Toward Understanding the Hofmeister Series. 3. Effects of Sodium Halides on the Molecular Organization of H₂O As Probed by 1-Propanol

Abstract

We investigated the effects of NaF, NaCl, NaBr, and NaI on the molecular organization of H2O by a calorimetric methodology developed by us earlier. We use the third derivative quantities of G pertaining to 1-propanol (1P) in ternary 1P-a salt-H2O as a probe to elucidate the effects of a salt on H2O. We found that NaF and NaCl worked as hydration centers. The hydration numbers were 19 +/- 2 for NaF and 7.5 +/- 0.6 for NaCl. Furthermore, the bulk H2O away from the hydration shell was found unaffected by the presence of Na+, F-, and Cl-. For NaBr and NaI, in addition to the hydration to Na+, Br- and I- acted like a hydrophilic moiety such as urea. Namely, they formed a hydrogen bond to the existing H2O network and retarded the fluctuation nature of H2O. These findings were discussed with respect to the Hofmeister ranking. We suggested that more chaotropic anions Br- and I- are characterized as hydrophiles, whereas kosmotropes, F- and Cl-, are hydration centers.

Dynamic Equilibria in Solvent‐Mediated Anion, Cation and Ligand Exchange in Transition‐Metal Coordination Polymers: Solid‐State Transfer or Recrystallisation?

“…A further aspect to consider is the issue of solvation of free anions in solution. The Hofmeister series or bias confirms [53,54] the low relative hydration of ClO 4 À compared to other anions in this study and is consistent therefore with the lack of exchange observed for [Ag(4,4'-bipy)ClO 4 ] 1 in water.…”

Towards an Understanding of the Mutual Solubilities of Water and Hydrophobic Ionic Liquids in the Presence of Salts: The Anion Effect

“…Recent works concerning the effect of salts on the aqueous solubility of complex molecules 37,[43][44][45][46] are suggesting that watermediated interactions between hydrophobic solutes and salt ions are closely related to the extent of hydration of individual ions.…”

Counterion and composition effects on discotic nematic lyotropic liquid crystals

“…These authors concluded that ions with higher polarizability and ionic radii reside near the surface of water clusters, whereas smaller size and polarizability ions remained fully solvated at the interior of the cluster. The effects of halide ions on the structure of water have been also studied experimentally [27]. It was found that chloride presents a cosmotropic effect on the structure of water, whereas bromide shows a chaotropic behavior.…”