IR and Raman spectral and X-ray structural studies of polymorphic forms of sulfamethoxazole

The crystal structure of the polymorphic form III (hemihydrate) of sulfamethoxazole (SMZ) was determined to exist in both the E- and Z-forms by X-ray analysis and was compared with the polymorphic forms I and II which an known to exist in the E-form. IR spectra of I-III and their. corresponding forms I-D-IIID which contain the deuterated amino and amido groups and D2O and Raman spectra of I-III have been measured. For I-III, assignment of the stretching vibration [nu (NH) and nu (CH)] bands of amino and amido groups and the C-H bond of the: isoxazole ring involved in the inter-molecular hydrogen bonds has been proposed based on consideration of the IR and Raman spectra and the results of X-ray analysis. A relationship was established between the relative intensity and wavenumbers for the nu (CH) band in the inter-molecular C(sp(2))-H . . .X hydrogen bond of the E-form. (C) 2001 Elsevier Science B.V. All rights reserved.