How much weaker are the effects of cations than those of anions? The effects of K+ and Cs+ on the molecular organization of liquid H2O.

We characterized the effects of K(+) and Cs(+) ions on the molecular organization of H2O by the 1-propanol probing methodology, previously developed by us (Phys. Chem. Chem. Phys. 2013, 15, 14548). The results indicated that both ions belong to the class of "hydration center", which is hydrated by 4.6 ± 0.8 and 1.1 ± 0.5 H2O molecules, respectively, and leave the bulk H2O away from hydration shells unperturbed. Together with our previous results for the total of 7 cations and 11 anions, we display resulting characterization on a 2-D map and show a quantitative difference in their strength of the effects on H2O between anions and cations.