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SUMMARY:Water Mediated Hydrophobic and Specific Ion Interactions 
DTSTART:20130522T101500
DTSTAMP:20260510T164815Z
UID:ee3512f75ca65383650a0b40f2684b2f5bf27a703856bff7d7ce2723
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Dor Ben-Amotz\, Purdue University\nBio: B.A.\, 1976\, Be
 nnington College\; M.A.\, 1981\, Brandeis University\; Ph.D.\, 1986\, Univ
 ersity of California\, Berkeley\; Postdoctoral Fellow\, Exxon Corporate Re
 search Laboratory\, 1986-89.\nAll 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\, densitome
 try and sound velocity measurement as well as computer simulation and stat
 istical mechanical modeling. Applications of our experimental and theoreti
 cal discoveries range from disease screening\, chemical imaging\, industri
 al monitoring and plastic recycling\, to global thermodynamic quantitation
  of chemical processes such as protein folding\, drug binding and hydropho
 bic hydration.\nRaman and fluorescence microscopy are combined with near-I
 R lasers\, fiber optics and optical array detector to develop new instrume
 nts for micro-chemical analysis\, proteomic diagnostics and real-time chem
 ical imaging. These make it possible to identify and map chemical substanc
 es in less than 1 second -- fast enough for robotic vision\, multiplexed d
 isease screening\, on-line process monitoring and automated recycling appl
 ications.\nOur 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 yi
 eld optimization. We use laser spectroscopy\, densitometry and sound veloc
 ity 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 mechanica
 l models for the effects of aqueous and non-aqueous solvents on chemical p
 rocesses.\nHydrophobic and specific ion interactions are considered to pla
 y a key role in a wide range of biological processes. Historically\, hydro
 phobic hydration shells we re thought to resemble solid clathrate hydrates
 \, with solutes surrounded by polyhedral cages composed of tetrahedrally h
 ydrogen-bonded water molecules. But more recent experimental and theoretic
 al studies have challenged this view and emphasized the importance of the 
 length scales involved. Specific ion interactions are also a subject of lo
 ngstanding interest and current heated debate\, as experimental and comput
 er simulation studies have yielded conflicting results regarding the affin
 ity 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 spectrosco
 pic features arising from the hydrophobic hydration shells of alcohols and
  tetraalkylammonium cations containing up to twenty methyl/methylene group
 s. Moreover\, by adding salts into the mix we have quantified the degree t
 o which ions such as F- and I-penetrate into molecular hydrophobic hydrati
 on shells\, as well as the influence of methyl group partial charge and ne
 ighboring polar groups.
LOCATION:SV 1717A http://plan.epfl.ch/?reset_session&room=sv1717a
STATUS:CONFIRMED
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