Chemistry

Abstracts

Dr. Jon Amster, UGA: Fourier Transform Mass Spectrometry and It's Bioanalytical Applications

Mass spectrometry currently plays a significant role in biological analysis due to its high sensitivity (fmol or lower detection limits), speed of analysis, applicability to high molecular weight molecules, as well as its capability to interface directly to separation methods such as liquid chromatography or capillary electrophoresis. Proteins, carbohydrates, nucleic acids, and complex lipids are routinely analyzed by mass spectrometry. Among the many types of mass spectrometers that are used for biological analysis, Fourier transform mass spectrometry stands out because of its extraordinarily high mass resolution, high accuracy, and capability for structure analysis by tandem mass spectrometry. This seminar will introduce the audience to the basic principles of Fourier transform mass spectrometry and will illustrate its powerful capabilities by showing applications to protein and carbohydrate analysis from the speaker's laboratory

Dr. Brent Gunnoe, UVA: Development of Homogeneous Catalysts for the Conversion of C-H Bonds

Greater than 90% of materials produced by the chemistry industry are derived from a handful of basic hydrocarbon building blocks. Typically, synthetic methods for the conversion of these compounds into higher value functionalized materials are capital and energy intensive. With rising demand for fossil resources, the development of new catalyst technologies for the selective and efficient functionalization of simple hydrocarbons is of increasing importance. The presentation will focus on fundamental studies of metal-mediated activation of C-H bonds including incorporation into catalytic cycles and opportunities for enhanced selectivity of large-scale commodity chemical processes.

Dr. Liguo Song, UTK: Liquid chromatography atmospheric pressure photoionization mass spectrometry: trace level analysis of organic explosives

It is well known that gas chromatography mass spectrometry (GC/MS) favors the analysis of volatile and thermally stable compounds. On the other hand, liquid chromatography electrospray ionization mass spectrometry (LC/ESI-MS) and liquid chromatography atmospheric chemical ionization mass spectrometry (LC/APCI-MS) favor the analysis of compounds with solution acid-base chemistry. Therefore, it is challenging to analyze thermally labile neutral compounds, e.g. organic explosives. Recently, liquid chromatography atmospheric pressure photoionization (LC/APPI-MS) has been demonstrated to be able to ionize both polar and non-polar compounds. Our contribution in this research field is to use LC/ negative ion-APPI-MS (LC/NI-APPI-MS) for the analysis of neutral compounds. By using organic explosives as an example, we have demonstrated that LC/NI-APPI-MS can be one order or two orders magnitude more sensitive than GC/NICI-MS and LC/NI-APCI-MS, respectively. We anticipate that LC/NI-APPI-MS is also going to provide superb sensitivity in the analysis of other neutral compounds such as fullerenes, halogenated compounds, nitrated compounds, and their corresponding derivatives of other compounds.

Dr. Ted Burkey, Memphis: Development of Photochromic Organometallic Compounds

Photochromic compounds reversibly change color when irradiated with light. These compounds have applications in smart devices like transition eye glasses and data storage. Potential applications include optical switches, optically-driven nanogates and nanopumps, and optical computing. In the last eight years we have been developing a strategy to make organometallic compounds that have high quantum yields for a photochromic response and respond on sub-picosecond timescales. The chemical and physical processes that must be controlled to achieve these goals will be discussed. Studies of compounds that model these processes and new photochromic organometallics base on these results will be presented.

Dr. Emanuel Waddell, UA-Huntsville:Modification of Polymer Substrates by Excimer Radiation

Surface modification of polymer substrates is typically achieved by "wet- chemical" treatments that involve a number of time-consuming steps.  Previously we investigated the ability to pattern polymer substrates via laser ablation under different chemical atmospheres.  In this one-step process, polymers were micro-machined while simultaneously chemically modifying the surface.  As an extension of this research, we have exposed various polymer substrates to narrow band excimer radiation under inert atmospheres and the resultant surface is characterized by attenuated total reflectance infrared spectroscopy, contact angle goniometry, atomic force microscopy, and scanning electron microscopy.  Finally, some of the polymer substrates as characterized by electroosmotic flow.  In this presentation, the modification of polydimethylsiloxane and polymethylmethacrylate will be discussed.  The modification of polydimethylsiloxane (PDMS) by narrow band 254 nm excimer radiation under a nitrogen atmosphere is  characterized and it is determined that the UV irradiation results in the formation of the carboxylic acids that influences the wettability of the surface.  Continued exposure results in the formation of an inorganic surface (SiOx, (1 < x < 2)) which hinders the ability to continually increase the wettability.  These results have implications in the fabrication and chemical modification of microfluidic or micro-electro-mechanical systems.  The application in microfluidics is observed with the modification of PMMA by 222 nm excimer radiation that results in the formation of hydroxyl groups which in turn contribute to increased electroosmotic flow.