, Scott O, Bienvenue J, Landers JP, Chassagne L, Mazancourt P.  Analytical Chemistry. 86:8192-8199 (2014).

Rapid, cost-effective DNA quantification via a visually-detectableaggregation of superparamagnetic silica-magnetite nanoparticles.  Liu Q, Li J, Liu H, Tora I, Ide M, Lu J, Davis R, Green D, Landers JP.  Nano Research. 7:755-764 (2014).

Dual-force aggregation of magnetic particles enhances label-freequantification of DNA at the sub-single cell level.  Nelson D, Strachan B, Sloane H, Li J, Landers JP.  Analytica Chimica Acta. 819:34-41 (2014).

Enhanced recovery of spermatozoa and comprehensive lysis of epithelialcells from sexual assault samples having a low cell counts or aged up to one year.  Loundsbury J, Nambia S, Karlsson A, Cunniffe H, Norris J, Ferrance J, Landers JP. Forensic Science International: Genetics. 8:84-89 (2014).

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Ultrasensitive Spectroscopy

There are many problems of both fundamental and of practical importance that requires measurement of extremely low concentrations of certain impurities. Molecular spectroscopy provides one approach that excels in the high specificity provided by the detailed structure in the spectrum, particularly for molecules in the gas phase. Lehmann’s group has been working on the development of new trace sensors, largely based upon the method of cavity ring-down spectroscopy (CRDS). In CRDS, one forms a stable optical cavity using mirrors with reflectivity > 99.99 percent and observes absorption of a sample contained inside the cavity by an increase in the rate of decay of light that is trapped between the mirrors. Sample absorption as low as 1 part in 109 per pass of the cell can be measured in this way. The Lehmann group pioneered the use of low cost and rugged diode lasers developed for the telecom industry in CRDS and has demonstrated detection of a number of small molecules, such as H2O, NH3, NO, and CH4 at levels below one part per billion in a sample gas. Tiger Optics, Inc. is now selling instruments based upon this work to several industries. 

A current focus of the research is development of a version of CRDS that exploits near-resonant two-photon IR absorption of a low-pressure gas.  A low-loss optical cavity can enhance the intensity of light up to ten thousand times over the intensity of the laser used to excite the cavity.  Two-photon absorption of counter propagating photons is with out Doppler Broadening, resulting in transitions with widths ~103 times narrower than the Doppler width of transitions.   While the spectrum of polyatomic molecules often have crowded spectra due to the large number of thermally populated rotational and vibrational states, the two-photon spectrum is dominated by only a few transitions where there is a pair of transitions, sharing an intermediate level, that are very nearly at the same frequency.   For modest size polyatomic molecules, the two-photon absorption spectrum has less than 0.1% as many strong lines at the one photon spectrum.  The combination of the small number and small widths of the lines mean that the typical two-photon spectrum is ~106 times more selective than the one photon spectrum in the same spectral region.  In addition, the two-photon loss of a cavity can be separated from linear loss contributions to the cavity from mirrors, scattering, and one-photon absorption, which results in increased sensitivity as well.

Double Resonance Spectroscopy

There are many situations, such as in combustion and for “Hot Jupiter” Exoplanets, where simulation of spectra of hot samples of polyatomic molecules is needed.  Traditionally, such spectra are difficult to study experimentally due to spectral congestion and sample decomposition.  Great strides have been made in theoretical modeling of such spectra but these theoretical spectra need to be tested experimentally to assess their accuracy, particularly with respect to transitions starting from excited vibrational states.   The Lehmann group, in collaboration with a group in the Univ. of Umea in Sweden, has developed a novel double resonance method that involves using a narrow bandwidth infrared Optical Parametric Oscillator to pump a single ro-vibrational transitions of a molecule (so far we have focused on methane) and then probe absorption transitions from this excited state with a frequency comb, which allows us to simultaneously detect absorption has tens of thousands of discrete frequencies, each determined with ~1 KHz frequency accuracy.  As the pump laser only pumps molecules with a narrow width of Doppler Shift, the probe transitions are sub-Doppler with a width of only a few MHz. 

Meta-Science

There is currently a “replication crisis” is several fields of science, such as psychology and cancer research, where it has been found that a majority of published experiments fail to give the reported results when carefully repeated by independent laboratories.   There are more isolated reports that a substantial fraction of chemical syntheses cannot be reproduced using only what is in the published papers.    Spectroscopy is most often more about measurement than hypothesis testing and has substantially redundancy in that many transitions are fit to high accuracy with a Hamiltonian with a limited number of constants.   However, the accuracy of derived molecular parameters are often dependent upon the details of statistical analysis and poorly understood model errors.  The lab is currently doing systematic investigations the historical reproducibility of spectroscopic constants and the molecular properties derived from them, such as equilibrium structures.

Recent Publications

1. Simon Lobsiger, Cristobal Perez, Luca Evangelisti, Kevin K. Lehmann, and Brooks H. Pate, Molecular Structure and Chirality Detection by Fourier Transform Microwave Spectroscopy, J. Phys. Chem. Lett. 6, 196-200 (2015)
2. Y. Chen, P. Mahaffy, V. Holes, J. Burris, P. Morey, K.K. Lehmann, B. Sherwood Lollar, G. Lacrampe-Couloume, and T.C. Onstott, Near Infrared Cavity Ring-Down Spectroscopy for Isotopic Analysis of CH4 on Future Martian Surface Missions, Planetary and Space Sciences 105, 117-122 (2015).
3. Vitali I. Stsiapura, Vincent K. Shuali, Benjamin M. Gaston, and Kevin K. Lehmann, Detection of S‑Nitroso Compounds by Use of Midinfrared Cavity Ring-Down Spectroscopy, Analytical Chemistry 87, 3345-53 (2015).
4. Z Meng, G.I. Petrov, S Cheng, J.A. Jo, K.K. Lehmann, V.V. Yakovlev, M.O. Scully, Lightweight Raman Spectroscope using time-correlated photon counting detection, Proceedings of the National Academy of Sciences, 112, 12315-12320 (2015).
5. Chen, Y., K. K. Lehmann, Y. Peng, L. M. Pratt, J. R. White, S. B. Cadieux, B. S. Lollar, G. Lacrampe-Couloume and T. C. Onstott, Hydrogen Isotopic Composition of Arctic and Atmospheric CH4 Determined by a Portable Near-Infrared Cavity Ring-Down Spectrometer with a Cryogenic Pre-Concentrator, Astrobiology 16(10): 787-797. (2016).
6. Lehmann, K. K., Influence of resonant collisions on the self-broadening of acetylene, Journal of Chemical Physics 146(9): 094309 (2017).
7. Seifert, N. A., D. P. Zaleski, R. Fehnel, M. Goswami, B. H. Pate, K. K. Lehmann, H. O. Leung, M. D. Marshall and J. F. Stanton, The gas-phase structure of the asymmetric, trans-dinitrogen tetroxide (N2O4), formed by dimerization of nitrogen dioxide (NO2), from rotational spectroscopy and ab initio quantum chemistry, Journal of Chemical Physics 146(13): 134305 (2017).
8. K.K. Lehmann, Theory of Enantiomer-Specific Microwave Spectroscopy, in Frontiers and Advances in Molecular Spectroscopy, pgs 713-743 (2018).  Edited by Jaan Laane, Elsevier publisher. 
9. K.K. Lehmann, Influence of spatial degeneracy on rotational spectroscopy: Three-wave mixing and enantiomeric state separation of chiral molecules, Journal of Chemical Physics 149(9): 094201 (2018).
10. J. Karhu, K.K. Lehmann, M. Vainio, M. Metsala, and L. Halonen, Step-modulated decay cavity ring-down, Optics Express 26(22): 094201 (2018)
11. K. K. Lehmann, Resonant enhanced two-photon cavity ring-down spectroscopy of vibrational overtone bands: a proposal, Journal of Chemical Physics 151: 144201(2019), https://doi.org/10.1063/1.5122988.
12. Gang Zhao, D. Michelle Bailey, Adam J. Fleisher, Joseph T. Hodges, and Kevin K. Lehmann, Doppler-Free two-photon cavity ring-down spectroscopy of a nitrous oxide (N2O) vibrational overtone transition, Physical Review A 101, 062509 (2020).
13. Kevin K. Lehmann, Optical cavity with intracavity two-photon absorption, Journal of the Optical Society of America B 37, 3055 (2020).
14. Aleksandra Foltynowicz, Lucile Rutkowski, Isak Silander1, Alexandra C. Johansson, Vinicius Silva de Oliveira, Ove Axner, Grzegorz Soboń, Tadeusz Martynkien, Paweł Mergo, and Kevin K. Lehman, Sub-Doppler Double-Resonance Spectroscopy of Methane Using a Frequency Comb Probe, to be published in Physical Review Letters.
15. Aleksandra Foltynowicz, Lucile Rutkowski, Isak Silander1, Alexandra C. Johansson, Vinicius Silva de Oliveira, Ove Axner, Grzegorz Soboń, Tadeusz Martynkien, Paweł Mergo, and Kevin K. Lehman, Measurement and assignment of double-resonance transitions to the  8900--9100 cm-1 levels of methane, to be published in Physical Review A.

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The Machan Group is interested in energy-relevant catalysis, particularly at the interface of molecular electrochemistry and materials. The development of efficient and selective transformations to produce commodity chemical precursors and fuels using CO2, O2, H2, and H2O as reagents remains an ongoing challenge for the storage of electrical energy within chemical bonds. Our approach is inspired by the numerous metalloproteins capable of catalyzing kinetically challenging reactions with significant energy barriers in an efficient manner under ambient conditions. This type of reactivity is achieved through the convergent evolution of active sites with tailored coordination environments and macromolecular structures which can, among other things, transport substrates and products to and from the active site. Our research focuses on developing new inorganic complexes and materials which incorporate co-catalytic moieties, non-covalent secondary sphere interactions, and substrate relays as catalysts.

In order to characterize and optimize these systems, research in the Machan Group uses synthetic inorganic chemistry, electrochemistry, and advanced characterization techniques (spectroelectrochemistry, stopped-flow IR and UV-vis spectroscopies). This enables us to develop an understanding of electronic structure and mechanism in transformations of interest. A brief summary of current projects is listed below.

Electrochemical Reduction of Dioxygen
The reduction of dioxygen (O2) is of vital importance to energy related reactions. In biology, respiration uses O2 reduction as a thermodynamic sink, whereas fuel cells pair the oxygen reduction reaction (ORR) to H2O as a proton-dependent half-reaction to the oxidation of chemical fuels. Catalytic ORR processes mediated by molecular species continue to garner interest as models for more complex heterogeneous systems. We are interested in the understanding selective activation and reduction of O2 to H2O2 or H2O by molecular species through electrochemical, spectrochemical, and spectroelectrochemical studies. Using these studies, we are developing new ligand frameworks for aqeuous and non-aqeuous systems, some of which are models for metalloenzyme active sites.

