Voronoi polyhedra probing of hydrated OH radical

Abstract

We present 3D-characterization of the solvated ˙OH radical in water at 37 °C using the Voronoi polyhedron technique. Assuming that the ˙OH solvation cage is represented by the minimal-volume polyhedron we have calculated statistical distributions of the metric and topological properties of the solvation cage. The statistical means 10.1, 3.26 Å, 27.2 Å3, and 1.50, have been obtained for the solvation number, the face-weighted cage-radius, the free volume of ˙OH_aq, and the asphericity factor, respectively. The mean value of the face-weighted radius coincides with the maximum of the radical-water radial distribution function. Similar properties of the polyhedra constructed for the hydrogen bonded radical and for the unbound one confirm the mechanistic view of the localization of ˙OH in cavities in the hydrogen-bond network. The distribution of the asphericity factor reveals the existence of ice-like regions. A short review of the graphical software used for 3D-visualization includes MS Excel, Maple, and POV-Ray programs. A practical user guide is provided in the ESI.