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I organized a COLL division symposium entitled “The Influence of Ions and Osmolytes on Aqueous Macromolecules” for the spring 2009 ACS meeting help in Salt Lake City Utah. The symposium consisted have three half day sessions in which professors as well as graduate students and postdocs were speakers. The lectures probed the chemistry which occurs when oil, water, and salts are mixed in solution. It is well known that the physical behavior of these systems follows a recurring trend known as the Hofmeister series. This series was first found 120 years ago, but it is only within the last five years that the molecular-level basis for it is starting to be understood. As such, there was much excitement surrounding this symposium and the attendance was outstanding. Indeed, many talks had over 50 people in the audience, a few had over 70, and the high point was nearly 90.

Many of the participants in this field are Americans and many we were fortunate to get most of the biggest players from North America to show up and describer their work. However, a very significant portion of this research is conducted in Europe. In particular, the preeminent theoretical European chemist in this field is Prof. Pavel Jungwirth at the Academy of Sciences of the Czech Republic. We wrote for and received a grant from the PRF for $1500 to help offset his travel costs to this meeting. He gave a talk entitled “Ions at aqueous interfaces: From water surface to hydrated proteins.” This talk was particularly well attended and well received. He elucidated the theory of how various cations and anions in solution can interact with hydrophobic and hydrophilic portions of macromolecules. Moreover, he noted the potential use of this theory for understanding everything from crude oil extraction to protein folding.

Prof. Jungwirth’s talk was a perfect foundation for additional talks at this symposium which covered the oil/water, protein/water, and air/water interfaces. One of the largest reasons for the success of this symposium was the fact that it was almost evenly divided between theoreticians and experimentalists, whose talks complemented each other extremely well.

The greatest conclusion from this symposium is that the effects of ions in solution are local rather than effects on bulk water. It was believed throughout the entire 20^th century that Hofmeister ion effects were general because the influence on the physical properties of macromolecules and colloids was indirect and involved changes in the molecular bonding between water molecules. The theoretical and experimental work shown at this symposium, however, was consistent with a picture in which the ions influenced macromolecules by direct interactions as well as interactions with their first hydration shell.

The symposium was also crucial for pointing the way into the future of this field. It was made clear by many of the participants, including Prof. Jungwirth, that we need a better understanding of the chemistry of cation interactions with acetate and the role that electrostatic screening plays in hydrophobic collapse. Finally, this field is expanding into the field of osmolytes to address questions such as how urea denatures proteins or how TMAO stabilizes them. In fact, it was shown that this may be the ultimate frontier of this field, because unlike ions, osmolytes may truly work by altering water structure.