·         Electrocatalytic Reduction of Dioxygen to Hydrogen Peroxide by a Molecular Manganese Complex with a Bipyridine-Containing Schiff Base Ligand (J. Am. Chem. Soc. 2018 DOI:10.1021/jacs.7b09027)

·         Dioxygen Reduction to Hydrogen Peroxide by a Molecular Mn Complex: Mechanistic Divergence between Homogeneous and Heterogeneous Reductants (J. Am. Chem. Soc. 2019 DOI:10.1021/jacs.8b13373)

·         ​Electrocatalytic Reduction of Dioxygen by Mn(III) meso-Tetra(N-methylpyridinium-4-yl)porphyrin in Universal Buffer (Dalton Trans. 2019 DOI: 10.1039/C9DT01436E)

Molecular Electrocatalysts for the Electrochemical Conversion of Carbon Dioxide 

The efficient and cost-effective catalytic reduction of CO2 using renewable energy remains a significant challenge for molecular species. Heterogeneous systems can produce highly reduced products like methane and ethylene from CO2, but these generally suffer from a lack of selectivity. The intrinsic advantage of molecular systems is the relative ease with which they may be characterized and quantified, relative to the distribution of active site morphologies that may be present in a bulk material. Using bioinspired design principles, we are investigating catalytic conversion strategies for producing CO and formic acid from CO2.

·         Electrocatalytic Reduction of CO2 to Formate by an Iron Schiff Base Complex (Inorg. Chem. 2018, DOI: 10.1021/acs.inorgchem.7b02955)

·         Highly Efficient Electrocatalytic Reduction of CO2 to CO by a Molecular Chromium Complex (ACS Catalysis 2020, DOI: 10.1021/acscatal.9b04687)

·         Electrochemical CO2 Reduction in a Continuous Non-Aqueous Flow Configuration with [Ni(cyclam)]2+ Catalyst (Inorg. Chem. 2020 DOI: 10.1021/acs.inorgchem.9b03171)

·         Electrocatalytic CO2 Reduction to Formate with Molecular Fe(III) Complexes Containing Pendent Proton Relays (Inorg. Chem. 2020 DOI: 10.1021/acs.inorgchem.9b03341)

Porous Electrocatalyst Materials
Metal-organic frameworks (MOFs) and covalently linked organic frameworks (COFs) continue to attract significant interest in materials chemistry. MOFs and COFs offer many advantages in terms of porosity and stability over more amorphous materials or zeolites. Indeed, the translation of molecular properties to bulk materials in this manner has implications for the development of electrochemically responsive films and membranes. We are focused on developing new methods for synthesizing and processing conducting and semi-conducting 2D MOF and COF materials sensitive to the chemical environment. This is primarily focused on applications in molecular detection, separation, and catalysis. A fundamental understanding of how molecular properties are translated in these systems will enable future studies focusing on other applications in energy storage and optoelectronic devices.

·         Metal-Organic Frameworks as Porous Templates for Enhanced Cobalt Oxide Electrocatalyst Performance (ACS Applied Energy Materials 2019 DOI: 10.1021/acsaem.9b00127)

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Lisa Morkowchuk is an instructor for Introductory College Chemistry lecture (1410/1610) and laboratories (1411/1611). She received a B.S. in Chemistry from Moravian College in Bethlehem, Pennsylvania and a Ph.D. in Chemistry from Rensselaer Polytechnic Institute in Troy, New York. Much of her undergraduate education was presented in a guided-inquiry format, and she quickly realized the value of peer interaction in education and the depth of understanding that comes from inquiry-based learning. Implementation of these approaches can be a challenge in courses with large enrollments, but it is one way that physical institutions can provide value above that offered by online courses. Lisa strives to continually increase the proportion of “lecture” time spent utilizing non-lecture, evidence-based pedagogical techniques.

Before coming to the University of Virginia, she taught chemistry and mathematics courses at Albany College of Pharmacy and Health Sciences and at Rensselaer Polytechnic Institute. She currently lives in Charlottesville, Virginia with her partner and kids and enjoys endurance running in her free time.

Broadband Rotational Spectroscopy for Chemical Analysis

The Pate lab develops instruments for molecular rotational spectroscopy and uses these instruments to solve challenging problems in chemical analysis.  Molecular rotational spectroscopy uses low frequency light, typically in the microwave region of the electromagnetic spectrum, to excite transitions between the quantized energy levels that come from the rotational kinetic energy.  The energy level patterns for the rotational kinetic energy are determined by the principal moments-of-inertia of the molecule and are, therefore, directly related to the mass distribution relative to the molecular center-of-mass.  The fact that the measurement is connected to the mass distribution, and not just the total mass, makes molecular rotational spectroscopy ideally suited for isomer analysis.

Broadband Rotational Spectroscopy

The Pate lab has pioneered the technique of chirped-pulse Fourier transform rotational spectroscopy.  The key advantage of this technique over previous instrument designs is the ability to measure a large spectral range in a single spectrum acquisition event.  The method has similarities to Fourier transform nuclear magnetic resonance (NMR) spectroscopy: A high-power light pulse (the chirped pulse) creates a macroscopic polarization in the sample by aligning the molecular dipole moments.  After the excitation pulse dissipates, the molecular rotational resonances are detected by the light waves coherently emitted by the rotating molecules.  This coherent emission eventually decays through Doppler dephasing or collisions.  The broadband free-induction decay (FID) from the rotational motion is collected using a high-speed digitizer.  Sensitivity is enhanced by acquiring several measurements and co-adding the FIDs.  The molecular rotational spectrum is produced by subsequent Fourier transform analysis of the FID.  This measurement approach has been extended to low-frequency instruments (2-8 GHz) that are used for analysis of large molecules and to high-frequency instruments (mm-wave range) for smaller molecules such as those important in astrochemistry

Initial Applications of Broadband Rotational Spectroscopy

The first application of chirped-pulse Fourier transform rotational spectroscopy was in the field of intramolecular dynamics.  In this application, the instrument is used to acquire the rotational spectrum of a highly vibrationally excited molecule that is prepared by laser excitation.  The complex nuclear motion from intramolecular vibrational energy redistribution and conformational isomerization produce dynamic effects in the spectrum.  For example, the coalescence of rotational spectra associated with different conformational geometries can be used to measure the energy-resolved unimolecular isomerization rate under collision free conditions.

A second area of application is the structure of molecular clusters.  Clusters form in the pulsed jet expansion used to create the cold gas sample used for analysis.  The aggregation is driven by non-covalent interactions such as hydrogen bonding and London dispersion forces.  A challenge for the analysis of the clusters is that a wide range of cluster sizes are produced and there can be many isomeric structures for each cluster size.  Rotational spectroscopy provides the highest spectral resolution of molecular spectroscopy techniques used for chemical analysis.  As a result, the technique has no trouble resolving the spectra from all cluster geometries present in the sample.  The application of broadband rotational spectroscopy to water clusters has dramatically increased the number of known structures, demonstrated the presence of multiple isomers for a single cluster size, and revealed the dynamics of quantum mechanical tunneling within the water cluster.

Chiral Analysis with Applications to Pharmaceutical Chemistry

The most recent work in the Pate lab is the application of broadband rotational spectroscopy to chiral analysis.  The group is developing techniques for quantitative chiral analysis that uses the formation of clusters of an analyte and a small, enantiopure chiral molecule (called the chiral tag) to determine the enantiomeric excess of the sample.  Using quantum chemistry modeling of the chiral tag complexes it is also possible to establish the absolute configuration of the dominant enantiomer.  A key strength of rotational spectroscopy is that the measurement can simultaneously perform other analyses that are related to the synthesis of chiral molecules.  For example, when the analyte has multiple chiral centers there are two types of stereoisomers: the enantiomers (left- and right-handed versions of a molecule) and diastereomers (isomers with different structures and mass distributions that are easily distinguished by molecular rotational spectroscopy).  The technique can also be used to quantify regioisomers that are often present due to addition reactions that occur at other activated sites of the reagent in the reaction step.  The high-resolution of rotational spectroscopy makes it possible to perform these analyses without extensive sample purification.  Furthermore, cavity-enhanced rotational spectroscopy instruments can be used to monitor the synthesis of chiral molecules in real-time by sampling directly out of the reaction flask.   

Representative Publications

Gordon G. Brown, Brian C. Dian, Kevin O. Douglass, Scott M. Geyer, and Brooks H. Pate, “A Broadband Fourier Transform Microwave Spectrometer Based on Chirped Pulse Excitation” Rev. Sci. Instrum. 79, 053103 (2008).

Brian C. Dian, Gordon G. Brown, Kevin O. Douglass, and Brooks H. Pate, “Measuring Picosecond Isomerization Dynamics via Ultra-broadband Fourier Transform Microwave Spectroscopy”, Science 320, 924-928 (2008).

Cristóbal Pérez, Matt T. Muckle, Daniel P. Zaleski, Nathan A. Seifert, Berhane Temelso, George C. Shields, Zbigniew Kisiel, and Brooks H. Pate, “Structures of Cage, Prism, and Book Isomers of Water Hexamer from Broadband Rotational Spectroscopy”, Science 336, 897-901 (2012).

Jeremy O. Richardson, Cristóbal Pérez, Simon Lobsiger, Adam A. Reid, Berhane Temelso, George C. Shields, Zbigniew Kisiel, David J. Wales, Brooks H. Pate, and Stuart C. Althorpe, “Concerted hydrogen-bond breaking by quantum tunneling in the water hexamer prism”, Science 351, 1310-1313 (2016).

B.H. Pate, L. Evangelisti, W. Caminati, Y. Xu, J. Thomas, D. Patterson, C. Perez, and M. Schnell, “Quantitative Chiral Analysis by Molecular Rotational Spectroscopy”, in Chiral Analysis 2nd Edition Advances in Spectroscopy, Chromatography, and Emerging Methods, P.L. Polavarapu, Editor, Elsevier (2018).

Justin L. Neill, Yuan Yang, Matt T. Muckle, Roger L. Reynolds, Luca Evangelisti, Reilly E. Sonstrom, Brooks H. Pate, and B. Frank Gupton, “Online Stereochemical Process Monitoring by Molecular Rotational Resonance Spectroscopy”, Org. Process Res. Dev. 23, 1046-1051 (2019).

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Organic, Polymer and Organometallic Chemistry; Asymmetric Catalysis; Chiral Sensors; Optically Active Materials

Multi-disciplinary research programs involving organic synthesis, molecular recognition, fluorescent sensing, asymmetric catalysis, and polymers are conducted in our laboratory.  The 1,1′-bi-2-naphthol (BINOL) and its derivatives are chosen as the chiral building blocks to construct novel chiral molecules and macromolecules for diverse applications.  We have developed a family of enantioselective fluorescent sensors for the recognition of organic molecules such as alpha-hydroxycarboxylic acids, amino acids, amino alcohols, and amines.  These sensors are potentially useful for rapid assay of the enantiomeric composition of chiral compounds and for high throughput chiral catalyst screening.  They are also potentially useful for biological analysis and imaging.  New chiral conjugated polymers and dendrimers are prepared for applications in materials, catalysis, and sensing.  We have discovered that the Lewis acid complexes of the optically active binaphthyl molecules and polymers can carry out highly enantioselective organic reactions such as organozinc additions to aldehydes, hetero-Diels-Alder reactions, 1,3-dipolar cycloadditions, reductions of ketones, Michael additions, epoxidations, and others.  Interesting chiral organic molecules including those of biological functions are prepared by using these catalysts.

