Crystal structures of three newly synthesized flavanone hydrazones.

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.

Crystal structure of racemic (R/S,E)-2-(4-hy-droxy-phen-yl)-4-(2-phenyl-hydrazin-1-yl-idene)chromane-5,7-diol ethanol monosolvate.

The crystal structure of racemic (R/S,E)-2-(4-hy-droxy-phen-yl)-4-(2-phenyl-hydrazin-1-yl-idene)chromane-5,7-diol ethanol monosolvate, C21H18N2O4·C2H6O, in a centrosymmetric lattice is reported. The two racemates occupy the same position in the asymmetric unit - a disordered mixed enanti-omeric structure. Hydrogen bonds of the type O-H⋯C(π) in addition to typical C-H⋯O, O-H⋯O and O-H⋯N are identified. A positional disorder is seen in the solvent mol-ecule (ethanol) as well. The phenyl-hydrazone group is nearly coplanar with the chromane ring system [dihedral angle = 15.5 (1)°], while the the 4-hy-droxy-phenyl ring is perpendicular [dihedral angle = 87.2 (1)°] to the chromane. The pyran ring has an envelope pucker [Q = 0.363 (3) Å, θ = 57.6 (3)°; and for the enanti-omer: Q = 0.364 (3) Å, θ = 127.4 (4)°].