Calendar
Calendar
Seminar Series: Fall 2008
All seminars are Fridays, 3-4pm Druckenmiller room 20 and a student reception in Druckenmiller 26 prior to the seminar, unless otherwise noted.
Chemistry Faculty & Student Lunch
When: Every Friday at 12:30pm
Where: Pinette Dining Room, Thorne Dining Hall
Why: Get to know the chemistry faculty and other students interested in chemistry
Friday, September 12, 2008
Suzanne Blum, UC Irvine
Assistant Professor of Chemistry
Development of Single Molecule Tools for the Organic and Organometallic Chemist
The development of single molecule fluorescence microscopy as a technique to image reactions in real time will provide unprecedented resolution for determining reaction mechanisms. This technique will be particularly powerful in the area of transition metal catalysis. The first single-molecule imaging of spectator fluorophore-tagged transition metal complexes with relevance to catalysis will be described.
Friday, September 19, 2008
Lori Watson, Earlham College
Assistant Professor of Chemistry
The 18 electron "suggestion": Structure and Reactivity of (PNP)RuCl
The design of metal compounds that are electronically (having fewer than 18 electrons in their valence shell) and coordinatively (having an available metal based orbital to participate in ligand binding) unsaturated has given rise to a wealth of diverse reactivity and potential application in a wide variety of chemical processes. These compounds can coordinate and cleave strong bonds (C-H, C-C, Si-H, C-F) and normally unreactive molecules (H2, N2, CO), allowing the addition of new functionality to organic molecules. The use of a diphosphine amido ligand, [N(Si(CH3)2CH2P(tBu))2], (PNP-tBu), provides a convenient way to stabilize highly unsaturated transition metal complexes and has resulted in the successful synthesis of (PNP-tBu)RuCl. This 4-coordinate, d6 ruthenium complex has been shown to have a square planar geometry and be paramagnetic. Because of its unique geometric and electronic structure, this 14 electron complex exhibits interesting reactivity toward a variety of small molecules, including C-X activation chemistry. The synthesis, structure, and reactivity of (PNP-tBu)RuCl will be discussed.
Friday, September 26, 2008
Christopher Hadad, Ohio State University
Professor of Chemistry
Development of a Novel Bioscavenger against Chemical Warfare Agents
Organophosphorus (OPs) anticholinesterases are toxic substances which were initially developed as insecticides, but have been utilized as warfare agents due to these agents’ extreme toxicity toward higher vertebrates. Many OPs have been utilized as chemical weapons and nerve agents, including Sarin and VX. Acetylcholinesterase (AChE), a critical enzyme involved in signal communication at the neuromuscular junction, is inhibited by such organophosphorus compounds. Protecting a human population, such as military or civilian personnel, from the use of these OP agents, including efforts by terrorists, is of critical importance. One approach is the development of novel catalytic human therapeutics (bioscavenger enzymes) that can react with OPs and provide protection for AChE and other critical enzymes. Another approach is the use of additives, such as pyridinium oximes, which can assist in the re-activation of inhibited AChE after OP exposure. We will present our experimental and computational studies which intend to develop a catalytic bioscavenger against organophosphorus agents using both human butyrylcholinesterase and paraoxonase as platforms for improvements in catalytic efficiency. Using both computational and experimental approaches, we are determining the active sites of these enzymes and also proposing and verifying mutant forms of the enzymes for improved efficacy against OP agents. We will present some of our current results for wild-type and recombinant mutant forms of OP hydrolase enzymes for the development of these novel therapeutics against organophosphorus nerve agents.
Wednesday, October 8, 2008
Bernadette Donovan-Merkert, UNC
Professor & Chair, Chemistry
Friday, October 24, 2008
Elaine Marzlaff, Grinnell College
Associate Professor of Chemistry
Gas Phase Peptide Structure and Reactivity
My groups uses mass spectrometry combined with computational chemistry to probe the structure of peptides in the gas phase. Our long term goal it to determine the structure of these molecules in the absence of water to better understand the role water plays in structure determination of larger biological systems such as proteins. Hydrogen/deuterium exchange is the key reaction we will use to probe protein structure. Deuterium is an atom with the same chemical properties as hydrogen, however the nucleus has twice the mass and this mass difference is easily detected in a mass spectrometric experiment. A protein or peptide in the presence of deuterated water will exchange some of its hydrogens for deuteriums very rapidly. However, hydrogens involved in the hydrogen bonding or other types of interactions exchange more slowly. The gas phase hydrogen deuterium exchange/mass spectrometry techniques we use, while powerful, provide only an indirect measure of structure. Full interpretation of our experimental measurements into structural information requires a combination of theoretical chemistry techniques, and we employ electronic structure calculations to determine the most likely set of structures adopted and to fully probe the mechanism of reaction. In this talk I will present our most recent results with peptides with acidic and aromatic side chains.
Friday, November 7, 2008
Jon Clardy, Harvard Medical School
Hsien Wu and Daisy Yen Wu Professor of Biological Chemistry and Molecular Pharmacology
What Chemists Can Learn From Bugs
What you see usually depends on what you’re looking for, and for the last two years, we’ve been looking for insect-bacteria mutualisms – close associations between insects and bacteria that confer benefits on both parties. The world is full of them. Most of the talk deals with the chemical ecology of these systems using examples from beetles, ants, mud daubers and honeybees. The last part of the talk deals with larger lessons that can be learned from these examples: Why are such associations are so common?, How can they be used as a search paradigm for interesting and potentially useful molecules?, and How do multigene traits – like the biosynthesis of natural products evolve? All of the work involves a close collaboration with an evolutionary biologist, Cameron Currie, and his laboratory at the University of Wisconsin.
Friday, November 14, 2008
Aria Amirbahman, University of Maine
Associate Professor of Civil and Environmental Engineering
Mercury dynamics in estuarine sediments
Friday, November 21, 2008
Sarah E. O'Connor, Massachusetts Institute of Technology
Latham Family Career Development Associate Professor of Chemistry
Alkaloid Biosynthesis in Periwinkle
Madagascar periwinkle (Catharanthus roseus) produces more than 100 alkaloids from the terpene indole alkaloid family. We study the mechanism, substrate specificity and redesign of the central enzyme of the terpene indole alkaloid biosynthetic pathway and also explore the capacity of this pathway for production of novel alkaloid structures via metabolic engineering.