Laser Raman investigation of pharmaceutical solids: griseofulvin and its solvates

Laser Raman spectroscopy is convenient for characterizing griseofulvin solvates and investigating solute-solvent interactions and desolvation. The spectra of both lattice and intramolecular vibrations were monitored. A new solvate of griseofulvin wih bromoform was characterized by Raman spectroscopy. A temperature-dependence study of the solvates of griseofulvin with chloroform, and benzene revealed no phase transformation or chemical change. In the benzene solvate, only weak Van der Waals interactions existed between the solute and solvent. However, in solvates with chloroform and bromoform, a weak hydrogen binding existed between the proton of the solvent and the C = O group of the benzofuran ring in griseofulvin. Examination of desolvation in these solvates revealed that the crystal did not go through any intermediate structure during desolvation. As the solvent molecule escaped, the lattice reverted to the structure of unsolvated griseofulvin.