Crystallographic Study of Solvates and Solvate Hydrates of an Antibacterial Furazidin

In this study we present a detailed crystallographic analysis of multiple solvates of an antibacterial furazidin. Solvate formation of furazidin was investigated by crystallizing it from pure solvents and solvent-water mixtures. Crystal structure analysis of the obtained solvates and computational calculations were used to identify the main factors leading to the intermolecular interactions present in the solvate crystal structures and resulting in formation of the observed solvates and solvate hydrates. Furazidin forms pure solvates and solvate hydrates with solvents having large hydrogen bond acceptor propensity and with a hydrogen bond donor and acceptor formic acid. In solvate hydrates the incorporation of water allows formation of additional hydrogen bonds and results in more efficient hydrogen bond network in which water is “hooking” the organic solvent molecule, and this slightly reduces the cut-off of solvent hydrogen bond acceptor propensity required for obtaining a solvate. The crystal structures of all pure solvates are formed from molecule layers and in almost all structures solvent is hydrogen bonded to the furazidin, but the packing in each solvate is unique. In contrast, the hydrogen bonding and packing in most solvate hydrates are nearly identical.