Enantioselective Fluorescent Sensors

Asymmetric Catalysts

Recent Publications

Enantioselective Fluorescent Recognition of Free Amino Acids:  Challenges and Opportunities.  Pu, L.  Angew. Chem. Int. Ed.  2020, 59, 21814-21828.

Free Amino Acid Recognition:  A Bisbinaphthyl-Based Fluorescent Probe with High Enantioselectivity.  Zhu, Y.-Y.; Wu, X.-D.; Gu, S.-X.; Pu, L.  J. Am. Chem. Soc. 2019, 141, 175−181. 

Simultaneous Determination of Concentration and Enantiomeric Composition in Fluorescent Sensing.  Lin Pu.  Acc. Chem. Res.  2017, 50, 1032-1040. 

Regiospecific Hydration of N-(Diphenylphosphinoyl)propargyl amines:  Synthesis of b-Amino Ketones by Au(III) Catalysis.  Ying, J.; Pu, L.  J. Org. Chem. 2016, 81, 8135−8141.  A Featured Article.  Highlight on the cover.

Conjugated polymer-enhanced enantioselectivity in fluorescent sensing.  Zhang, X. –P.; Wang, C.; Wang, P.; Du, J. –J.; Zhang, G. –Q.; Pu, L.  Chem. Sci. 2016, 7, 3614–3620.

Rational Design of a Fluorescent Sensor to Simultaneously Determine Both the Enantiomeric Composition and Concentration of Chiral Functional Amines.  Wen, K. –L.; Yu, S. –S.; Huang, Z.; Chen, L. –M.; Xiao, M.; Yu, X. –Q.; Pu, L.  J. Am. Chem. Soc. 2015, 137, 4517-4524.

Asymmetric Functional Organozinc Additions to Aldehydes Catalyzed by BINOLs. Pu, L. Acc. Chem. Res.  2014, 47, 1523–1535.

Zn(II) Promoted Dramatic Enhancement in the Enantioselective Fluorescent Recognition of Chiral Amines by a Chiral Aldehyde.  Huang, Z.;  Yu, S. S.;  Yu, X. Q.;  Pu. L.  Chem. Sci.  2014, 5, 3457-3462. 

Enantioselective Fluorescent Sensors: A Tale of BINOL.  Pu, L.  Acc. Chem. Res. 2012, 45, 150–163.

Simultaneous Determination of Both the Enantiomeric Composition and Concentration of a Chiral Substrate with One Fluorescent Sensor.  Yu, S.;  Plunkett, W.;  Kim, M.;  Pu, L.  J. Am. Chem. Soc.  2012, 134, 20282–20285.  A spotlight article reported in J. Am. Chem. Soc., 2013, 135 (3), 949–950.

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1,1'-BINAPHTHYL-BASED CHIRAL MATERIALS:  OUR JOURNEY

My work focuses on considering what Chemical Education should look like today and in future decades.  Chemistry, “the central science” has many important pillars that have to be established in order to understand advanced applications and mechanisms.  It is essential that as chemical educators we continuously and critically evaluate whether our curricula are current in applications and technologies that are relevant to today’s science and industry, and will be applicable for our students as they encounter their future.

I define Chemical Education broadly and am interested in the range of students including chemistry, science and chemical education majors as well as non-science majors. The focus of the non-majors course that I teach, Chem 1210, is to address college science literacy and to explore the question of what every college student should know about chemistry and impact of chemical issues.   In my courses, I strive to establish student centered learning environments in the classroom to maximize the student involvement and focus.

My consideration of curricula parallels my interest in building support networks, especially for those students taking college level chemistry for the first time.  It is important that the appropriate supports are in place so that student’s interest does not wane as a result of frustration.  I have been involved in departmental efforts to establish support for students.

I am interested in bridging the Chemistry Department with other areas on campus, and have done this with the Curry School and the School of Nursing.  These connections encourage facile flow of information on teaching methods and current chemistry content which allows us superior approaches to serving the needs of today’s students.  I currently teach in the Chemistry Department and the School of Nursing.

Professor Kevin Welch is interested in developing curricula for undergraduate instruction in general chemistry and organic chemistry.  In particular, his focus is on updating these courses to accommodate the diverse educational background in chemistry of the students enrolling in chemistry at the University of Virginia, as well as providing a strong chemical foundation for the students as they continue on in their educational and post-educational careers in a variety of fields.  In the past, he has taught undergraduate courses in general chemistry, organic chemistry, inorganic chemistry, environmental chemistry, and scientific writing.

In addition to a focus on undergraduate education, Kevin’s interests in chemistry involve research investigating metal-ligand bonding interactions and the use of transition metal complexes to address challenges in fuel generation and energy storage.

A native of northern Virginia, Kevin received his B.S. in chemistry from Gettysburg College in 2002, and his Ph.D. in chemistry from the University of Virginia in 2007, where he focused on synthetic organometallic chemistry. He spent three years in central Washington as a Department of Energy Postdoctoral Researcher at the Pacific Northwest National Laboratory, working on the development of transition metal catalysts for energy storage and fuel cell technology. From 2010 to 2016, Kevin was a visiting assistant professor at Swarthmore College outside of Philadelphia, Pennsylvania, where he taught and conducted research with undergraduate students. He returned to the University of Virginia in the fall of 2016 and currently teaches courses in general chemistry and laboratories for organic chemistry.

The Zhang group focuses on the development of inorganic nanoscale and sub-nanoscale materials with atomically precise surfaces, interfaces and ordered architectures that enables notable physicochemical properties and emerging applications. Combining the efforts in materials synthesis, advanced characterization, and functional device engineering and simulation, we aim to derive new design principle and new synthetic methodology for critical materials in catalysis, magnetism, plasmonics and biosensing.

Synthetic Methodology for Atomically Precise Materials: Central to functionalizing materials is our ability to synthetically control materials physical dimensions, compositions, and structures with atomic precision. We concentrate our research on the fundamental aspects of inorganic solid nucleation and formation mechanisms. Using colloidal chemistry and operando X-ray scattering and spectroscopic probes, we seek to elucidate the reaction kinetics governing the transformation from atomic monomer to nanocrystals with atomically well-defined structures and surfaces. In particular, we are interested in the nonclassical nucleation and growth phenomena mediated by magic-sized clusters and mesocrystals, and the design of new functional ligands that allow the surface atomic structure engineering of nanocrystals and the programmable formation of ordered nanocrystal superlattices.

Catalysis for Clean Energy and Environmental Sustainability: Taking advantage of synthetic control over atomic surfaces and sites of catalytic materials, our research contributes to the fundamental understanding of structure-property relationship of nano/single-site catalysts for critical energy conversion and chemical transformation processes. Ongoing projects include the development of electrocatalysts for hydrogen economy (water electrolyzer and low-temperature fuel cells) and sustainable carbon management (CO2 reduction and biomass-derived molecule conversion) as well as the thermal catalysts for CO2 hydrogenation and light alkane dehydrogenation. A suite of operando spectroscopic tools (X-ray absorption spectroscopy and X-ray photoelectron spectroscopy), in combination with synchrotron radiation X-ray diffraction and environmental electron microscopy, are employed in our research to reveal the atomic structure of catalysts and their evolution under reaction conditions. Our in-house surface enhanced infrared absorption spectroscopy (SEIRAS) and differential electrochemical mass spectrometry (DEMS) allow us to elucidate the reaction pathways and kinetics. This mechanistic investigation over atomically precise material can be seamlessly integrated with theoretical computation for an ultimate understanding of catalyst design and optimization.

Functional Magnetic and Plasmonic Materials: Another area of focus for the Zhang group is the dimension-dependent magnetic and plasmonic properties of nanomaterials. We are interested in the modulation of magnetic anisotropy using 1-D and 2-D metal oxide materials and their ordered assemblies. In addition, we are collaborating with bioanalytic chemists and engineers to design new strategies to modify biological objects (cells, bacteria, viruses, etc.) with functionalized plasmonic and magnetic nanocrystals to enable the efficient sensing in microfluidic devices.

Recent publications

Chang Liu, Jin Qian, Yifan Ye, Hua Zhou, Cheng-Jun Sun, Colton Sheehan, Zhiyong Zhang, Gang Wan, Yi-Sheng Liu, Jinghua Guo, Shuang Li, Hyeyoung Shin, Sooyeon Hwang, T. Brent Gunnoe, William A. Goddard III*, Sen Zhang*, “Oxygen Evolution Reaction over Catalytic Single-Site Co in a Well-Defined Brookite TiO2 Nanorod Surface”, Nature Catalysis 2021, 4, 36-45.

Perrin Godbold, Grayson Johnson, Akachukwu D. Obi, Rebecca Brown, Sooyeon Hwang, Robert J. Gilliard Jr.*, Sen Zhang*, “Surfactant Removal for Colloidal Nanocrystal Catalysts Mediated by N-Heterocyclic Carbenes​” J. Am. Chem. Soc. 2021, 143, 2644–2648.

Yulu Zhang, Na Li, Zhiyong Zhang, Shuang Li, Meiyang Cui, Lu Ma, Hua Zhou, Dong Su, and Sen Zhang* "Programmable Synthesis of Multimetallic Phosphide Nanorods Mediated by Core/Shell Structure Formation and Conversion"  J. Am. Chem. Soc., 2020, 142, 8490-8497. 

Cheng Hao Wu, Chang Liu, Dong Su, Huolin L. Xin, Hai-Tao Fang, Baran Eren, Sen Zhang*, Christopher B. Murray*, Miquel B. Salmeron*, "Bimetallic Synergy in Cobalt-Palladium Nanocatalysts for CO oxidation", Nature Catalysis, 2019, 2, 78-85.

Zhiyong Zhang, Qiyuan Wu, Grayson Johnson, Yifan Ye, Xing Li, Na Li, Meiyang Cui, Jennifer D. Lee, Chang Liu, Shen Zhao, Shuang Li, Alexander Orlov, Christopher B. Murray, Xu Zhang, T. Brent Gunnoe, Dong Su*, and Sen Zhang*. "Generalized Synthetic Strategy for Transition Metal Doped Brookite-Phase TiO2 Nanorods" J. Am. Chem. Soc., 2019, 141, 16548-16552.

Li An, Zhiyong Zhang, Jianrui Feng, Fan Lv, Yuxuan Li, Rui Wang, Min Lu, Ram B. Gupta, Pinxian Xi*, Sen Zhang*, "Heterostructure-Promoted Oxygen Electrocatalysis Enables Rechargeable Zinc-Air Battery with Neutral Aqueous Electrolyte", J. Am. Chem. Soc., 2018, 140,17624-17631.

Chang Liu, Zhong Ma, Meiyang Cui, Zhiyong Zhang, Xu Zhang, Dong Su, Christopher B. Murray, Jia X. Wang, Sen Zhang*, "Favorable Core/Shell Interface within Co2P/Pt Nanorods for Oxygen Reduction Electrocatalysis", Nano Lett., 2018, 18, 7870-7875.

