Crystal structures of three newly synthesized flavanone hydrazones

Abstract

The crystal structures of racemic mixtures of three new flavanone-hydrazones in the centrosymmetric space group (P ), are reported. The structures of (±,E)-N'-[5,7-dihy-droxy-2-(4-hy-droxy-phen-yl)chroman-4-yl-idene]-2-(naphthalen-1-yl)acetohydrazide ethyl acetate monosolvate, C₂₇H₂₂N₂O₅·C₄H₈O₂, and of (±,E)-N'-[5,7-dihy-droxy-2-(4-hy-droxy-phen-yl)chroman-4-yl-idene]-4-hy-droxy-benzo-hydra-zide ethanol monosolvate, C₂₂H₁₈N₂O₆·C₂H₅OH, both exhibit an intra-molecular O-H⋯N and multiple inter-molecular O-H⋯O and C-H⋯O-type hydro-gen bonds. The third structure, that of (±,E)-N'-(6-methoxy-2-phenyl-chroman-4-yl-idene)-2-(naphthalen-1-yl-oxy)acetohydrazide, C₂₈H₂₄N₂O₄, has only one inter-molecular N-H⋯O-type hydrogen bond. In each of the three cases, the crystal packings are stabilized by π-π stacking inter-actions between various aromatic components of symmetry-related mol-ecules. The chiral carbon atom of the substituted chromane ring system in each case is puckered away from rest of the ring system.

Keywords: crystal structure; flavanone; flavonoid; hydrazone; naringenin.