Research in the Alexanian Group focuses on the general areas of reaction development and chemical synthesis. Our studies are ultimately driven by the discovery of new and useful forms of chemical reactivity. A theme of these studies is an emphasis on catalytic transformations employing easily accessed substrates and common molecular functionality. We also use the wide array of unique architectures found in nature to challenge and inspire ourselves to develop creative solutions to current problems in complex molecule synthesis.
One current area of investigation is the utilization of simple hydroxamic acids to develop general, radical-mediated approaches to the metal-free difunctionalization of alkenes. We are also exploring novel approaches to the catalytic activation of alkyl electrophiles for the development of new carbon-carbon bond-forming processes, and the development of new complexity-generating multi-component cycloadditions for synthesis. Ultimately, we strive to apply these new processes to the efficient syntheses of bioactive natural and un-natural products.
The Gagné Lab is interested in the development of new synthetic methods for complex bond constructions. To mimic sterol biosynthesis, we have developed several "carbophilic" late metal catalysts (Pd, Pt, and Au) for alkene and allene activation, while in other projects we seek new catalysts for glycosidic C-O bond activation. The goal in this latter project is to use polysaccharides as renewable feedstocks for complex molecule synthesis. A third major thrust is in dynamic combinatorial chemistry (DCC), a dynamic templating strategy that selects for new receptors under competitive binding conditions. This strategy is additionally being used for new catalyst discovery.
The Chemistry Department's Commencement Ceremony will be held on Sunday, May 10, 2015, at the Friday Center Atrium and Grumman Auditorium immediately following the University-wide Commencement Ceremony.
A reception will begin at 12:00 pm, followed at 1:15 pm by the Chemistry ceremony, consisting of the formal awarding of degrees and presentation of awards to selected undergraduate students.
Congratulations to Professor Joseph DeSimone, winner of the 2014 Dickson Prize in Science, awarded annually to the person judged by Carnegie Mellon University to have made the most progress in the scientific field in the United States for the year in question. DeSimone was formally presented with the award during a February 16, 2015 ceremony where he delivered his Dickson Prize Lecture titled "Breakthroughs in Imprint Lithography and 3-D Additive Fabrication."
Biotherapeutics, monoclonal antibodies, mAbs, in particular, represent a multi-billion dollar industry that continues to expand. In order to be used as a therapeutic agent the biomolecule must be rigorously characterized in order to ensure safety, efficacy, and potency. However, the size and complexity of mAbs makes this a challenging task. In work published in Analytical Chemistry, researchers in the Ramsey Group describe an integrated microfluidic capillary electrophoresis-electrospray ionization, CE-ESI, device for the separation of intact monoclonal antibody charge variants with online mass spectrometric, MS, identification.
Schematic for CE-ESI devices with a 23 cm separation channel with an enlarged image of the asymmetric turn tapering. Red channels indicate an APS coating while black channels indicate an APS-PEG450 coating. S: sample reservoir; B: background electrolyte reservoir; SW: sample waste reservoir; EO: electroosmotic pump reservoir.
The surface chemistry utilized in the device channels suppressed the electroosmotic flow and prevented analyte adsorption, eliminating the need for complex background electrolyte additives. The microfluidic ESI interface proved vital to the successful ionization and resulting MS analysis by maintaining fluid flow to generate stable ESI. The effectiveness of the technique was demonstrated with the determination of five charge variants in the separation of Infliximab with an additional two mAbs analyzed to show the general applicability of the approach.
Protein quinary interactions organize the cellular interior and its metabolism. Although the interactions stabilizing secondary, tertiary, and quaternary protein structure are well defined, details about the protein–matrix contacts that compose quinary structure remain elusive. This gap exists because proteins function in the crowded cellular environment, but are traditionally studied in simple buffered solutions.
Researchers in the Pielak Group use NMR-detected H/D exchange to quantify quinary interactions between the B1 domain of protein G and the cytosol of Escherichia coli. In their work, published in PNAS, the group demonstrates that a surface mutation in this protein is 10-fold more destabilizing in cells than in buffer, a surprising result that firmly establishes the significance of quinary interactions. Remarkably, the energy involved in these interactions can be as large as the energies that stabilize specific protein complexes. These results will drive the critical task of implementing quinary structure into models for understanding the proteome.
Chemists have long sought new ways to create energy-rich fuels - ideally via reactions powered by a renewable resource such as the sun. But scientists still have a lot to learn about solar-powered reactions, and a new study by Thomas Eisenhart and Jillian Dempsey sheds light on how they occur. The proton-coupled electron transfer reaction, PCET, is a key light-driven step in the conversion of small molecules into energy-rich fuels. Although prior research has provided a basic understanding of PCET reactions between molecules in their ground states, much less is known about the reactions between electronically excited molecules.
In the article, which made the cover of JACS, and was also featured in JACS Spotlights, the team reports results from a mechanistic study of excited-state PCET reactions between two small molecules, acridine orange and tri-tert-butylphenol. The step-by-step process by which the reaction occurs has not been determined previously, but since each of the reaction components has a unique spectroscopic signature, the researchers can monitor each step with transient absorption spectroscopy. The results help explain the intimate coupling of light absorption with both proton and electron transfer, which the authors say will help pave the way for new avenues in solar fuel production.
Christine Herman, Ph.D., JACS
First, Professor Brian Hogan was recognized with a University Diversity Award, then, just a few days later selected as the 2015 recipient of the Carolina Chiron Award. The former recognizes significant contribution to the enhancement, support and/or furtherance of diversity on our campus and in the community.
The recipient of the Carolina Chiron Award is selected by a committee of undergraduate students, representing a wide range of student groups, considering a large pool of nominations, Professor Hogan was selected for his commitment to students both inside and outside the classroom. They believe that he exemplifies what the Chiron Award stands for: excellence in teaching and going above and beyond to help students succeed. Congratulations, Professor Hogan!