Upcoming Events

Peter Woodruff, Chemistry Seminar: "Harnessing Enzymes to Synthesize Probes Against Pathogenic Mycobacteria"

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April 3, 2015 3:00 PM  – 4:00 PM
Druckenmiller Hall, Room 020

Mycobacteria, including the pathogenic Mycobacterium tuberculosis, require the sugar trehalose for construction of their cell wall. Trehalose analogs are emerging as valuable tools for inhibiting Mycobacterium tuberculosis, but progress in this area is slow due to the difficulty in synthesizing these compounds using traditional organic synthesis. 

In this chemistry seminar, Peter Woodruff discusses the invention of a chemoenzymatic method for the synthesis of trehalose analogs that employs the heat-stable enzyme trehalose synthase (TreT) from the hyperthermophile Thermoproteus tenax. He examines how, by using TreT, various trehalose analogues were prepared quickly (one hour) in high yield in a single step from readily available glucose analogues. In addition, he explains data that reveals how several of these analogs are incorporated into the mycobacterial cell wall used to detect the bacteria, laying the groundwork for imaging tuberculosis infections in live patients.

Woodruff is assistant professor of chemistry at the University of Southern Maine. 

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Michael Ardolino: "Catalyst Design, Methodology Development and Mechanistic Studies in Asymmetric Organo-Organometallic Catalysts."

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April 10, 2015 3:00 PM  – 4:00 PM
Druckenmiller Hall, Room 020

Carbon- and heteroatom-bearing stereocenters are common in natural products and have become increasingly prevalent in many of today's leading pharmaceutical compounds. As a result, enantioselective methods to build chiral molecules are of central importance to fields within organic chemistry ranging from total synthesis to the design and production of therapeutic drugs.

Michael Ardolino will discuss how, in that context, his graduate and post-doctoral research has focused on the development of highly selective, efficient, and robust catalytic asymmetric methodologies that utilize both organic- and organometallic-based catalysts. Specifically, his work in the Morken laboratory at Boston College focused on the development of palladium-catalyzed asymmetric allyl-allyl and allyl-propargyl cross-couplings. These methods allowed for the synthesis of synthetically useful branched 1,5-dienes and 1,5-enynes with previously unprecedented enantio- and regioselectivity.

Ardolino's ongoing work at Harvard University in the Jacobsen lab is focused on the development of silicon- and tin-based catalysts for anion-binding. These catalysts provide an attractive alternative to current urea- and thiourea-based anion-binding catalysts as they engage hard anions such as hydroxide and alkoxides through sigma-hole interactions rather than hydrogen-bonding.

His talk will summarize each of these areas of research, with a focus on the laboratory and computational-based mechanistic studies that have been utilized to probe elements of reactivity and selectivity and guide further development.

Michael Ardolino is a Post-doctoral Research Fellow at Harvard University. He graduated from Bowdoin in 2008.

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Joseph Dinnocenzo: "Revised View of Electron Transfer Dependence on Free Energy"

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April 17, 2015 12:00 PM  – 1:00 PM
Druckenmiller Hall, Room 020

In a landmark publication over forty years ago, Rehm and Weller
used a comprehensive set of data to show that photoinduced
electron transfer (PET) rate constants correlate with excited state energies and ground state redox potentials. The Rehm Weller paper has been cited more than 3000 times and the data contained in it interpreted by a variety of theoretical models. 

In this talk, Joseph Dinnocenzo will show that the widely accepted Rehm Weller equation and plot have serious flaws. He explains that revised measurements obtained in the lab differ significantly from those of Rehm and Weller and are interpreted in terms of a simple Boltzmann type equation that takes into account not only Coulombic stabilization of contact ion radical pairs produced by PET, but also solvation and desolvation processes. In addition, he will speak to finding that the mechanism for the PET reactions studied by Rehm and Weller does not involve simple, one electron transfer, but instead occurs by two partial electron transfers via exciplex intermediates. 

The general implications of the results and a variety of lessons learned will be discussed.

Joseph Dinnocenzo is a professor of chemistry at the University of Rochester in Rochester, New York. He received his Ph.D. from Cornell University in 1983. 



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Chemistry Seminars

April 24, 2015 3:00 PM  – 4:00 PM
Druckenmiller Hall, Room 020

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Chemistry Seminars

May 1, 2015 3:00 PM  – 4:00 PM
Druckenmiller Hall, Room 020

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