The effects of interactions between ions, proteins and water have been debated for over 120 years, since Franz Hofmeister first ordered ions by their tendency to precipitate hen egg albumin in aqueous solutions.  The ordering of this �Hofmeister series� has been observed for other chemical properties as well.  Results from infrared photodissociation spectroscopy of ion-containing aqueous nanodrops that are trapped, mass selected, and temperature controlled in the ion cell of a Fourier-transform ion cyclotron resonance mass spectrometer show that some ions can significantly affect the hydrogen bonding network of fully hydrogen bonded water molecules well past the second and even third solvation shells.  These results indicate the long-range effects that some ions induce on the hydrogen bonding network of water molecules plays an important role in the Hofmeister phenomena.  Ion-specific effects on the orientation of water molecules and how these data at larger cluster size can provide insights into the surface of bulk water will be presented.  Electrochemical reduction of ions in nanodrops results in significant droplet heating and sequential water molecule loss.  From these nanocalorimetry experiments, the absolute reduction enthalpy of a single ion can be obtained and used to establish an absolute electrochemical red-ox scale.  Use of these nanocalorimetry experiments to �weigh� florescent photons emitted upon UV excitation of ions in nanodrops, and effects of water and counter-ions on ion fluorescence will be presented.

Investigating ion solvation and patterning of the hydrogen-bonding water networks at long distance in aqueous nanodrops

246th National Meeting (2013)

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