Effect of the Zn²⁺ and Hg²⁺ Ions on the Structure of Liquid Water

The effect of ions on the structure of liquid water is still not completely understood, despite extensive experimental and theoretical studies. A combined XANES and molecular dynamics investigation on diluted Zn²⁺ and Hg²⁺ aqueous solutions reveals that the influence of a single ion on the bonding pattern of water molecules is strongly dependent on the nature of the ion. While the structure of water is not altered by the presence of the Zn²⁺ ion, the Hg²⁺ cation has a strong impact on the hydrogen-bond network of water that extends beyond the first coordination shell.