Gas solubility and preferential solvation phenomena in mixed-solvents

We probe the solute-induced perturbation of the mixed-solvent environment around simple gaseous solutes, identify the universal molecular-based signature for the underlying preferential solvation phenomenon, characterize the cosolvent effect on gas solubility as a manifestation of their preferential solvation in mixed-solvent environments, derive the explicit macroscopic-to-microscopic rigorous connections between the thermodynamic non-idealities and precisely defined fundamental structure making/breaking functions Y alpha beta. We illustrate the approach by analysing the solvation behavior of a series of non-polar gaseous solutes including noble gases and light hydrocarbons in polar mixed-solvent environments at ambient conditions. We link rigorously the thermodynamic response of a solute to the change of cosolvent environment to either a linear combination of fundamental structure making/breaking functions Y alpha beta or the universal preferential solvation function PY. Finally, we highlight their underlying connections with other thermodynamic preferential interaction parameters, and caution about the potential modeling risks when invoking the Kirkwood-Buff inversion protocol for the interpretation of preferential solvation.