A Simple Strategy for Crystal Engineering Water Clusters

We report the X-ray crystal structure of the protonated phenazine-2,3-diamine cation (3) salt (3)2SeO4·6H2O (4), which contains a discrete water decamer. This material is representative of a broad strategy to bring about the occurrence of solid-state water clusters in ionic structures by the combination of amphiphilic ions with large hydrophobic residues in combination with small, highly charged counterions. The strategy is illustrated by a wide range of examples taken from the Cambridge Structural Database (CSD).