Role of Nonbonding Interactions in the Crystal Growth of Phenazinediamine Tetrahydrate: New Insights into the Occurrence of 2D Water Layers in Crystal Hydrates

Long fibers of 2,3-phenazinediamine tetrahydrate, 1, were grown from aqueous ammoniacal solution containing
o-phenylenediamine and catalytic amounts of ammonium molybdate under ambient conditions. Single-crystal analysis of 1 revealed
the presence of 2D water layers made of hexameric clusters that are exclusively in the chair conformation similar to that found in
hexagonal ice (Ih) on the {0001}; organic molecules were stacked as columns in between water layers dictated through strong
supramolecular interactions. We hereby propose an intuitive mechanism to show how nonbonding interactions lead to the crystallization
of 1 and other solids exhibiting 2D water sheets. Ab initio calculations at the density functional level for 1 further confirm the origin
of their stability.