Awards and Honors

2022 NSF CAREER Award, US National Science Foundation

2021 Research Excellence Award, University of Virginia

2021 CAPA Distinguished Junior Faculty Award, Chinese-American Chemistry & Chemical Biology Professors Association (CAPA)

2021 Scialog Collaborative Innovation Award for Negative Emissions Science, Research Corporation for Science Advancement and Alfred P. Sloan Foundation 

2020 Rising Star 2020, Frontiers in Chemistry, Frontiers

2020 Emerging Investigator, Nanoscale, The Royal Society of Chemistry

2019 Emerging Investigator, Journal of Materials Chemistry A, The Royal Society of Chemistry

2019 Sustainability Course Development Fellowship, University of Virginia

2014  William R. Potter Prize for Doctoral Thesis of Outstanding Merit, Brown University

2013-2016  NatureNet Postdoctoral Fellowship, The Nature Conservancy

Spectroscopy and Photochemistry of Matrix Isolated Species

Normally inaccessible chemical species including free radicals, hydrogen-bonded complexes, unusual inorganic species, transition metal containing intermediates, metal hydrides, and molecular ions are under investigation using infrared matrix-isolation spectroscopy. These transient molecules are prepared by reactions of suitable atoms and/or molecules prediluted in argon by precursor photolysis, or by microwave discharge of the reagents during condensation at 7 K in a vacuum chamber. Solid argon isolates the reaction or photolysis products and preserves them for spectroscopic study at 7 K. Neon is used to isolate new reactionproducts on a 4 K substrate. Pure H2 and D2 are also be employed as a reagent and matrix for the investigation of novel metal hydrides. A new source of atoms that require high temperatures to generate, namely pulsed laser ablation from solid samples, has been developed for use in matrix-infrared spectroscopy in this laboratory. This method exploits two advantages: first, the ablated atoms contain excess energy which can activate reactions with small molecules, and second, collisions with matrix atoms during the condensation process relax energetic product molecules and allow them to be trapped in the solid matrix for spectroscopic study. In addition, laser-ablation also produces cations and electrons for reactions to make charged products.

The experimental apparatus used in hydrogen matrix investigations is sketched in the figure. Infrared spectra are recorded after co-depositing reagent and host matrix gases on the cold sample window and rotating by 90 degrees to face the infrared light beam.

These infrared spectroscopic matrix-isolation studies characterize the bonding and structure of chemical intermediates, interesting new inorganic molecules and complexes and molecular ions and often provide a useful complement and guide to high resolution gas phase work. Stable isotopes are used to determine assignments of the observed infrared absorptions to fundamental vibrational frequencies. Comparison of vibrational energies within related chemical species provides conclusions about the bonding of these newly observed chemical intermediates. Selection rules based upon molecular symmetry and vibrational analysis help determine the molecular geometry. Ab initio electronic structure calculations are done to find molecular structures compatible with the infrared spectrum. Agreement between calculated and observed isotopic vibrational spectra provides further evidence for the discovery of new transient molecular species.

Please click here for a full list of publications.

Nuclear Magnetic Resonance in Chemistry

The Bryant laboratory utilizes a wide range of nuclear and electron spin resonance methods to characterize intra and intermolecular dynamics. A primary focus is the rich information available from the study of the magnetic field dependence of the nuclear spin-lattice relaxation rate as a function of the magnetic field strength or what is called the magnetic relaxation dispersion (MRD). We have constructed unique instrumentation that permits acquisition of MRD profiles for a variety of nuclear resonances in high resolution. These measurements provide a direct measure of the time fluctuations in various nuclear or nuclear-electron dipolar couplings. The resulting MRD profile reports relative inter and intramolecular motions over the time range from about ten microseconds to one picosecond. We are developing methods for probing the fluctuation spectrum of specific vectors defined in structurally interesting proteins and are trying to understand how these fluctuations affect molecular function. In related work, we apply the nuclear spin relaxation induced by freely diffusing paramagnetic solutes in cosolutes to define how one molecule samples the local environment of another and explores the surface or even penetrates into a complex structure like a folded protein. The measurements are sensitive to relatively weak intermolecular interactions and permit definition of highly localized intermolecular free energy differences in solutions. Multinuclear studies of proteins in a number of dynamical environments provide a fundamental characterization of how the protein structure fluctuates in time and how energy is redistributed in the folded structure. The practical implications range from understanding protein catalytic function to developing new techniques for diagnostic medicine in the context of magnetic resonance imaging or MRI.

Recent Publications

Water-proton-spin-lattice-relaxation dispersion of paramagnetic protein solutions. Diakova G, Goddard Y, Korb JP, Bryant RG. J Magn Reson. 208:195-203 (2010).

Water and backbone dynamics in a hydrated protein. Diakova G, Goddard YA, Korb JP, Bryant RG. Biophys J. 98:138-46 (2010).

Dynamics of water in and around proteins characterized by 1H Spin-Lattice Relaxometry. Bryant RG. Comptes Rendus Physique. 11(2), 128-135(2010).

Dimensionality of diffusive exploration at the protein interface in solution. Grebenkov DS, Goddard YA, Diakova G, Korb JP, Bryant RG. J Phys Chem B. 113, 13347-13356 (2009).

Water molecule contributions to proton spin-lattice relaxation in rotationally immobilized proteins. Goddard YA, Korb JP, Bryant RG. J Magn Reson. 199, 68-74 (2009).

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Francis A. Carey is a native of Pennsylvania, educated in the public schools of Philadelphia, at Drexel University (B.S. in chemistry, 1959), and at Penn State (Ph.D. 1963). Following postdoctoral work at Harvard and military service, he was appointed to the chemistry faculty of the University of Virginia in 1966. Prior to retiring in 2000, he regularly taught the two-semester lecture courses in general chemistry and organic chemistry. With his students, Professor Carey has published over forty research papers in synthetic and mechanistic organic chemistry. In addition to this text, he is coauthor (with Robert C. Atkins) of Organic Chemistry: A Brief Course and (with Richard J. Sundberg) of Advanced Organic Chemistry, a two-volume treatment designed for graduate students and advanced undergraduates. He was a member of the Committee of Examiners of The Graduate Record Examination in Chemistry from 1993-2000.

Russ Grimes was raised in Pennsylvania and is a B.S. Chemistry alumnus of Lafayette College He received his Ph.D. in Chemistry from the University of Minnesota as a student of Professor William Lipscomb, although his thesis research was conducted at Harvard University where he was a Harvard Fellow. Following postdoctoral work at Harvard and with Professor M. F. Hawthorne at the University of California, Riverside, he was a faculty member in the Department of Chemistry from 1963 to 2003, becoming a Full Professor in 1973 and serving a term as Department Chair from 1981 to 1984. Over a 40-year period he and his students were among the pioneers in the synthesis and study of polyhedral molecular cage compounds of boron, along the way discovering metal-promoted oxidative cage fusion, tricarbon and large tetracarbon carboranes, stable triple-decker sandwich complexes (which were also the first electrically neutral triple-deckers), isolable tetra-, penta-, and hexadecker molecular sandwiches, linked multidecker complexes, polyhedral metallaboranes, and many novel clusters ranging from C2B3H7 to 14-vertex M2C4B8 systems. A major theme in their work was the development and exploration of small carborane ligands in the designed synthesis of novel transition-metal organometallic systems, especially those having electrically conducting or catalytic properties. The Grimes group together with William Hutton, in work initially reported in the Journal of the American Chemical Society in 1980 and 1981, developed the first successful 2D COSY (correlated spectroscopy) NMR technique involving a quadrupolar nucleus (11B) and in a 1984 JACS full paper detailed its use in both homonuclear 11B-11B) and heteronuclear (11B-1H) spectroscopy.

Professor Grimes was a Senior Fulbright Scholar at the University of Canterbury, New Zealand, in 1974-75, a Guest Professor at the University of Heidelberg, Germany, in 1986, a Humboldt Scholar there in 1997-98, and a Visiting Scholar at the Korea Advanced Institute for Science and Technology in 1997. He received a Boron U.S.A. (BUSA) Award for Distinguished Achievements in Boron Science in 1990 and was elected a Fellow of the American Association for the Advancement of Science in 1981. He served as an American Chemical Society Tour Speaker on six occasions. He is the author or co-author of 240+ research publications and the books Carboranes (Academic Press, 1970, Russian translation 1974) and Carboranes Second Edition, (Elsevier, 2011). He edited the book Metal Interactions with Boron Clusters (Plenum, 1982) and is Editor-in-Chief of Inorganic Syntheses, Vol. 29 (John Wiley, 1992). He has served on the editorial board of Inorganic Chemistry and the editorial review panel of Dalton Transactions, and is a past president of the Board of Directors of Inorganic Syntheses.

The Third Edition of Carboranes was published by Elsevier in August, just 5 years following the Second Edition. The book reflects the rapid pace of development in this field, which is generating hundreds of publications each year in areas as diverse as nanomaterials, pharmacology, diagnostic and therapeutic medicine, extraction of radioactive metals from nuclear waste, catalysis, and organic synthesis. Professor Grimes was recently honored by a special issue of the Journal of Organometallic Chemistry, featuring over 40 contributed papers from international scientists in recognition of his contributions to boron chemistry throughout his 50-year career.

In our research we identify natural products with interesting, often novel, structures and useful biological properties that may lead to medicinal agents for treatment of cancer, cardiovascular disorders and infectious diseases. We focus on key structural and stereochemical features present in these target natural products and devise mechanism or analogy based methodology for efficient construction of potentially useful subunits. Finally, we assemble the foregoing subunits by a combination of new and known reactions to synthesize the target substance and/or analogues thereof. Our overall program is thus target directed but methods driven.

Recent Publications

A cascade cyclization route to adjacent bistetrahydrofurans from chiral triepoxyfarnesyl bromides. Marshall JA, Hann RK. J Org Chem. 73, 6753-7(2008).

A formal synthesis of the callipeltoside aglycone. Marshall JA, Eidam PM. Org Lett. 10, 93-6 (2008).

Chiral allylic and allenic metal reagents for organic synthesis. Marshall JA. J Org Chem. 72, 8153-66 (2007).

ABC synthesis and antitumor activity of a series of Annonaceous acetogenin analogs with a threo, trans, threo, trans, threo-bis-tetrahydrofuran core unit. Marshall JA, Sabatini JJ, Valeriote F. Bioorg Med Chem Lett. 17, 2434-7 (2007).

Palladium- and copper-catalyzed 1,4-additions of organozinc compounds to conjugated aldehydes. Marshall JA, Herold M, Eidam HS, Eidam P. Org Lett. 8, 5505-8 (2006).

Synthesis of a bistetrahydrofuran C17-C32 fragment of the polyether antibiotic ionomycin. Marshall JA, Mikowski AM. Org Lett. 8, 4375-8 (2006).

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Professor Frederick S. Richardson earned his B.S. degree at Dickinson College summa cum laude in 1961. In 1966, he received his Ph.D. at Princeton University working with Walter Kauzmann. He served in the US Army for two years before starting his NSF Postdoctoral Research Fellowship at the University of California, San Diego. In 1969, he joined the faculty in the Chemistry Department at the University of Virginia. Prof. Richardson served as chair of the department from 1983 – 87 and 1992 – 1997. In 1991, he was appointed a Commonwealth Professor. Prof. Richardson is an exceptional physical chemist and is known for his research, teaching, and mentorship.

He was appointed as a Henry Dreyfus Foundation Teacher-Scholar from 1973-78. He taught undergraduate general, physical, and biophysical chemistry, as well as, graduate courses in all areas of physical chemistry. He research supervised 36 Ph.D. students, 6 M.S. students and 28 postdoctoral fellows.

