Journal of the American Chemical Society, Vol.138, No.1, 96-99, 2016
Delayed Onset of Crystallinity in Ion-Containing Aqueous Nanodrops
Water exhibits remarkable properties in confined spaces, such as nanometer-sized droplets where hundreds of water molecules are required for crystalline structure to form at low temperature due to surface effects. Here, we investigate how a single ion affects the crystallization of (H2O)(n) clusters with infrared photo-dissociation spectroscopy of size-selected La3+(H2O)(n) nanodrops containing up to 550 water molecules. Crystallization in the ion-containing nanodrops occurs at n >= 375, which is approximately 100 more water molecules than what has been reported for neutral water clusters. This frustration of crystallinity reveals that La3+ disrupts the hydrogen-bonding network of water molecules located remotely from the ion, a conclusion that is supported by molecular dynamics simulations. Our findings establish that a trivalent ion can pattern the H-bond network of water molecules beyond the third solvation shell, or to a distance of similar to 1 nm from the ion.