Probing solute clustering in supercritical solutions using solvatochromic parameters.
Kamlet and Taft polarity parameters are presented for three supercritical solutions containing solutes of different polarities at two concentrations. It is shown that the polarizability and hydrogen-bond-donating ability change significantly with pressure. In the lower pressure regime, naphthalene and salicylic acid cause a decrease in the polarity parameters compared with the pure fluid, whereas toluic acid causes an increase. These differences can be explained in terms of solute-solute and solute-indicator clustering. It is shown that there is, however, a direct correlation between the change in the hydrogen-bond-donating ability and polarizability for all solutes and all pressures and concentrations, which is thought to result from changes in the amount of solvent required to solvate the solute.
Abbott
Andrew P
AP
Chemistry Department, University of Leicester, Leicester, LE1 7RH, U.K. andrew.abbott@le.ac.uk
Hope
Eric G
EG
Palmer
Donna J
DJ