Water Mediated Hydrophobic and Specific Ion Interactions
Event details
| Date | 22.05.2013 |
| Hour | 10:15 |
| Speaker |
Prof. Dor Ben-Amotz, Purdue University Bio: B.A., 1976, Bennington College; M.A., 1981, Brandeis University; Ph.D., 1986, University of California, Berkeley; Postdoctoral Fellow, Exxon Corporate Research Laboratory, 1986-89. All of our research involves the development of new tools for use in the solution of practical chemical problems. The techniques we employ include Raman spectroscopy, fluorescence, densitometry and sound velocity measurement as well as computer simulation and statistical mechanical modeling. Applications of our experimental and theoretical discoveries range from disease screening, chemical imaging, industrial monitoring and plastic recycling, to global thermodynamic quantitation of chemical processes such as protein folding, drug binding and hydrophobic hydration. Raman and fluorescence microscopy are combined with near-IR lasers, fiber optics and optical array detector to develop new instruments for micro-chemical analysis, proteomic diagnostics and real-time chemical imaging. These make it possible to identify and map chemical substances in less than 1 second -- fast enough for robotic vision, multiplexed disease screening, on-line process monitoring and automated recycling applications. Our experimental and theoretical modeling efforts are aimed at better understanding liquid and supercritical fluid chemical processes of relevance to drug design and delivery, polymer processing and reaction yield optimization. We use laser spectroscopy, densitometry and sound velocity to measure changes in molecular vibration, rotation, isomerization, dissociation and solvation-shell structure as a function of pressure and temperature. The results are compared with classical and quantum mechanical models for the effects of aqueous and non-aqueous solvents on chemical processes. |
| Location | |
| Category | Conferences - Seminars |
Hydrophobic and specific ion interactions are considered to play a key role in a wide range of biological processes. Historically, hydrophobic hydration shells we re thought to resemble solid clathrate hydrates, with solutes surrounded by polyhedral cages composed of tetrahedrally hydrogen-bonded water molecules. But more recent experimental and theoretical studies have challenged this view and emphasized the importance of the length scales involved. Specific ion interactions are also a subject of longstanding interest and current heated debate, as experimental and computer simulation studies have yielded conflicting results regarding the affinity of various ions for hydrophobic interfaces and hydration shells. Here we report combined polarized, isotopic, temperature, and concentration-dependent Raman scattering measurements that reveal vibrational spectroscopic features arising from the hydrophobic hydration shells of alcohols and tetraalkylammonium cations containing up to twenty methyl/methylene groups. Moreover, by adding salts into the mix we have quantified the degree to which ions such as F- and I-penetrate into molecular hydrophobic hydration shells, as well as the influence of methyl group partial charge and neighboring polar groups.
Links
Practical information
- Informed public
- Free
- This event is internal
Organizer
- Prof. Sylvie Roke
Contact
- Institute of Bioengineering (IBI, Dietrich Reinhard)