(E)-3,4,5-Trimeth­oxy-N′-[(4-oxo-4H-chromen-3-yl)methyl­idene]benzo­hydrazide

In the title chromone-tethered benzohydrazide derivative, C₂₀H₁₈N₂O₆, the atoms of the E-3-(hydrazonometh­yl)-4H-chromen-4-one segment are essentially coplanar, the largest deviation being 0.065 (6) Å. The dihedral angle between this segment and the benzene ring of the tri­meth­oxy­benzene unit is 40.18 (10) Å. In the crystal, the mol­ecule is linked to its inverse-symmetry equivalent by pairs of N—H...O hydrogen bonds and C—H...π inter­actions. The –CH=N—NH– segment is stacked on the benzene ring of the chromone unit of a translation-related equivalent mol­ecule [centroid–centroid distance = 3.413 (6) Å].

(E)-4-Methyl-N′-[(4-oxo-4H-chromen-3-yl)methyl­idene]benzohydrazide

In the title chromone-tethered benzohydrazide derivative, C₁₈H₁₄N₂O₃, the 4H-chromen-4-one and the –CH=N–NH–CO– units are each essentially planar, with the largest deviations from thei planes being 0.052 (2) and 0.003 (2) Å, respectively. The dihedral angles between the 4H-chromen-4-one and the –CH=N–NH–CO– units, the 4H-chromen-4-one unit and the benzene ring of the 4-tolyl group, and the benzene ring of the 4-tolyl group and the –CH=N–NH–CO– unit are 8.09 (7), 9.94 (5) and 17.97 (8)°, respectively. In the crystal, the mol­ecules form two types of centrosymmetric dimers: one by N—H...O hydrogen bonds and the other by π–π stacking inter­actions between the 4H-chromen-4-one unit and the 4-tolyl group [centroid–centroid distance = 3.641 (5) Å]. These dimers form one-dimensional assemblies extending along the a-axis direction. Additional π–π stacking inter­actions between two 4H-chromen-4-one units [centroid–centroid distance = 3.591 (5) Å] and two 4-tolyl groups [centroid–centroid distance = 3.792 (5) Å] organize the mol­ecules into a three-dimensional network.

(E)-4-Meth­oxy-N′-[(6-methyl-4-oxo-4H-chromen-3-yl)methyl­idene]benzo­hydrazide monohydrate

In the title hydrate, C₁₉H₁₆N₂O₄·H₂O, the 4H-chromen-4-one segment is slightly twisted, with a dihedral angle between the two six-membered rings of 3.30 (5)°. The dihedral angles between the plane of the pyran­one ring and the hydrazide plane and between the planes of the pyran­one ring and the benzene ring of the p-meth­oxy­benzene unit are 26.69 (4) and 2.23 (3)°, respectively. The mol­ecule is connected to the solvent water mol­ecule by an N—H...O hydrogen bond. In the crystal, there are π–π stacking inter­actions between centrosymmetrically related pyran­one rings [centroid–centroid distance = 3.5394 (9) Å], as well as bridges formed by the water mol­ecules via O—H...O hydrogen bonds.

(E)-3,4,5-Trimeth­oxy-N′-[(6-meth­oxy-4-oxo-4H-chromen-3-yl)methyl­idene]benzohydrazide monohydrate

In the title chromone-tethered benzohydrazide derivative, C₂₁H₂₀N₂O₇·H₂O, the atoms of the 4H-chromen-4-one segment are essentially coplanar (r.m.s. deviation = 0.0073 Å) with the largest deviation from the mean plane [0.012 (3) Å] being found for the benzene C atom. The dihedral angles between the chromone segment and the hydrazide plane and between the chromone segment and the benzene ring of the tri­meth­oxy­benzene unit are 24.67 (9) and 41.28 (8) Å, respectively. The mol­ecule is connected to the solvent water mol­ecule by O—H...O hydrogen bonds and weak C—H...O inter­actions. Additional N—H...O inter­actions are observed and together they link the mol­ecules into chains forming a two-dimensional network along (011).