Crystal structures of alkaloid peganine and its cocrystal with peganol

Abstract

X-ray diffraction (XRD) is used to investigate the crystal structures of the alkaloid peganine, its hemihydrate and nitrate. It is shown that (±)-peganine forms a cocrystal with the alkaloid peganol. It is typical of the alkaloid (−)-peganine crystal structures to form a closed dimer pair because of reciprocal O-H⋯N1 hydrogen bonds. Analogous H-bonds are also observed in the (±)-peganine-(±)-peganol cocrystal, where the center of symmetry binds together similar molecules to form associates. In (±)-peganine nitrate crystals, the NH+ and OH groups of the alkaloid form H-bonds simultaneously with two oxygen atoms of nitric acid anions.