Prof. Richardson has published over 220 papers in scientific journals or books. His principal research interests are:

• Electronic structure and spectroscopy of molecules and ions in solution and in crystals.
• Natural and magnetic chiroptical properties of molecular systems.
• Intermolecular chiral recognition and discrimination phenomena.
• Spectroscopic probes of metal-ion coordination sites in biomolecular systems.
• Rare-earth chemistry and spectroscopy.
• Theory and measurement of nonlinear optical processes in condensed-phase materials.

Professor Shen was born in Peking, China in 1924. He graduated from National Central University of China in 1946, and a year later traveled to England to study organic chemistry on an Overseas Scholarship form the Chinese Ministry of Education. In 1950,  he came to the United States for a postdoctoral position at Ohio State University, followed by a research associateship at MIT. From MIT, he joined Merck & Co. in 1956. He was appointed to the U.Va. Chemistry Department in 1986 as Commonwealth Professor of Chemistry, and in 1986 he was  named the Alfred Burger Professor of Medicinal Chemistry. Professor Shen’s research focused on the development of three antiinflammatory – analgesic drugs (indomethacin, clinoril®, Dolobid®), and potential chemo-therapeutic agents for viral infections, immunolgical, neoplastic, and other metabolic disease. He also synthesized and characterized molecular probes for biomembrane receptors and receptor ligands for targeted drug delivery. Professor Shen served on many editorial boards including the Journal of Medicinal Chemistry. He received many awards throughout his career, including the Rene Descartes Medal, the Galileo Medal of Scientific Achievement, and an Achievement Award from the Chinese Institute of Engineers-USA. He was also a fellow of the AAAS.

Research in Computational Modeling and Theoretical Chemistry

In the past twenty-five years molecular mechanics and quantum mechanical methods have become essential helpers to experimental chemists of all kinds. Modern software systems teamed with powerful computers now make possible practical representation of many aspects of chemical structure and reactivity. I help newcomers to modeling to develop good judgment in their use of these techniques, and apply some of the most powerful techniques to chemical problems.

I use computer modeling to study reaction pathways in organic systems, structures and energetics of systems likely to possess low-lying states of high spin, and the bonding and reactivity of metal-organic complexes. Much of my work is done in collaboration with graduate students conducting experimental investigations with other UVA faculty.

Some projects I am pursuing now:

• Modeling of aryl carbenes, so to characterize Tomioka’s long-lived methylene species (Presented at the International Symposium on Reactive Intermediates and Unusual Molecules [ISRIUM], Nara Japan, Sept 2001.)
• Characterization of Dearomatization induced by complexation with Osmium, Rhenium, and Tungsten species (presented at the Faraday Discussion York University, April 2003)
• Stereochemical consequences of weak interactions loosely termed “hydrogen bonding” (presented in preliminary form at Rutgers University, February, 2004)
• Characterization of Closed shell and open shell dianions stable with respect to autoionization and dissociation (Presented at ISRIUM, Edinburgh UK August 2005)
• TDDFT characterization of circular dichroism spectra of high symmetry organic species (presented at the ACS National Meeting in New Orleans, April 2008
• Structural characterization of organic cations which bind protons and the resulting dications (to be presented at the Int Conf of Quantum Chemistry, Helsinki June 2009
• TDDFT characterization of fluorescence spectra of Iridium and Ruthenium systems

Computed anharmonic frequencies for Formic Acid Dimers can guide experimental detection of short-lived isomers [figure by Ilhan Yavuz].

Recent Publications

Environmental Sensitivity of Ru (II) Complexes: The Role of the Accessory Ligands, Eileen N. Dixon †, Michael Z. Snow †, Jennifer L. Bon †, Alison M. Whitehurst †, Benjamin A. DeGraff *†, Carl Trindle ‡, and James N. Demas ‡, Inorg. Chem., 2012, 51 (6), pp 3355–3365

Communication: Frequency shifts of an intramolecular hydrogen bond as a measure of intermolecular hydrogen bond strengths, Q Gu, C Trindle, JL Knee, J. Chem. Phys. 2012 137, 091101

Structure and energetics of cyclopropane carboxaldehyde.  Trindle, C., Bleda, E. A. and Altun, Z. (2012), . Int. J. Quantum Chem.. doi: 10.1002/qua.24201

Computational thermochemistry of glycolaldehyde.  Bleda, E. A., Yavuz, I., Altun, Z. and Trindle, C. (2012), . Int. J. Quantum Chem.. doi: 10.1002/qua.24200

Photophysical and Analyte Sensing Properties of Cyclometalated Ir (III) Complexes, Leavens BB, Trindle CO, Sabat M, Altun Z, Demas JN, DeGraff BA., J Fluoresc. 2012 , 22:163-74

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Development and application of  BINOL-based chiral catalysts and enantioselective fluorescent sensors.

Professor Mattson is a member of the faculty at Randolph College in Richmond, VA.  He spends his summers here at UVA teaching Introductory College Chemistry.

My passion is teaching. I am one of the richest people on the planet in that I get paid for doing something I thoroughly enjoy.

In all of my classes, I expect my students to work hard and to strive for excellence.

Accomplishments are not measured in how many details are memorized or in how many processes are mastered. What is important is that a true, quality understanding is achieved, such that the student both sees the world with different eyes and can deal with the challenges in her or his future.

To improve my ability to communicate an understanding of chemistry, I have spent the previous fifteen summers teaching general chemistry at the University of Virginia. A memorable piece of student feedback: “I took the chemistry test. I did not know the answers to all of the questions, but what I did not know I could figure out. I made a perfect 800.”

I was invited to present an ACS Webinar on Creative Problem Solving in Chemical Research(May 5, 2011). The ACS weekly webinar series is designed to connect ACS members and scientific professionals with subject matter experts and global thought leaders in chemical sciences, management, and business on relevant professional issues. In addition to presenting the webinar, I have participated in numerous weeklong ACS Speakers Tours, been invited multiple times to speak to several local ACS sections, was invited to be the 27th Annual Harold Hammond Garretson Speaker at Lynchburg College, and have been invited back dozens of times to talk about problem solving in research to undergraduate students at the University of Virginia. In each case, the audience response has been positive, reflecting both their improved insights and abilities in problem solving and the entertaining nature of the talk.

In addition to teaching general, analytical, and instrumental chemistry and to working both on and off campus with students on research projects, I offer a popular course in creative and critical problem solving. The students greatly improve their abilities to think and to solve problems. A memorable piece of student feedback came from a student after a summer: “After I was working on my job for two weeks everyone was calling me MacGyver because I was so good at problem solving.”

I have spent 23 of the past 25 summers teaching or conducting research at the University of Virginia, James Madison University, the University of North Carolina, and the University of Tennessee. I served as a senior reviewer charged with helping to audit all Advanced Placement chemistry courses in the nation, a consultant for the South Carolina Course Alignment Project, a question writer for the American Dental Exam, an Educational Testing Service chemistry Advanced Placement reader, a National Science Foundation panel member for grant evaluation, a director of the Central Virginia Regional Science Fair, and a master of ceremonies for a high school Academic Competition for Excellence program.

It is very important to me that my students like me, but what is most important is that, 10 years into their futures, they are grateful for what they have learned.

In Memorium

John Thomas Yates, Jr.

August 3, 1935 – September 26, 2015

John T. Yates, Jr., Professor of Chemistry at the University of Virginia, member of the US National Academy of Sciences, and a pioneer of modern surface science, passed away at his home on Saturday morning September 26, 2015, from a recurring glioblastoma.  John was both courageous, pragmatic and forthright about his diagnosis right to the end.  His wife, Kerin, related that John, upon learning of his diagnosis, said that he had had a great life and was not going to ‘let the last 1.25%’ define him.   It did not.  He had a wonderful family and a stellar career.

Born in Winchester, Virginia on August 3, 1935, he received his B.S. degree in chemistry from Juniata College in Huntingdon, Pennsylvania in 1956, and his Ph.D. in physical chemistry from the Massachusetts Institute of Technology in 1960 — working with Professor Carl W. Garland.  Following three years as an Assistant Professor at Antioch College in Yellow Springs, Ohio, he joined the National Bureau of Standards, Gaithersburg, Maryland (now the National Institute of Standards and Technology), first as an NRC Postdoctoral Research Fellow and then, from 1965 until 1982, as a member of its scientific staff.  He was a Senior Visiting Scholar at the University of East Anglia, Norwich, UK in 1970-71, and the Sherman Fairchild Distinguished Scholar at the California Institute of Technology in 1977-78.  He joined the University of Pittsburgh in 1982 as the first R.K. Mellon Professor of Chemistry, and as the Founding Director of the University of Pittsburgh Surface Science Center.  In 1994 he received a joint appointment in the Department of Physics.  In 2006, he retired from the University of Pittsburgh and moved to the University of Virginia as Professor and Shannon Research Fellow.

Throughout his career, his research was in the fields of surface chemistry and physics, including interests in the structure and spectroscopy of surface species, the dynamics of surface processes, and the development of new methods for research in surface chemistry.  When he moved to the University of Virginia, he also became professionally active in the field of astrochemistry.  He was an accomplished amateur astronomer and woodworker.  He had a passionate lifelong interest in clocks, accuracy in timekeeping, and precision instrumentation, both antique and modern.  To his core, he was “a measurer” with accuracy and precision.  His colleagues and competitors alike knew that they could always trust, without question, the measured quantities in his published works.

John Yates was an exceptional scientist and gifted communicator.  He had a knack for making complex problems seem simple after he studied them in depth and communicated his results so beautifully, typically with his own meticulously hand-drawn diagrams.  He published more than 750 scientific papers on surface chemistry and physics, and is among the 100 most-cited chemists in the world.  His professional accomplishments have been recognized by many prestigious awards and honors, including: Silver Medal – U.S. Department of Commerce (1973); Sherman Fairchild Distinguished Scholar – Caltech (1977-78); Stratton Award for Distinguished Research – NBS (1978); Gold Medal, U.S. Department of Commerce’s Highest Award (1981); Kendall Award for Colloid or Surface Chemistry of the American Chemical Society (1987); Inaugural President’s Distinguished Research Award – University of Pittsburgh (1989); E.W. Morley Medal of the Cleveland ACS (1990); Fellow of the American Physical Society (1992); Medard Welch Award –American Vacuum Society’s highest technical award (1994); Fellow of the American Vacuum Society (1994); Alexander von Humboldt Senior Research Award (1994); Member of the National Academy of Sciences (1996); Pittsburgh-Cleveland Catalysis Society Award (1998); Pittsburgh Award of the Pittsburgh ACS (1998); Arthur W. Adamson Award for Distinguished Service in the Advancement of Surface Chemistry of the ACS (1999); J.W. Linnett Visiting Professorship – Cambridge University (2000); Outstanding Alumnus of Juniata College (2000); G.N. Lewis Lecturer, University of California-Berkeley (2002); Japan Society for the Promotion of Science Fellowship (2002); Gwathmey Visiting Professor, University of Virginia (2002-03); Fellow of The Institute of Physics (2004); and the Peter Debye Award in Physical Chemistry of the ACS (2007); Theodore Madey Award of the AVS (2011); Gerhard Ertl Lecturer Award for Surface Chemistry and Catalysis (2013).

