News and Events - Chemistry

 

NOTE: Prior to Fall 2016 seminars below refreshments
 will be served from 3 pm in 39/1003
 

 

October 21, 2016 
3.30 - 4.30 pm
Bldg 39/1003
Seminar:"Electrochemical Oxidation of Americium for Nuclear Fuel Cycle Applications"Dr. Christopher Dale (FIU)
In an effort to continue using of nuclear energy as a large scale energy source, it is imperative that a complete nuclear fuel cycle be devised. This includes recycling useable fuel, and, minimizing the volume of waste generated. The relatively small fraction of americium formed during nuclear energy generation is not currently removed during the initial fuel reprocessing steps where uranium and plutonium are recovered. Allowing it to remain in the waste stream dramatically increases the volume of waste, and the size of the repository needed as it constitutes the majority of the heat generated from the high level waste. Therefore, the separation of americium from the other minor actinides, and the lanthanides in high level waste is imperative as it will dramatically improve storage efficiency.

The selective separation of americium is difficult due to its similarity in size and charge (+3) to the other minor actinide and lanthanides. While a great deal of research continues to be performed to develop ligands which will selectively coordinate to trivalent americium, there are trade-offs in selectivity and stability. An alternative approach to its separation is to oxidize it from the common trivalent oxidation state to the hexavalent state which exists as a dioxo cation in acid solutions [AmO2]+. This requires very strong oxidizers to achieve chemically.

I will present here the successful electrochemical oxidation of Am(III) to Am(VI) in nitric acid using a derivatized metal oxide electrode. Along with these electrochemical results, I will highlight our current work with its selective removal, and plans for future work where many research opportunities exist
October 7, 2016 
3.30 - 4.30 pm 
Bldg 39/1003
Seminar: "Transition metal catalysis with triazole-based metal complexes" Dr. Xiadong Shi (USF)

Homogeneous gold catalysis has been developed explosively during the past decades. Despite the remarkable electrophilic activation of alkynes by cationic Au(I) catalysts, such as PPh3Au+, one challenge is to overcome their poor stability at high temperature. However, in order to activate some less reactive substrates, such as internal alkynes, harsher reaction conditions are usually required.

 

As a good σ-donor and π-receptor, triazole has been applied as a ligand to improve the stability of cationic Au(I) catalysts. Taking advantage of the good stability of triazole-Au(I) complexes (TA-Au), we successfully achieved good reactivity of intermolecular hydroamination for both terminal and internal alkynes. Unlike previous reported gold catalysts, the TA-Au catalysts activate alkynes selectively over allenes. With this excellent chemoselectivity, TA-Au catalysts showed interesting reactivity in propargyl ester and vinyl ether rearrangement. This facilitates the development of otherwise challenging transformations, for instance, asymmetric synthesis of substituted allenes, Schmittel cyclization, dienal synthesis, and so on.

 

Gold-catalyzed intermolecular propargyl alcohol addition to alkyne was also achieved using TA-Au catalyst, giving the vinyl ether followed by a 3,3-rearrangement to generate synthetically useful allenes with high efficiency, substrate tolerability, chemoselectivity and chirality transfer. Other gold catalysts gave the hydration product almost exclusively. While gold-catalyzed homopropargyl alcohol intramolecular cyclization is a known process, an intermolecular addition to terminal alkynes was achieved with TA-Au catalyst. A sequential 1,6-enyne cycloisomerization gave an unusual 2,3-dihydrooxepine, which revealed a new reaction pathway. Diels−Alder reaction of oxepine followed by a 1,3-alkoxyl shift gave hydrobenzofuran derivatives in high yields. Diastereoselective reaction of homopropargyl alcohol to final product enabled a one-step formation of five stereogenic centers with excellent enantiomeric selectivity.

September 23, 2016 
3.30 - 4.30 pm 
Bldg 39/1003
Seminar: "Photon Upconversion Dye-Sensitized Solar Cells via Self-Assembled Bilayers on Nanocrystalline Metal Oxides" Dr. Kenneth Hanson (FSU)
September 16, 2016 
(Rescheduled) 
Seminar: "Enhanced Lithography Through Chemistry" Dr. Thomas "TJ" Mullen, UNF Department of Chemistry

Complex surface structures with molecular-scale organization and chemical functionalities have garnered tremendous attention in recent years for applications including biochemical sensors and lithographic resists.  Multicomponent alkanethiol-based chemical films assembled onto noble metal surfaces are commonly utilized due to their rich and well-characterized structures and chemistries. However, the patterning of these films is generally limited to two-dimensional features due to the reliance on the assembly of monomolecular films and the limited library of molecules available for patterning. The enhancement of two scanning probe lithographic strategies (nanoshaving and nanografting) by exploiting molecular assembly, topology, and intermolecular interactions will be described and discussed. The combination of scanning probe lithography and molecular assembly illustrates a general hybrid approach to enhance and to extend the precision, capabilities, and versatility of lithographic strategies.

September 9, 2016 
3.30 - 4.30 pm 
Bldg 39/1003
Seminar: "Developing Novel Tools and Methodologies for Studying Guanidinium Modifying Enzymes" Dr. Bryan Knuckley, UNF Department of Chemistry

The guanidinium modifying enzymes are a large class of enzymes that have been identified to play a significant role in a number of diseases, such as atherosclerosis, cancer, and multiple sclerosis. The guanidinium modifying enzyme family includes the protein arginine methyltransferases (PRMTs) and the agmatine deiminases (AgDs), which have only recently become more attractive as drug targets. However, the development of novel pharmaceuticals has been hindered by the lack of tools and methodologies that are currently available to study these enzymes. To this end, we have successfully developed a novel screening methodology for evaluating the substrate specificity of the PRMT family of enzymes. This screen has resulted in the identification of PRMT-specific substrates, development of a new inhibitor, and a chemical probe to further study this enzyme family. Furthermore, we have elucidated the catalytic mechanism of an agmatine deiminase found in Listeria monocytogenes, which is a major contributing factor to Listeriosis infection. Listeriosis is an infection that can lead to miscarriages in pregnant women, meningitis in newborns, and death in immunocompromised individuals caused by consuming food contaminated with the bacteria, Listeria monocytogenes. Also, these mechanistic studies have provided valuable information to designing chemical probes that target this family of enzymes.

July 1, 2016

Dr. Christos Lampropoulos has won an NSF-MRI grant as co-PI with Dr. Tom Pekarek (Physics). This is for an AC magnetic susceptibility measurement system for the SQUID magnetometer, and it is from the Division for Materials Research.

June 1, 2016 Dr. Stuart Chalk received a grant ($50K) from Springer Materials to extract chemical property data from PDF files that are volumes of the Landolt-Börnstein database.
April 5, 2016 Dr. Bryan Knuckley and Dr. Thomas "TJ" Mullen both received outstanding teaching awards for 2016
April 1, 2016 Dr's Lane, Causey, and Lampropoulos all receive tenure and promotion to Associate Professor