Crystal structure determination of three polycyclic compounds and comparative Rietveld refinement between MS and GSAS programs

Abstract

The crystal structures of normethisterone, gestonoronacetat, and griseofulvin were directly determined from the X-ray powder diffraction (XRPD) using the direct space approach by means of material studio (MS), the Rietveld refinement (RR), based on MS and generalized structural analysis system (GSAS) programs, was examined to practice and expand the Rietveld (whole-profile) technique in the pharmaceutical field. The RR converges to Rwp=8.85%, 10.56%, and 5.92% for normethisterone (6.88%), gestonoronacetat (9.58%), and griseofulvin (5.24%), respectively. The crystallographic data obtained from the powder diffraction data were compared with the single-crystal X-ray diffraction (SXRD) data. The results showed that the maximum relative errors of lengths a, b, and c and volume were respectively 0.18%, 0.18%, 0.22%, and 0.39% between SXRD and XRPD. Thus, MS and GSAS programs were useful to powder diffractionists in determining the crystal structure of organic polycyclic molecules.