Professor Yates was a kind, patient, trusted and generous mentor and advisor to the more than 1000 students, postdocs and collaborators with whom he interacted. He was an inspirational undergraduate and graduate teacher and mentor.  He demonstrated and conveyed an excitement about science, the wonders of scientific discovery, and a love of learning that encouraged and helped many to pursue scientific careers.  In addition, he developed strong professional relationships with a number of surface science research programs in academic, government, and industrial research laboratories throughout the world. He served on the editorial boards of six scientific journals and two book series in surface science and catalysis. He was Associate Editor of the ACS journal, Langmuir.  He also served on the Advisory Board of Chemical & Engineering News and on the International Advisory Board of Chemistry World.

Yates was generous in his service of scientific societies such as the American Vacuum Society, the American Physical Society, and the American Chemical Society, including past service as a member of the AVS Board of Directors, AVS Trustee Chair, and twice as the AVS Surface Science Division Chair.  He was the past chairman of the APS Division of Chemical Physics, and the ACS Division of Colloid and Surface Chemistry. He organized many symposia for ACS and APS national meetings, and was Chairman of three Gordon Research Conferences. He co-edited two books, Vibrational Spectroscopy of Molecules on Surfaces, Plenum, 1987 and Chemical Perspectives of Microelectronic Materials, Materials Research Society, 1989. He co-authored a book entitled, The Surface Scientists Guide to Organometallic Chemistry, ACS, 1987.  He also co-authored a textbook, Molecular Physical Chemistry for Engineers, University Science Books, published in 2007.  His book, Experimental Innovations in Surface Science, was originally published by Springer-Verlag and The American Institute of Physics in 1998; a second edition, his last major project, was published in 2015.

John is survived by Kerin – his wife of 57 years, his sons Geoffrey (Michelle), and Nathan (Jan), and six grandchildren, Andrew, Steven, Caitlin, Lauren, Hannah and Sara. His passing is a loss for his family and for science, but he has left a lasting legacy in his published work, and in the generations of scientists he mentored.

John N. Russell, Jr., Ph.D.
Head, Surface Chemistry Branch, Naval Research Laboratory, Washington DC

Thomas P. Beebe, Jr., Ph.D.
Professor of Chemistry, University of Delaware, Newark DE

(former graduate students)

Victoria is from Herndon, Virginia and is studying chemistry with a minor in Russian language and literature. She began research with Dr. Landers in the fall of 2015, working with Shannon Krauss on an explosives detection project. The project is working to develop a portable device in which colorimetric reactions occur in the presence of various explosive materials. Reactions for nitrates, hydrogen peroxide, perchlorates, TNT, DNT, and tetryl have been implemented on the device. Victoria focused most of her work on the nitrates. By modifying the Griess reaction, which turns bright pink when reagents form an azo dye with nitrate, the reaction and limits of detection were optimized for use in the field.

When she isn’t working in the lab, Victoria loves to dance, read, and cook. She has been a member of University Dance Club throughout her college career, and joined University Salsa Club during her third year. She also volunteered as an elementary school tutor through Madison House and was a fundraiser for Dance Marathon for UVA Children’s Hospital.

Jack Cronk grew up in Charlottesville, Virginia and graduated from Western Albemarle High School. He is currently pursuing a Bachelors of Science in Chemistry with a specialization in Biochemistry along with ACS certification. Jack conducts research in the School of Medicine in the laboratory of Dr. Michael Brown, Ph.D. Over the last 3 semesters, Jack has designed and utilized genetic approaches to systematically and specifically induce mutations in the genes of natural killer (NK) cell receptors. NK cells play an essential role in the innate immune response as cytotoxic lymphocytes that recognize cells infected with virus. Jack’s research investigates genetic mutations in NK cell receptors, the effects of which will ultimately be evaluated with respect to how these mutations impact receptor functionality. His thesis focuses on the validation of a meticulous experimental approach to study the immediate impact of these gene disruptions. Current and future work will involve testing his experimental design and evaluating the effects of the receptor mutations at the genomic level. Following graduation, Jack plans to continue his research at UVa, spend time with his two miniature dachshunds, Piper and Elly, and eventually pursue a Ph.D in Immunology.

I am from Atlanta, GA, and I went to The Lovett School. I will graduate with a BSc in Chemistry and a BA in Studio Art, painting concentration. I stated research with the Demas lab Spring 2016, focusing on fluorescence anisotropy. I have worked with the oxygen sensor Ru(bpy)3, Fraser’s promising boron complex nanoparticles, and fluorescent dye-polymer equilibria that model biological binding systems. Measuring the anisotropy of these compounds gives valuable information about the excited state(s) and information about binding. Fluorescence anisotropy is the study of emission polarization and is commonly used to measure the binding of biological equilibria. When a polarized excitation source excites a fluorophore, that fluorophore can emit in the same orientation, or it can rotationally diffuse before it has the chance to emit, thus producing an unpolarized emission. Anisotropy is a ratiometric measurement of the extent of the emitted polarization.

In addition to painting, I sing in two different groups on Grounds, the Harmonious Hoos co-ed a cappella group and the Virginia Women’s Chorus.

Ellen Howerton grew up in Fairfax, Virginia and graduated from Thomas Jefferson High School for Science and Technology.  She will graduate from UVa with a Bachelor of Science in Chemistry with a biochemistry specialization.

Ellen joined the Bushweller lab group in the Molecular Physiology and Biological Physics department in January, 2015.  For her distinguished major, she focused on the Ets-domain family of transcription factors, which are deregulated in multiple cancers.  Many Ets-domain proteins exhibit autoinhibition, a phenomenon that occurs when a separate portion of a protein inhibits the function of another domain.  As the autoinhibitory domain is likely unique between Ets family members, it provides a promising target for therapeutics.

Outside of her studies, Ellen is a violinist and an active member of Radio Music Society, a student-run group that writes and performs string quartet covers of popular songs.  She is also a Soprano 1 with the Virginia Women’s Chorus and a member of the Washington Literary Society and Debating Union.  After graduation, Ellen will be working at the National Human Genome Research Institute at the NIH and later hopes to pursue graduate study in Public Health.

Joshua attended Franklin County High School in Rocky Mount, VA. He is pursuing a B.Sc. in Chemistry with a Specialization in Biochemistry with ACS certification.

His research is in the lab of Dr. Lin Pu where he worked on a project with graduate student Shifeng Nian synthesizing a bimetallic catalyst to control the tacticity in atomic transfer radical polymerizations (ATRP) of functional alpha-olefins (e.g. acrylamide) by synthesizing a salen-derived macrocyclic ligand to coordinate a Lewis acidic metal and copper. Previous research showed that addition of a Lewis acid to Cu-mediated ATRP was promising for producing steroregular polymers. We confined the Lewis acidic center and the copper center in close proximity on a macrocyclic ligand to couple their roles in the polymerization and enhance the catalytic efficiency. Our work has provided evidence that these bimetallic catalyst systems incorporate a cooperative effect utilizing the Lewis acidic monomer activation with the copper-chlorine radical generation and stabilization process in order to provide stereocontrol and catalysis to the ATRP processes. Following the introduction of chirality into the catalyst system, the reaction of the Lewis acid coordinated monomer with the adjacent transient free radical, generated from the copper-chlorine abstraction at the polymer end, proceeds with significant stereocontrol to give the desired isotactic polymers. We are still working to optimize the degree of monomer conversion and stereocontrol.

In addition to research, Joshua has been a teaching assistant for CHEM 3410 and CHEM 3420 (physical chemistry, thermodynamics and quantum chemistry) under Dr. Dave Metcalf. Though still undecided on his particular focus, he will study organic, organometallics, or polymer chemistry in graduate school.

Nick Lee is a fourth-year Distinguished Major in Biochemistry from Winchester, Virginia. He conducts research in the School of Medicine in the laboratory of Anindya Dutta, M.D., Ph.D., where he investigates the function of the CRL4(Cdt2), an E3 ubiquitin ligase, in the cell cycle. The complex is responsible for marking cell cycle regulators for degradation by the proteasome. Previously, he worked to elucidate the stabilizing role that 14-3-3 exerted over Cdt2. His thesis is focused on characterizing the interaction between BRAF35 and Cdt2. BRAF35 is relatively uncharacterized in the literature, but it interacts with BRCA2, the breast cancer susceptibility protein. For his research endeavors, he has received a U.Va. Summer Scholars Award, a Harrison Undergraduate Research Award, a College Council Fall Research Grant, and a Small Research and Travel Grant, along with being a published co-author in Molecular and Cellular Biology.

Currently, he serves as the Vice Chair for Trials for the Honor Committee, the Chair of the Undergraduate Research Network, and the President of the College Science Scholars Council. Outside of those commitments, Nick has taught his own CavEd class, Current Topics in Neuroethics, served as a TA for Organic Chemistry, and is an Echols Scholar, College Science Scholar, a member of the Raven Society, and a Lawn Resident. After graduation, he will be pursuing his M.D. with the desire to become a professor of medicine.

Dr. Collins earned a B.S. in Chemistry at the University of Virginia in 1970 (mentor Carl Trindle). He went on to attain a Ph.D. in physical chemistry at Yale University in 1974. He then  enrolled in medical school at the University of North Carolina at Chapel Hill, earning there an M.D. in 1977. From 1978 to 1981, Dr. Collins served a residency and chief residency in internal medicine at North Carolina Memorial Hospital in Chapel Hill. He then returned to Yale, where he was named a Fellow in Human Genetics at the medical school from 1981 to 1984. During that time, he developed innovative methods of crossing large stretches of DNA to identify disease genes. In 1984, Dr. Collins joined the University of Michigan in a position that would eventually lead to a Professorship of Internal Medicine and Human Genetics. Dr. Collins accepted an invitation in 1993 to succeed James Watson as Director of the National Center for Human Genome Research, which became NHGRI in 1997. As Director, he oversaw the International Human Genome Sequencing Consortium. Dr. Collins’ accomplishments have been recognized by numerous awards and honors, including election to the Institute of Medicine and the National Academy of Sciences, and the Presidential Medal of Freedom. On July 8, 2009, President Barack Obama announced he will nominate Dr. Collins to lead the National Institutes of Health. On August 17, 20019, he was sworn in as the 16th Director of the NIH and was asked to continue by both Presidents Trump and Biden. The NIH Biographical Sketch of Dr. Collins can be found here. 

Professor Dowd earned her B.A. degree from the University of Virginia and her Ph.D. in Medicinal Chemistry from Virginia Commonwealth University (working with Richard Glennon). Following postdoctoral work at the University of Pennsylvania (with Irwin Chaiken), she joined the NIH where she directed a synthetic chemistry group finding novel small molecules against Mycobacterium tuberculosis. In 2007, she joined the Chemistry Department of George Washington University as an assistant professor.  Her research interests broadly include anti-infective drug discovery, structure-based ligand design, and the development of chemical tools to understand important biological processes.

Professor Love is an assistant professor in chemical engineering at MIT. He is also an associate member at the Eli and Edythe L. Broad Institute, and associate faculty at the Ragon Institute of MGH, MIT, and Harvard. He was named a Dana Scholar for Human Immunology and a Keck Distinguished Young Scholar in Medical Research in 2009.

