The effect of water molecules in stabilizing co-crystals of active pharmaceutical ingredientsElectronic supplementary information (ESI) available: Experimental procedure for the synthesis of 2 and 4. CCDC reference numbers 853500853511. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2ce06506a

A series of co-crystallization reactions were carried out on two hydrazone compounds in order to determine their effectiveness in forming co-crystals in a consistent manner, as well as to establish whether their thermal behaviour can be tailored in a predictable fashion. The crystal structures of twelve hydrated co-crystals with both aromatic as well as aliphatic carboxylic acids are reported. In the structures that display structural consistency, the thermal behaviour of the bulk materials can be correlated with molecular structure. All twelve co-crystals of two different pharmaceutical compounds display hydrated crystal structures.