Spectroscopic and physical–chemical characterization of ambazone–glutamate salt

Abstract

Ambazone monohydrate C₈H₁₁N₇S · H₂O (AMB), a well-known antimicrobial compound, was used together with Glutamic Acid C₅H₉NO₄ (Glu) to obtain a new solid form using the solvent-drop grinding procedure. The screening of the new solid form was best achieved by the combined use of X-ray Powder Diffraction (XRPD) and several spectroscopic techniques (Fourier Transformed Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Raman and ¹³C-NMR spectroscopy) together with Differential Scanning Calorimetry (DSC), Differential thermal analysis and thermogravimetry (DTA–TGA). The combination of the mentioned analytical techniques allows the compound to be assigned to an ambazone–glutamate salt which crystallizes in monoclinic system having the following lattice parameters: a=9.8352, b=4.7014, c=40.0987 Å and β=94.505^°. DSC, TGA data and the before mentioned spectroscopic techniques support the ambazone–glutamate salt formation.