Relationships between structural and thermal properties of anhydrous and solvated crystalline forms of brodimoprim

The isolation and physicochemical characterization of four crystalline modifications of brodimoprim (5-[(4-bromo-3,5-dimethoxyphenyl)methyl]-2,4-pyrimidinediamine,
hereinafter BMP), a structural analog of trimethoprim (TMP), are reported. These phases include an unsolvated form of BMP, a hemihydrate (BMP0.5H2O), a 1:1 solvate containing isopropanol (BMPC3H7OH(iso)), and a hemichloroformate (BMP0.5CHCl3). Unsolvated BMP was isolated both by recrystallization from a range of common solvents as well as by thermal decomposition of the above solvates and no evidence for polymorphism was found. PXRD data indicated that the three solvates crystallize in different arrangements. Data from thermal analysis (thermogravimetry (TGA), hot stage microscopy (HSM), differential scanning calorimetry (DSC)) of the solvates containing water and iso-propanol were interpreted on the basis of their singlecrystal X-ray structures which revealed that the modes of solvent inclusion in BMP0.5H2O and BMPC3H7OH(iso) may be described as ‘isolated site’ and ‘lattice channel’ type inclusions, respectively.