Professor Love graduated with a B.S. degree in chemistry from the University of Virginia in 1999 (conducted research with Cassandra Fraser). He received his Ph.D. in 2004 in physical chemistry at Harvard University under the supervision of George Whitesides. Following completion of his doctoral studies, he extended his research into immunology at Harvard Medical School with Hidde Ploegh from 2004-2005, and at the Immune Disease Institute from 2005-2007. His current research uses microsystems to characterize heterogeneity among single cells with specific studies in HIV/AIDS, autoimmunity, and biopharmaceutical manufacturing. He was selected as on  of a Brilliant 10 for 2010 in PopSci.

Professor Rojas earned his B.A. from the University of Virginia in 1989, where he did research with Ralph O. Allen on neutron activation analysis of archaeological artifacts. He received a Ph.D. in organic chemistry from Indiana University, working with David R. Williams. Following a postdoc with Julius Rebek at both MIT and The Scripps Research Institute, Professor Rojas joined the faculty at Barnard College, a liberal arts college for women in New York City. His research involves the development of nitrogen atom transfer reactions and their application to the synthesis of 2-amino sugars.

Director of Chemical Biology at and Founding Member of the Broad Institute of Harvard and MIT, where he is a Investigator. He is also the Morris Loeb Professor of Chemistry and Chemical Biology at Harvard University. He is a member of the National Academy of Sciences and the American Academy of Arts & Sciences (1995).

Dr. Schreiber was born February 6, 1956 and raised in Virginia. After receiving a B.A. degree (conducting research with Richard Sundberg) at the University of Virginia in June of 1977, he carried out graduate studies at Harvard University under the supervision of R. B. Woodward and Y. Kishi. Following completion of his doctoral studies, he joined the faculty at Yale University in May of 1981. He was promoted to Associate Professor with tenure in 1984 and to Full Professor in 1986. In 1988, he returned to Harvard.

Dr. Schreiber is known for having developed systematic ways to explore biology, especially disease biology, using small molecules and for his role in the development of the field of chemical biology. Currently, the Schreiber group research is focused on:

• Development of next-generation synthetic chemistry affording a transformative small-molecule screening collection.
• Investigating small molecules using human primary cells in an environment that mimics their in vivo niche.
• Exploiting the remarkable ability of genetic approaches to illuminate the roles of genes in biology and disease
• Attempting to discover small molecules that increase pancreatic beta cell numbers and function using organ cultures of human primary pancreatic islets

After Robert Sell earned his B.S. in Chemisty with High Distinctions from UVA in 1975, he worked for four years in the U.S. Navy as an instructor at the Naval Nuclear Power School teaching Chemistry, Radiological Fundamentals, and Materials Science. From 1979 to 2009, he worked with Corning Incorporated in a wide variety of positions in manufacturing, process engineering, product and market development, strategy development, intellectual property, product line management. During his time at Corning, he obtained a Masters in Business Administration from West Virginia University in 1987. Over the 30 years he worked at Corning , he participated in the areas of glass products for the pharmaceutical industry, environmental laboratory analysis, and semiconductor manufacturing. He is now retired from Corning and instructing at Corning Community College.

Professor Kian Tan graduated with a B.S. in chemistry with a specialization in biochemistry from the University of Virginia in 1999. At UVa, Kian performed research in the group of Professor Dean Harman working on the development of an osmium-mediated asymmetric Diels-Alder reactions and the synthesis of epibatidine derivatives as analgesics. Subsequently, Kian worked jointly with Professors Robert Bergman and Jonathan Ellman at the University of California Berkeley on novel metal-mediated C-H activation reactions. He obtained his Ph. D. from UC-Berkeley in 2004. Working as a postdoctoral researcher in Professor Eric Jacobsen’s group at Harvard University, Kian focused on bifunctional urea catalysts for the enantioselective allylation of hydrazones. In 2006, Kian began as an Assistant Professor at Boston College where he enjoys teaching organic chemistry and guiding a research program focused on the new catalysts for the transformation of organic molecules. 

Erskine Williams was born and raised in Richmond, Va. He graduated from the University of Virginia in 1996 with degrees in Biochemistry & Cognitive Science. After graduating, he moved to Hood River, OR for two years to windsurf. In 1998, he moved to Portland, OR and started software engineering for Intel. From 2000 -2001, he rode the dot.com bubble with a small consulting firm in San Francisco. When the bubble popped, Erskine worked for Barclays Global Investors as a software engineer in San Francisco from 2001 – 2003. In 2003, he married and moved back to Portland working with Fujitsu Biosciences to write 3D molecular modeling software. Then, in late 2005, Erskine joined a company which brings social networking software to businesses.

John M. Butler is NIST Fellow and Group Leader of Applied Genetics at the National Institute of Standards and Technology. He is author of the internationally acclaimed textbook Forensic DNA Typing—now in its third edition—as well as more than 100 scientific articles and invited book chapters. His book was also been translated into Chinese (2007) and Japanese (2009). He earned his Ph.D in 1995 from the University of Virginia with Ralph Allen (Analytical Chemistry). His Ph.D. research was conducted in the FBI Laboratory, involved pioneering the techniques now used worldwide in modern forensic DNA testing. Over the past 15 years, Dr. Butler has worked in government and industry.  He designed and maintains STRBase (http://www.cstl.nist.gov/biotech/strbase), an information resource for short tandem repeat DNA markers. As a member of the World Trade Center Kinship and Data Analysis Panel, he aided the New York City Office of Chief Medical Examiner in their work to identify the remains of victims of the 9/11 terrorist attacks. He also serves on the Department of Defense Quality Assurance Oversight Committee for DNA Analysis and advises numerous national and international forensic DNA efforts. Dr. Butler has received numerous awards during his career including the Presidential Early Career Award for Scientists and Engineers (2002), the Department of Commerce Gold Medal (2008) and Silver Medal (2002), the Arthur S. Flemming Award (2007), Brigham Young University’s College of Physical and Mathematical Sciences Honored Alumnus (2005), and the Scientific Prize of the International Society of Forensic Genetics (2003). In August 2011, ScienceWatch.com announced that Dr. Butler was number one in the world as a high-impact author (number of citations per paper published) in legal medicine and forensic science for the decade of 2001-2011.

Dr. Frazier graduated from Harvey Mudd College with a B.S. in Applied Chemistry. In 2003, she  earned her Ph.D. from the University of Virginia Chemistry Department with Prof. David Cafiso. She works at Pro-Cure Therapeutics (a Prostate Cancer Stem Cell Company)  where she performs two roles. She is the Commercial Operations Manager and a research scientist. She manages business relationships with corporate partners and tests and develops assays for novel prostate cancer stem cells.

Dr. McWhorter earned a Ph.D. in Chemistry (with Brooks H. Pate) from the University of Virginia and a B.S. in Chemistry from Washington and Lee University. 

After a postdoctoral appointment at The National Institute for Science and Technology (NIST), Dr. McWhorter spent over seven years at the Institute for Defense Analyses (IDA), a Federally Funded Research and Development Center.  There, in addition to several Department of Defense projects, he served as the Deputy Project Leader for IDA on the US Department of Homeland Security’s (DHS) SAFETY Act (the Support Anti-terrorism by Fostering Effective Technologies Act of 2002).  In this position he led the technical evaluations of anti-terrorism products and services across a broad spectrum of countermeasures for chemical, biological, explosive, nuclear, cyber and human threats, including services. 

In 2007, Dr. McWhorter joined Catalyst Partners, a DC-based homeland security consulting and government relations firm. In his role as a Principal, he began Catalyst’s SAFETY Act Practice and Technology Evaluation Practice. He represented clients in front of DHS, private sector companies, and other potential customers, spearheading dozens of successful SAFETY Act applications.

Dr. McWhorter started his own firm in 2014: The Homeland Security Consulting Group (HSCG). Working with industry partners, The HSCG continues serving clients across the Homeland Security space. He constantly scouts the anti-terrorism and security marketplaces to identify relevant technology, performs independent evaluations, and helps his clients assemble quantitative evidence of the effectiveness of the technologies. The HSCG also provides business development services for its clients. Leveraging his vast network of security professionals, Dr. McWhorter brings his clients’ technology directly to potential end users and to potential industry partners. In the years since The HSCG was founded, Dr. McWhorter has prepared several more dozen successful SAFETY Act applications for his clients. Representative clientele includes Fortune 500 companies, start-up tech companies, and everything in between.

Professor Shipman received his B.A. from Rice University and earned his Ph.D. from the University of California-Berkeley under Charles Harris in 2005. He was then a post-doctoral researcher from 2006 until 2008 at the University of Virginia with Professor Brooks Pate. He is currently an Assistant Professor of Physical Chemistry at New College of Florida, a small liberal arts college in Sarasota, FL. His research is concerned with the study of the rotational spectra of molecules in vibrationally-excited states at room temperature.

Professor Zhou received his B.S.and Ph.D degrees from Fudan University in 1990 and 1995, respectively. He was a postdoctoral fellow at the University of Virginia with professor Lester Andrews from 1997 to 1999. He then joined the chemistry department of Fudan University and became a professor of physical chemistry in 2000 and Cheung Kong Scholar in 2002. He is currently a member of the editorial advisory board of the Journal of Physical Chemistry.

Protein Engineering: Advancing Imaging, Therapeutics, and Diagnostics

The Ai lab specializes in protein engineering and employs interdisciplinary approaches, including biophysics, bioanalytical chemistry, chemical biology, synthetic biology, and optical imaging. One of our main areas of focus is the development of molecular biosensors that provide insights into cellular and organismal signaling. We employ state-of-the-art techniques such as directed evolution, fluorescence imaging, bioluminescence imaging, synthetic chemistry, genetic screening, and mass spectrometry to unravel complex biological pathways related to redox biology, metabolism, and neuronal activity. Furthermore, we explore the application of protein-based tools in live cells and rodent models to better understand pathophysiology and develop innovative therapies for conditions like diabetes, Alzheimer’s disease, and cancer. As an emerging direction, we are also working on the development of biosensors that can serve as self-wellness alert devices or diagnostics in resource-limited settings.

Recent publications:

H.W Yeh, and H-w. Ai*, “Development and Applications of Bioluminescent and Chemiluminescent Reporters and Biosensors”, Annu. Rev. Anal. Chem., 12: Doi: 10.1146/annurev- anchem-061318-115027.

H.W. Yeh, Y. Xiong, T. Wu, M. Chen, A. Ji, X. Li, and H-w. Ai*, “ATP-independent bioluminescent reporter variants to improve in vivo imaging”, ACS Chemical Biology, 2019, 14 (5): 959-965.

H.W. Yeh, O. Karmach, M. Martins-Green, and H-w. Ai*, “Red-shifted luciferase-luciferin pairs enhance bioluminescence in vitro and in vivo”, Nature Methods, 2017, 14: 971–974.

Y. Fan, and H-w. Ai*, “Monitoring thioredoxin redox with a genetically encoded red fluorescent biosensor”, Nat. Chem. Biol., 2017, 13: 1045-1052.

W. Ren, A. Ji, and H-w. Ai*, “Light Activation of Protein Splicing with a Photocaged Fast Intein”, J. Am. Chem. Soc., 2015, 137: 2155–2158.

A. Ji, W. Ren, and H-w. Ai*, “A Highly Efficient Oxidative Condensation Reaction for Selective Protein conjugation”, Chem. Commun., 2014, 50: 7469-7472

Z. Chen, W. Ren, Q.E. Wright and H-w. Ai*, “Genetically Encoded Fluorescent Probe for the Selective Detection of Peroxynitrite”, J. Am. Chem. Soc., 2013, 135: 14940-14943.

Tao received his B.S. from Wuhan University in China and earned his Ph.D. in medicinal chemistry from the University of Virginia, under the supervision of Professor Timothy Macdonald.  His Ph.D. work focused on chemical biology study of Sphingosine 1-Phosphate (S1P) receptors and Sphingosine Kinases for immune modulation, which is directly relevant to human diseases such as autoimmune disorder and cancer.  During his post-doc training in UVA’s School of Medicine, he extended his expertise into molecular imaging and nanotechnology for cancer diagnosis and therapy.  In the Hsu lab, Tao will be working on immunotherapy for cancers.

Ryan Holland has joined the Department of Chemistry as a Research Associate in the Gunnoe Lab.  Ryan obtained his B.S. in Chemistry at the University of Idaho, then went on to earn his Master’s Degree and Ph.D. in Chemistry at the University of California, San Diego.  His graduate work consisted of studying the small molecule reactivity of Werner-type uranium complexes and the synthesis and characterization of stable metallacyclobutenes and vinylcarbenes.  In the Gunnoe lab, Ryan will be engaged in the development of catalysts relevant to selective chemical oxidations, including the design, preparation and study of new catalysts.

My research focuses on understanding the molecular and physical origins of planetary systems such as our own.  By using clues from interstellar molecular emission, I study young planetary systems in formation around low-mass stars, i.e. protoplanetary disks: the very materials from which planets, comets, and other solar system bodies eventually form. 

While I focus on the theoretical modeling of these systems, my work is guided by observational results from the Atacama Large Millimeter/Submillimeter Array, the Submillimeter Array as well as the Herschel Space Observatory.  In addition to clues from the astronomical data, our group furthermore endeavors to connect all scales by incorporating our knowledge of the primitive solar nebula from the cometary and meteoritic record. 

Recent Publications

"Constraining Gas-phase Carbon, Oxygen, and Nitrogen in the IM Lup Protoplanetary Disk," Cleeves, Oberg, Wilner, Huang, Loomis, Andrews, Guzman, 2018, ApJ, 865, 155.

"Variable H13CO+ Emission in the IM Lup Disk: X-ray Driven Time-Dependent Chemistry?," Cleeves, Bergin, Oberg, Andrews, Wilner, and Loomis, 2017, ApJL, 843, 1.

"Multiple Carbon Monoxide Snow-lines in Disks Sculpted by Radial Drift" Cleeves, 2016, ApJL, 816, 21.

"Indirect Detection of Forming Protoplanets via Chemical Asymmetries in Disks," Cleeves, Bergin, Harries, 2015, ApJ, 707, 2.

"The ancient heritage of water ice in the solar system," Cleeves, Bergin, Alexander, Du, Graninger, Oberg, and Harries, 2014, Science, 345, 1590.

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Barat grew up in Ashland, OH, and graduated as the valedictorian from Ashland High School. He will be graduating from UVA with a Bachelor of Science in Chemistry (Specialization in Biochemistry) with ACS Certification and a minor in Psychology.

Upon beginning his studies at UVA, Barat joined the lab of Professor Wladek Minor in the Department of Molecular Physiology and Biological Physics (School of Medicine). Barat investigated serum albumin, the most abundant protein in mammalian blood plasma, and its interactions with non-steroidal anti-inflammatory drugs (NSAIDs). The goal of his project was to determine structures of mammalian albumins in complex with NSAIDs and understand how the modes of binding compare across species. Barat has been a co-author of three structures in the Protein Data Bank and of two publications (one article as the second author and a book chapter). He has two more manuscripts in writing.

Outside of the lab, Barat enjoys reading, watching films, listening to music, attempting to learn new languages (he speaks four), and playing the violin for First Year Players (for which he has played in five musical productions). He has also served a a TA for CHEM 4410 (Biological Chemistry I) for two semesters and for GNUR 5390 (Introduction to the U.S. Healthcare System) for three semesters. He also worked with the Undergraduate Research Network (serving as the Vice-Chair for one year) and volunteered at the UVA Medical Center through Madison House for six semesters. He also loves supporting his Cleveland and Columbus sports teams and following tennis, cricket, and golf, among many other sports.

Following graduation, Barat will attend medical school at the University of Toledo College of Medicine and Life Sciences.

Elizabeth is from Burke, Virginia and graduated from Lake Braddock Secondary School. She is graduating a year early with a Bachelor of Science in Chemistry with a specialization in biochemistry.

Elizabeth has been a member of Ken Hsu’s lab in the Department of Chemistry since September 2017. Her project has been based around expressing and purifying the mammalian enzyme, diacylglycerol kinase alpha (DGKα), in a bacterial system. DGKα has been recently recognized as a cancer therapy target due its important roles in regulating cell proliferation pathways. Elizabeth hopes that her project in the Hsu Lab will assist in the characterization of the enzyme in future proteomic experiments.

Outside of lab, Elizabeth played piccolo for the Cavalier Marching Band, worked with a company to train and develop AI software for colon cancer detection, and has been a TA for CHEM 2410 and CHEM 2321. After graduating, she will take a gap year to continue her project with DGK α and plans on pursuing an Md-PhD the following year.

Chemical Education Research: Enhancing Students’ Outcomes by Unpacking Postsecondary Instructors’ Practices

National initiatives to improve undergraduate science education build upon decades of research and development of effective instructional practices for science, technology, engineering, and mathematics (STEM) postsecondary classrooms. These evidence-based instructional practices (EBIPs) promote students’ conceptual understanding and attitudes toward STEM, with the greatest impacts observed among women and members of underrepresented groups. By improving retention rates and attracting a more diverse student population to the sciences, these practices can help address the national need to educate STEM-literate graduates and advance workforce development goals. The challenge is fostering their effective use on a national scale. Successful instructional reform requires STEM faculty engagement, yet we know little about them. We need to better understand faculty’s knowledge base for teaching, instructional practices and the relationship between the two as well as how these characteristics evolve under varying reform environments and departmental constraints. Results of this foundational research are critical to ensure the success of current and future national and local STEM instructional reform efforts. Our research group focuses on addressing this extensive gap in the literature. As discipline-based education researchers (DBER), we are specifically interested in:

• developing new methods to characterize instructional practices in STEM college classrooms,
• exploring how faculty and teaching assistants think about their teaching,
• identifying individual, departmental, and institutional factors that influence instructors' instructional decisions, and
• characterizing the impact of different types of pedagogical professional development programs.

Selected publications:

• Lane, A. K., McAlpin, J. D., Earl, B., Feola, S., Lewis, J. E., Mertens, K., Shadle, S. E., Skvoretz, J., Ziker, J. P., Couch, B. A., Prevost, L. B., & Stains, M.* (2020). Innovative teaching knowledge stays with users. Proceedings of the National Academy of Sciences, 202012372.
• Popova, M., Shi, L., Harshman, J., Kraft A., and Stains, M.* (2020) Untangling a complex relationship: Teaching beliefs and instructional practices of assistant chemistry faculty at research-intensive institutions, Chemistry Education Research and Practice, 21, 513-527 DOI: 10.1039/C9RP00217K
• Stains, M.*, Harshman, J., Barker, M.K., Chasteen, S.V.,  Cole, R., DeChenne-Peters, S.E., Eagan, M.K., Esson, J.M., Knight, J.K., Laski, F.A., Levis-Fitzgerald, M., Lee, C.J., Lo, S.M., McDonnell, L.M., McKay, T. A., Michelotti, N., Musgrove, A., Palmer, M.S., Plan, C.M., Rodela, T.M., Sanders, E.R., Schimpf, N.G., Schulte, P.M., Smith, M., Stetzer, M., Stewart, J., Van Valkenburgh, B., Vinson, E., Weir, L.K., Wendel, P.J., Wheeler, L.B., and Young, A.M.  (2018) Anatomy of STEM Teaching in North American universities. Science, 359(6383), 1468 DOI: 10.1126/science.aap8892
• Harshman, J. and Stains, M.* (2017) A Review and Evaluation of the Internal Structure and Consistency of the Approaches to Teaching Inventory, International Journal of Science Education, 39(7), 918-936 DOI:10.1080/09500693.2017.1310411
• Stains, M.* and Vickrey, T. (2017) Fidelity of implementation: An overlooked yet critical construct to establish effectiveness of evidence-based instructional practices, CBE Life Sciences Education, 16(1), rm1 DOI: 10.1187/cbe.16-03-0113
• Lund, T.J. and Stains, M.* (2015) The Importance of Context: An Exploration of Factors Influencing the Adoption of Student-Centered Teaching among Chemistry, Biology, and Physics Faculty, International Journal of STEM Education, 2(13), DOI: 10.1186/s40594-015-0026-8
• Stains, M*, Pilarz, M., and Chakraverty, D. (2015) Short and Long-Term Impacts of the Cottrell Scholars Collaborative New Faculty Workshop, Journal of Chemical Education, 92(9), 1466-1476 DOI: 10.1021/acs.jchemed.5b00324
• Lund, T.J., Pilarz, M., Velasco, J.B., Chakraverty, D., Rosploch, K., Undersander, M., and Stains, M.* (2015) The Best of Both Worlds: Building on the COPUS and RTOP Observation Protocols to Easily and Reliably Measure Various Levels of Reformed Instructional Practices, CBE Life Sciences Education, 14(2), ar18    DOI:10.1187/cbe.14-10-0168
• Vickrey, T, Rosploch, K., Rahmanian, R., Pilarz, M. and Stains, M.* (2015) Research-based implementation of Peer Instruction: A literature review, CBE Life Sciences Education, 14(1) DOI: 10.1187/cbe.14-11-0198

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Dr. Jelena Samonina joined the faculty of the UVA Chemistry Department in 2019, where her teaching interests include Organic Chemistry and Chemistry for the Health Sciences. She earned her M.S. and her Ph.D. in Organic Chemistry at Warsaw University. After two postdoctoral trainings at the University of Virginia and at Stanford University she joined the faculty of Washington and Lee University.

Dr. Samonina is passionate about teaching and she designs her courses to motivate and excite students through proactive learning. Her teaching style effectively engages the students and encourage them to develop into future thinkers, inventors, and researchers, whether it be in industry, academia, or public service.

Dr. Samonina’s research interests lie at the interface of Organic and Polymer Chemistry, Nanomaterials and Medicine, and include the development of new concepts in drug delivery, imaging and diagnostics.

Selected Publications

Sawyer C. W., Suffield B. H., Finnefrock A. C., Billings H. M., Uffelman E. S., Zoeller J. R., Dombrowski M. S., Delaney J.K., Dooley K. A., Mass J. L., Samonina J., Whitesell M. M., A John White Alexander Painting at the Virginia Museum of Fine Arts: A Comparison of Imaging Technologies for Resolving a Painting under Another Painting, Journal of American Institute for Concervation. 2019, 58, 37–53.